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  • Impact of surface-modified molybdenum disulphide on crystallization, thermal and mechanical properties of polyvinylidene fluoride
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-10
    M. S. Gopika, B. Bindhu, K. Y. Sandhya, V. L. Reena

    Abstract Polymer nanocomposite based on layered structure such as graphene, MoS2, MoO3 and WS2 has become an active field of research due to their exceptional thermal, mechanical and electrical properties. Achieving uniform dispersion of layered nanostructures within the polymer matrix is challenging because of the agglomeration of nanostructures which occurs due to the Van der Waals attraction and the cohesive nature between the two phases. In this work, we report the preparation of PVDF-modified MoS2 nanocomposites by the solvent blending method. The XRD results reveal the interaction of the negatively charged surface of MoS2 sheets and the positive CH2 group of PVDF through the predomination of β-phase. Morphological observation through SEM suggests the MoS2 induced formation of nanofibres in the composite. Enhancement in the thermal stability of the nanocomposite is observed and is possibly due to the heat barrier by the exfoliated MoS2 which in turn supports the tortuous effect. The DSC of the PVDF-modified MoS2 composite indicates the domination of β-phase and the hindrance to crystallization of PVDF. Improvement in the mechanical strength of the composites was also noticed on higher filler concentration.

    更新日期:2020-01-16
  • Plasma-initiated polymerization of N -isopropylacrylamide and functionalized with dopamine for the adhesion to Hela cells
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-23
    Xu Yang, Zhaojie Sun, Jingru Gao, Chunhui Yang, Dongyan Tang

    Temperature-responsive films of poly(N-isopropylacrylamide) (PNIPAM) were facilely fabricated by one-step plasma-initiated polymerization and then functionalized by self-polymerization of dopamine on the surface. High retention of the monomer structure and temperature-responsive properties in PNIPAM films were confirmed. After plasma-initiated polymerization, PNIPAM films formed protrusions and ridges surfaces. Moreover, cross-linker of N,N′-methylenebisacrylamide with different dosage was introduced into the systems to effectively modulate the roughness of PNIPAM films and to supply better adhesive surface. Furthermore, in cell culture, satisfactory survival rate of the attached Hela cells was obtained on PNIPAM films, and the cell viability was improved further on PNIPAM/PDA films. The results indicated that such films might be applicable in medical treatment and tissue engineering, due to their adjusted adhesion ability and less toxicity to cells.

    更新日期:2020-01-16
  • Synthetic talc as catalyst and filler for waterborne polyurethane-based nanocomposite synthesis
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-23
    Guilherme Dias, Manoela Prado, Christophe Le Roux, Mathilde Poirier, Pierre Micoud, Rosane Ligabue, François Martin, Sandra Einloft

    In this work, synthetic talc was used as catalyst and filler aiming to obtain waterborne polyurethane (WPU) nanocomposites by in situ polymerization. Filler was used both in gel and in powder forms in order to compare its effects into the WPU matrix. The use of synthetic talc as filler is interesting due to the possibility of hydrogen bond formation between WPU chains/Si–O–Si and OH groups in synthetic talc edges promoting changes in physical, mechanical and thermal properties. Moreover, WPUs are environmentally friendly polymers replacing organic solvents by water as dispersion medium reducing pollutant emission in the atmosphere. Material structure analyzed by FTIR evidenced that it is possible to synthesize WPU using synthetic talc as catalyst and proved hydrogen bonding formation between synthetic talcs and WPU matrix. Synthetic talcs were well dispersed even with higher filler content, as supported by XRD, TEM, FESEM and AFM analyses. Thermal and mechanical performance was improved with synthetic talc fillers’ addition in order to obtain WPU nanocomposites. Also, Tg of WPU nanocomposites was affected by fillers’ addition as presented by DSC corroborating synthetic talc good dispersion as evidenced by XRD and TEM analyses. Synthetic talcs used as catalyst/filler resulted in nanocomposites with superior thermal and mechanical properties being a new path to utilize synthetic talcs to obtain multifunctional materials.

    更新日期:2020-01-16
  • Thermo-sensitive gellan maleate/ N -isopropylacrylamide hydrogels: initial “in vitro” and “in vivo” evaluation as ocular inserts
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-10
    Mihaela Hamcerencu, Jacques Desbrieres, Marcel Popa, Gérard Riess

    Abstract Hydrogels are among the most used polymer–drug systems, polysaccharide-based materials presenting many advantages to be used for controlled release applications. Gellan maleate/NIPAm hydrogels are hydrophilic swelling matrixes that were originally developed for biomedical applications as controlled release dosage forms. The purpose of this study is to explore the ability of gellan maleate/NIPAm thermoreversible hydrogels for ophthalmic applications as ocular inserts. Studied hydrogels were synthesized by free radical grafting/polymerization of unsaturated esters (gellan maleate) with N-isopropylacrylamide (NIPAm) and N,N′-methylenebisacrylamide as cross-linker. They are evaluated for swelling degree, in vitro inclusion and release of drugs (adrenaline and chloramphenicol) and in vivo biocompatibility. The hydrogel is shown to be a temperature-responsive material with a LCST close to 36 °C. The swelling properties and the release of biologically active compounds occur when polymer conformation changes determining phase transition at LCST. Gellan-based hydrogels present reproducible responses to alternation between ambient temperature and human body one. The stability and biocompatibility were evaluated in vitro and in vivo. Tissue response to implantation of hydrogel was determined by histological analysis (haematoxylin–eosin–methylene blue and periodic acid–Schiff). A thin fibrous capsule was observed around the implanted hydrogels. No necrosis, calcification and acute inflammatory reaction were noted. Successful preliminary results were obtained for ophthalmic applications.

