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  • Enhancement of Service Life and Electrical Insulation Properties of Polymeric Cables With the Optimum Content of Aromatic Voltage Stabilizer
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-17
    Xiangrong Chen; Ashish Paramane; Haiyan Liu; Jiang Tie; Zuojun Wei; Yasuhiro Tanaka

    This article presents the possibility of extending the service life of XLPE insulation based on high voltage cables by blending the optimum concentration of the aromatic voltage stabilizer. The insulation performance of XLPE is analyzed by adding the 0.5, 1, and 3 wt% of 3‐aminobenzoic acid voltage stabilizer. The investigated insulation properties include the DC step‐by‐step breakdown to estimate the life exponent, space charge, DC conductivity, surface potential decay, dielectric loss, and dielectric constant measurements. The results illustrate that the 1 wt% voltage stabilizer addition increases the life exponent from 10 up to 15, which is highly suitable for the high voltage cables. Moreover, it exhibits the negligible space charge accumulation and the least electrical field distortion inside the insulation bulk. It also exhibits the lower DC conductivity by one order of magnitude comparing to the pure XLPE. The highest bandgap value of 1 wt% addition further supports its better insulating properties. Furthermore, the dielectric measurements show that the XLPE with 1 wt% voltage stabilizer exhibits the least dielectric constant and dielectric loss. The differential scanning calorimetry and thermogravimetric analysis results show that the thermal properties are significantly improved after the voltage stabilizer addition. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Polarization study of poly(vinylidene fluoride) films under cyclic electric fields
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-17
    Shuang Qin; Xu Zhang; Zheng Yu; Feng Zhao

    Poly(vinylidene) fluoride (PVDF) is a prototypical piezoelectric polymer, which exhibits a strong piezoelectricity after a poling treatment. In this work, we investigate the polarization behaviors of PVDF film under cyclic electric fields by measuring polarized currents. A compensation method is used to distinguish the polarized current from the capacitive and resistive currents. The PVDF samples with a thickness of 20 or 30 μm and an electrode area of 3 × 3 or 4 × 4 mm2 are employed, respectively. From the observations, we find that the electrode area does not affect the current density, but a thicker film has a higher residual polarization due to its larger fraction of effective switchable dipoles. The amplitude of the applied field primarily determines the residual polarization. Impressively, an α‐ to β‐phase transformation occurs above 225 MV · m−1 and the polarized current reaches the maximum and becomes converges at 350 MV · m−1. Moreover, a high degree and reproducible residual polarization is obtained through gradually increasing applied field from 50 to 350 MV · m−1, and the relative standard deviation is 3.74% for 20 available samples. Furthermore, a dipole switching model is used to describe the polarization behaviors of PVDF with a form of f(E) = Ae−B|E + C| and the fitting parameters give a further illustration of polarization behaviors in PVDF. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Design and Evaluation of General Purpose, Barrier, and Multichannel Plasticating Extrusion Screws
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-16
    David O. Kazmer; Clemens M. Grosskopf; David Rondeau; Varun Venoor

    Extrusion screw designs and validation are presented for three multiple channel, fractal screws for comparison with common general purpose, and barrier screws using an instrumented single screw extruder with high impact polystyrene (HIPS) and low density polyethylene (LDPE) at varying screw speeds. The fractal screws are designed with multiple channels and pressure–volume–temperature relations to control shear heating with cooling by adiabatic decompression. The general‐purpose design had the highest throughput but did not provide sufficient mixing and so resulted in excessive variation in the melt temperature and pressure at screw speeds above 40 RPM. The barrier screw was a capable design with good performance for LDPE and HIPS with screw speeds from 20 to 60 RPM. However, it tended to provide excessive shear heating at higher screw speeds due to the large surface area of the barrier and mixing sections. The first fractal screw design was a multichannel variant of the general‐purpose design and exhibited good consistency but excessive heating due to the large bearing area between the flights and barrel. The second fractal screw design provided decompression in the feed zone and metering zone to improve throughput but was limited by a poor transition section design. The third fractal screw design remedied these deficiencies with an improved transition section and intermittent clearances for dispersive mixing. Its performance rivaled that of the barrier screw with respect to volumetric output and energy efficiency but provided better melt pressure consistency. Cold screw freezing experiments were performed for all five screws with 5% black, blue, and violet colorants serially added to neat HIPS. The cold screw pulls showed that the general purpose and barrier screws exhibited significant racing of the materials within their screw channels and, thus, broad residence time distributions. Examination of the material cross sections indicated persistent coiled sheet morphologies, which were best dispersed with the third fractal screw. POLYM. ENG. SCI., 2020. © 2020 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.

  • Multifunctional Characteristics of Glass Fiber‐Reinforced Epoxy Polymer Composites with Multiwalled Carbon Nanotube Buckypaper Interlayer
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-16
    Bruno Ribeiro; Jefersson Alexander Rojas Corredor; Michelle Leali Costa; Edson Cocchieri Botelho; Mirabel Cerqueira Rezende

    In this work, multiwalled carbon nanotube buckypaper (MWCNT‐BP) was inserted at the middle‐plane of glass fiber/epoxy resin prepregs to obtain three‐phase nanostructured composite. Preliminary tests conducted by differential scanning calorimetry and thermogravimetric analyses (TGA) revealed that the proposed curing cycle to prepare the laminates in a hot compression‐molding machine was appropriated. The mechanical properties of the BP‐based composite studied by short beam shear and compression shear tests presented no improvements compared to the base laminate. On the other hand, the thermal properties of the nanostructured composite improved as demonstrated by dynamical mechanical analyses and TGA. Besides, the reflectivity results revealed an average value of −12.2 dB in the X‐band with a maximum attenuation of 99.4% of the incident wave at 9.5 GHz. The improvements in both thermal and electromagnetic properties demonstrate the potential for both structural and multifunctional applications of the obtained BP‐composite. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Limitations of Reptation Theory for Modeling the Stress‐Dependent Rheological Behavior of Polyethylene Terephthalate Above the Glass‐Transition Temperature
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-16
    Christian Hopmann; Benjamin Twardowski; Can Bakir

    The biaxial stretch blow molding is an established process for manufacturing plastic containers, in which preforms are stretched both in circumferential and axial directions while being blown into a mold. In the development phase of these products, computer‐aided analysis tools are extensively used to increase the material and process efficiency. The accuracy of these tools depends on the underlying material models and parameters. The aim of this article is to investigate the suitability of reptation theory for the prediction of the strain‐dependent rheological behavior of polyethylene terephthalate (PET) in the stretch blow molding process. Reptation theory has already been successfully applied to a number of polymer melts in the past decades. However, the practical applicability of reptation theory for predicting the strain‐dependent rheological behavior of highly viscous polymers slightly above the glass‐transition temperature, as is the case with stretch blow molding, has not yet been fully investigated. In the first step, the constitutive material model equation of reptation theory is implemented and the necessary model parameters are determined using various measurement methods. However, the measurements could not be conducted with the same accuracy as in the case of polymer melts, because the measurement methods used showed instabilities in the glass‐transition temperature range, which led to high measurement uncertainties. Consequently, the application of the material model does not match quantitatively to biaxial stretch tests. Qualitatively, on the other hand, the material model successfully reproduces the stress–strain behavior of PET films at low strains. In case of temperature dependence, the model results are neither qualitatively nor quantitatively satisfactory. The temperature dependency of the material model has been further investigated in the second step. It was shown that the derivative of the Doi–Edwards memory function with respect to the temperature has an inflection point if the stretching duration is equal to the disengagement time. For very small disengagement times compared to the stretching duration, the results of the model match the experimental observations. For high disengagement times induced by the large viscosities near the glass‐transition temperature and for low stretching times induced by high strain rates; however, the Doi–Edwards memory function cannot predict the experimental observations correctly. The investigations show that reptation model qualitatively predicts the strain behavior of biaxial stretched PET films at low strains correctly. However, different measurement approaches for a more accurate and reproducible determination of the material properties and a modification of the model are required in order to adapt the model to highly viscous melts above the glass‐transition temperature. The results have shown that the process conditions of the two‐stage stretch blow molding, such as high strain rates and low processing temperatures, exceed the validity limits of reptation theory. POLYM. ENG. SCI., 2020. © 2020 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.

  • Magnetic and conducting composites of cobalt ferrite nanorods in a polyaniline matrix
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-13
    Nicolás A. García Saggión; Paula S. Antonel; Fernando V. Molina

    Composites of cobalt ferrite nanorods in a polyaniline matrix have been synthesized and characterized by electron microscopy observation, X‐ray diffraction, infrared spectroscopy, thermogravimetric analysis, electrical conductivity, and DC magnetization measurements. The composites were prepared using dodecylbenzenesulphonic acid both as a particle protector and as acid media. In the magnetic experiments, hysteresis loops were observed, revealing ferromagnetism for both particles and composites. The results indicate that the magnetic properties of the particles were preserved in the composites, and on the other hand, the conductivity was almost independent on the polymer/particle ratio. These composites are new materials that show easily tunable magnetic properties, and are expected to be candidates for applications such as microwave shields. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • From hybrid fibers to microfibers: The characteristics of polyamide 6/polypropylene blend via one‐step twin‐screw melt extrusion
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-08
    Siti Zaharah Kunchimon; Muhammad Tausif; Parikshit Goswami; Vien Cheung

