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  • Catalytic Application of Silver Nanoparticles in Chitosan Hydrogel Prepared by a Facile Method
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-24
    Mohammad Sherjeel Javed Khan, Sher Bahadar Khan, Tahseen Kamal, Abdullah M. Asiri

    Abstract In this research work, a simple method of silver nanoparticles’ self-synthesis in chitosan (CH) biopolymer hydrogels without utilizing a reducing agent is shown. The synthesized material was used as a catalyst in different reduction reactions. For this purpose, different amounts of CH powder were dissolved in acidic aqueous solutions and then crosslinked it with the formaldehyde solution to make a CH biopolymer hydrogel. Among all the prepared samples, a CH hydrogel prepared from a dense solution was found to be suitable for this study because of good mechanical stability. For the self-synthesis of silver nanoparticles inside hydrogel, it was immersed in an aqueous solution of AgNO3 (10 mM) for 3 days at room temperature. The color of the chitosan hydrogel changed to brown from transparent which indicated the successful formation of silver nanoparticles on CH hydrogel (Ag-CH). No reducing agent for conversion of the Ag1+ ions to nanoparticles in this whole synthesis method. Instrumental techniques such as FESEM, XRD and EDX analysis confirmed the successful preparation of Ag-CH. The Ag-CH was checked as a catalyst in the 2-nitrophenol (2-NP) and acridine orange (ArO) reduction reactions. Both reactions were carried out at high rate constants (2-NP = 0.260 min−1, ArO = 0.253 min−1) by using the Ag-CH hydrogel catalyst. In addition, we discussed the mechanism of action of the reducing agent, the effect of kapp on the two reduction reactions of Ag-CH and the recyclability.

  • A Review of the Sustainable Approaches in the Production of Bio-based Polyurethanes and Their Applications in the Adhesive Field
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-22
    Adrián Tenorio-Alfonso, Mª Carmen Sánchez, José Mª Franco

    Abstract On account of the irreversible environmental damage caused by the utilization of non-renewable raw materials in industrial production, since the end of the twentieth century, the interest in replacing the traditionally applied petroleum-based starting compounds in the polyurethane production by more sustainable feedstocks has grown enormously. Such pursuit of Green Chemistry has been fostered by the implementation of a set of national and international initiatives and stricter regulations, especially in the field of adhesives. In this respect, the latest advances in the production of bio-based polyurethanes are collected in this review. Thus, after a brief introduction to this subject and main tendencies towards the production of more sustainable polyurethanes, the first section reviews the feasibility of manufacturing polyurethanes from a range of natural platforms, including lignocellulosic biomass and vegetable oils, whether modified or in their original form, along with some industrial wastes. Afterwards, the hitherto considered synthetic routes for the preparation of greener polyurethanes are assessed, encompassing waterborne, radiation-curable and non-isocyanate polyurethane techniques. Finally, the last section focuses on the research advancement on the synthesis, properties and different uses of bio-based polyurethanes specifically implemented in the field of adhesives.

  • Flame Retardant Properties and Thermal Stability of Polylactic Acid Filled with Layered Double Hydroxide and Rice Husk Ash Silica
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-20
    Chuenkhwan Tipachan, Rakesh K. Gupta, Sushant Agarwal, Somjai Kajorncheappunngam

    Abstract Polylactic acid (PLA) samples containing a layered double hydroxide modified with sodium dodecyl sulfate (PKL_DS), silica from rice husk ash (SiRHA) and a combination of the two nanofillers were prepared by both solvent casting and a more practical approach involving dry blending of constituents and their melting in a mixing tank followed by compression molding. The morphology of the nanocomposite films was investigated using transmission electron microscopy (TEM) and X-ray diffraction (XRD), and it was confirmed that the nanocomposite structures were intercalated. Additionally, SEM pictures of surfaces of nanocomposite films suggest that PKL_DS was well dispersed throughout the PLA matrix, and the films were essentially featureless except at the highest concentration examined. In the case of SiRHA, there was filler aggregation at low concentration, while holes and cavities were clearly visible at higher concentrations. The addition of PKL_DS to films containing SiRHA ameliorated these effects, and ultimately a dense structure was obtained. From TGA results, it was determined that only the addition of SiRHA significantly improved the thermal stability of PLA. The flammability performance of PLA nanocomposites was investigated using limiting oxygen index (LOI) and UL-94V type measurements. A maximum LOI value of 32.8% could be achieved for PLA nanocomposites containing 10 wt% PKL_DS and 5 wt% SiRHA. This was 78% higher than the LOI of neat PLA alone. Furthermore, PLA containing 10 wt% PKL_DS and 3–5 wt% SiRHA attained a V-0 rating on UL-94 type tests with anti-dripping behavior. It was found that there was synergism between PKL_DS and SiRHA, and this was very effective in improving the flame retardant performance of PLA. That this performance came about without having to completely exfoliate the nanofillers is a remarkably useful result.

  • Arsenic Sorption on Chitosan-Based Sorbents: Comparison of the Effect of Molybdate and Tungstate Loading on As(V) Sorption Properties
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-17
    Pamela V. Sierra-Trejo, Eric Guibal, José F. Louvier-Hernández

    Abstract Modified chitosan gel beads, prepared by molybdate and tungstate coagulation methods, were tested for As(V) removal from solutions in the range of 5–200 mg As L−1. The sorbent is efficient at removing As(V) from acid solutions (optimum pH close to 3), the sorption capacities for As uptake in molybdate- and tungstate-loaded beads are 75 and 44 mg As g−1 of dry mass, respectively. The mechanism of As(V) sorption is related to the ability of molybdate and tungstate ions to complex As(V) ions in acid solutions. As(V) sorption process is mainly influenced by the presence of phosphate ions, but there is no influence of co-ions as nitrate and chloride. Arsenic desorption can be performed using phosphoric acid solutions. Arsenic adsorption proceeds in acidic solutions with a partial release of molybdate and tungstate and with residual concentrations of arsenic above the regulations for drinking water. For that reason, this material is a candidate for the treatment of industrial effluents. Graphic Abstract

  • Cardanol-Imidazole Based Benzoxazine Blends and Bio-silica Reinforced Composites with Enhanced Surface, Thermal and Dielectric Properties
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-10
    Govindraj Latha, Arumugam Hariharan, Pichaimani Prabunathan, Muthukaruppan Alagar

    Abstract In the present work, imidazole core mono-amine (ima) was synthesized and used with cardanol (C) and bisphenol-F (BF) to obtain corresponding benzoxazines (C-ima and BF-ima) respectively. Similarly aniline (a) was used as amine precursor for synthesis of benzoxazines (C-a and BF-a) of cardanol (C) and bisphenol-F (BF) respectively for the purpose of blending and comparative studies with ima based benzoxazines. Benzoxazines (C-ima, C-a, BF-ima and BF-a) matrices and blends were prepared using both monofunctional and bifunctional benzoxazines in different weight percent (25/75 wt%, 50/50 wt% and 75/25 wt%) ratios and were characterized using different analytical techniques. From DSC analysis, it was observed that the curing temperature obtained for imidazole based benzoxazines (C-ima and BF-ima) was significantly lower than that of benzoxazines (C-a and BF-a) made using conventional aniline. Similarly, the blends prepared using ima based benzoxazine possess the lower curing temperature, with enhanced thermal stability and char yield than those of conventional cardanol-aniline benzoxazines to an appreciable extent. Hybrid blend composites were developed by reinforcing varying weight percentages (1, 3, 5, 7 and 10 wt%) of GPTMS functionalized bio-silica with selected blends (50:50) of imidazole based benzoxazines (C-ima and BF-ima) and their properties were studied. Data obtained from different studies, suggest that these hybrid composites possess an enhanced thermal stability, higher values of Tg, improved hydrophobic behavior, higher value of char yield and lower dielectric constant than those of neat matrices and blended matrices. It is concluded that the imidazole amine based benzoxazines (C-ima and BF-ima) blends and hybrid composites developed in the present work possess better properties than those of conventional benzoxazine based materials, hence it is suggested that these blends and composites can be used for high performance thermal and dielectric applications.

  • Design of AgNPs -Base Starch/PEG-Poly (Acrylic Acid) Hydrogel for Removal of Mercury (II)
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-10
    Atefeh Saberi, Mohammad Sadeghi, Eskandar Alipour

    Abstract In the present study, we introduce the formation of Starch/PEG-poly (acrylic acid) hydrogel (St-PEG-AcAH) and nanocomposite of AgNPs-base St-PEG-AcAH (AgNPs-St-PEG-AcANCH) free radical method, and their characterization using analytical techniques of FT-IR, TEM, SEM, EDX, AFM, XRD, TGA/DTG. The thermodynamic parameters and application of prepared hydrogels was investigated for the removal of Hg2+ ions in water and the various solvents such as ethanol-water (30:70), ethanol-water (50:50), 2-propanol–water (40:60), respectively. The maximum adsorption capacity of Hg2+ ions for St-PEG-AcAH and AgNPs-St-PEG-AcANCH was achieved 158.21 mg/g and 182.53 mg/g in pH 7 and 6 in aqueous solutions, respectively. On the other hand, the results of adsorption isotherms revealed that adsorption process for both adsorbents occurred as a homogenous and monolayer process with L-shape isotherm. Furthermore, investigating the bioactivity of bioadsorbents, the good antimicrobial efficiency of the prepared samples was confirmed on E. coli bacteria.