    更新日期:2020-01-16
  • Cellulose-supported Pd nanoparticles: effective for the selective oxidation of glucose into gluconic acid
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-24
    Xinxin Zhang, Haoyan Shi, Quan Chi, Xixi Liu, Lianqing Chen

    Cellulose-supported on Pd nanoparticles (Pd/cellulose) were successfully prepared by chemical reduction technique and characterized by various experimental tools. The Pd/cellulose catalyst was found to effectively promote the oxidation of glucose into gluconic acid under mild conditions. The base played a crucial role in the oxidation of glucose into gluconic acid. Glucose was fully converted at room temperature after 3 h by the use of stoichiometric amount of Na2CO3 to neutralize gluconic acid, and gluconic acid was obtained in a high yield of 91.2%. The catalyst was recovered from product and reused up to five times without significant loss in its catalytic activity.

    更新日期:2020-01-16
  • Crystallization kinetics and morphology of dynamically vulcanized poly(vinylidene fluoride)/silicone rubber blends
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-05
    Yanpeng Wang, Tao Ding

    Effects of silicone rubber (SR) on the isothermal crystallization kinetics, non-isothermal crystallization kinetics, crystal structure, spherulitic morphology, rheological properties and mechanical properties of dynamically vulcanized poly(vinylidene fluoride) (PVDF)/SR blends were investigated. Relative to the pure PVDF, incorporation of SR component has not only enhanced the non-isothermal crystallization rates of PVDF in the blends at the same cooling rate, but also increased the isothermal crystallization rates at the same crystallization temperature. The crystalline structure does not change for PVDF/SR blends. The poor interfacial adhesion and poor compatibility between the two phases play a critical role in the reduced Izod impact strength.

    更新日期:2020-01-16
  • Structural and mechanical properties of fibrous poly (caprolactone)/gelatin nanocomposite incorporated with cellulose nanofibers
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-09
    Zahra Moazzami Goudarzi, Tayebeh Behzad, Laleh Ghasemi-Mobarakeh, Mahshid Kharaziha, Mohammad Saied Enayati

    To proceed with the electrospun poly (caprolactone) (PCL)/gelatin (Gel) combinations, the current research was aimed to explore the incorporation of cellulose nanofibers (CNF) into the PCL/Gel blends for the first time. Accordingly, various amounts of CNF were added to different ratios of PCL/Gel, and the corresponding electrospun nanocomposites were examined. Observing morphology via scanning electron microscopy proved, unexpectedly, increasing fibers diameter upon CNF addition into PCL/Gel blends. Mechanical analysis in tensile mode revealed more brittle electrospun PCL/Gel when more Gel was included into the blend due to higher Young’s modulus and lower ultimate tensile strength and strain at break. Addition of various contents of CNF led to strain reduction while displayed a summit-like curve for UTS and modulus, where registered maximum values at 2 wt% CNF for all PCL/Gel/CNF. Among the electrospun nanocomposites the highest UTS (3.24 ± 0.22 MPa) belonged to sample including 70 wt% PCL, 30 wt% Gel, and 2 wt% CNF (P70/2CNF), while P30/2CNF recorded maximum modulus (93.89 ± 10.44 MPa). The wide-angle X-ray scattering confirmed increase in PCL crystallinity upon CNF incorporation Furthermore, the presence of PCL, Gel, and CNF in electrospun composites was confirmed with Fourier transform infrared spectroscopy. Degradability of electrospun nanocomposites was carried out in PBS solution, which showed that CNF addition reduced degradation rate of PCL/Gel blends.

    更新日期:2020-01-16
  • Preparation of cadmium sulfide nanoparticles and mediation thereof across poly(hydroxybutyrate) nanocomposite
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-10
    Shahina Riaz, Zulfiqar Ali Raza, Muhammad Irfan Majeed

    Herein, we used chemical precipitation method to synthesize cadmium sulfide (CdS) nanoparticles (NPs) with different concentrations of CdNO3. The CdS NPs of size 105 nm and the corresponding zeta potential of 42.2 mV were achieved at CdNO3 concentration of 1 mM. X-ray diffraction (XRD) analysis revealed W-type hexagonal geometry of CdS NPs. The prepared CdS NPs were introduced into poly(hydroxybutyrate) (PHB) matrix to fabricate CdS/PHB composite nanomaterial. The physicochemical characterization showed successful synthesis of a novel nanocomposite. The XRD analysis showed that CdS/PHB nanocomposite exhibited hexagonal crystal structure, i.e., crystallite orientation of nanocomposite was majorly controlled by CdS NPs. Scanning electron micrographs of CdS NPs and CdS/PHB nanocomposite revealed spherical morphology of CdS NPs and their successful placement into PHB matrix with some random aggregations. The results were further confirmed using transmission electron microscopy (TEM) and a high-resolution TEM. Thermogravimetric analysis showed improved thermal characteristics of nanocomposites after incorporation of CdS NPs into PHB matrix.