    Multimaterial textiles are frequently employed to attain a certain function or aesthetic effect. The multimaterial assemblies face recycling limitations due to challenges to sort and separate the component materials. A one‐step melt extrusion approach to process two mixed common textile polymers, polyamide 6 (PA6), and polypropylene (PP), into PA6:PP hybrid fibers is reported in this study. PA6:PP hybrid fibers were produced in four different configurations; PA6‐50 (50 wt% PA6), PA6‐60 (60 wt% PA6), PA6‐65 (65 wt% PA6), and PA6‐80 (80 wt% PA6). The PP component was sacrificially removed from the hybrid fibers and the resultant PA6 fiber structure was analyzed. The SEM images show the development of PA6 microfibers in PA6‐50 and PA6‐60 hybrid fibers with mean diameters of 0.76 μm and 1.13 μm upon fiber drawing, respectively. In PA6‐65 hybrid fibers, the PA6 microfibers were found along with areas where PA6 was encapsulating the PP. Thermal and mechanical properties of the untreated and treated hybrid fibers were also investigated. PA6‐60 hybrid fibers were processed into single jersey knitted fabrics and treated to obtain PA6 microfibers fabrics. The bursting strength and wicking properties of the fabric, before and after treatment, were comparatively studied. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Geometrically Constrained Polymerization of Styrene Over Heterogeneous Catalyst Layer in Silica Nanotube Reactors
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-08
    Joong Jin Han; Sang Bok Lee; Kyu Yong Choi

    Styrene has been polymerized to syndiotactic polystyrene (sPS) over a layer of heterogeneous Cp*Ti(OCH3)3/MAO catalyst immobilized onto the surfaces of silica nanotube reactor (SNTR) arrays of 60–200 nm in diameter. The polymer produced in the SNTR arrays has been found to have the molecular weights much larger than the polymers synthesized by a liquid slurry polymerization over silica‐supported catalysts. A dynamic reactor model that consists of diffusion and reaction terms has been derived and solved to quantify the kinetics of styrene polymerization in a single nanotube reactor. The two‐site kinetic model applied to the silica nanotube reactor model shows that the experimentally observed high polymer molecular weight can be fitted if the chain transfer rate constants for monomer and β‐hydride elimination are reduced significantly. The simulation results suggest that the presence of dense crystalline sPS nanofibrils filling the nanotubes constrain the molecular movements of polymer chain ends in the proximity of catalyst sites to limit the chain transfer reactions. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • In situ Polymerization of Polyamide 6/Boron Nitride Composites to Enhance Thermal Conductivity and Mechanical Properties via Boron Nitride Covalently Grafted Polyamide 6
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-08
    Hui Fang; Denghui Li; Fangjuan Wu; Xiangfang Peng; Anlin Chen; Lingjie Zhang; Sheng Chen

    Polyamide 6/boron nitride (PA6/BN) composites were synthesized via anionic ring‐opening polymerization using ε‐caprolactam as the monomer and functional boron nitride (f‐BN) as the thermal conductive filler. Besides the homopolymerized PA6, some PA6 molecule chains would grow from the f‐BN sheets through the “grafting from” strategy. Compared with unfunctional hexagonal BN (h‐BN), the introduction of f‐BN not only improved the dispersion of f‐BN in the matrix but also enhanced the interface bonding between f‐BN and PA6. The homogeneous dispersion of f‐BN in the PA6/f‐BN composite favored the formation of the continuous thermal conductive paths or network at a low f‐BN loading, and the good interface bonding reduced the phonon scattering in the interface, which improved the thermal conductivity (TC) of the PA6/f‐BN composite by 66.0% compared with that of the pure PA6, when only 5 wt% f‐BN was added. In contrast, with the same content of unfunctional h‐BN loading, the TC of the corresponding composite merely improved by 29.7%. Moreover, Young's modulus and yield strength of PA6/f‐BN composites had increased obviously with the introduction of f‐BN, whereas those of PA6/h‐BN composites showed small fluctuation with the same contents of BN. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Ablative Properties of Polyurethanes Reinforced with Organoclay
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-06
    Javier Andrés Bocchio; Mariano Martín Escobar; Javier Carlos Quagliano Amado

    Ablation resistance and mechanical properties of polyurethane‐based composites containing different amounts (up to 5 wt%) of organoclay were correlated with the morphological characterization. The crosslinking density of the polyurethane increased with the amount of organoclay. At low concentration (up to 1 wt%), the organoclay was well exfoliated, while at higher concentration, both exfoliated and intercalated platelets were found. A linear correlation was observed between the tensile test and the concentration of organoclay. Erosion velocity decreased 40% with the incorporation of 5% of organoclay. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Fabrication of Biocompatible Composites of Poly(lactic acid)/Hydroxyapatite Envisioning Medical Applications
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-06
    Eduardo Henrique Backes; Laís De Nóbile Pires; Cesar Augusto Gonçalves Beatrice; Lidiane Cristina Costa; Fabio Roberto Passador; Luiz Antonio Pessan

    Over the last years, orthopedic procedures for bone repairs have been developed due to an increase in trauma and diseases. The development of bioactive composites using biodegradable polymers like poly(lactic acid) (PLA) and bioactive fillers as hydroxyapatite (HA) originate biomaterials, which combine bioactivity of HA and PLA biocompatibility. Therefore, using additive manufacturing is possible for the production of customized products made from these materials; however, a thorough study of these materials is required. In this context, melt‐compounding has been used to manufacture bioactive composites of PLA/HA, and rheological, molecular, and thermomechanical behavior were assessed. The biocomposite of PLA with 10 wt% HA presented a strong shear thinning behavior, which makes it more suitable for fused filament fabrication since lower printing pressure is required. Furthermore, this composite presented an enhancement of 12% in thermomechanical properties in comparison to PLA and a slight increase in cell proliferation. PLA and PLA/HA were fabricated and used to produce 3D calibrations cube as a proof of concept. They presented good printability and high accuracy, and therefore, further investigation needs to be performed to unleash its use in bone tissue engineering applications. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Studies on the Complexation of 3d Transition Metal Ions with NR/PEO Block Copolymer in Aqueous Medium
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-06
    Mundanayil Sasidharan Mrudula; Mazhuvadyil Ramakrishna Pillai Gopinathan Nair

    Polyethylene oxide (PEO) was chemically linked to natural rubber (NR) segments to form a block copolymer (BC), which proved to be a suitable material for complexing with selected first row transition metal ions in aqueous solution through batch adsorption method under noncompetitive mode. Optimum conditions for sorption were found to be 20 mmol/L initial concentration, pH at 6, ambient temperature, and 24 h. The order of decreasing adsorption capacity obtained is Mn(II) > Co(II) > Zn(II) > Ni(II) > Cu(II) > Fe(III). Freundlich isotherm shows the best fit indicating that the adsorption is of heterogeneous in nature. The complexation follows pseudo second‐order kinetics. Exothermic character of the complexation was confirmed by thermodynamic study. For all metal ions, the standard free energy change values are negative for the different temperatures studied, which confirms the spontaneous character of the process. At ambient temperature, the free energy change lies between −2.35 and − 7.83 kJ/mol for all complexes. Values of activation energy for all the metal ion complexation is within the range 11–25 kJ/mol, which indicates chemical interaction via activated physico–chemical adsorption. Variation in stability constant of the complexes also follows the same order as given above. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Study of C─H⋯O Bond of Organic–Inorganic Hybrids Based on Polyhydroxybutyrate and Oxides Obtained Via an In Situ Sol–Gel Route
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-06
    Anna Lecticia Martinez Martinez Toledo; Elton Jorge da Rocha Rodrigues; José Carlos Dutra Filho; Domethila Mariano de Souza Aguiar dos Santos; Suelen Adriani Marques; Maria Inês Bruno Tavares

    Sol–gel‐based zirconia (ZrO2) and silica (SiO2) were obtained in situ via hydrolysis–polycondensation of metal alkoxide precursors in membranes of poly(3‐hydroxybutyrate) (PHB). What followed was an assessment of thermal and spectroscopic effects from the insertion of the inorganic network in the PHB matrix. The findings exhibited a dependence of both the concentration and the chemical nature of the precursor on the properties of the as‐formed inorganic–organic hybrids. The results also indicated that positive nucleating effects, a reduction of the crystallite size and a variation in thermal transitions correlate with spectroscopic data from the alpha and beta crystal forms of the PHB matrix, as well as the crystallization data obtained through polarized light microscopy. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Facile Visible‐Light‐Induced Preparation and Hydrophobization of Porous polyEGDMA and polyTEGDMA Thick Monoliths
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-06
    Nina A. Lenshina; Maxim V. Arsenyev; Maxim A. Baten'kin; Yuri V. Polushtaytsev; Sergey A. Chesnokov

    The simple low‐cost method for synthesis and post‐functionalization of thick macroporous polymer monoliths was proposed and realized by example of obtaining and hydrophobization of monoliths based on mono‐ and triethylene glycol dimethacrylates. Described procedures comprise using of ubiquitous visible‐light projection system and single photoinitiator (9,10‐phenanthrenequinone) in both cases. This approach eliminates the need in “material” photomasks and permit to operate with computer generated virtual photomask to form the pattern of functionalization. Macroporous polymer monoliths of 2 and 4 mm in thickness with a system of interconnected pores were synthesized and hydrophobized. The thick layers of functionalized porous polymer with wetting pattern through the entire sample thickness with the water contact angle for hydrophobic parts reaching120–125° were obtained. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Effect of viscoelastic properties of the base polymer on extrusion foaming with thermally expandable microcapsules
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2020-01-06
    Tomoki Uchio; Shota Takiguchi; Tomonori Koda; Akihiro Nishioka

    Thermally expandable microcapsules (MCs) are applicable to the foam processing of polypropylene (PP). The purpose of this study is to clarify the influence of processing conditions, such as temperature, shear rate and resin selection, on the behavior of thermally expandable MCs in PP. In this study, MC was added to several types of PP and extrusion foaming was performed. The average diameter of the MCs after processing was calculated to characterize the expansion of PP including MCs. Two types of molecular architecture, homo‐ and impact‐PP, were examined in this study. The expansion behavior could be summarized by the shear viscosity at the extrusion die. Irrespective of the molecular architecture, data were summarized on one curve on a plane that expressed the relation between the shear viscosity and average MC diameter. Shear viscosity is thus an effective parameter to examine base resin selection for MC foaming. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

  • Injection Molding and Appearance of Cellulose‐Reinforced Composites
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-15
    Lilian Forsgren; Johan Berglund; Johannes Thunberg; Mikael Rigdahl; Antal Boldizar