  • Effect of Liquefied Lignin Content on Synthesis of Bio-based Polyurethane Foam for Oil Adsorption Application
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-09
    Raziyeh Mohammadpour, Gity Mir Mohamad Sadeghi

    Abstract The present study focused on synthesizing polyurethane foams with different contents of liquefied lignin. To fulfill that, the weight ratios of liquefied lignin to polypropylene glycol triol (PPG as chain extender) were altered from 25 to 100%. The lignin based polyurethane foams (LPUFs) were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), scanning electron microscopy (SEM), and compression strength test. The experimental results revealed that LPUFs structures became more disorganized and their density diminished while their heat stability increased with increasing lignin polyol content. Moreover, the specific compressive properties of LPUFs grew from 1.35 to 35.23 kPa Kg−1 m3 and their glass transition temperature elevated from 38.5 to 90 °C with an increase in lignin polyol due to the three-dimensional lignin structure. Finally, the oil adsorption behavior of LPUFs was studied with Langmuir, Freundlich and Redlich–Peterson isotherms. It was observed that oil adsorption properties enhanced for LPUFs with higher contents of lignin polyol. The current work demonstrated that lignin polyol in polyurethane formulation even up to high concentrations, can be appropriately used in the production of soft and rigid bio based foams for different applications such as bio-friendly oil absorbent.

  • Starch/Poly(butylene succinate) Compatibilizers: Effect of Different Reaction-Approaches on the Properties of Thermoplastic Starch-Based Compostable Films
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-11-11
    Barbara Fahrngruber, Marta Fortea-Verdejo, Rupert Wimmer, Norbert Mundigler

    The property profile of thin thermoplastic starch (TPS)/poly(butylene succinate) (PBS) films was investigated and the potential improvement, which can be achieved due to the utilization of hydrophilic/hydrophobic compatibilizer systems, was assessed. The evaluation in terms of morphology exhibited a very good TPS dispersion (under optimized processing conditions) within the polyester matrix, while an average particle size of 1.5 µm was obtained. Two different raw material approaches were applied for the preparation of the compatibilizers: (a) native corn starch and (b) destructurized TPS. In the course of the compounding process 0.5 and 1.0 wt% of the two compatibilizer systems (a) and (b) were added. In comparison, the addition of the TPS-based compatibilizer resulted in improved incorporation of TPS within the polyester matrix, which was accompanied by higher tensile strength and tear resistance. Explanations for this observation could be that pre-plasticized starch provides a larger reaction surface and enables better homogenization during the course of compounding. In contrast, for native starch the reaction only can take place at the granule surface and thus, the compatibilization was less efficient. The outcome of this investigation is a compostable film material with high bio-based content, which exhibits great potential for single-use, light-weight packaging applications.

  • The Effect of Hydroxyapatite Prepared by In Situ Synthesis on the Properties of Poly(Vinyl Alcohol)/Cellulose Nanocrystals Biomaterial
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-26
    Panee Panyasiri, Nga Tien Lam, Prakit Sukyai

    Polyvinyl alcohol/cellulose nanocrystals (CNC) and hydroxyapatite (HA) (PCH) were combined using an in situ method to fabricate porous scaffolds. CNC was extracted from sugarcane bagasse and the effect of HA on PVA/CNC composites was varied with 0, 0.5, 1 and 3 wt%. The scanning electron microscopy images of the PCH composites showed interior pores with pore channels, while the energy dispersive spectroscopy (EDS) results confirmed the increased HA content in the nanocomposite with a Ca/P ratio of 1.67. Porosity and the equilibrium swelling ratio were slightly affected by the HA content. The Fourier transform infrared spectra supported the EDS results by identifying significant peaks belonging to the HA curves of the PCH composites. The crystallinity revealed decreased crystal regions at higher HA content, whereas the mechanical behavior showed the improvement at 0.5 wt% of HA. Cytotoxicity with L929 demonstrated the compatibility of the PCH composites, with 85 ± 0.92% cell viability.

  • Polymer Nanocomposites Based on Poly(ε-caprolactone), Hydroxyapatite and Graphene Oxide
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-11-20
    Gabriela S. Medeiros, Pablo A. R. Muñoz, Camila F. P. de Oliveira, Laura C. E. da Silva, Ritika Malhotra, Maria C. Gonçalves, Vinícius Rosa, Guilhermino J. M. Fechine

    Standard and hybrid polymer nanocomposites based on poly(ɛ-caprolactone) (PCL), hydroxyapatite (HAp) and graphene oxide (GO). The GO synthetized here is made up of multilayer graphene oxide (mGO), in which up to five layers are stacked and lateral size around of 1 µm. The nanocomposites (PCL/Hap, PCL/mGO and PCL/HAp/mGO) were prepared by melt mixing in a twin-screw extruder and characterized by mechanical test, transmission electron microscopy (TEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), contact angle (CA), surface zeta potential by streaming and cell proliferation. The HAp content was maintained at 20% (w/w) while mGO was used at three levels of content (0.05, 0.1, and 0.3 w/w). In terms of bulk properties, the presence of mGO even in very low content (0.05 to 0.3%) was very effective in order to increase mechanical properties of PCL (stress and strain at beak and tenacity) while HAp tends to decrease them. When the two fillers are inserted mGO act to recover the properties lost by the presence of HAp. TEM images showed single GO sheets very well dispersed alone or combined with HAp. For surface properties, significant changes have been achieved by the presence of mGO, HAp and mGO/HAp. The water contact angle drops to values below 90° for all nanocomposites making the material hydrophilic, but again by the presence of only 0.05% of mGO it was reached easily. Surface ξ-potential for all nanocomposite was lower than neat PCL. As a consequence of surface modifications improvements in cell proliferation ability could be also observed. All modification by the presence of GO point out these materials as excellent candidates to resorbable suture, drug delivery system, and bone graft substitutes.

  • Nano-Ag/DLC/Cellulose Free-Standing Films Towards Anti-bacterial and Bio-compatible Futuristic Bandage Applications
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-11-15
    Debabrata Das, Rajkumar Dey, Subhadeep Das, Shamima Hussain, Anup Kumar Ghosh, Arun Kumar Pal

    Abstract Nano-Ag/DLC/cellulose composite free-standing films were deposited by using hybrid chemical routes. Cellulose fibers were extracted from banana pseudostem fibers by chemical route. Modulation of bonding environment on cellulose upon nano-Ag and diamond-like carbon (DLC) inclusions was studied by X-ray photoelectron spectroscopy (XPS), Raman and Fourier transformed infrared spectroscopy (FTIR) measurements. Changes in microstructural and bonding environmental properties of the cellulose films with nano-Ag and DLC loadings were also addressed. These composite films would harness the development of anti-bacterial and bio-compatibility in futuristic bandage applications. Antibacterial studies using Staphylococcus aureus (gram positive) and Escherichia coli (gram negative) bacteria were carried out on the above n-Ag/DLC/cellulose composite films.

  • Enhancing the Thermal, Mechanical and Swelling Properties of PVA/Starch Nanocomposite Membranes Incorporating g-C 3 N 4
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-25
    Arooj Ahmed, Muhammad Bilal Khan Niazi, Zaib Jahan, Ghufrana Samin, Erum Pervaiz, Arshad Hussain, Muhammad Taqi Mehran

    A ground-breaking and soft nanomaterial, namely graphitic carbon nitride (g-C3N4) has gained importance as two-dimensional filler in polymeric membranes. In this research, g-C3N4 was synthesized by “thermal oxidation etching process”, employing melamine as a precursor. The porous nanosheets were characterized by SEM, XRD and FTIR. g-C3N4 nanosheets showed remarkable thermal stability up to 620 °C. The PVA starch nanocomposite membranes were fabricated with varying amounts of g-C3N4. Owing to strong interactions between g-C3N4, and polymers, the composite membranes showed exceptional thermal and mechanical stability and resist to degrade in various mediums including water, saline and blood. The hybrid membranes showed remarkable swelling abilities up to 96 h. Moreover, g-C3N4 enhanced the hydrophilicity, consequently, moisture retention capability and water vapor transmission were improved. XRD and SEM results revealed the proper dispersion of g-C3N4 into the polymeric matrix. The results suggested that prepared hybrid PVA/St/g-C3N4 membranes could be used as wound dressings.

  • Reducing Biochar Particle Size with Nanosilica and Its Effect on Rubber Composite Reinforcement
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-11-19
    Steven C. Peterson, Sanghoon Kim

    Abstract Since biochar is a renewable source of carbon, it has been examined as a substitute for carbon black as rubber composite filler. Although biochar can approach carbon black in terms of carbon and ash content, substituting carbon black with biochar typically degrades the mechanical properties of rubber composites because of the much larger particle size of biochar. Biochar is produced from biomass and must be size reduced by “top-down” methods such as milling. Thus, biochar frequently has populations of particles greater than 10 µm in diameter, which greatly reduce reinforcement properties by introducing localized stresses in the rubber composite. In this work we explore using nanosilica as a co-milling material with biochar as a means to reduce its particle size and consequently improve its ability to replace carbon black as rubber composite filler. Biochar co-milled with 1 wt% nanosilica was able to replace 40% of the carbon black filler in a styrene–butadiene rubber composite with virtually no loss in tensile strength. Also, elongation and toughness properties of the optimal biochar substituted composites were improved by over 31 and 24%, respectively.