    更新日期:2020-01-16
  • Preparation and characterization of biogenic CaCO 3 -reinforced polyvinyl alcohol–alginate hydrogel as controlled-release urea formulation
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-02
    Nisha Stanley, Biswanath Mahanty

    Abstract A slow-release fertilizer formulation was prepared by incorporation of urea in polyvinyl alcohol–alginate hydrogel core followed by deposition of calcium carbonate coating using HCO3−/CO32−-rich alkaline cell-free ureolytic culture broth. High urea encapsulation efficiencies were evident in both CaCO3-reinforced (23.48% w/w) and regular (38.71% w/w) hydrogel matrices. Deposition of carbonate over the matrix surface in the reinforced hydrogel was evident from scanning electron microscopy and typical FTIR band near 1465 cm−1 due to C–O stretch of carbonate ion. Aqueous phase release behaviour was not significantly different between the two hydrogel variants. In the soil column, two-stage urea release pattern (i.e. a slow followed by a fast) was eminent that can extend into hours. Therefore, the modified hydrogel for controlled release could be expected to have wide potential application as slow-release fertilizer in agriculture.

    更新日期:2020-01-16
  • Thermal characterization by DSC and TGA analyses of PVA hydrogels with organic and sodium MMT
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-20
    Fatiha Reguieg, Lucia Ricci, Nabahat Bouyacoub, Mohamed Belbachir, Monica Bertoldo

    Polyvinyl alcohol (PVA) hydrogels were prepared by a cyclic freezing–thawing technique without any cross-linker agent, using PVA and Maghnite water dispersion with different ratios. The obtained results have shown a higher thermal stability of samples with sodium than with alkylammonium Maghnite. Furthermore, thermal stability was maximum at the lowest investigated Maghnite/PVA ratio, but higher than for the pure PVA at all the investigated compositions. DSC analysis has shown both a low crystal degree and a low heat capacity jump at the glass transition temperature for samples with high Maghnite content. This phase does not seem to depend on the kind of cations, sodium or alkylammonium into the gallery of the clay.

    更新日期:2020-01-16
  • Microencapsulation of 2-phenyl ethanol with methylcellulose/alginate/methylcellulose as the wall material and stability of the microcapsules
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-23
    Bining Qiu, Hua Tian, Xueqiong Yin, You Zhou, Li Zhu

    In this study, 2-phenyl ethanol (2-PEA) was microencapsulated with natural and semisynthetic carbohydrate polymers as the wall material. The wall material components methylcellulose (MC), alginate sodium (ALG), and carboxymethyl chitosan were optimized according to the results of microscopy images, zeta potential, and 2-PEA content. The combination of MC/ALG/MC was selected as the best wall components. Cobalt chloride (CoCl2) was used as the core material to prepare microcapsules whose color was measured with a colorimeter to intuitively express the water absorption of the microcapsules. The absorbed water mass and b* were related to one variable quadratic equation. The rapid release properties and the natural long-term release properties of 2-PEA microcapsules were measured.

    更新日期:2020-01-16
  • Gamma irradiation effects on conductivity and dielectric behaviour of PEO-based nano-composite polymer electrolyte systems
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-05
    V. R. Sunitha, S. Radhakrishnan

    The effect of gamma irradiation on physical and electrical properties of polyethylene oxide (PEO)-based nano-composite polymer electrolyte films was investigated. The structural change induced and the reduction in crystallinity of the electrolyte film before and after irradiation were confirmed by FTIR spectra and X-ray diffraction studies. Microstructural studies carried out by scanning electron microscope technique reveal significant change in the surface morphology on irradiation. The bulk conductivities of the films were studied using standard impedance spectroscopic technique. A maximum ionic conductivity of 1.717 × 10−4 S cm−1 was observed for 40 kGy radiation dose, which is higher than earlier reported studies. Ion dynamics behaviour of the films was studied by frequency-dependent conductivity measurements which follow universal power law. The dielectric constant tends to be higher for films with higher lithium ion conductivity.

    更新日期:2020-01-16
  • Study on the effects of polyhedral oligomeric silsesquioxane on compatibility, crystallization behavior and thermal stability of polylactic acid/polycaprolactone blends
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-04
    Elham Moeinifar, Maryam Otadi, Javad Seyfi, Hossein Ali Khonakdar

    Abstract Herein, the effect of polyhedral oligomeric silsesquioxane (POSS) on compatibility, crystallization and thermal stability of polylactic acid (PLA)/polycaprolactone (PCL) blends was investigated. Scanning electron microscopy results revealed that the blend morphology became finer and much more uniform once lower contents of POSS were used. However, the compatibility level was notably reduced once the nanoparticle content increased which was attributed to the lower dispersion quality of POSS at higher concentrations. Differential scanning calorimetry results showed that lower contents of POSS suppressed the solution crystallization of PLA component due to the enhanced interactions between PLA and PCL as a result of the improved compatibility. However, at higher POSS contents, nanoparticles’ nucleating effect became dominative leading to a higher degree of crystallinity. Thermogravimetric analysis showed that lower contents of POSS (1 and 2 wt%) greatly improved the thermal stability of the blend. Apart from the heat shielding role of POSS, the higher level of compatibility and, thus, more interactions between PLA and PCL were also responsible for the improved thermal stability since PCL is much more thermally stable than PLA. In conclusion, the nanoparticle-induced blend compatibility could impose positive and negative influences on different properties of PLA/PCL systems, which needs to be further investigated.