    Composite materials based on an ethylene‐acrylic acid (EAA) copolymer and 20 wt% cellulose fibers were compounded by two runs in a twin‐screw extruder. The composite material with cellulose fibers (CF) and a reference of unfilled EAA were injection molded into plaques using three different temperature profiles with end zone temperatures of 170°C, 200°C, and 230°C. The injection molded samples were then characterized in terms of their mechanical properties, thermal properties, appearance (color and gloss), and surface topography. The higher processing temperatures resulted in a clear discoloration of the composites, but there was no deterioration in the mechanical performance. The addition of cellulose typically gave a tensile modulus three times higher than that of the unfilled EAA, but the strength and strain at rupture were reduced when fibers were added. The processing temperature had no significant influence on the mechanical properties of the composites. Gloss measurements revealed negligible differences between the samples molded at the different melt temperatures but the surface smoothness was somewhat higher when the melt temperature was increased. In general, addition of the cellulose to the EAA reduced the gloss level and the surface smoothness. POLYM. ENG. SCI., 60:5–12, 2020. © 2019 Society of Plastics Engineers

  • Fracture and Orientation of Long‐Glass‐Fiber‐Reinforced Polypropylene During Injection Molding
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-01
    Xu‐Qin Hou; Xing‐Yuan Chen; Bao‐Chen Liu; Sheng‐Chao Chen; Hai‐Mei Li; Wei Cao

    Injection processing parameters directly influence the final fiber length and may have a negative effect on the mechanical properties of a part. The aim of the work is to investigate and quantify the effects of the injection rate (2/10/50 cm3/s) on the fiber length, the distribution, and orientation during injection molding and the mechanical properties of long‐glass‐fiber‐reinforced polypropylene (LGF/PP) by experimental and simulated methods. When the injection rate increases from 2 to 10 cm3/s, the fiber length sharply decreases from the original 11 mm to 3.43 mm at the nozzle and 1.30 mm at the filling end, and almost 88% of the fibers are less than 3 mm when the injection rate is 50 cm3/s. A distinct hierarchical orientation (skin‐shear‐core) for the fiber distribution in the thickness is obtained via a metallographic microscope, which shows that the shear layer (here the shear stress is larger and the fiber is more inclined to oriented along the flow direction) decreases with increasing injection rate. Moreover, the numerical results of the residual fiber length and orientation at different injection rates are in accord with the trend of the measured results. POLYM. ENG. SCI., 60:13–21, 2020. © 2019 Society of Plastics Engineers

  • Experimental study on filling imbalance of plastic parts with microcylinders
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-24
    Bin Xu; Ailin Deng; Song Xue

    To examine the microscale filling imbalance in the present work, an eight‐cavity injecting mold with microcylindrical‐hole arrays fabricated by micro‐electrical discharge machining milling technology was developed. Polypropylene (PP) was used to carry out single factor filling flow experiments with vacuuming the mold cavities. The filling height difference of micro cylindrical hole at the same position between cavity I and cavity II, which was the index of filling imbalance and the effect of mold temperature and injection rate on the filling imbalance of microholes with diameters of 200 μm and 300 μm was investigated. The results revealed that the maximum height difference reached 101 μm with low process parameters, and the filling imbalance was obvious. With the increase in mold temperature and injection rate, the filling imbalance was weakened. In addition, the impact of the scale effect on filling imbalance was checked. The filling imbalance of micro holes in 200 μm was greater than that in 300 μm using identical process parameters. With the increase in mold temperature and injection rate, the filling height difference of the two kinds of micro holes decreased. POLYM. ENG. SCI., 60:22–31, 2020. © 2019 Society of Plastics Engineers

  • Contraction and capillary flow of a carbon black filled rubber compound
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-23
    Sebastian Stieger; Roman Christopher Kerschbaumer; Evan Mitsoulis; Michael Fasching; Gerald Roman Berger‐Weber; Walter Friesenbichler; Joachim Sunder

    Highly filled rubber compounds exhibit a unique rheological behavior, which is affected by its filler–filler and filler–matrix interactions leading to pronounced nonlinear viscoelasticity. The necessity to consider these characteristics in rheological testing and modeling, adds further complexity providing universally valid numerical descriptions. In the present study, the pressure driven contraction and capillary flow of a carbon black filled hydrogenated acrylonitrile–butadiene rubber compound is studied both experimentally and numerically. Rheological testing indicates no pronounced slippage at the wall but a shear sensitive plug flow at the centerline. The viscoelastic Kaye‐Bernstein–Kearsley–Zapas/Wagner, the viscoplastic Herschel–Bulkley and the viscous power‐law models are used in computational fluid dynamic simulations aiming to predict measured pressure drops in an orifice and various capillary dies. Viscoelastic modeling is found of particular importance describing contraction flow dominated areas, whereas viscous models are able to predict pressure drops of capillary flows well. POLYM. ENG. SCI., 60:32–43, 2020. © 2019 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.

  • Shear Stress‐Dependent Viscosity Master Curves for Practical Applications
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-18
    Ryszard Steller; Jacek Iwko

    It was shown using several examples that the ratio of apparent viscosity and Newtonian viscosity at the same temperature as function of shear stress is independent of temperature. It means that viscosity curves for different homogeneous polymer systems measured in various temperatures create a common master curve, which is very convenient for practical calculations of many technically important flows. It was also shown that for such systems, the stress dependence can be often very well described by simple function of Kohlrausch type. Moreover, it was found that for small‐amplitude oscillatory shear, similar master curves can be created by representing the absolute value of complex viscosity or its components as functions of absolute value of complex modulus. For nonhomogeneous systems, second‐order temperature effects may appear. They were taken into account by additional rule based on the so‐called no‐flow temperature. It was also shown that the first normal stress difference as function of shear stress is temperature independent. POLYM. ENG. SCI., 60:44–54, 2020. © 2019 Society of Plastics Engineers

  • Non‐linear rheological response as a tool for assessing dispersion in polypropylene/polycaprolactone/clay nanocomposites and blends made with sub‐critical gas‐assisted processing
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-01
    Thomas Ellingham; Galip Yilmaz; Lih‐Sheng Turng

    Polypropylene (PP) was blended with polycaprolactone (PCL) and nanoclay (NC) in a twin‐screw extruder (TSE) using a traditional extrusion process and a sub‐critical gas‐assisted process (SGAP). SGAP is a new and facile processing method that injects compressed gas (CO2 or N2) at low pressures (~10 bars) into the barrel of the extruder to induce rapid and repetitive foaming and resolubilization as the melt travels through regions of high pressure and low pressure. Bubble expansion during foaming introduces an equibiaxial elongational flow not otherwise generated in TSE, adding to the total stress the polymer matrix can exert to break up nanoparticle agglomerates and reduce the droplet size of secondary polymers in blends. Impact, morphology, and X‐ray diffraction (XRD) properties confirmed a smaller PCL phase droplet size and an increase in dispersion of the NC when SGAP was used. Standard small amplitude oscillatory (SAOS) rheological tests for the storage modulus G′ were not sensitive enough to discern the difference between the traditionally extruded samples and the SGAP samples. However, the zero‐strain non‐linearity parameter, Q0, determined by the Fourier‐Transform rheology, was able to distinguish the enhanced dispersive and mixing capabilities of SGAP. Practical implications of SGAP and Fourier‐Transform (FT) rheology are also discussed in this paper. POLYM. ENG. SCI., 60:55–60, 2020. © 2019 Society of Plastics Engineers

  • Probing the Damping Property of Three‐Dimensional Graphene Aerogels in Carboxylated Nitrile Butadiene Rubber/Polyurethane Blend
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-22
    Han Yan; Hao Li; Wen Li; Xiaoqiang Fan; Lin Zhang; Minhao Zhu

    Three‐dimensional (3D) graphene aerogel (GA) with a spatial porous structure and network skeleton was facilely prepared via one‐step self‐assembly hydrothermal reduction. Such network structure is regarded as a critical advantage in resolving the dispersion of graphene in polymer matrix, thereby enhancing the damping property. Here, as‐prepared GA was added to the carboxylated butadiene nitrile rubber/polyurethane blend (XNBR/PU) by melting/mechanical complex method. Their dynamic mechanical properties were investigated in detail, and the relationship between thermal aging and dynamic mechanical properties had also been studied. Finding that the storage modulus and loss modulus of XNBR/PU were continually improved with the increase in addition amount of high‐performance GA, reaching 3,219 and 316 MPa with the content of 3 wt% GA, respectively. Loss factor (tanδ) of XNBR/PU with GA shows two sets of maximum values (0.22 and 0.61) at around −25 and 0.6°C, respectively. Results illustrate that GA can greatly improve the damping performance, damping temperature range, mechanical properties, and thermal aging resistance of XNBR/PU blend, mainly depending on the performance characteristics of GA and interface interaction between GA and XNBR/PU. Verifying that GA with 3D network structure holds a great prospect for damping materials. POLYM. ENG. SCI., 60:61–70, 2020. © 2019 Society of Plastics Engineers

  • Crystalline Films of L‐Threonine Complexed with Copper (II) Dispersed in a Galactomannan Solution: A Structural, Vibrational, and Thermal Study
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-18
    João G. Oliveira Neto; Lincoln A. Cavalcante; Eduardo S. Gomes; Adenilson O. Dos Santos; Francisco F Sousa; Fernando Mendes; Ana Angélica M Macêdo

    The study's aim was to synthesize a crystalline film formed by L‐threonine crystals complexed with Cu2+ ions (LTCu) dispersed in a galactomannan (Gal) solution as well as to characterize its structural, vibrational, and thermal properties. Gal(LTCu) films were prepared by the addition of copper II L‐threoninate crystals in concentrations of 0.25, 0.50, and 0.75 in 2% Gal solution. To characterize the Gal(LTCu) properties, we used X‐ray diffraction (XRD), UV–Vis and Raman spectroscopy, thermogravimetry, and thermal analyses (TG‐DTA). XRD showed that the Gal(LTCu) films are crystalline and have acquired coloration similar to the one of LTCu crystal. The UV–Vis spectra revealed that the films tend to assume a square planar conformation due to Jahn Teller effect. Bands related to the interaction between the metal ion with the organic compounds were observed through the Raman spectra. TG‐DTA showed that the films exhibit low thermal stability due to the dehydration process. POLYM. ENG. SCI., 60:71–77, 2020. © 2019 Society of Plastics Engineers