  • Recycling of an Agricultural Bio-waste as a Novel Cellulose Aerogel: A Green Chemistry Study
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-11-20
    Mehmet Kaya, Ahmet Tabak

    Abstract Cellulose aerogel (CA) isolated from tea stem wastes (TSW) is a good fire retardant and heat insulator, environmentally friendly, thermally stable and highly porous material with a network structure. These outstanding properties have attracted a huge interest in the materials world. In this study, firstly, following delignification and removing hemicellulose, pure raw cellulose was isolated using TSW, hydrogel form of cellulose was prepared by regeneration of cellulose solution, and then, the final product (CA) was produced via freeze-drying. The data results showed that the aerogel had a three dimensionally network structure. Moreover, it can be deduced that thermal durability of the studied CA could be effective because of its fire retardant and heat insulating property. In addition, the production process of CA is easily available at low cost and sustainable.

  • Graft Copolymerization of Crosslinked Polyvinyl Alcohol with Acrylonitrile and Its Amidoxime Modification as a Heavy Metal Ion Adsorbent
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-26
    Lelin Zeng, Qian Liu, Wenyuan Xu, Guoxiang Wang, Yixue Xu, Enxiang Liang

    Abstract Polyvinyl alcohol (PVA) hydrogel was crosslinked with glutaraldehyde. The crosslinked polyvinyl alcohol (CPVA) was grafted with acrylonitrile using cericammonium nitrate as an initiator (CPVA-PAN), and then modified by hydroxylamine hydrochloride (CPVA-AO-PAN). CPVA, CPVA-PAN, and CPVA-AO-PAN were characterized by Fourier Transform Infrared spectroscopy. Cu2+ adsorption by CPVA-AO-PAN reached the equilibrium at contact time of 40 h with a adsorption capacity of 40.7 mg g−1. The effects of initial metal concentration, adsorption time, and pH on adsorption capacity were investigated, respectively. Pseudo-first-order and pseudo-second-order models were employed to evaluate the adsorption kinetics, with the R2 values of 0.9524 and 0.9972, respectively. Langmuir and Freundlich isotherm models were compared, and the Langmuir model shows high goodness-of-fit. The adsorption process was endothermic and spontaneous, as evidenced by the positive ∆H and the negative ∆G.

  • Effect of Surface Functionalization of SiO 2 Nanoparticles on the Dynamic Mechanical, Thermal and Fire Properties of Wheat Straw/LDPE Composites
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-11-18
    Behzad Kord, Mohammad Dahmardeh Ghalehno, Farnaz Movahedi

    The scope of the present article is to study the effect of surface functionalization of SiO2 nanoparticles on the dynamic mechanical, thermal and fire properties of wheat straw flour (WSF) reinforced low-density polyethylene (LDPE) composites. Firstly, the SiO2 nanoparticles were modified by 3-aminopropyl-trimethoxysilane (APTMS), and then the WSF/LDPE composites containing different percentages of modified nano-SiO2 were prepared via a melt compounding using an internal mixer followed by injection molding. Changes in the chemical structure of treated SiO2 were tracked by Fourier transform infrared (FTIR). The appearance of N–H bond at 695 cm−1 and aliphatic C–H bonds at 2841 cm−1 and 2947 cm−1 were indications of successful grafting of APTMS on the SiO2 nanoparticles. Finally, the viscoelastic behavior, thermal stability and fire retardancy of the nanocomposites were evaluated by means of DMTA, TGA, DSC and CCT techniques. Results indicated that the dynamic modulus of the composites was greatly improved through the addition of functionalized SiO2 nanoparticles. In general, the specimens filled with 3 phr modified nano-SiO2 showed the highest values of storage and loss modulus compared with the other ones. Moreover, the tan δ peak signifying the glass transition temperature of nanocomposites shifted to higher temperature. The TGA results demonstrated that the introduction of APTMS grafted SiO2 nanoparticles can distinctly enhance thermal stability of the composites by increasing the thermo-oxidation decomposition temperature and char residues. The maximum activation energy value represents a higher thermal stability of the nanocomposites was obtained with modified nano-SiO2 at 5 phr content. In addition, the DSC data revealed that both the melting temperature and the degree of crystallinity of the specimens tended to substantially increase in presence of modified nano-SiO2. The surface functionalization of SiO2 particles produced remarkable evolution in the fire performance as indicated by reductions in the heat release rate, burning rate and mass loss rate. Furthermore, promoting the time to ignition and limiting oxygen index of the specimens equally to accommodate the addition of treated SiO2 nanoparticles.

  • The Effect of Simultaneous Radical Polymerization of Poly( N -vinyl pyrrolidone)/α,ω-Bis(methacryloyloxy-poly(ethylene glycol)) on Physical Properties of Marine Polysaccharide
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-28
    D. Enescu, L. M. Pastrana

    In order to expand the application in biomedical field of bio-derived polymers it is imperative that the issues related to their surface properties be addressed. Here we explore the approach of simultaneous radical polymerization to modify the surface properties of chitosan by grafting/crosslinking with poly(N-vinyl pyrrolidone) (PNVP)/α,ω-bis (methacryloyloxy-poly(ethylene glycol) (M-PEG) in the presence of potassium persulfate. The structure of the resultant copolymer membranes was proved by Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry. Scanning Electron Microscopy and Atomic Force Microscopy revealed the crosslinked copolymer membranes are porous materials with pore dimension, distribution and shape depending on the content of vinyl sequences. In addition, was revealed that the presence of vinyl crosslinked sequences linked to CS is disturbing the thermodynamic equilibrium conformation of CS. As a consequence, the ordering of CS chains into crystalline domains is reduced and the planes giving rise to the diffraction peaks are modified. Thus, the resultant copolymer membranes, depending by the weight ratio PNVP/M-PEG, became more amorphous. As a result of the crosslinking, the copolymer membranes were characterized by a smaller water swelling degree (about 300%) as compared with neat chitosan membrane (700%). The thermo-oxidative data have revealed an enhancement of the thermal stability of CS by crosslinking with PNVP/M-PEG copolymers. The water contact angles of the copolymer membranes proved to be more water wettable as compared to neat chitosan membrane.

  • Development of Poly(lactic acid) Nanocomposites Reinforced with Hydrophobized Bacterial Cellulose
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-18
    Jhon Alejandro Ávila Ramírez, Jimena Bovi, Celina Bernal, María Inés Errea, María Laura Foresti

    Poly(lactic acid)/bacterial cellulose nanocomposites were prepared by solvent casting. Aiming to reduce the incompatibility between polar bacterial cellulose (BC) and the nonpolar poly(lactic acid) (PLA) matrix which induces filler aggregation and poor reinforcement dispersion, BC was acetylated by the use of a non-conventional route catalyzed by citric acid. The derivatized BC (AcBC) was incorporated into de PLA matrix at varying filler loadings, and optical, morphological, structural, thermal, tensile and barrier (water vapor) properties of PLA/AcBC in comparison with PLA/BC were evaluated. Noticeable changes in the nanocomposite properties were ascribed to the success of the route proposed to surface hydrophobize BC, which significantly improved its dispersibility within the PLA matrix and the matrix-filler interaction. By the way, the variation of filler loading allowed attaining remarkable increases in the nanocomposite films stiffness without significant reductions in tensile strength and water vapor permeability.

  • Correlation Between Gel Strength of Starch-Based Hydrogel and Slow Release Behavior of Its Embedded Urea
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-06
    Xiaoqi Wei, Xianyang Bao, Long Yu, Hongsheng Liu, Kai Lu, Ling Chen, Lianyang Bai, Xiaomao Zhou, Zhuren Li, Wanming Li

    Starch-based hydrogels have attracted increasingly attention for application in controlled release fertilizers. However, there is currently a lack of knowledge on ways to characterize this system. In this work, we employed a hot-compression vulcanizer to in-situ synthesize monolithic urea-embedded grafted starch hydrogels with a slab geometry, which facilitates the subsequent measurement of gel strength and urea release kinetics. The results revealed that the greater the gel strength induced by a decreased urea load, an increased graft content, and an increased cross-linking density of starch-based hydrogels, the less the initial burst release of embedded urea. The unavoidable burst release could be ascribed to the heterogeneous network structure of starch-based hydrogels. The network of the hydrogels also afforded an zero-order, or at least time-independent, release kinetics of urea at intermediate stable stage, regardless of their microstructural parameters. Our results could provide a guideline to the design of hydrogel-based fertilizer delivery systems.