    更新日期:2020-01-16
  • Low-temperature plasma modification of carbon nanofillers for improved performance of advanced rubber composites
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-24
    Mariusz Siciński, Dariusz M. Bieliński, Hieronim Szymanowski, Tomasz Gozdek, Anna Piątkowska

    Abstract In modern polymer industry, there still is a room for new generations of fillers capable of enhancing the performance of composite materials. Currently, much effort is being put into a process of improving mechanical properties of elastomer materials. In this work, multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) were modified with silane, titanate, or zirconate using plasma treatment, in order to apply them as fillers for styrene/butadiene rubber. Following its modification, filler surface was analyzed: Surface free energy (SFE) was measured with tensiometry, and micromorphology and chemical composition were studied with scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), while elemental composition and bonding were assessed with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Low-temperature oxygen plasma activation of MWCNT fillers leads to a significant increase in the SFE polar component, with the same effect being much weaker for GnP fillers. Grafting silanes, zirconates, and titanates on activated filler surface results in a decrease in SFE polar component—surface oxygen-containing active groups react with silane/zirconate/titanate molecules. Fillers modified in this way exhibit different micromorphology and surface chemical composition what is revealed with the SEM–EDS, ToF-SIMS, and XPS techniques. As the ultimate step, either MWCNT or GnP rubber nanocomposites were manufactured using the modified fillers with their mechanical properties and cross-link density being studied. Filler modification resulted in substantial changes both in composite performance, and in its cross-linking density. In the case of modified filler containing composites, improved tensile strength and elongation at break were observed.

    更新日期:2020-01-16
  • Adsorption of Eosin Y, methyl orange and brilliant green from aqueous solution using ferroferric oxide/polypyrrole magnetic composite
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-25
    Mengmeng Zhang, Zehao Yu, Hongchao Yu

    Ferroferric oxide/polypyrrole (Fe3O4/PPy) composites were prepared by an in situ polymerization method. Several analysis techniques including X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis and scanning electron microscopy are applied to analyze the structure and morphology of Fe3O4/PPy. The magnetic Fe3O4/PPy was further used as an adsorbent for removing Eosin Y, methyl orange and brilliant green from aqueous phase. The adsorption kinetics were investigated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and the experimental data were well fitted to the pseudo-second order. The equilibrium adsorption data can be described by both the Langmuir and Freundlich isotherm models. The calculated Langmuir maximum adsorption capacities of Eosin Y, methyl orange and brilliant green at 25 °C are 212.31, 149.48 and 263.85 mg/g, respectively. Thermodynamic studies indicated that the adsorption process occurred spontaneously, in an endothermic and physisorption nature, and with increased disorder. Furthermore, the convenient magnetic separability of Fe3O4/PPy makes it a good candidate for practical application in the removal of organic dyes from polluted water.

    更新日期:2020-01-16
  • Effect of filler type on properties of PBAT/organoclay nanocomposites
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-13
    Tiago T. Santos, Tatiara G. Almeida, Dayanne D. S. Morais, Fernão D. Magalhães, Rui M. Guedes, Eduardo L. Canedo, Laura H. Carvalho

    Abstract The goal of this study is to evaluate the effect of different organoclays on the properties of poly(butylene adipate-co-terephthalate) (PBAT)/organoclay systems. PBAT/organoclay nanocomposites containing 2.5, 5.0 and 7.5% of three different commercial organically modified clays (Cloisite® C10A, C20A and C30B) were prepared as a masterbatch in a laboratory internal mixer, let down to the appropriate concentration in a co-rotating twin-screw extruder, and test specimens were injection molded. Nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetry (TGA) and dynamic mechanical analysis (DMA) as a function of clay identity and content. XRD results showed a significant increase in the interlayer spacing of the clay, suggesting that intercalated structures were obtained with all systems investigated, as confirmed by TEM. Organoclay incorporation into PBAT resulted in lower melt crystallization temperatures compared with the neat polymer, particularly in PBAT/C30B nanocomposites, slightly improved thermal stability, increased stiffness and no changes in the glass transition temperature. Compounding PBAT with up to 7.5% of C10A, C20A or C30B organoclays is an option to improve the performance of PBAT.

    更新日期:2020-01-16
  • Stability analysis of PA-6/ethylene elastomer blends for outdoor and nuclear applications
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-04
    Traian Zaharescu, Alina Ruxandra Caramitu, Virgil Marinescu

    The comparative behaviour under the oxidative degradation occurred during accelerating conditions of ageing (γ-irradiation and artificial weathering) is analysed for three polyamide-6-based formulations destined to special services like outdoor and nuclear fields. Pristine PA-6 and its blends with two ethylene elastomers (ethylene–propylene copolymer and ethylene–acrylic ester terpolymer) grafted with maleic anhydride were tested under accelerated degradation (radiation processing and weathering) by chemiluminescence and swelling. The elastomers are minor components with three loading degrees (5, 10 and 20%). The influence of elastomer fractions on the promotion of oxidation is revealed by the comparison with neat PA-6, which is a most stable of the three involved polymers. The results demonstrate that the minor components are the sources of radicals that are reactive spots. The competition between degradation and partial cross-linking is analysed. The calculated activation energies of oxidation allow the prediction of stability for long-term operation. The mechanistic aspects connected to the availability of blending components to oxidation are discussed for the explanation of ageing propagation under various factors acting during ageing promotion service.

    更新日期:2020-01-16
  • Fabrication of pristine -multiwalled carbon nanotubes/cellulose acetate composites for removal of methylene blue
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-05
    Mónica A. Silva, L. Hilliou, M. T. Pessoa de Amorim

    Here, we report the effect of mixing different amounts of pristine-multiwalled carbon nanotubes (p-MWCNTs) with the cellulose acetate (CA) on dye removal. The p-MWCNTs loadings of the composites were varied from 0 to 1.0 wt%, and the non-solvent-induced phase separation methodology was used to fabricate the composite membranes, which were extensively characterized. The rheological tests confirmed that with 1.0 wt% of p-MWCNTs there was a classical filler effect in the viscoelastic behavior of the composite solution, but with no percolation of CNTs. The ATR-FTIR spectra identified specific interactions between CNTs and acetate groups of CA. SEM images showed a top dense layer sustained by a porous support layer consisting of a sponge-like structure in the middle layer. Aggregates of CNTs were seen at higher loadings of CNTs (> 0.1 wt%). The XRD diffractograms of composite membranes showed peak shifts compared to CA membranes due to the presence of CNTs into the CA structure, and their thermal stability was effective up to 320 °C. From the water permeability experiments, the calculated values of the membrane hydraulic resistance (Rm) of the composites were higher since a dense top layer and reduced pore size were achieved. Among all the composite membranes, M7 and M8 had the most desirable antifouling properties due to the high surface hydrophilicity imparted by the CNTs, and also showed an improvement in the removal of methylene blue (MB).