  • Processing Fiber‐Reinforced Polymers: Specific Wear Phenomena Caused by Filler Materials
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-18
    Andreas Blutmager; Thomas Spahn; Markus Varga; Walter Friesenbichler; Helmut Riedl; Paul Heinz Mayrhofer

    Fiber‐reinforced polymers allow for the implementation of plastic materials in structural components. However, increasing incorporation of fibers up to 50 wt% causes accelerated component wear in injection molding machines. In particular, the barrel and screw in the compression zone suffer from increased wear. The abrasive fibers of the compacted polymer pellets in the solid bed protrude from the surfaces of the resin having an abrasive, brush‐like behavior. A modified pin‐on‐disk testing system with specially designed polymer pins was used to emulate the described tribological system in laboratory scale. Through varying contact pressure, temperature, and surface modifications of the counterparts (blank or coated powder‐metallurgical steel), abrasive wear as observed in industrial‐sized extruder screws could be successfully simulated on a laboratory‐scale testing system. Detailed investigations of the pins and disks highlighted that the glass fibers plow and cut the surface leading to abrasion as observed in the real field application. Temperature has been proven to be the most decisive driving force. Surface modifications such as protective physical vapor‐deposited CrN coatings are effective against abrasive wear, clearly outperforming untreated steels. The presented pin‐on‐disk‐test setup will improve screening of materials for extruders, thus enhancing the durability of injection molding machines. POLYM. ENG. SCI., 60:78–85, 2020. © 2019 Society of Plastics Engineers

  • Chemically Functionalized Reduced Graphene Oxide as Additives in Polyethylene Composites for Space Applications
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-18
    Zach Seibers; Matthew Orr; Graham S. Collier; Adriana Henriquez; Matthew Gabel; Meisha L. Shofner; Valeria La Saponara; John Reynolds

    The discovery of radiation‐shielding materials remains a critical technology to enable long‐term space travel and extraterrestrial colonization. Hydrocarbon polymers, such as high‐density polyethylene (HDPE), are among the best radiation attenuators due to their rich H content and lightweight. Due to their simple chemical structure that lacks larger heteroatoms, HDPE is also resistant to numerous radiation‐induced degradation pathways that often limit the applicability of more sophisticated polymers. One drawback of hydrocarbon polymers is their inferior mechanical properties, such as tensile strength and impact toughness, relative to metals and other high‐performance polymer systems. In this report, we develop an alkylated reduced graphene oxide that is used as an additive to enhance the storage and tensile moduli of HDPE by 10–15% across the lunar temperature range. These additives outperform unmodified reduced graphene oxide by 30% due to better dispersion through the polymer matrix as observed by cross‐sectional scanning electron microscopy. POLYM. ENG. SCI., 60:86–94, 2020. © 2019 Society of Plastics Engineers

  • Study of the Photocrosslinking of Ethylene Propylene Diene Monomer Terpolymer Under UV Irradiation
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-25
    Lucas Jégo; Daniel Milési; Jean‐Jacques Robin; Christine Joly‐Duhamel

    The photocrosslinking of thick samples of 5‐ethylidene‐2‐norbornene–ethylene propylene diene monomer (ENB‐EPDM) under air at room temperature was investigated. First, a model study was carried out on low‐molecular weight oligomers: squalene, 1,2‐polybutadiene, and 1,4‐polybutadiene. Several crosslinking agents (meth(acrylics), bismaleimide, and thiol) combined with various photoinitiators were tested to improve the reactivity of these oligomers under UV irradiation. Gel contents, crosslinking densities, viscosities, and viscoelastic properties were measured in order to characterize the extent of crosslinking. Acrylate‐based crosslinking agents appeared to be the most reactive species and these results were then applied to a low‐molecular weight EPDM. Several photoinitiators were tested and benzophenone turned out to be the most efficient photoinitiator when combined with trimethylolpropane triacrylate. Finally, a commercial EPDM was subsequently photocrosslinked and high gel content and crosslinking density were obtained after only 2 min of irradiation. POLYM. ENG. SCI., 60:95–103, 2020. © 2019 Society of Plastics Engineers

  • Bond behavior of epoxy resin–polydicyclopentadiene phase separated interpenetrating networks for adhering carbon fiber reinforced polymer to steel
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-23
    Meng Liu; Brian J. Rohde; Ramanan Krishnamoorti; Megan L. Robertson; Mina Dawood

    The performance of bonded joints of carbon fiber reinforced polymer (CFRP) and steel relies on the mechanical properties of the adhesive used. Despite the high strength and modulus of epoxy adhesives, their brittleness limits their application to defect‐sensitive structures. The development of interpenetrating polymer networks (IPNs), either homogeneous or phase separated, provides a route to toughen the epoxy while maintaining its high strength and modulus. Microphase separated IPNs consisting of a diglycidyl ether of bisphenol A‐based epoxy resin and a thermoset with high toughness, polydicyclopentadiene (PDCPD), has been previously shown to demonstrate superior combinations of strength and toughness. This work investigates the most critical adhesive properties that affect bond strength by characterizing CFRP‐steel double‐lap shear joints containing the epoxy resin–PDCPD blend as the adhesive, using a wet lay‐up manufacturing technique. The epoxy resin–PDCPD blend adhesives realized much higher bond strengths compared to either neat epoxy or neat PDCPD. Correlations between the bond strength and the bulk material properties are presented. Theoretical calculation of the bond strength indicates that the higher bond strength that can be achieved by using the epoxy resin–PDCPD blend adhesive is due to the increased shear toughness of the new formulations. POLYM. ENG. SCI., 60:104–112, 2020. © 2019 Society of Plastics Engineers

  • Bimodal Microcellular Morphology Evaluation in ABS‐Foamed Composites Developed Using Step‐Wise Depressurization Foaming Process
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-22
    Radhakrishna G; Rupesh Dugad; Abhishek Gandhi

    In this article, the fabrication of bimodal type of cellular structures and multimodal type of cellular structures of acrylonitrile–butadiene–styrene foams has been reported using solid‐state batch foaming process by distinct, stepwise depressurization technique. Each depressurization step induces a distinct nucleation phenomenon, which leads to the development of multimodal cellular microstructures. The significance of crucial process parameters, which includes saturation pressure, holding pressure, holding time and holding steps, was studied in the development of bimodal and multimodal cellular structures. Further, the influence of the depressurization rate on the volume ratio of small cells to large cells vice versa was also studied. The morphological attributes, which includes cell size, cell density, and cell morphologies, were investigated in detail. This study puts forward a basic mechanism to develop and simultaneously control bimodal and multimodal cellular microstructures by altering the crucial process parameters. POLYM. ENG. SCI., 60:113–131, 2020. © 2019 Society of Plastics Engineers

  • Effect of Talc Size on Surface Roughness and Glossiness of Polypropylene Injection Molding Application to Automotive Plastics
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-18
    Shinichi Kuroda; Atsushi Mizutani; Hiroshi Ito

    Talc‐containing polypropylene (PP) resin is extensively employed in automobiles. Herein, considering the microstructure transfer process in injection molding, the effect of the talc's dispersibility and particle size on this process and its impact on the gloss level of the product were investigated. Results show that a fine unevenness of about several micrometers was self‐formed by the shrinkage of PP in nontransferred areas due to the blending of talc. Additionally, the amount of self‐formed unevenness tended with an increase in the average particle size of talc. Furthermore, due to PP shrinkage and different densities of talc, it was observed that a fine tiger‐stripe pattern was self‐formed using special molds with modified microstructure. This self‐formed fine unevenness changes the gloss level owing to the diffused light reflection effect. This study proposes controlling this change by controlling the average particle size of talc and structure of the mold. POLYM. ENG. SCI., 60:132–139, 2020. © 2019 Society of Plastics Engineers

  • Synthesis of Self‐Healing Bio‐Based Tannic Acid‐Based Methacrylates By Thermoreversible Diels–Alder Reaction
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-07
    Junali Handique; Joly Gogoi; Jayashree Nath; Swapan Kumar Dolui

    This investigation reports the effective use of the Diels–Alder (DA) click reaction in the preparation of self‐healing bio‐based dendritic methacrylates having reactive furfuryl functionality. Bio‐based methacrylates were synthesized by modifying tannic acid with glycidyl methacrylate and furfuryl functionality was introduced by atom transfer radical polymerization with varied amount of furfuryl methacrylate monomer. The thermoreversible network was successfully achieved by DA and retro‐DA reaction between the furfuryl groups and a bifunctional maleimide crosslinker, bismaleimide. This process was studied by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and solvent exposure tests. Differential scanning calorimetry analysis was used to determine the endothermic retro‐DA reaction in the DA adduct. The self‐healing property of the above crosslinked material was demonstrated by monitoring the repair of a scratch in the polymer film upon heating and cooling. This was analyzed by scanning electron microscopy. POLYM. ENG. SCI., 60:140–150, 2020. © 2019 Society of Plastics Engineers

  • A Conveying Model of Fluid Partially Filled in a Nontwin Screw Extruder Allowing for a Positive Displacement
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-08
    Huiwen Yu; Baiping Xu; Biao Liu; Yaoxue Du; Jian Song; Yanhong Feng

    Fill degree is a key parameter impacting twin screw extruders' (TSEs) mixing performance and melting behavior. The conventional conveying model of partially filled fluid relies mainly on empirical methods. A nontwin screw geometry introduces a speed difference between the two intermeshing screws to change the conveying means, and this speed difference offers a challenge for establishing a new conveying model. A visualization prototype with a global transparent barrel was developed in this article with carboxymethylcellulose sodium solution used as working fluid. Fill length was measured under different outputs and screw rotation speeds in a nontwin screw channel versus a corresponding twin screw channel; thus, fill degree was obtained using the observed fill lengths and nontwin screw geometries. A new conveying model of partially filled fluid was proposed which isolated positive displacement flow as an independent factor, and visualization observations revealed that due to differences in screw flight width, the positive displacement flow in a nontwin screw channel is larger than that in a traditional twin‐screw channel. Results showed that dimensionless positive displacement conveying increased linearly with fill degree for a non‐TSE geometry while it was independent of fill degree for a TSE geometry. POLYM. ENG. SCI., 60:151–160, 2020. © 2019 Society of Plastics Engineers