  • Effect of the Addition of Citric Acid and Whey Protein Isolate in Canna indica L. Starch Films Obtained by Solvent Casting
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-06
    Liliana Ávila-Martín, Ángela A. Beltrán-Osuna, Jairo E. Perilla

    In this study, the effect of the addition of citric acid (CA) and whey protein isolate (WPI) on film properties of the starch extracted from the achira rhizome (Canna indica L.) was evaluated. For this purpose, starch films were prepared by solvent casting with different CA and WPI concentrations. Starch granules were fully characterized and the chemical and thermal behavior of the obtained starch films were also studied. The retrogradation phenomenon was analyzed in films from 1 week to 1 year of preparation. Maximum tensile strength (max) and maximum elongation at break (max), as well as water vapor permeability, were measured for all films. It was found that both molecules, CA and WPI, show a plasticizing effect on starch films, favoring the formation of a more uniform and resistant material by means of hydrogen bonding. A partial crosslinking between CA and starch was found by Fourier transform infrared, which is coherent with a higher degradation temperature peak found by thermogravimetric analysis. It was also observed that starch retrogradation was affected by the presence of both molecules, CA and WPI. The highest max (5.7 ± 0.1 N/mm2) and max (35%) values were achieved at the eighth weeks when both CA (6%) and WPI (11%) were used. Addition of CA and WPI did not show a significant difference in permeability values of starch films (1.40 × 10−9 ± 0.10 g/m s Pa).

  • Towards the Production of mcl-PHA with Enriched Dominant Monomer Content: Process Development for the Sugarcane Biorefinery Context
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-02
    Guilherme H. D. Oliveira, Marcelo Zaiat, José Alberto D. Rodrigues, Juliana A. Ramsay, Bruce A. Ramsay

    The production of short-chain-length polyhydroxyalkanoates (scl-PHAs) in a sugarcane biorefinery setting has been demonstrated to be an effective strategy to reduce production costs. Medium-chain-length PHA (mcl-PHA) have elastomeric properties and are more suitable for high value-added applications, but its industrial production is not yet established. Mcl-PHA synthesis occurs via different metabolic routes and thus requires distinct microorganisms and substrates compared to scl-PHA. In the present study, sucrose-derived carbohydrates were evaluated as co-substrates for the production of mcl-PHA from decanoic acid (DA). Fermentation strategies were investigated to produce mcl-PHA with enriched dominant monomer content, which is desirable for commercial applications. The mcl-PHA production was investigated in carbon-limited, fed-batch fermentations with wild-type and β-oxidation knockout mutant strains of Pseudomonas putida KT2440. The experimental results demonstrated that a mixture of glucose and fructose was a suitable co-feed with DA for mcl-PHA production, yielding equivalent results to those obtained with starch-derived glucose, a more traditional feedstock for PHA production. The use of a β-oxidation-impaired strain was essential to attain high dominant monomer content. A near-homopolymeric mcl-PHA was produced under exponential feeding, containing 99 mol% of 3-hydroxydecanoate. This work demonstrates the potential for near-homopolymeric mcl-PHA production in a sugarcane biorefinery, using hydrolyzed sucrose and DA.

  • New Spray-Dried Microcapsule Based on Brazilian Cashew Polysaccharide ( Anacardium othonianum Rizz.) and Maltodextrin as Wall Material
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-02
    Thâmara M. Silva, Leonardo L. Borges, Suzana F. Alves, Priscila D. S. Vaz, Luciano P. Silva, José R. de Paula, Maria T. F. Bara, Edemilson C. Conceição, Samantha S. Caramori

    Abstract The study describes the microencapsulation of Pterodon emarginatus fruit essential oil (OE) by spray drying using Brazilian Cerrado cashew polysaccharide (PEJU, Anacardium othonianum Rizz.) and maltodextrin (M) as wall materials. The microcapsules presented particles with irregular and rough surfaces confirmed by X-ray diffraction, with 57% in dry diameters ranging from 0 to 1 μm. Thermogravimetry showed a thermostable encapsulating material (peaks at 301 °C and 429 °C), with no loss of the encapsulated core. Zeta potential (ζ = − 0.18 mV) demonstrated the material’s amphiphilic power. The ratio of 1:3:3.6 of OE:cashew PEJU:M (w/w/w) showed the best encapsulation effect (75% yield and 6.25% of the OE retained) in the same proportion of β-caryophyllene retained. The Brazilian Cerrado cashew PEJU is a promising source for use as wall material in microcapsules, especially in protecting the OE of P. emarginatus fruits, as replacement for other gums, such as gum Arabic.

  • Synthesis and Characterization of β-Cyclodextrin/poly(1-naphthylamine) Inclusion Complex and In-Vitro Release Studies of Metformin Hydrochloride
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-02
    Shabab Khan, Elham S. Aazam, Sapan Kumar Jain

    The present preliminary study reports the synthesis of β-cyclodextrin/poly(1-naphthylamine) (PNA) inclusion complexes at varying concentrations of 1-naphthylamine as monomer. The synthesized complexes were investigated for their spectral and morphological characteristics. IR studies confirmed that with the increase the loading of PNA, the hydrogen bonding interaction between NH of PNA and OH of β-cyclodextrin increased which was corroborated by the increase in the peak intensity corresponding to the OH stretching vibration of pristine β-cyclodextrin. UV studies confirmed the presence of higher number of quinoid units in PNA and tits interaction with β-cyclodextrin upon higher loading. The occurrence of phase transition during complex formation was confirmed by XRD analysis. Morphological studies highlighted the core–shell like morphology of the complexes. Metformin hydrochloride (MET-HCl) was chosen as a model drug to study the in-vitro drug release characteristics of these inclusion complexes. The validity of kinetic models for the adsorption of MET-HCl was studied using pseudo-first order model, pseudo-second order model, Elovich kinetic model and Intra-Particle Diffusion kinetic model and it was found that highest correlation coefficient was shown by pseudo-second-order model as well as by Elovich kinetic model. Hence the drug adsorption predominantly followed the pseudo-second order kinetics model. The drug release was investigated at gastric fluid (pH 1.2) and intestinal fluid (pH value 7.4) for a period of 1 h. The model with the highest correlation coefficient was confirmed to be of zero order and the value of n at gastrointestinal as well as intestinal fluids was calculated to be 1.2781 and 1.3262 respectively indicating super case-II transport mechanism.

  • Recycling of Chrome Plated ABS Parts Pickled with Nitric Acid Free Solution
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-01
    Isabel Narloch Cardoso, Taise Ranzan, Ana Paula Kurek, Noeli Sellin

    Abstract One of the barriers to the recycling of chrome plated acrylonitrile–butadiene–styrene (ABS) is the degradation caused by the solution containing nitric acid used in the pickling of the metal layer. In this study, defective chrome plated ABS parts were pickled in a solution composed of lactic and sulfuric acids and hydrogen peroxide, and recycled by injection molding with different proportions of virgin ABS. The influence of pickled ABS on the chemical composition, thermal and mechanical properties of the samples was evaluated. The samples were chrome plated and characterized by visual inspection and adhesion tests. A slight yellowing of the virgin ABS/pickled ABS samples was observed due to the degradation of butadiene component. The thermal and mechanical properties were similar to those of virgin ABS. After the new chrome plating, all samples were approved in the adhesion tests, demonstrating that pickled ABS can be recycled by injection molding and chrome plating.

  • Methodologies for Microplastics Recovery and Identification in Heterogeneous Solid Matrices: A Review
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-01
    Federica Ruggero, Riccardo Gori, Claudio Lubello

    Abstract The missing link in plastic mass balance between mismanaged plastic waste worldwide and plastic waste effectively detected in marine environments has recently risen the attention on microplastics. In fact, beside primary sources of microplastics such as cosmetic products and textile fires, there are secondary microplastics generated from plastic items due to weathering agents and biological degradation. While the marine and fresh water environments are actually of great concern, ground environments, and matrices related to it, have been less considered in the last years research about microplastics detection. Major attention should be reserved to solid heterogeneous matrices, such as soil, compost, sediments and sludges. Worldwide regulations about compost, which is used as amendant in agricultural fields, have a threshold ranging from 2 to 15 mm for the requirements related to plastic impurities. Microplastics which pass through the mesh of the threshold sieve are considered assimilable to compost. One of the main lacks that prevents the improvement of these regulation, is a standard protocol for microplastics detection in solid heterogeneous matrices. To this purpose, the current review proposes an outline of methods tested in previous research for microplastics recovery and identification in the matrices of our interest.