    更新日期:2020-01-16
  • Fabrication of a photoelectric-sensitive imprinting polymer by PPy-cross-linked Gel/CS complex and its comprehensive treatment of Cr(VI)
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-13
    Jianyu Xing, Yu Shen, Wenwen Dang, Bin Yang, Wanchen Fu, Wei Wang, Bo Bai

    Adsorption is a common method for treating pollutants. High-concentration chemical reagents are always involved in the traditional desorption process, which leads to chemical waste and secondary environmental pollution. To alleviate this problem, polypyrrole (PPy), combined with two inexpensive and renewable biomass compounds, gelatin (Gel) and chitosan (CS), was used to fabricate a novel photoelectric-sensitive Cr(VI) ion-imprinting composite, namely, Gel/CS/PPy. Except for the higher selectivity to Cr(VI), the photoelectric property of PPy enables Gel/CS/PPy to be regenerated with the aid of light and electricity. The result shows that electro-assistant can improve the desorption efficiency by 140%, while photo-assistant can improve the desorption efficiency by 19.8%. As a result, the desorption process will greatly reduce the dependence on chemical reagents and the secondary pollution to the environment.

    更新日期:2020-01-16
  • Silver nanoparticle-embedded pectin-based hydrogel for adsorptive removal of dyes and metal ions
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-03
    Arun K. Kodoth, Vishalakshi Badalamoole

    Silver nanoparticles made by green synthesis have been incorporated into pectin-based copolymer gel to make a nanocomposite gel to be used as an adsorbent material for the removal of divalent metal ions and dyes from aqueous solutions. Silver nanoparticles were obtained by mixing silver nitrate with aqueous solution of pectin followed by microwave irradiation. The nanocomposite hydrogel was obtained by the microwave-assisted polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and acrylamide (AAm) in the presence of N,N’-methylene-bis-acrylamide (MBA) in pectin solution containing silver particles. Characterization of the nanocomposite gel was done by FTIR, TGA, XRD, FESEM and EDS techniques. The system was evaluated for its capacity to adsorb cationic dye, crystal violet (CV) and metal ions [Cu(II) and Pb(II)] from aqueous solutions. The presence of Ag nanoparticles is observed to enhance the adsorption capacity of the gel for the above mentioned adsorbates. The kinetic studies revealed second-order adsorption processes which fit well into Langmuir model. The evaluation of thermodynamic parameters indicated the adsorption process to be exothermic and spontaneous. A maximum of 1950 mg/g CV, 111 mg/g Cu(II) and 130 mg/g Pb(II) could be removed from the aqueous solution which is quite high in comparison with other reported materials. The desorption studies indicated the possible reusability of the nanocomposite.

    更新日期:2020-01-16
  • Study of formation constant, thermodynamics and β-ionone release characteristic of β-ionone-hydroxypropyl-β-cyclodextrin inclusion complex
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-13
    Guangyong Zhu, Guangxu Zhu, Zuobing Xiao

    Abstract β-Ionone has a characteristic violet-like odor and is an important flavor and fragrance ingredient used in food and perfumery. Furthermore, it has the ability to selectively kill tumor cells and is a promising anticancer agent. In order to improve its solubility, stability and long-release characteristics, β-ionone was encapsulated in hydroxypropyl-β-cyclodextrin (HP-β-CD) to form inclusion complex. The formation constants (K) and thermodynamics were explored by ultraviolet–visible (UV/V) absorption method. The values of K obtained at 35 °C, 45 °C and 55 °C were 29.6 × 103 l/mol, 8.4 × 103 l/mol and 4.9 × 103 l/mol, respectively. Gibbs free energy changes (ΔG) for the interactions of β-ionone and HP-β-CD at 35 °C, 45 °C and 55 °C were − 26.4 kJ/mol, − 23.9 kJ/mol and − 23.6 kJ/mol, respectively. Enthalpy change (ΔH) and entropy change (ΔS) were − 1.1 kJ/mol and − 2.3 J/(K mol), respectively. The solid β-ionone-HP-β-CD inclusion complex was characterized by FTIR and thermogravity analysis (TGA). The FTIR results confirmed that β-ionone was successfully encapsulated in HP-β-CD and that encapsulation of β-ionone did not change the frame of HP-β-CD. The TGA results showed that the release of most of the β-ionone from β-ionone-HP-β-CD inclusion complex mainly occurred in the temperature range of 210–320 °C. A relative larger release rate appeared at 240 °C and the beginning stage of HP-β-CD decomposition. It also revealed that the thermal stability of β-ionone was improved by the encapsulation technology.