  • Evaluation of Polymethylmethacrylate Cohesion Behavior with a Gas‐Assisted Thermal Bonding Method
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-06
    Pei‐Kang Sun; Ronald S. Besser

    By applying heat and pressure to thermoplastic materials, the overlap of the two pieces can be bonded to form hermetic systems. Polymethylmethacrylate (PMMA) is a thermoplastic used in commercial microfluidic devices; its advantages include low cost, ready fabrication, and high transparency. In order to gain an understanding of PMMA's relevant characteristics (thermal behavior, material strength, and hermetic sealing strength), we study its bulk properties and mechanical behavior. Experimental results of the cohesion behavior of PMMA sheets were collected and are presented here. Samples were bonded by subjecting a sample to elevated pressure and temperature in the glass transition range (85°C–165°C), which was determined beforehand by differential scanning calorimetry and literature. Five different bonding temperatures (140°C, 150°C, 160°C, 170°C, and 180°C) and three bonding pressures (1.2, 1.4, and 1.6 MPa) were applied for making samples; mechanical strength tests were then carried out to understand separately the bulk mechanical strength and the interfacial properties (shear strength and bonding strength) of a cohesive laminate at the temperatures near the glass transition range. POLYM. ENG. SCI., 60:161–167, 2020. © 2019 Society of Plastics Engineers

  • The Effect of Spray‐Freeze Drying of Montmorillonite on the Morphology, Dispersion, and Crystallization in Polypropylene Nanocomposites
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-29
    Wissam Abdallah; Victor Tan; Musa R. Kamal

    The spray‐freeze drying (SFD) technique was applied to sonicated aqueous suspensions of spray‐dried montmorillonite clay (MMT) to produce highly porous agglomerates (SFD‐MMT). Both MMT (used as a reference) and SFD‐MMT were subsequently incorporated in polypropylene (PP) via melt compounding to produce 2 wt % nanocomposites with and without maleic anhydride grafted polypropylene (PP‐g‐MA). Polypropylene nanocomposites containing SFD‐MMT exhibited thinner silicate flake layers compared to large agglomerates in PP/MMT nanocomposites. SFD‐MMT particles became even more finer in the presence of PP‐g‐MA (i.e., in PP/PP‐g‐MA /SFD‐MMT) where it hindered PP crystallization instead of serving as nucleation sites for the PP crystallization during rapid cooling. SFD‐MMT improved the thermal stability of PP/PP‐g‐MA by 30°C compared to only 5–8°C for MMT/nanocomposites. MMT acts as a heterogeneous nucleating agent in the nucleation‐controlled PP nanocomposites, but the hindrance effect was observed for the PP/PP‐g‐MA with SFD‐MMT. PP/PP‐g‐MA/SFD‐MMT exhibited twice the edge surface energy as compared to PP/PP‐g‐MA/MMT. The incorporation of both types of MMT raised the tensile moduli of PP and PP/PP‐g‐MA, with no improvement in their tensile strength and a decrease in the elongation at break. The PP/PP‐g‐MA/SFD‐MMT showed brittle failure. POLYM. ENG. SCI., 60:168–179, 2020. © 2019 Society of Plastics Engineers

  • Silane‐Modified Graphene Oxide as a Compatibilizer and Reinforcing Nanoparticle for Immiscible PP/PA Blends
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-08
    Adi Kol; Samuel Kenig; Naum Naveh

    Graphene oxide (GO) and aminosilane (AS)‐modified GO (GOAS) have been studied as possible compatibilizers for immiscible polyblends. Ideally, for localization of nanoparticles (NPs) at the interface, the thermodynamics of the constituents and mixing dynamics have to be tailored and controlled, respectively. Accordingly, a variety of oxidation levels (10%–40%) of GOs were prepared using Hummer's method and further modified by AS. Experimental results indicated that the GO goes through thermal reduction (above 200°C) during blending and reduced GO (rGO) is produced. The GOAS moderated the reduction reaction and stabilized the GO. The thermodynamic wetting coefficient of PP (polypropylene)/PA (polyamide)/rGOAS system was shown to drive the rGOAS from the PP phase to the blend's interface during time‐controlled blending. The localization of the rGOAS at the interface resulted in significant enhancement of mechanical properties using only 2–3 wt% of rGOAS. Over 100% enhancement in strength, 40% enhancement in modulus, and 30% in toughness were shown, compared with neat PP/PA. Reduced GOAS and its location at the interface resulted in a third glass transition temperature (Tg), in addition to the PP and PA respective Tgs. Rheological percolation at 2–3 wt% rGOAS (20%) supports the localization of rGOAS at the interface. Storage moduli increase with interfacial tension, in accordance to the rheological models. POLYM. ENG. SCI., 60:180–191, 2020. © 2019 Society of Plastics Engineers

  • Preparation and characterization of strong cation exchange terpolymer resin as effective adsorbent for removal of disperse dyes
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-23
    Gulay Bayramoglu; Gul Kunduzcu; Mehmet Yakup Arica

    In this study, (hydroxypropylmethacrylate‐co‐ethyleneglycol dimethacrylate‐co‐glycidylmetharylate) terpolymer resin functionalized with sulfonic acid groups was prepared and used as cation exchange resin for removal of two different disperse dyes (i.e., Direct Red R [DR‐R] and Disperse Violet 28 [DV‐28]) from aqueous solution. The properties of the adsorbent were determined using Fourier transform infrared, dynamic light scattering, scanning electron microscopy, and Brunauer, Emmett, and Teller methods. The maximum adsorption capacity of the resin for the DR‐R and DV‐28 was found to be 86.1 and 179.6 mg/g, respectively. Desorption study was realized to evaluate the reusability of the resin and the percent desorption from the resin for DR‐R and DV‐28 dyes was found to be approximately 89.4% and 91.7%, respectively. The experimental data were evaluated using different kinetics and isotherm models. These results show that the experimental data could be designated with the second‐order kinetic model and both Langmuir and Temkin isotherm models. Finally, the presented resin was able to remove large amounts of organic pollutants in a short process time with a low amount of adsorbent. Thus, it was shown that the prepared resin has high potential for use as an effective and sustainable adsorbent for the treatment of industrial wastewater. POLYM. ENG. SCI., 60:192–201, 2020. © 2019 Society of Plastics Engineers

  • Wood Plastic Composites Produced from Postconsumer Recycled Polystyrene and Coconut Shell: Effect of Coupling Agent and Processing Aid on Tensile, Thermal, and Morphological Properties
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-05
    Sing Li Ling; Seong Chun Koay; Ming Yeng Chan; Kim Yeow Tshai; Thevy Ratnam Chantara; Ming Meng Pang

    Expanded polystyrene (EPS) has been widely used as a disposable packaging material in many industries thanks to properties like low density, lightweight, high impact, and vibration damping. Although usage of EPS increases annually, recycling facilities often refused to process postconsumed EPS due to the poor economic viability associated with high logistics and transportation cost in collection, storage, and shipment of the material. The objective of this research is to enhance the value chain of postconsumed EPS by investigating its potential as feedstock in the development of sustainable wood plastic composites (WPC), thereby providing an attractive business opportunity that also increases interest in EPS recycling and indirectly continue the lifespan of disposed EPS. Varying compositions of recycled polystyrene (rPS), coconut shell (CS), maleated polystyrene (MAPS) and Ultra‐Plast WP516 were compounded using a HAAKE internal mixer and compression molded to form WPC. The effects of material formulation on mechanical, thermal, and morphological properties of the composites were studied. The experiment showed that WPC formulated with 100 phr of rPS, 30 phr of CS, 3 phr of MAPS, and 1 phr of Ultra‐Plast WP516 possesses higher modulus and tensile strength compared to the neat EPS, measured at 2.5 GPa and 27.5 MPa, respectively. Although the WPC experienced initiation of thermal degradation at a temperature lower than neat rPS, but the thermal stability of rPS/CS composites containing varying composition of MAPS and Ultra‐Plast WP516 was better at high temperature. Furthermore, a 50% weight loss took place at a higher temperature. Nevertheless, the glass transition temperature of the rPS/CS composite with addition of MAPS and Ultra‐Plast WP516 was found lower than the neat rPS. POLYM. ENG. SCI., 60:202–210, 2020. © 2019 Society of Plastics Engineers

  • Micro/nanocellular polyprolene/trans‐1,4‐polyisomprene (PP/TPI) blend foams by using supercritical nitrogen as blowing agent
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-10-29
    Li Zou; Huan Li; Dan Wang; Leyuan Ma; Kundil Prakashan; Zhen Xiu Zhang

    Toughed polypropylene (PP) foams, with the combination of blending with trans‐1,4‐polyisoprene (TPI) and micro/nanocellular structure in the matrix, were prepared using a batch foaming process and N2 as the blowing agent. The incorporation of TPI in the PP matrix induces the enhanced formability and the slightly improved ductility and toughness compared to the neat PP. The simultaneous existence of the TPI phase and micro/nanocellular structure makes the fracture behavior follow the shear yielding of a bundle of fibrils in the tensile load direction. The results of mechanical properties measurements show that the notched Izod impact strengths of foamed PP/TPI blend are two to three times larger than those of the unfoamed counterparts. The PP/TPI blend foam with 5phr TPI content shows the highest impact strength when the foaming temperature is 140°C, which is fivefold increase over that of the neat PP. The enhanced ductility and toughness of PP/TPI foams were found with the increasing foaming temperature. The insert of micro−/nanocellular in PP/TPI blends simultaneously makes the notched impact strength increase significantly, tensile strength decrease, and elongation at break increase obviously, which provides the possibility to combine the higher impact strength and toughness with the advantage of microcellular foaming. POLYM. ENG. SCI., 60:211–217, 2020. © 2019 Society of Plastics Engineers