  • Crystallization and Enzymatic Degradation of Maleic Acid-Grafted Poly(butylene adipate-co-terephthalate)/Organically Modified Layered Zinc Phenylphosphonate Nanocomposites
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-01
    Hsiang-Ting Wang, Erh-Chiang Chen, Tzong-Ming Wu

    Biodegradable nanocomposites were successfully synthesized using the maleic acid-grafted poly(butylene adipate-co-terephthalate) (g-PBAT) and organically modified layered zinc phenylphosphonate (m-PPZn), containing covalent linkages between g-PBAT and m-PPZn. Differential scanning calorimetry, wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM) were used to determine the crystallization behavior and morphology of g-PBAT/m-PPZn nanocomposites. The isothermal crystallization kinetics of g-PBAT/m-PPZn nanocomposites was determined using the Avrami equation. It was found that the half-time for the crystallization of the neat g-PBAT matrix is larger than that of g-PBAT/m-PPZn nanocomposites. This result suggests that the incorporation of m-PPZn can improve the crystallization rate of nanocomposites. The WAXD and TEM data illustrate that most of the m-PPZn layered materials are partially intercalated or exfoliated in the g-PBAT matrix. As the enzyme, lipase from Pseudomonas sp. was used for the enzymatic degradation tests. The degradation rates of the neatly fabricated g-PBAT copolymers using the heat pressing technique increase in the order of g-PBAT-80 > g-PBAT-50 > g-PBAT-20. The growing degradation rate of g-PBAT-80 is due to the growing amount of the adipate acid group and the increasing chain flexibility of the polymer backbone. Moreover, the increasing loading of m-PPZn enhances the weight loss of nanocomposites, suggesting that the existence of m-PPZn enhances the degradation of g-PBAT copolymers. The degradation rate of the freeze-drying samples containing a highly porous structure is greater than those prepared using the heat pressing technique.

  • Solution Blow Spinning of Polylactic Acid to Prepare Fibrous Oil Adsorbents Through Morphology Optimization with Response Surface Methodology
    J. Polym. Environ. (IF 2.765) Pub Date : 2020-01-01
    Tingting Zhang, Hua Tian, Xueqiong Yin, Zhiming Li, Xiaohui Zhang, Jianxin Yang, Li Zhu

    Abstract Polylactic acid (PLA) fibrous membrane (PFM) was prepared through solution blow spinning (SBS). The effects of spinning parameters (solution concentration, gas pressure, and spinning distance) on the fiber diameter were studied by response surface methodology. The optimized preparation conditions of PFM were the concentration of PLA solution 8%, gas pressure 0.2 MPa, spinning distance 12 cm. Under the optimized conditions, the average diameter of PLA fibers was 770.45 nm. The oil saturated adsorption capacity of PFM to crude oil, peanut oil and diesel oil was up to 32.28 g/g, 28.80 g/g, and 19.50 g/g, respectively, while that of the commercialized nonwoven polypropylene was only 9.34 g/g, 9.17 g/g, 7.79 g/g, respectively. The adsorption capacity remained at about 50% of the saturated adsorption capacity after 10 cycles of reuse. Similar membrane was also successfully prepared from a waste PLA lid through SBS, which expressed similar oil adsorption behavior with PFM. SBS is potential to deal with the pollutions from waste oil and waste plastic.

  • New Lignocellulosic Aristida adscensionis Fibers as Novel Reinforcement for Composite Materials: Extraction, Characterization and Weibull Distribution Analysis
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-24
    P. Manimaran, S. P. Saravanan, M. R. Sanjay, Mohammad Jawaid, Suchart Siengchin, Vincenzo Fiore

    In this research, the Aristida adscensionis fibers (AAFs) were taken out from the plants and its fundamental properties anlayzed for the first time. The AAFs were characterized and compared with other natural fibers by the use of physico-chemical analysis and various characterization techniques such as FT-IR, XRD, NMR, TGA, SEM and AFM. Chemical analysis showed that A. adscensionis fibers have a high cellulose content of 70.78% whereas the contents of lignin and wax are equal to 8.91% and 2.26%, respectively. The FT-IR, XRD and NMR analysis confirmed that AAFs are rich in cellulose content with CI and CS equal to 58.9% and 11.5 nm, respectively. Pycnometer analysis allowed to estimate a density of 790 kg/m3. The TGA revealed that these fibers are thermally stable up to 250 °C while SEM and AFM analysis evidenced that the fiber surface was rough. The fiber diameter and tensile properties was analysed by Weibull distribution. The characterization results and Weibull distribution analysis for the A. adscensionis fibers are an agreement with other natural fibers reported in literature. So this new lignocellulosic material is suitable as reinforcing phase in composites for potential engineering semi-structural applications like roofing sheets, bricks, door panels, furniture panels, interior paneling, storage tanks, pipelines, etc.

  • Removal of Al(III) Ions Using Gellan Gum-Acrylic Acid Double Network Hydrogel
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-21
    Bengi Özkahraman, Zehra Özbaş

    Abstract The objectives of this research were to evolve a gellan gum based double network (DN) hydrogel with high mechanical properties, and investigate its potential as an adsorbent to remove Al(III) ion. The double network hydrogel was synthesized for the first time in the literature, and Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were utilized for structural and morphological characterization. Gellan gum hydrogel was characterized in terms of mechanical strength. The Al(III) removal behaviour studies were performed in 100 ppm aqueous Al(III) solution, and the kinetic data were correlated with the models of pseudo-first order and second-order. In addition, the equilibrium adsorption data were applied to Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Moreover, the DN hydrogel adsorption capacities were calculated for the regeneration and reuse studies. The DN hydrogel could be used at least five times without significant decreasing in its adsorption capacity. In this work, the possibility of the mechanically developed strong DN hydrogel was observed for Al(III) ion removal behaviour.

  • A Recycling-Focused Assessment of the Oxidative Thermomechanical Degradation of HDPE Melt Containing Pro-oxidant
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-21
    Alex S. Babetto, Marcela C. Antunes, Sílvia H. P. Bettini, Baltus C. Bonse

    Abstract This study shows the effect of a pro-oxidant (oxo-biodegradable) additive on the oxidative thermomechanical degradation of high-density polyethylene (HDPE). It also allows us to predict the behavior of the material when subjected to mechanical recycling or to biodegradation. When HDPE, one of the most consumed thermoplastics worldwide, is transformed into a product or when subjected to primary and/or secondary recycling it will undergo thermomechanical degradation. According to current standards HDPE is not biodegradable, therefore pro-oxidants are added to many HDPE products, which can compromise the product's life. Knowledge on the influence of pro-oxidants on HDPE in the melt is limited and the objective of this study is to assess the behavior of HDPE containing pro-oxidant manganese stearate (MnSt) in the oxidative thermomechanical degradation process. Thermomechanical degradation tests were conducted in a closed-chamber torque rheometer. FTIR and SEC results agreed with those of torque rheometry and showed that oxidative thermomechanical degradation of HDPE increases with increasing manganese stearate concentration. Degradation resulted in an increase in the number of oxygenated functional groups, mainly ketones, aldehydes and carboxylic acids, and reduction in the weight-average molar mass of HDPE. MnSt may have acted both as a lubricant and pro-oxidant during processing with predominance of one or the other effect at different stages along the oxidative thermomechanical degradation of HDPE.

  • Carboxymethyl and Nanofibrillated Cellulose as Additives on the Preparation of Chitosan Biocomposites: Their Influence Over Films Characteristics
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-20
    Talita Szlapak Franco, Rosa María Jiménez Amezcua, Adriana Villa Rodrìguez, Salvador García Enriquez, Maite Renteria Urquíza, Eduardo Mendizábal Mijares, Graciela Bolzon de Muniz

    Abstract The aim of this research was to prepare chitosan composite films with commercial carboxymethylcellulose (CMC) and nanofibrillated cellulose (CNF) from palmito sheaths pulp (agroindustrial discard) and compare their influence over the film’s properties. The morphology of cellulose additives influenced their interaction with the polymer matrix as verified on the FTIR spectra and on the SEM images, where the poor dispersibility of CMC could be visualized as aggregates and clusters on chitosan matrix. The extensive defibrillated particles of CNF were well dispersed mainly by their high number of hydrogen bridges that promoted an increase in crystallinity index even in the low level of addition (0.5%). Molecule interactions directly influenced the film’s mechanical properties, where the addition of 1.5% of CNF resulted in an increment of 1.300% for Young’s modulus and 280% for tensile strength; a reduction of 20% of UV light transmittance and a decrease of almost 50% on water absorption. By the other side, even with an increase on the crystallinity index, the addition of CMC resulted in films with low mechanical and barrier properties as compared to the control film. The addition of nanocellulose overcame chitosan main weakness and leaded to a total renewable, biodegradable nanocomposite with adequate mechanical and physical properties to be applied on package development and with the extra attractive of being obtained from an agroindustrial residue, contributing with sustainability and environmental safety concerns.

  • Aqueous Solution of a Basic Ionic Liquid: A Perspective Solvent for Extraction and Regeneration of Silk Powder from Bombyx mori Silk Cocoons
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-17
    Muhammad Samie, Nawshad Muhammad, Muhammad Arfat Yameen, Aqif Anwar Chaudhry, Hamad Khalid, Ather Farooq Khan

    The rationale behind this study was to investigate the potential new low cost and biocompatible aqueous choline based ionic liquid for dissolution and regeneration of silk fibroin obtained from the mulberry silkworm. The silk due to its high biocompatibility and mechanical properties finds many applications in the field of biomedical science. Earlier, silk extraction methods have issues of either extraction efficiency or environmental concerns. The ionic liquid is a relatively green solvent was used to dissolve silk fibroin and optimized the process with respect to variables like temperature, time, stirring speed, type of ionic liquid and maximum dissolution ability. The dissolution process was observed through the naked eye as well as using optical microscopy. The optimized conditions at which maximum dissolution i.e. 25% was obtained, are heating the mixture at 50 °C for 2 h. Various analytical characterization such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), Zeta potential, nuclear magnetic resonance (1H NMR) and thermogravimetric analysis (TGA) was performed for cocoon, fiber and regenerated silk powder in order to understand the effect of ionic liquid treatment. FTIR, NMR and Raman spectra shows the characteristic peaks assigned to the silk. SEM analysis shows nanoparticles of silk fibroin powder. The crystallinity and thermal stabilities were decreased for regenerated silk as observed from XRD and TGA analysis. The nano-silk exhibited a zeta potential of − 24.6 ± 3 mV.