    更新日期:2020-01-13
  • The properties of nanofiber scaffolds of polyurethane- Cinnamomum zeylanicum against pathogens of Pseudomonas aeruginosa and Staphylococcus aureus
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-11
    H. Hosseinpor, A. Khaledi, D. Esmaeili

    Abstract This study designed to investigate the properties of antibacterial nanofiber scaffolds of polyurethane-Cinnamomum zeylanicum against virulence gene expression inhibition of Pseudomonas aeruginosa and Staphylococcus aureus that are important in burn wounds. With attention to burn wound infections in hospitals and mortality increase in patients, it is necessary to design nanodressing. Clinical isolates were confirmed by biochemical and microbiological tests. DNA of isolates was extracted and PCR used to confirm the alp gene of P. aeruginosa and Pv gene of S. aureus. Polyurethane nanofiber and cinnamon polymers were used to prepare the scaffold under the electrospinning process. Infrared spectroscopy, electron microscopy, and mechanical tensile tests were used to confirm the scaffolds. The susceptibility testing and minimum inhibitory concentration of polyurethane-cinnamon nanofiber scaffold were determined against P. aeruginosa and S. aureus. For confirmation of polyurethane-cinnamon nanofiber scaffold were used the cytotoxicity test (MTT), FTIR, mechanical tensile test, and a scanning electron microscope. The expression of virulence genes was investigated using the real-time RT-PCR technique. The results of the susceptibility testing indicated that P. aeruginosa and S. aureus were susceptible to polyurethane-cinnamon nanofiber scaffold. The MTT, FTIR, mechanical tensile test, and SEM confirmed the different features of the polyurethane-cinnamon nanofiber scaffold. Results of real-time PCR demonstrated that the expression levels of p–v and alp genes after treatment decreased, respectively, 2.71- and 1.06-fold. Results indicated that the electrospun polyurethane-cinnamon nanofiber scaffold for the first time could inhibit both important pathogens of the hospital and the expression of the virulence genes. Considering the susceptibility of P. aeruginosa and S. aureus to and its inhibitory effect on an alp and p–v genes, this system could probably be a candidate in wound dressing for commercial purposes to burn healing and infection inhibition.

    更新日期:2020-01-13
  • Enhancing the adhesion strength of polyurethane coatings by dispersing layered silicates via sonication and high-shear mixing method
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-10
    Sifiso John Skosana, Caroline Khoathane, Thomas Malwela

    Low adhesion strength of polyurethane coating to a steel substrate is often attributed to poor steel preparation. However, the ratio of diisocyanate/polyol and dispersion of fillers within a polyurethane coating matrix influence the adhesion strength, optical and corrosion resistance properties. Poor dispersion of nano-fillers in a polymer coating matrix can lead to low adhesion strength, because close packing of nanoparticles often hides the hydroxyl groups required to form polar–polar bonds with the steel surface. This study combines sonication and high-shear mixing methods with shorter mixing times to prepare polyurethane nanocomposite coatings with various clay concentrations while keeping the ratio of diisocyanate/polyol constant. Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray diffraction, thermogravimetric analysis and pull-off are used to characterize polyurethane nanocomposite coatings. FTIR results confirm that sonication and high-shear mixing successfully prepare polyurethane-based coatings. TEM shows uniformly dispersed clay particles in polyurethane matrices. The adhesion strength improved on addition of 1–5 wt% C30B organoclay, with the highest improvement (34.4%) at 3 wt% loading. The corrosion resistance of polyurethane coatings was improved by the incorporation of organoclays into their matrices. Onset degradation temperature is also delayed by 4.1–8.5% as the clay concentration increased from 1 to 5 wt%.

    更新日期:2020-01-11
  • The crystallization behavior of poly( l -lactide)/poly( d -lactide) blends: effect of stirring time during solution mixing
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-09
    Jun Shao, Lanli Xu, Shouzhi Pu, Haoqing Hou

    Blending of poly(l-lactide) and poly(d-lactide) (PLLA, PDLA) results in the formation of poly(lactide) stereocomplex crystallites (SC). For the preparation method, numerous reports employed solution mixing and stirring to receive a product with uniform performance. However, the effect of stirring time during solution mixing on the subsequent crystallization behavior did not clear yet, and which is important for solution crystallization, casting and spinning. In this paper, linear PLLA and PDLA with various molecular weights were synthesized. The PLLA and PDLA solutions were mixed together and stirred for different times before casting. Results revealed that the structures of PLA SC and homochiral crystallites (HC) did not vary with change in the stirring time. More amount of content of SC with uniform structure and less amount of content of HC were produced in the specimens stirred for longer time. When the specimens crystallized either from the melt or from the melt-quenching, less amount of content of crystallites (total crystallinity of SC and HC) was produced and the melting temperature of SC and HC depressed in the specimens that were stirred for longer time. With the increase in molecular weights, the effect of stirring time on the crystallization behaviors declined. This investigation provides a route to tailor the crystallization behavior of PLLA/PDLA specimens.

    更新日期:2020-01-11
  • The synergetic effect of antimony (Sb 2 O 3 ) and melamine cyanurate (MCA) on the flame-retardant behavior of silicon rubber
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-09
    Xuezheng Huang, Zhenjun Tian, Dasheng Zhang, Qi Jing, Jianxi Li

    The silicone rubber composites with antimony trioxide (Sb2O3) and melamine cyanurate (MCA) additive were fabricated. The results of scanning electron microscope are shown that the Sb2O3 and MCA are uniformly dispersed into the silicone rubber (SR). It was found that tensile strength and elongation at break were down to 300% and 5.3 MPa with the increase in MCA content. The flammability of the composite was also studied by limiting oxygen index (LOI) and cone calorimetry test. The results indicated that a 31.5% LOI of the composite was achieved, and the heat release rate and total heat release values of the composite with MCA were apparently reduced compared to that without MCA. Meantime, the retention of elongation and tensile strength keeps good behavior. The time to ignition of the composite with MCA is belonged. The results show that the microstructure of combustion residue of MCA additive is continuous and smooth, and it is a good barrier to isolate combustible gas and oxygen. All these test results demonstrated that the synergistic effect of Sb2O3 and MCA successfully enhanced the flame-retardant properties of the SR composite.