  • Synthesis, characterization, and ionic conductivity of electrospun organic–inorganic hybrid gel electrolytes
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-31
    Emre Aytan; Mustafa H. Uğur; Nilhan Kayaman‐Apohan

    In this work, we described the synthesis of organic–inorganic hybrid gel electrolytes combining electrospinning, sol–gel, and ultraviolet (UV) curing techniques in order to investigate their ionic conductivity properties. First, 3‐glycidyloxypropyl trimethoxysilane modified polyamic acid and alkoxysilane functional poly(dimethyl siloxane) were electrospun together. Then, the following thermal imidization, the obtained fiber was cured in the UV curable gel formulation. To improve the interaction between fiber and gel matrix, 3‐(trimethoxysilyl)propyl methacrylate was partly hydrolyzed and then used as a bifunctional crosslinker. Finally, the membrane was soaked into 0.5 M LiFP6 salt solution to obtain organic–inorganic hybrid gel electrolytes. The chemical structure, ionic conductivity, and range of electrochemical stability window of the photocured nanocomposite electrolytes were investigated by using FTIR, thermogravimetric analysis, differential scanning calorimetry, electrochemical impedance spectroscopy, linear sweep voltammetry, and SEM analysis. The acquired results from experiments indicate that a convenient nanocomposite electrolyte for lithium‐ion batteries with high electrolyte (Li salt) uptake, adequate conductivity (1.02 × 10−3 S cm−1) at ambient temperature and electrochemically stable between 1 and 6 V had been prepared. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Environmental Friendly Radiation Hard d‐Limonene and Laccol Copolymers Synthesized via Cationic Copolymerization
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-30
    Imalka H. A. M. Arachchilage; Milly K. Patel; Joseph Basi; Julie P. Harmon

    In the modern world, petroleum‐based synthetic polymers have a great number of applications in fields ranging from food packaging to space travel. However, the processing of petroleum products and the resulting depletion of fossil fuels are major environmental concerns in today's society. As a result, the development of sustainable polymers which are made up of renewable resources and waste products is an immerging area of research. Considering the world food production, citrus fruit is most abundant and its contribution to waste generation is immense. Therefore, this study focuses on offering an alternative to the use of petroleum‐based polymers and also providing a regulatory pathway to manage citrus waste by developing novel copolymers of laccol and limonene. Two environmental friendly compounds, laccol, derived from the sap of Toxicodendron succedaneum tree and limonene, extracted from orange peels, were copolymerized via cationic polymerization to generate d‐limonene:laccol copolymers with radiation hardening capabilities which is relevant in fields such as nuclear energy generation, medicinal sterilization, commercial irradiation, and space exploration. Formation of these copolymers was verified with infrared and nuclear magnetic resonance analysis. The synthesized copolymers were characterized using different methods and exposed to Co‐60 gamma radiation to identify alterations to their properties. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Translation of segment scale stiffening into macroscale reinforcement in polymer nanocomposites
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-27
    Marek Zboncak; Frantisek Ondreas; Vojtech Uhlir; Petr Lepcio; Jan Michalicka; Josef Jancar

    Structuring of polymer nanocomposites (PNCs) with an aid of relatively weak external magnetic fields has been studied as a method for control of the nano‐ and microstructure. Magnetic nanoparticles (NPs) were assembled into high aspect ratio one‐dimensional strings and unidirectionally oriented with the magnetic field (B = 0–50 mT) within the photopolymer matrix. The effect of the anisotropic MNPs assemblies on the mechanical properties was studied over a wide temperature range for the first time. The impact of various reinforcing mechanisms was distinguished with respect to the position of the glass transition temperature (Tg). The reinforcing effect exhibits temperature dependency with a maximum ~65°C above the glass transition and only negligible effect below the Tg. In addition, significant directional anisotropy of stiffness was observed. Composite micromechanics was applied to interpret the orientation and size‐dependent reinforcement of PNCs, and temperature‐dependent stiffness of the polymer‐MNP structures was quantified. The presence of polymer chains with altered dynamics surrounding the MNPs inside the anisotropic assemblies was proposed to be an essential nanoscale mechanism mediating the stress transfer and contributing to mechanical robustness of the hybrid structures and PNCs. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Synthesis and Characterization of Amphiphilic Hairy Nanoparticles with pH and Ionic Dual‐Responsiveness
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-25
    Rui Liu; Yuanyuan Lu; Wanfen Pu; Pan Hu; Qiang Luo; Haoyu Luo

    Recently, polymeric shell hybrid nanoparticles with multiresponse to external triggers have attracted much interests in academic researches and technical industries. This work provided a novel of amphiphilic hairy nanoparticles (APNPs) with distinct pH and ionic dual‐responsiveness based on silica nanoparticles as the core, amphiphilic‐polymeric chains containing amine‐moieties, and carboxylic groups as the layer by a facile emulsion polymerization. The structural parameters of APNPs were characterized by combining thermal gravimetric analysis, infrared spectroscopy, proton nuclear magnetic resonance, transmission electronic microscopy, and dynamic light scattering. The polymeric shell in water was compressed due to proton‐transference from carboxylic groups to amine‐moieties, where APNPs behaved as colloidal particles. By adding HCl, carboxyl groups were deionized, whereas the electrostatic repulsion of protonated amine‐moieties between the neighboring chains expanded the polymeric shell, and thus APNPs self‐assembled into a typical viscoelastic fluid. APNPs reconstructed into branch‐like viscoelastic gel in the presence of cationic ions under alkaline environment. Such transformation was reversible by adjusting the pH of APNPs dispersion. APNPs might have potential application in enhanced oil recovery of unconventional reservoirs because of their original low viscosity for desirable injectivity from ground to micro‐nanopores of subsurface, and the dramatic increase in viscosity for mobility control triggered by pH and ionic ions. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Residence Time Distribution and Specific Mechanical Energy in Solid‐State Shear Pulverization: Processing‐Structure‐Property Relationships in a Chilled Extruder
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-18
    Philip R. Onffroy; Evan V. Miu; William J. Confer; Caleb M. Darkes‐Burkey; William C. Holler; Katsuyuki Wakabayashi

    Solid‐state shear pulverization (SSSP) is a continuous polymer processing methodology based on a modified twin‐screw extruder. The unique application of low barrel temperatures and mechanochemistry has contributed to the development of an extensive range of polymer‐based materials, from environmentally responsible polymer blends to nanocomposites, for more than 30 years. The complex processing‐structure‐processing relationships in SSSP can be elucidated by way of integrated, measured covariants that capture the interplay between numerous processing parameters. Residence time distribution and specific mechanical energy are evaluated in a base case polypropylene (PP) study under a full factorial experiment involving screw design, screw speed, and throughput parameters. These factors are in turn correlated to dispersion morphology and thermal property results from a parallel study based on a model PP/carbon black composite. This investigation highlights the tunability of SSSP processing parameters for tailored output with desired purposes and applications. In particular, enhanced residence distribution can be achieved with low screw speed and high throughput settings, leading to high levels of material mixing and shear. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Optical and Mechanical Properties of Nanocomposite Films Based on Polymethyl Methacrylate (PMMA) and Fumed Silica Nanoparticles
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-17
    Chi‐Ping Li; Robert C. Tenent; Colin A. Wolden

    Nanocomposite polymer films are prepared by using ultrasonic spray deposition (USD) technique through mixing polymethyl methacrylate as matrix and fumed silica nanoparticles as second phase in dimethyl carbonate solvent. Annealing procedure improves the film uniformity and optical transmission. The addition of fumed silica nanoparticles impedes the transmission of the electrolyte films due to agglomeration of fumed silica nanoparticles. Fortunately, adding surfactant, cetyltrimethylammonium bromide, disperses the fumed silica nanoparticles and retrieves the optical transmission of nanocomposite polymer films to around 90%. The hardness and elastic modulus of the nanocomposite polymer films are better than the commercial bulk. The USD deposited nanocomposite polymer film comprises of PMMA and fumed silica nanoparticles is a promising candidate of solid‐state electrolyte for EC windows application. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Direct Observations on Structure Evolutions in Polyamide 6 during Deformation at High Temperatures with WAXS and SAXS
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-17
    Huilong Guo; Jingqing Li; Jiayi Wang; Yanfeng Meng; Zhonghua Wu; Shichun Jiang

    The deformation induced structure evolutions of polyamide 6 (PA6) during uniaxial tension at high tensile temperatures (60 °C and 90°C) were investigated with in situ wide‐ and small‐angle X‐ray scattering (WAXS and SAXS) technologies. The obtained data on structure evolutions revealed that they were different from the results measured at low temperature (30 °C). The α‐phase got oriented once upon the beginning of deformation. After yielding the γ‐phase started to be oriented following the α‐phase. While, the breakdown of PA6 crystals along a and c axis overcame partial crystalline orientation at the high tensile temperatures (60 and 90 °C). The competition between stretch of amorphous phase and slippage of lamellae after yielding affected the deformation behavior of PA6. The collapse of lamellae was also confirmed from SAXS analysis and such disrupted lamellar structure resulted in the decrease of long spacing of PA6. The results showed that PA6 materials may show higher ductility at high temperatures. Therefore the crystals could be broken more easily and the formed lamellar fragments of PA6 could be preserved at larger strain at 90 °C. In addition, the yielding of PA6 and γ‐phase orientation depended on the lamellar slippage during the deformation. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Evaluation of Mechanical and Thermal Performance of Polyethylene Terephthalate Recycled Ribbon and Carbon‐Reinforced Compatibilized Polypropylene
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-17
    Abul B.M. Saifullah; Venkata V.K. Inampudi; Mostafa Nikzad; Igor Sbarski; Manwar Hussain