  • Effect of Heat-Treatment on Self-healing and Processing Behavior of Thermally Reversible Polyurethanes
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-14
    Libang Feng, Yaohui Bian, Changsheng Chai, Xiaohu Qiang

    Given its thermal reversibility, high yield, and minimal side reactions, the Diels–Alder (DA) reaction is a particularly desirable technique for the preparation of polymeric materials with heat-stimulated self-healing properties. A linear self-healing polyurethane containing thermally reversible DA bonds (PU-DA) was developed in this study. Results revealed that the introduction of DA bonds conferred outstanding mechanical property and thermal reversibility to PU-DA films. Thus, the as-prepared PU-DA films demonstrated excellent self-healing performance. The self-healing behavior of the PU-DA films under various heat treatments was examined through qualitative observation and quantitative measurements. The PU-DA underwent self-repair through the combination of two healing actions, i.e., the thermal movement of molecular chains and the thermally reversible DA reaction. Moreover, the self-healing behavior of the PU-DA was repeatable, and the PU-DA continued to present high strength even after undergoing three damage–repair cycles at the same site. In addition, the as-prepared PU-DA exhibited excellent macro-scale self-healing behavior, and it endowed the PU-DA presented reprocessing performance. The PU-DA can be recycled given its excellent self-healing and outstanding reprocessing performances.

  • Physical, Mechanical, Structural and Antibacterial Properties of Polyvinyl Alcohol/Oregano Oil/Graphene Oxide Composite Films
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-13
    Derong Lin, Zhijun Wu, Yichen Huang, Jingjing Wu, Chunxiao Li, Wen Qin, Dingtao Wu, Suqing Li, Hong Chen, Qing Zhang

    Polyvinyl alcohol/oregano oil/graphene oxide antibacterial composite film was prepared from PVA and GO by adding OEO as the antibacterial agent. The effect of different OEO contents on the properties of the composite film was studied. The results showed that the OEO improved the performance of the composite film. With the increase of OEO content, the thicknesses were increased, the mechanical properties were improved, and the antibacterial activities were increased. The performances of the film with 1% OEO were the best. The tensile fracture elongation and the tensile strength were 249% and 20.760 MPa, respestively. The diameter of the antibacterial ring of E. coli and L. monocytogenes was 11.70 mm and 12.61 mm, respectively. FTIR revealed that there were chemical bonds among PVA, GO and OEO. SEM showed that OEO made the surface of the composite film smoother. TGA showed that OEO did not affect the coke yield of composite films. DSC indicated that OEO reduced the exothermicity of composite films. The antibacterial properties of natural essential oils were taken advantage of to make the antibacterial composite films, which was beneficial to expand the use of essential oils in packaging films, and provides a reliable reference for other researchers.

  • Removal and Preconcentration of Pb(II) Heavy Metal Ion from Water and Waste-Water Samples onto Poly (vinyl alcohol)/polyethyleneimine/Fe 3 O 4 Microfibers Nanocomposite
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-11
    Elnaz Bavel, Abbas Afkhami, Tayebeh Madrakian

    In this research, poly (vinyl alcohol)/polyethyleneimine/Fe3O4 (PVA/PEI/Fe3O4) microfibers nanocomposite was synthesized in order to remove and/or preconcentrate Pb(II) ions. The microfibers nanocomposite was characterized by FT-IR, SEM, and XRD methods. The effects of various parameters such as pH, amount of adsorbent, and contact time on the adsorption efficiency of Pb(II) ions at the adsorbent were fully investigated and the optimum conditions were established. The adsorption capacity was found to be 370.9 mg g− 1 of the adsorbent. The kinetics of metal ions adsorption was evaluated using pseudo-first-order and pseudo-second-order models. The results showed that the adsorption of the investigated metal ion is in agreement with the pseudo first-order kinetics. The adsorption–desorption process was conducted for five cycles and the removal efficiency still kept 97% after three cycles.

  • Hybrid Crosslinked Chitosan-Epichlorohydrin/TiO 2 Nanocomposite for Reactive Red 120 Dye Adsorption: Kinetic, Isotherm, Thermodynamic, and Mechanism Study
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-11
    Ali H. Jawad, Nur Shazwani Abdul Mubarak, Ahmed Saud Abdulhameed

    Hybrid crosslinked chitosan-epichlorohydrin/TiO2 nanocomposite (CTS-ECH/TNC) was synthesized as an inorganic–organic hybrid nanocomposite bioadsorbent for the removal of reactive red 120 (RR120) dye from aqueous environment. Various analytical techniques were utilized to investigate the surface area, surface morphology, martial crystallinity, elemental composition, amino group content, and fundamental functional group of CTS-ECH/TNC. The impact of key adsorption parameters such as adsorbent dosage (0.02–1.2 g), initial RR120 dye concentration (30–400 mg/L), solution pH (3–12), contact time (0–300 min), and temperature (303–323 K) were explored by batch adsorption process. The adsorption data were well illustrated by pseudo-second order (PSO) kinetic and Langmuir isotherm model. The adsorption process was also found to be a spontaneous and endothermic in nature as indicated by thermodynamic study. The maximum adsorption capacity of CTS-ECH/TNC for RR120 dye was recorded to be 210 mg/g at 303 K. Various types of interactions such as electrostatic attraction, n-π stacking, and H-bonding were responsible for adsorbing RR120 dye molecules on the surface of CTS-ECH/TNC as investigated by tailored adsorption mechanism. Thus, this work introduces CTS-ECH/TNC as promising hybrid biosorbent for the removal of RR120 dye as model of reactive azo dyes from aqueous environment.

  • Blends of Chalcone Benzoxazine and Bio-benzoxazines Coated Cotton Fabrics for Oil–Water Separation and Bio-silica Reinforced Nanocomposites for Low-k Applications
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-10
    Arumugam Hariharan, P. Prabunathan, S. S. Subramanian, M. Kumaravel, Muthukkarupan Alagar

    In the present work, chalcone benzoxazine (Chal-Bz) was co-polymerized with two bio-based benzoxazines namely cardanol (CrAb) and eugenol (EuAb) benzoxazine and coated over cotton fabric. The Chal-Bz/CrAb and Chal-Bz/EuAb blends coated cotton fabrics show water contact angle values of 163° and 156° respectively and their oil–water separation efficiency were observed found to be 97 and 96% respectively. In addition, the glycidoxypropyltrimethoxysilane (GPTMS) functionalized bio-silica in varying weight percentages (1, 3, 5, 7 and 10 wt%) was also reinforced with two co-polymerized blended matrices to obtain respective composites. The developed composites were studied for their dielectric, thermal and morphological behaviours. The values of dielectric constant of 10 wt% bio-silica reinforced Chal-Bz/CrAb and Chal-Bz/EuAb composites were found to be 2.1 and 2.3, respectively. Similarly the values of contact angle of 10 wt% bio-silica reinforced chal-Bz/CrAb and Chal-Bz/EuAb composites were 137° and 116°, respectively. Data obtained from different studies suggest that these bio-silica reinforced benzoxazine composites can be used in the form of coatings, adhesives, sealants and encapsulants for high performance micro-electronics insulation applications under adverse environmental conditions.

  • pH-Sensitive Nanocomposite Hydrogels Based on Poly(Vinyl Alcohol) Macromonomer and Graphene Oxide for Removal of Cationic Dyes from Aqueous Solutions
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-09
    Mina Rabipour, Zahra Sekhavat Pour, Razieh Sahraei, Mousa Ghaemy, Mehdi Erfani Jazi, Todd E. Mlsna

    In this study, a pH-sensitive nanocomposite hydrogel based on poly(vinyl alcohol) (PVA)/graphene oxide (GO) was prepared and used as a potential adsorbent for the removal of crystal violet (CV) and methylene blue (MB) from aqueous solutions. The prepared nanocomposite hydrogels were fully characterized and their swelling capacity and gel content were investigated by changing the GO and acrylic acid (AA) content. Adsorption experiments were carried out as a function of contact time, concentration, temperature, pH and dosage. The adsorption process was favored at higher pHs, followed pseudo second-order kinetics while the adsorption equilibrium data well fitted to the Langmuir isotherm model with the maximum capacity of 173.2 and 169.6 mg g−1 for MB and CV, respectively. A thermodynamic study showed the spontaneity nature of the adsorption process for MB and CV. The removal percentage of MB dye increased with increase of temperature from 25 to 55 °C while the adsorption of CV dye showed the opposite trend. This different trend can be attributed to the differences in the pattern of adsorption.