    更新日期:2020-01-09
  • Synthesis of surface ion-imprinted polymer for specific detection of thorium under acidic conditions
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-09
    N. A. F. Othman, S. Selambakkannu, H. Azian, C. T. Ratnam, T. Yamanobe, H. Hoshina, N. Seko

    Abstract A fibrous surface ion-imprinted polymer (IIP) was synthesized for thorium removal through direct electron beam radiation using thorium as a template. Polypropylene coated by polyethylene non-woven fabrics (PE/PP) was used as a substrate. The PE/PP non-woven fabrics were irradiated in the presence of the phosphoric monomer (2-HMPA) composed of 2-hydroxyethyl methacrylic phosphoric acid diester (50%) and monoester (50%) emulsified with the crosslinker. Hence, the formation of the three-dimensional IIP-Th crosslinked network and complexation between thorium (template) and 2-HMPA was investigated. The emulsion stability and particle size distribution of emulsion were determined using dynamic light scattering (DLS). Various factors influencing the synthesis of the thorium ion-imprinted (Th-IIP) non-woven PE/PP such as the absorbed radiation dose, monomer concentration, and type of crosslinker were investigated. The IIP-Th was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy–energy-dispersive X-ray (SEM–EDX), and X-ray photoelectron spectroscopy (XPS) and applied as an adsorbent for the removal of thorium using the batch adsorption method. The IIP-Th achieved a maximum distribution coefficient of 3.293 g/L and selectivity ratio (Th(IV)/U(VI)) of 9.5 after 90 min of contact time under acidic conditions. The adsorption kinetics of IIP-Th followed the pseudo-second-order kinetic model for both Th(IV) adsorption and U(VI) adsorption. The synthesized fibrous surface ion-imprinted polymer is a promising candidate for the selective removal of thorium ions from aqueous solution.

    更新日期:2020-01-09
  • Effect of boron methacrylate monomer on the thermal and pressure-sensitive adhesive properties of 2-EHA-based copolymer latexes synthesized via mini-emulsion polymerization procedure
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-08
    Ecem Temelkaya Bilgin, Cansu Akarsu Dülgar, Tuba Çakır Çanak, İ. Ersin Serhatlı

    Abstract Pressure-sensitive adhesives (PSAs) are characterized by instantaneous adhesion upon application of light pressure. PSA performance is defined by peel strength, tack and shear strength. The adhesion and cohesion mechanisms are well defined as peel adhesion, loop tack and shear strength in the state of the art and can be adjusted according to the specific requirements. 2-Ethylhexyl acrylate-based latexes have been synthesized with the incorporation of boron methacrylate (BoMA) via mini-emulsion polymerization, and latexes with high surface area were obtained enabling interactive relation with polar and nonpolar surfaces. Cetyl alcohol was used as a cosurfactant to have colloidally stable hydrophobic particles in mini-emulsion polymerization. The incorporation of BoMA at 2% and 4% into the latexes led to an increase in peel adhesion strength on polar and nonpolar substrates. The addition of BoMA decreased the shear strength on both polar and nonpolar substrates at initial and after aging conditions. The shear strength was higher after the polymer films were aged providing a stable and stiff material. The amount of BoMA incisively affects the type of PSA and should be taken into consideration while constructing a polymer for a pre-specified application. The thermal properties were also improved by the addition of BoMA in terms of thermal stability and char yield. The assumptions in question were strongly correlated with peel, shear, loop tack values and thermal analysis.

    更新日期:2020-01-08
  • CdSe nanorod-reinforced poly(thiophene) composites in designing energy storage devices: study of morphology and dielectric behavior
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-08
    Rashmi Singh, A. K. Bajpai, A. K. Shrivastava

    Abstract The present study reports the findings about developing the energy storage resources following a green and economically viable method. Polythiophene (PTh) and its nanocomposites (PTh/CdSe) were synthesized using a chemical oxidative polymerization method. The FTIR spectra of the as-prepared composite confirm the presence of CdSe in PTh matrix. The XRD spectra suggest for the amorphous nature of native PTh which further changes into semicrystalline nature when CdSe was incorporated into it. PTh/CdSe nanocomposites showed both cubic and hexagonal phases, and the crystallite size was found to increase from 8 nm to 45 nm when CdSe was reinforced into the PTh matrix. Transmission electron microscopic images of pure PTh showed spherical morphology of the particles joined to each other through van der Waals forces. The doping of CdSe also results in appearance of needle-like nanostructures over PTh surfaces. These isolated needles have CdSe nanorod-like structures. Impedance data reveal that charge transfer resistance (Rct) of pure PTh is higher than that of the PTh/CdSe nanocomposites. The reduced charge transfer resistance (Rct) indicates that conductivity of nanocomposites is higher than that of the native one. When PTh was reinforced with the CdSe, they showed an increase in dielectric constant which is due to the alignment of polarization charges with increased frequency. This mechanism of polarization is helpful in increasing the charge storage capacity of the material. Thus, the observed results may open up doors of new avenues to design energy storage devices using conducting polymer/semiconductor nanocomposites.