    Polypropylene (PP) and polyethylene terephthalate (PET) are the two most widely used plastics, which are not compatible with recycling as a blend. In this research work, two different compositions of recycled PP/PET ribbon 65/35 (v/v %) and 78/22 (v/v%) along with 5% (wt%) of polypropylene‐grafted maleic anhydride (PP‐g‐MAH) as compatibilizer were blended, 2– 5 wt% of carbon fiber (CF) was further added for reinforcement. The compositions of these materials are mechanically mixed and extruded by a twin‐screw extruder to make pellets. These pellets are then used to produce standard samples by injection molding for evaluation. The molded samples were tested under tensile, flexural and impact loads to evaluate mechanical properties. Scanning electron microscopy (SEM) was conducted on the fracture surface of the impact‐tested samples to understand polymer blend morphology. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) also carried out to check the thermal properties, mainly transition temperatures (Tg) and heat flow. These test results compared, which show substantial improvement in mechanical properties by adding CF and compatibilizer, without much change in transition temperatures. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Determination of the pressure dependence of polymer melt viscosity using a combination of oscillatory and capillary rheometer
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-11
    Sumanta Raha, Harindranath Sharma, M. Senthilmurugan, Sumanda Bandyopadhyay, Prasanta Mukhopadhyay

    For an accurate simulation of a high‐pressure injection molding process by using the CAE software, it is important to understand the pressure sensitivity of a polymer's melt viscosity. The current work describes a method for the determination of the pressure dependence parameter D3 of the Cross‐WLF model. It uses a combined rheological technique using both dynamic and capillary rheometers. Three grades of polycarbonate homopolymers were studied in this work and their complex viscosities were measured using a dynamic shear rheometer. The dynamic data were used to obtain six out of the seven parameters of the Cross‐WLF, except D3. A capillary rheometer fitted with a counter pressure chamber was further used to characterize the pressure dependence of the zero shear viscosity and to determine the D3 parameter. Finally, the derived parameters were validated by carrying out injection molding with a box tool and comparing the actual pressure profiles with simulation results using the Autodesk® MoldFlow® software. The validation results indicated that actual pressure profiles from the simulation were found to be less than 10% than that of injection molding. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Preparation of Polymer‐Based Nanocomposites Composed of Sustainable Organo‐Modified Needlelike Nanoparticles and Their Particle Dispersion States in the Matrix
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-10
    Shuhei Hirayama, Takuto Hayasaki, Rei Okano, Atsuhiro Fujimori

    Polymer‐based nanohybrid materials were created using sustainable sepiolite clay composed from ubiquitous elements. Although sepiolite is generally recognized as a fibrous natural clay mineral, it turned out to be an acicular microcrystal because of the organo‐modification of the outermost surface. Surface modification was performed using phosphonic acid derivatives containing hydrocarbon chains or fluorocarbon chains. Formation of a bidentate bond enhanced the desorption temperature and made nanocomposite preparation possible by melt compounding with polymers having a high melting point. As a result of organo‐modification, amphiphilic sepiolite was obtained, and nanodispersion in an organic solvent was achieved. This technology was useful for detailed evaluation of sepiolite morphology. The nanocomposite of crystalline polymers/organo‐modified sepiolites achieved uniform dispersion of these nanofillers in the matrix polymer. The introduction of 1 wt% nanofillers did not impair the transparency of the matrix polymer. As a result, a lamellae structure of the polymer developed, the crystallinity increased, and the mechanical properties improved. In addition, the crystallization temperature was improved, indicating that organo‐modified sepiolites may act as a nucleating agent. It was found that sepiolite nanofiller with a highly aggregated tendency can achieve a well‐nanodispersed state, even in phase‐separable fluoropolymers, by applying fluorocarbon modification. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Improvement of the dispersity of micro‐nano particles for PP/PVC composites using gas‐assisted dispersion in a controlled foaming process
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-10
    Ying‐Guo Zhou, Xu‐Dong Zhao, Bin‐Bin Dong, Chun‐Tai Liu

    Polyvinyl chloride (PVC) and nanosilicon dioxide (nano‐SiO2) were blended with neat polypropylene (PP) to improve its flame retardancy and cellular foam structure, and the dispersal effects of PVC and nano‐SiO2 and the foaming effect of the PP/PVC composites were investigated. PP/PVC samples with different compositions and foaming degrees were first fabricated by conventional injection molding with and without a blowing agent. Tensile testing, differential scanning calorimetry, scanning electron microscopy, limiting oxygen index testing, and vertical burn testing were used to study the mechanical properties, thermal features, microstructures, and flame‐retardant properties of the molded samples, and the samples with different degrees of foaming were compared. The results suggest that the foaming process facilitates the dispersion of PVC and nano‐SiO2, while the presence of PVC and nano‐SiO2 improves the foamability of PP. A method for a gas‐assisted dispersion technology to control the foaming process was hence proposed. Considering that the mechanical properties of PP/PVC could be retained with satisfactory flame retardancy and weight loss, convenient processing, and low‐cost materials; the technology presented can be directly applied for lightweight engineering and the manufacture of fire‐resistant material and can act as a reference for other micro‐nano processing involving the dispersion of particles. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Melt Mastication of Isotactic Polyproyplene for Improved Thermal and Physical Properties
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-05
    Brian M. Cromer, Edward Bryan Coughlin, Alan J. Lesser

    Herein a new polymer processing method referred to as Melt‐Mastication (MM) is presented as way to substantially improve the thermal and mechanical properties of Polypropylene (iPP) and other semi‐crystalline polymers. MM is a low temperature mixing technique that subjects molten iPP to chaotic flow under at temperatures between the melting and crystallization temperatures, thereby promoting flow induced crystallization (FIC). The resulting materials demonstrate an unusual crystal morphology that is highly crystalline by thermal calorimetry (57% crystal volume fraction), melts at a temperature 10.3 K higher than conventionally processed iPP, and demonstrates melt memory after annealing at 200°C. The highly crystalline morphology does not show birefringence in polarized optical microscopy and by SEM and AFM appears to be comprised of largely disorganized lamellar crystals, with possible stacked ordering in local (~1 μm) regions. Melt‐Masticated iPP demonstrates improved compressive modulus (+77%), strength (+40%), and strain hardening modulus in uniaxial compression, which are attributed to enhanced crystal volume fraction, lamellar crystal thickness, and network connectivity, respectively. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Kinetics of dynamic percolation in polymer/carbon composites
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-05
    Muhammad Azeem Arshad, AbdelKrim Maaroufi

    Dynamic percolation differs from static percolation in polymer composites owing to its occurrence at a particular filler fraction under thermal activation. Mechanistic insights into dynamic percolation might lead to develop polymer composites with controlled electrical properties at lower filler fractions and improved temperature coefficient of resistance phase transitions. Although attempts have been made to kinetically describe the dynamic percolation in polymer composites, a generalized mechanism‐based approach has not yet been reported. In this article, a systematic and generalized theoretical approach to kinetically model the dynamic percolation in polymer/carbon composites has been put forward. Based on the proposed approach, a kinetic expression to predict the quasi‐thermodynamic equilibrium state in a polymer/carbon composite at constant temperature is derived. The soundness of the proposed approach is justified by its effective applications on poly(vinylidene fluoride)/multiwalled carbon nanotube (PVDF/MWNT), poly(vinylidene fluoride)/carboxyl‐functionalized MWNT (PVDF/MWNT), high‐density polyethylene/carbon black, and poly(methyl methacrylate)/carbon black composites. Certain mechanistic complexities of dynamic percolation are also pointed out and discussed. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • The Effect of Different Smoke Suppressants with APP for Enhancing the Flame Retardancy and Smoke Suppression on Vinyl Ester Resin
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-03
    Xin Zhang, Weiwei Zhang, Gaofeng Zeng, Jianxin Du, Wenchao Zhang, Rongjie Yang

    Flame retarded and smoke suppressed vinyl ester resin (VER) were prepared through ammonium polyphosphate (APP) coupled with different smoke suppressants. The flame retardancy of these composites was tested by the limiting oxygen index and UL‐94 tests. The typical combustion parameters including heat release rate (HRR), peak of HRR (p‐HRR), total heat release, smoke production rate, and total smoke production were detected using a cone calorimeter. The smoke suppressants CaCO3, ZnMoO4, Cu2O, and Fe2O3 show different effect on flame retardancy and smoke suppression of VER composites when they are coupled with APP, the synergistic action of APP and CaCO3 is more effective on decreasing the HRR and smoke release rate than several other smoke suppressants. This is attributed to the fact that CaCO3 could promote the formation of a dense carbon layer with high thermal stability and anti‐oxidation property, which could act as an effective physical barrier. The flame retardant performances and mechanisms of APP and CaCO3 were evaluated and analyzed at length by thermogravimetric coupled with a Fourier transform infrared spectrometer (FTIR), scanning electron microscopy, FTIR, and X‐ray diffraction. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Mechanisms and Conditions that Affect Phase Inversion Processes. The Case of High‐Impact Polystyrene
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-03
    Juan M. Maffi, Natalia Casis, Pablo Acuña, Graciela Morales, Diana A. Estenoz

    The phase inversion (PI) during the bulk polymerization of the styrene–polybutadiene system (high impact polystyrene manufacturing process) is empirically and theoretically studied in this article. In the experimental work, a series of reactions were performed with benzoyl peroxide as initiator and at temperatures considered of industrial interest (80°C and 90°C), varying also the reactor stirring level. PI was determined by offline viscosity measurements and verified by scanning transmission electron microscopy. The rheological behavior of each reacting system was analyzed and an empirical correlation to predict its apparent viscosity from fundamental reaction parameters was derived. This was achieved successfully for both before and after the PI point. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Deformation Phenomena of Thermoplastic Materials in the Solid and Semifluid States
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-03
    Angel Andrés Leal