  • A Review on Recent Trends and Future Prospects of Lignin Based Green Rubber Composites
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-09
    Kumarjyoti Roy, Subhas Chandra Debnath, Pranut Potiyaraj

    In the last two decades, the utilization of non-petroleum based renewable materials on the development of advanced rubber composites has attracted increasing attention of polymer researchers from both industrial and environmental viewpoints. Recently, lignin has emerged as promising non-petroleum based filler in the progress of green rubber technology. This review article aims to present the recent advances of lignin based natural and synthetic rubber composites. The potential of lignin as alternative reinforcing filler in rubber technology is critically evaluated in terms of cure, mechanical, dynamic mechanical and thermal properties. The dispersion of lignin within the rubber matrix is the key parameter that decides the overall performances of lignin based rubber composites. The last section of the review will emphasize the major challenges regarding the broad application of lignin as reinforcing filler in rubber industry. This study will be the part of huge interest of modern rubber researchers concerning the utilization of lignin for the development of non-petroleum based renewable and sustainable rubber composites.

  • Effect of Different Fillers on the Biodegradation Rate of Thermoplastic Starch in Water and Soil Environments
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-09
    Markéta Julinová, Ludmila Vaňharová, Martin Jurča, Antonín Minařík, Petr Duchek, Jana Kavečková, Dana Rouchalová, Pavel Skácelík

    This work investigates the effect of filler type on the rate of biodegradation of thermoplastic starch-based films in water and soil environments. The authors applied the casting method to create films of thermoplastic starch, based on waste paper, filled with clays or organic fillers. Since such materials made from cellulose tend to absorb water, we hydrophobized the surfaces of the filled thermoplastic starch samples. The structures of the blends were characterized by infrared spectroscopy, while atomic-force microscopy was applied to observe change in surface topography and the distribution of the filler. We also studied moisture resistance of the blends. Biodegradation tests revealed that surface topography, distribution of the filler and starch-to-filler interactions were non-critical to the rate and degree of biodegradation of the blends. The biodegradation rate of the blends was strongly affected by the environmental conditions (relative humidity 54%, 100%, respectively; temperature 25 °C, 37 °C, respectively). Under anaerobic conditions, it was the mixtures that biodegraded to the greatest extent, whereas the hydrophobized mixtures did so the least.

  • Microwave-Assisted Synthesis of Polyethyleneimine Grafted Chitosan Beads for the Adsorption of Acid Red 27
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-07
    N. H. Yusof, K. Y. Foo, L. D. Wilson, B. H. Hameed, M. Hazwan Hussin, S. Sabar

    In this study, chitosan-polyethyleneimine beads were synthesized via graft copolymerization under microwave irradiation for the adsorption of Acid Red 27 (AR27). The integration of polyethyleneimine affords grafting of amino functional groups onto the chitosan backbone, while crosslinking with glutaraldehyde has significantly improved the mechanical and chemical properties of the resulting grafted and crosslinked chitosan beads (CS-PEI-GLA). The beads were characterized by the scanning electron microscopy, pore structure analysis and Fourier transform infrared spectroscopy. The adsorption experiments were conducted in a batch system and optimized with respect to different adsorbent dosages, pH, initial dye concentrations and contact time. The equilibrium data were well described by the pseudo-second-order kinetic model and the Langmuir isotherm model with the maximum adsorption capacity (qm) for AR27 of 48.3 mg g−1 at 27 °C. CS-PEI-GLA was successfully synthesized in this study by using a simple, green and cost-effective technique with promising prospects to enable future scale-up.

  • Emerging Use of Homogenic and Heterogenic Nano-colloids Synthesized via Size-Controllable Technique in Catalytic Potency
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-07
    Hossam E. Emam, Mariana A. Attia, Farida M. S. E. El-Dars, Hanan B. Ahmed

    The current work demonstrate a controllable technique for synthesis of silver nanoparticles and gold nanoparticles versus their bimetallic nano-alloy as homogenic and heterogenic nano-colloids and monitoring their employment as nano-catalysts. The required nano-colloids were spontaneously in-grained by using carboxymethyl methyl cellulose (CMC) as nano-generator and protector. Revolution of UV–Vis spectroscopic data affirmed that, surface plasmon resonance (SPR) peak characterized for Ag-Au bimetallic nano-alloys was ranged in 480–495 nm and X-ray diffraction patterns also approved the main role of CMC in production of bimetallic nanostructures. Transmission electron microscope (TEM) and zetasizer analyses were detected for monitoring the effect of reaction conditions on the topographical features and size distribution of the as-generated nano-colloids. Small sized Ag monometallic of 9.7 nm was enlarged to 16.8–34.2 nm for Ag–Au bimetallic nanostructures. The catalytic potency of the produced nano-colloids was monitored for the reduction of p-nitroaniline and the results revealed that, there was a quite strong relationship between catalytic activity and composition of nano-colloids. Half time of the reduction was sharply decreased from 22.95 to 5.27 min for Ag monometallic and Ag–Au bimetallic nano-colloids, respectively. Using of the bimetallic nanostructure as nano-catalyst could be beneficial for accelerating the reduction reaction 23 times.

  • Boric Acid Cross-linked 3D Polyvinyl Alcohol Gel Beads by NaOH-Titration Method as a Suitable Biomass Immobilization Matrix
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-07
    Li Sun, Jinxing Wang, Jidong Liang, Gaigai Li

    Granule-base immobilization of biomass is a potential method for a decent quality granular sludge cultivation. In this study, 3D polyvinyl alcohol (PVA) gel beads were chemically cross-linked via a simple NaOH-titration method. The PVA gel beads’ porous morphology was characterized using scanning electron microscope (SEM) and Brunauer–Emmette–Teller (BET), and their mechanical properties were evaluated by swelling rate and compressive stress tests. When cross-linking time was 10 min, high quality gel beads (P10) were synthesized, which demonstrated a homogeneous porous structure, good swelling rate, and high compressive strength. A mechanism for synthesis of the gel beads was proposed based on the results of Fourier transform infrared (FTIR) and X-ray diffractometer (XRD) analysis. Briefly, the intermolecular hydrogen bonds of PVA were firstly broken by NaOH to generate active bond of O–Na, which easily reacted with B(OH)4− to produce the PVA-boric acid gel beads. P10 showed excellent biocompatibility for anaerobic ammonia oxidation (anammox) biomass’ immobilization. After incubation for three months, well granule-base immobilized sludge on P10 was developed in up-flow reactor. The sludge had high abundance of anammox biomass and was in balance with other functional bacteria. This work provides a simple method for the rapid preparation of 3D PVA gel beads and verifies their potential in granule-base immobilization of biomass.

  • The Effect of Filler Loading and Silane Treatment on Kenaf Core Reinforced Polyurethane Composites: Mechanical and Thermal Properties
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-06
    A. B. Azizah, H. D. Rozman, A. A. Azniwati, G. S. Tay

    This investigation was aimed to study the mechanical and the thermal properties behavior of kenaf core (untreated and treated with silane)–polyurethane composites. Three different types of silane coupling agent were used to treat kenaf core (KC) which were, trimethoxyphenylsilane (TMPS), vinyltrimethoxysilane (VTMS), and tetramethoxyl orthosilicate (TMOS). The concentration of silane was varied from 0 to 3%. Silanization of KC filler is measured by the weight percentage gain (WPG), scanning electron microscopy and energy dispersive X-ray analysis. Kenaf core–polyurethane (KCP) composites were prepared using a one-shot process. Tensile, flexural and thermogravimetric analysis was carried out it to study mechanical and thermal properties of the KCP. Among the three types of silane, the most effective one for property improvement was TMPS. The results from TMPS showed tensile and flexural agreed to each other that TMPS was the suitable chemical to be used as a coupling agent for KC filler in the preparation of KCP composite.

  • Green Microcomposites from Renewable Resources: Effect of Seaweed ( Undaria pinnatifida ) as Filler on Corn Starch–Chitosan Film Properties
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-02
    Danila Merino, Vera A. Alvarez

    Natural seaweed microparticles obtained from Undaria pinnatifida waste (A) were used as fillers in thermoplastic starch (TPS)–chitosan (CH) blend in order to obtain microcomposites films for application in sustainable agriculture. The adequate proportion of both polymers was optimized with regards their mechanical, barrier, water interaction and morphological properties. Then, the effect of different content of seaweed on microcomposites properties was investigated. The seaweed used showed good interaction with the TPS–CH matrix. Its addition produced an increase in the tensile strength and a slight increase in the elongation at break. Contents of 10% of A lead to a more heterogeneous structure with the formation of aggregates. Low contents of A reduced the mobility of the polymer chains resulting in a lower moisture content and higher Tg, although the WVP increased with the content of A. The improvements achieved with microcomposites were finally discussed under the light of new agricultural mulch films regulations.