    The deformation phenomena of a thermoplastic elastomer, a polyamide 12 and a polyketone, are analyzed to identify the polymer characteristics that enhance the processability of a material both at temperatures around the melting point (i.e., in a semifluid state) and at temperatures close to ambient conditions. Dissipation factor isotherms in the frequency range associated with hot compaction, used in conjunction with a hot‐pressing technique that identifies the minimum temperature required for significant chain mobility during hot compaction, allow to evaluate the processability in the semifluid state. The experiments show that optimal processing by hot compaction is achieved when tan δ > 2 for the entire frequency range under consideration. Showing superior processability with respect to the other two polymers, the polyamide 12 is then compounded with a polyamide 12‐based elastomer to tune its stiffness and toughness in tension and bending, enhancing its cold forming characteristics. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Physico‐Chemical Characterizations of Poly(vinylidene fluoride)/Cu3(BTC)2 Composite Membranes Prepared by In Situ Crystal Growth
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-12-02
    Nadhem Missaoui, Gérald Chaplais, Ludovic Josien, Laure Michelin, Gautier Schrodj, Ayoub Haj Said

    In this work, we present a simple and fast method for elaborating hybrid membranes by growing metal–organic framework crystals inside a polymer solution. The solution thus obtained was casted then annealed at 90°C for 5 h. This method was tested with poly(vinylidene fluoride) (PVDF) as a piezoelectric polymer and the Cu3(BTC)2, BTC = 1,3,5‐benzene tricarboxylate, as a filler. The characterization of the obtained membranes by attenuated total reflectance Fourier transform infrared spectroscopy and X‐ray diffraction showed the presence of the characteristic signatures of Cu3(BTC)2 and the β‐phase of PVDF. Moreover, scanning electron microscopy images reveal that the Cu3(BTC)2 crystallites have grown along the PVDF membranes. The effect of the filler on both thermal and mechanical properties of the membranes was also studied. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Analysis of the Processing‐Pressure Dependent Refractive Index of Polycarbonate by Transmission Measurements of Glass‐Filled Specimen
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-29
    Benedikt Roth, Wolfgang Wildner, Dietmar Drummer

    In this study, the influence of pressure during processing on the refractive index (RI) of polycarbonate (PC) was investigated by transmission measurements on glass‐filled samples with a spectrometer. In order to isolate the pressure dependence of the RI from other influencing parameters such as cooling rate, orientation and stress states, the samples were prepared in a pressure‐specific volume‐Temperature (pvT) instrument under constant cooling rate and temperature history and without shear effects. Subsequently, the RI was determined at the intersection of the dispersion curves of the glass and the polymer by evaluating the wavelength of the maximal transmission of the samples. The mean RI over the entire cross section of the sample is determined by the transmission measurements without complex sample preparation. The investigations show that the RI of PC increases by 3.26 E‐6 per bar with increasing pressure. POLYM. ENG. SCI., 2019. © 2019 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.

  • Influence of Macromolecular Brushes with Polyimide Backbones and Poly(methyl methacrylate) Side Chains on Structure, Physical, and Transport Properties of Polyphthalamide
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-27
    Nadezhda S. Tian, Tamara K. Meleshko, Galina A. Polotskaya, Iosif V. Gofman, Anna V. Kashina, Nina V. Kukarkina, Elena N. Vlasova, Zoolsho F. Zoolshoev, Alexander V. Yakimansky

    Composite films based on polyamide (poly(m‐phenylene‐iso‐phthalamide)) (PA) and a brush‐like polymer with polyimide (PI) backbone and side poly(methyl methacrylate) chains (PI‐PMMA) were prepared by mixing individual solutions of PA and PI‐PMMA and subsequent film casting. Macromolecular brushes with the same backbone length and density of side chains but with various lengths of side PMMA chains were synthesized via activator generated by electron transfer atom transfer radical polymerization. Interactions between PA and PI‐PMMA, as well as distribution of PI‐PMMA filler inside the PA matrix, were studied by viscometry, dynamic light scattering, differential scanning calorimetry, scanning electron microscopy, and IR spectroscopy. The mechanical properties of polymer samples were also investigated. Microphase separation was revealed in PA/PI‐PMMA films. The length of side chains influences interactions between PA and PI‐PMMA. At the same time, the degree of reduction in the rigidity parameters and in the elasticity parameter depends on the side chain length. Diffusion membranes were prepared on the basis of compositions with the best mechanical properties; these membranes proved to be highly efficient in pervaporation of methanol–hexane mixture. It was established that the fluxes and separation factors of the studied membranes are several times higher as compared to the corresponding characteristics of known commercial membranes. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Preparation, Characterization, and Separation Performances of Novel Surface Modified LbL Composite Membranes from Polyelectrolyte Blends and MWCNT
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-26
    Merve Arslan, Göknur Dönmez, Ayça Ergün, Merve Okutan, Gülşen Albayrak Arı, Hüseyin Deligöz

    Here, it was aimed to modify the surface of NF90 with layer by layer (LbL) blended poly(allylamine hydrochloride) (PAH)‐chitosan (CHI) and poly(acrylic acid) (PAA) with/without functionalized multiwalled carbon nanotube (fMWCNT) for reverse‐osmosis applications. Using Quartz Crystal Microbalance Dissipation monitoring, it was observed that PAH‐CHI/PAA LbL films grew linearly after a few bilayers and no LbL film degradation occurred during synthetic seawater treatment. Thermal degradation of all LbL blended membranes was similar. NF90 had a heterogeneous surface while the surface of LbL blend membranes exhibited some agglomerations due to the polyelectrolyte (PE) complex formation and fibrillary appearance depending on the use of fMWCNT. [(PAH50‐CHI50/(PAA‐fMWCNT)]30 indicated the highest flux with 14.5 L m2 h−1 at 40 bar. The sodium and chlorine ion rejections were 75% and 87%, respectively, for the same membrane. The use of fMWCNT led to a significant enhancement in flux with a slight decay in ion rejections. On the other hand, chlorine ion rejection of [(PAH50‐CHI50/(PAA‐fMWCNT)]30 decreased by 25% at 40 bar while 60 and 90 bilayers of [(PAH50‐CHI50/(PAA‐fMWCNT)] disintegrated after NaOCl treatment. Briefly, the flux and ion rejections of the LbL blended membranes can be controlled depending on the use of fMWCNT and different PE couples without multilayer decomposition against synthetic seawater. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Polypropylene/Spray Dried and Silane‐Treated Nanofibrillated Cellulose Composites
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-22
    Ceren Tabak, Serhat Keskin, Tughan Akbasak, Guralp Ozkoc

    In this study, the spray dried nanofibrillated cellulose (NFC) was modified by a silane coupling agent to be used in polypropylene (PP)‐copolymer matrix in the presence of maleic anhydride grafted PP (PP‐g‐MAH) compatibilizer. The PP/NFC composites were melt compounded and injection molded. In the first stage, the NFC was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). It was shown that fibrillation in aqueous media through high‐pressure homogenization was successfully achieved. The nanofibrils having diameter smaller than 50 nm were obtained. The X‐ray photo electron spectroscopy (XPS) showed the presence of the silane groups on the NFC surface. Elastic modulus improved by the addition of the high modulus NFC to PP, but the yield strength was not improved. On the other hand, different than many inorganic micron‐sized fillers, the elongation‐at‐break value did not drop much. Differential scanning calorimeter experiments indicated that the NFC acted as a nucleating agent. Rheological investigations exhibited that NFC decreased the viscosity of the PP. The addition of NFC to PP improved the thermal resistance of the PP as can be understood from the TGA experiments. It was demonstrated that renewable nanofiller can be a feasible method to functionalize the existing synthetic polymers. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • A Novel Approach to Investigating Effect of Sulfur as a Coagent on the Quasi‐Static and Cyclic–Dynamic Fatigue Properties of Peroxide Cured EPDM
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-22
    Huimin Zou, Guixue Qiu, Guangyong Liu, Matthias Soddemann, Jiayong Xu

    The effect of sulfur on the quasi‐static and cyclic–dynamic fatigue properties of ethylene propylene diene monomer (EPDM) after three fatigue cycles were investigated under two specially designed test programs. The results turned out that sulfur as a coagent slowed down the vulcanization rate of EPDM compounds and reduced the chemical crosslinks. Further study on the effect of sulfur on the crosslinking behavior showed that this effect could be quantitatively described in linearity and became more distinct at higher crosslinking density. The addition of sulfur as a coagent improved the tearing performance of EPDM as a result of newly generated polysulfur bonds (Sx). The strain and frequency sweep procedures were designed to study the dynamic rheological behavior and we obtained that the storage modulus of EPDM depended less on the addition of sulfur as well as sweeping temperature in sulfur‐assisted curing system. The changes of loss factors obtained from the two sweep procedures were employed to survey the dynamic fatigue properties of EPDM, indicating that the fatigue behavior depended more on peroxide dosage than sulfur content, which might be due to the smaller proportion of polysulfur bridges in the final crosslinking structures of EPDM. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

  • Effect of Thermoplastic Starch and Photocrosslinking on the Properties and Morphology of Electrospun Poly(ethylene‐co‐vinyl alcohol) Mats
    Polym. Eng. Sci. (IF 1.92) Pub Date : 2019-11-22
    Margarita Mondragón, Oliver López‐Villegas, Saúl Sánchez‐Valdés, Francisco Javier Rodríguez‐González

    Nonwoven fibrous mats of poly(ethylene‐co‐vinyl alcohol) (EVOH) and thermoplastic starch (TPS) blends were successfully prepared through the electrospinning technique using a mixed solvent system of isopropyl alcohol and water. The influence of TPS on the morphology and structure of the fibrous mats was investigated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. The addition of TPS to EVOH resulted in beaded electrospun fibers. The SEM images revealed decreasing average width of the blend fibers and increasing quantity of beads with an increased TPS content. EVOH/TPS fibers mats irradiated under ultraviolet light using sodium benzoate as a photosensitizer were also prepared. The size and number of beads were diminished in the photocrosslinked EVOH/TPS fiber mats. The as‐spun and crosslinked EVOH/TPS fiber mats exhibit a superior fluid uptake ability (with 20 wt% of TPS) and superior barrier properties (with 20 and 40 wt% of TPS) in comparison to those observed in neat electrospun EVOH mats. These properties are of particular interest for use in dressing materials for the medical industry and for use in multilayer plastic fuel tanks for the automotive industry, respectively. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers

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