  • Garcinia gummigutta Vegetable Oil–Graphene Oxide Nano-composite: An Efficient and Eco-friendly Material for Corrosion Prevention of Mild Steel in Saline Medium
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-12-02
    Mahesh Bhaskar Hegde, Saurav Ramesh Nayak, Kikkeri Narasimha Shetty Mohana, Ningappa Kumara Swamy

    Garcinia gummigutta vegetable oil (GGVO) is a rich source of stearic and oleic acid which on heat treatment at around 300 °C, will get polymerized with highly conjugated network system. The present work intended to exploit the properties of GGVO for the production of eco-friendly anti-corrosion coating material. The oil extracted from GG seeds was used to prepare graphene oxide (GO) dispersion in oil and successfully employed as an efficient anti-corrosion coating material on mild steel (MS). All coatings are done by simple heat treatment of dip-coated MS specimen. The corrosion prevention ability of the coating was studied by potentiodynamic polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution. Electrochemical results showed that the addition of GO significantly enhances the corrosion inhibition performance of the GGVO coating. The inhibition efficiency of the GGVO coating increased from 93.0 to 99.8% on the incorporation of 0.3 wt% of GO into the oil. The enhancement of the corrosion prevention ability of the GO ink is discussed based on the impermeable action of GO to the corrosive ions and also suppression of the number of pores in the polymer that is formed during the curing of the coating.

  • Correction to: Critical Review of Microbial Degradation of Aromatic Compounds and Exploring Potential Aspects of Furfuryl Alcohol Degradation
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-12
    Priyaragini Singh, Rakesh Kumar

    The original version of this article, unfortunately omitted to publish the acknowledgement section, which is given below. This has been corrected by publishing this erratum.

  • Polyvinyl Alcohol (PVA)– Azadirachta indica (Neem) Nanofibrous Mat for Biomedical Application: Formation and Characterization
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-14
    Ayub Ali, Md. Abdus Shahid

    The present study provides credence to the formation of polyvinyl alcohol (PVA)–Azadirachta indica (neem) nanofibrous mat (PNNM) under optimum processing conditions of electrospinning technique from a mixer of PVA and neem extract to utilize the inherent medicinal properties of this herb for biomedical application. The bonding behavior, orientation of fibers, thermal behavior, and moisture management properties were evaluated by Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermo gravimetric analysis (TGA) and moisture management tester (MMT) reports respectively. The antibacterial activity of the developed sample at the maximum mixing ratio of neem extract (80%) was tested against Gram-positive (S. aureus) bacteria using agar disc diffusion method. The results reveal that the prepared nanofibrous mat exhibited better thermal and moisture management properties in comparison with PVA nanofiber alone. The formation of smooth fibers was confirmed by SEM images having average diameter of 185 nm under 5k, 10k and 15k magnifications. The characteristic peaks of PVA and neem constituents in FTIR spectra of the developed mat confirmed the presence of both components. Bacterial resistance was reached up to 20 mm due to the antibacterial constituents of neem extract. Thus the developed mat could be used as a biocompatible and bio based in biomedical applications.

  • Preparation of Chitosan, Sodium Alginate, Gelatin and Collagen Biodegradable Sponge Composites and their Application in Wound Healing and Curcumin Delivery
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-09-20
    Negar Naghshineh, Kambiz Tahvildari, Maryam Nozari

    This research aimed to produce three chitosan-based biodegradable sponge composites from collagen, gelatin, and sodium alginate and through addition of curcumin to investigate their biological effects on wound healing. To this end, the Chitosan-Collagen-Curcumin (Chs, Col, Cur), Chitosan-Gelatin-Curcumin (Chs, Gel, Cur), and Chitosan-Alginate-Curcumin (Chs, Alg, Cur) sponge composites were prepared and subject to FT-IR, SEM, TGA, water absorption, biodegradability, wound healing and anti-bacterial analyses. Based on the results, the highest and lowest water absorptions were associated with Chitosan-Alginate-Curcumin and Chitosan-Collagen-Curcumin composites, respectively. Moreover, according to the SEM images, the highest porosity and the largest cavity size were associated with the Chitosan-Alginate-Curcumin composite. The biodegradability analysis results revealed that Chitosan-Alginate-Curcumin was completely destroyed in 4 days, while the Chitosan-Collagen-Curcumin composite showed the lowest level of destruction. Moreover, the highest amount of curcumin was released by the Chitosan-Gelatin-Curcumin composite which happened during the first hour. Finally, the highest wound healing effect was achieved within a 10-day period using the Chitosan-Gelatin-Curcumin composite, completely healing the wound on the mouse skin. On the other hand, the lowest effect was associated with the Chitosan-Alginate-Curcumin composite. The antibacterial tests suggested that all composites exhibited anti-bacterial capabilities, the highest level of which was associated with the Chitosan-Gelatin-Curcumin composite. Moreover, based on the histological tests, the fastest tissue repair process with the highest quality was achieved using the Chitosan-Gelatin-Curcumin sponge composite.

  • Chemical Recycling of Polyethlylene Terephthalate by Glycolysis Using Deep Eutectic Solvents
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-14
    Emine Sert, Esra Yılmaz, Ferhan Sami Atalay

    In this study, the glycolysis of polyethylene terephthalate was studied in presence of deep eutectic solvents as catalyst. In the glycolysis of PET, five different deep eutectic solvents were synthesized using different hydrogen bond donors and acceptors. Among the synthesized DESs, the most efficient catalyst was found to be DES formed by potassium carbonate and ethylene glycol. Glycolysis reaction was performed between PET and ethylene glycol. The effects of process parameters such as temperature, ratio of EG/PET and ratio of DES/PET were examined. The maximum yield for monomer product, bis(2-hydroxyethyl) terephthalate was observed as 88% at the reaction temperature of 180 °C, ethylene glycol/deep eutectic solvent ratio of 15 and deep eutectic solvent/polyethylene terephthalate ratio of 6.

  • Green Composite Materials from Biopolymers Reinforced with Agroforestry Waste
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-09-17
    F. G. Torres, Sol Rodriguez, A. C. Saavedra

    Environmental concerns have triggered the development of green composites as a replacement of non-degradable polymers. A variety of biopolymers, including polysaccharides, polyesters and proteins are reported to be used as matrices. Such biopolymers feature low mechanical and thermic properties. In order to improve the properties of these biopolymeric matrices, organic fillers derived from agroforestry wastes can be used. This paper aims to provide an up-to-date review of the development of fully green composite materials. A systematical classification based on the chemical structure of the biopolymeric matrices and the morphology of the natural reinforcements is proposed. In most cases, treatments and additives are used to prepare these green composites and overcome the problems related to poor biopolymer-filler interaction. Several applications as well as the improved mechanical, thermic and barrier properties of various green composite are also discussed.

  • Fabrication of PVA/Nanoclay Hydrogel Nanocomposites and Their Microstructural Effect on the Release Behavior of a Potassium Phosphate Fertilizer
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-10-12
    Shokoufeh Hakim, Mohammad Reza Rostami Darounkola, HaniehTalari, Mohammad Barghemadi, Mahmoud Parvazinia

    Various PVA/nanoclay hydrogel nanocomposites with different weight fractions of nanoclay (0, 0.25, 0.5, 0.75 and 1) were prepared, characterized and their performances were investigated. The structures of the synthesized hydrogel nanocomposites and the samples loaded with a potassium phosphate fertilizer were proved by FTIR spectroscopy method. The interactions between the hydrogels and nanoclay and also the effect of fertilizer loading capacity on the nanocomposites were investigated using TGA method. TGA showed that the loading of the fertilizer decreased the hydrogel weight loss which was affected by the nanoclay weight percent. In addition, the effects of glutaraldehyde as crosslinking agent and incorporation of the nanoclay and fertilizer on the glass transition temperature of the prepared hydrogels were studied using DSC method. The Tg of the hydrogels increased by adding the nanoclay and decreased with the loading of the fertilizer. The SEM images showed that the microstructure and morphology of the hydrogel changed in the presence of the nanoclay and fertilizer. The increase of the nanoclay decreased the porosity of the hydrogel and made it denser. Furthermore, the EDX spectroscopy images of the samples proved the uniform dispersion of the fertilizer and nanoclay in the prepared hybrid hydrogels. The swelling of the hydrogels decreased with increasing of the nanoclay weight percent. The results showed that the swelling under load was the highest for the hydrogel nanocomposite with 0.5 wt% of the nanoclay. The increase of the nanoclay led to increasing of the physical networking that caused more desirable controlled release of the fertilizer.

  • Crystallization and Rheological Properties of the Eco-friendly Composites Based on Poly (lactic acid) and Precipitated Barium Sulfate
    J. Polym. Environ. (IF 2.765) Pub Date : 2019-09-11
    Ji-nian Yang, Shi-bin Nie, Yu-hui Qiao, Yue Liu, Zhen-yu Li, Guo-jun Cheng

    The environmental-friendly poly (lactic acid) (PLA) composites were fabricated by incorporating precipitated barium sulfate (BaSO4), and then the crystallization behaviors and rheological properties were investigated in detail. Results show that the added inorganic filler enhances the crystallization capacity, promoting the crystallization happened in advance and achieving increased crystallinity for the composites. Such promotion effect is further demonstrated by the calculated kinetic parameters including half-time of crystallization, F(T), activation energy and nucleation activity. Rheology tests reveal that pure PLA exhibits a typical linear viscoelastic feature while the shear-thinning behavior of the composites becomes manifest increasingly. However, the complex viscosity, storage modulus and loss modulus for the composites are all increased along with added inorganic filler.

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上海纽约大学William Glover