    更新日期:2020-01-08
  • Study of polydiacetylenes and rhodamine-800 mixed film at air–water interface and onto solid support: Trace of fluorescence resonance energy transfer (FRET)
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-08
    Sudip Suklabaidya, Sekhar Chakraborty, Jaba Saha, Bapi Dey, Surajit Sarkar, Debajyoti Bhattacharjee, Syed Arshad Hussain

    Abstract Here, we report the mixing behaviour of diacetylene monomer 10, 12-tricosadiynoic acid (TCDA) and rhodamine-800 (Rh8) using Langmuir–Blodgett (LB) technique. The presence of Rh8 affected the structures, phase behaviour as well as colorimetric properties of TCDA in the mixed films at air–water interface and onto solid support. The mixed LB films having TCDA molefraction ≥ 0.5 leads to multilayer formation, whereas multilayer formation was hardly observed for the films containing TCDA molefraction less than 0.5. It was observed that polymerization as well as phase change (blue to red) was possible only for multilayered films. Brewster angle microscopy, atomic force microscopy, and fluorescence inverted microscopy studies confirmed the formation of definite structures in the polymerized TCDA/Rh8 mixed films at air–water interface and onto solid support. Structure of TCDA polymer strands was largely influenced by the presence of Rh8 in the mixed films. Interestingly, energy transfer occurred from TCDA in red phase to Rh8 in the mixed films with TCDA molefraction greater than 0.4. Maximum energy transfer efficiency was found to be 47.3% for the mixed LB film with TCDA molefraction 0.9.

    更新日期:2020-01-08
  • Impact of environmental conditions on silicone pressure-sensitive adhesives
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-06
    Adrian K. Antosik, Mateusz Weisbrodt, Karolina Mozelewska, Zbigniew Czech, Marta Piątek-Hnat

    Abstract Silicone pressure-sensitive adhesives are characterized by very good self-adhesive and functional properties. The first group includes: tack, adhesion and cohesion. No less important are the functional properties: maximum working temperature, shrinkage, resistance to external factors and yellowing. It is well known that silicone adhesives are materials for special applications due to their properties, namely surface tension, high UV transparency, good thermal stability, low intermolecular interactions or low surface tension. This paper attempts to investigate the influence of environmental conditions and PSA aging time on the most important functional and self-adhesive properties. This is an important aspect in terms of the use of this type of materials and their suitability for use. The tests were carried out after 1 h days and after a 6 month. To investigate the impact of environmental conditions samples (tapes and joints tapes with a steel substrate), they were conditioned in a climatic chamber simulating environmental conditions by 20 days.

    更新日期:2020-01-06
  • Protection of copper from corrosion through electrodeposited poly-2,5-dimercapto-1,3,4-thiadiazole–TiO 2 composite film
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-06
    K. Vinothkumar, M. G. Sethuraman

    Abstract An efficient, simple, robust strategy for the protection of copper in a neutral medium has been developed by the fabrication of electropolymerised film of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) + TiO2 composite. The electrosynthesised polymeric and composite films were characterised by different spectroscopic methods (FTIR, Raman spectroscopy, XPS, and XRD pattern). Electrochemical impedance spectroscopy and potentiodynamic polarisation studies confirmed the superior corrosion inhibition performance of fabricated composite film on copper in 3.5% NaCl medium. The enhanced protection efficiency of the polymeric composite could be due to the synergism between the organic polymer and inorganic particles. It is also found that the protection efficiency of the DMTD–TiO2 composite film lasts for more than 24 h. Further, SEM analysis reveals the formation of the protective film of the composite over Cu surface, while EDAX analysis unravels its composition. The study on effect of scan rate on electropolymerisation revealed that the electrodeposition of the polymer is a diffusion-controlled process. Thus, the study suggests that the fabrication of DMTD–TiO2 composite is an ideal strategy for the protection of copper in a neutral medium.

    更新日期:2020-01-06
  • Strong alginate/reduced graphene oxide composite hydrogels with enhanced dye adsorption performance
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-04
    Daijun Xiao, Minghong He, Yulan Liu, Lijun Xiong, Qiao Zhang, Lai Wei, Liang Li, Xianghua Yu

    The alginate/reduced graphene oxide composite hydrogels with hierarchical network structures were synthesized through the hydrothermal treatment of graphene oxide and alginate in an aqueous solution followed by ionically cross-linking of metal ions. The network of reduced graphene oxide was prepared via self-assembly of graphene nanosheets in the presence of alginate during the hydrothermal process; then, the polymer network of alginate was obtained by ionically cross-linking, forming the composite hydrogel. The effect of metal ions on the physical properties of the composite hydrogels was investigated. The prepared alginate/reduced graphene oxide composite hydrogel cross-linked by Fe3+ ions showed higher compression strength and lower swelling ratio. Moreover, due to the synergetic interaction between graphene and alginate, the composite hydrogels exhibited the improved dye adsorption performance, especially for cationic dyes. Even after ten adsorption/desorption cycles, the composite hydrogels can retain more than 90% dye adsorption capacity. The results indicated that the composite hydrogel with good stability, adsorption and regeneration ability could be a promising candidate for dye removal from waste aqueous solutions.

    更新日期:2020-01-04
  • Synthesis and characterization of processable aromatic poly(ether ether ketone amide)s modified by phenoxy and 1,3 ketone moiety linkages
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-04
    A. B. Tamboli, N. N. Maldar

    New series of aromatic poly(ether ether ketone amide)s were synthesized by low-temperature solution polymerization of novel aromatic diamine, namely 1,3-bis-4′-(4″-aminophenoxy benzoyl)benzene (XIV), and aromatic diacid chlorides, viz. isophthaloyl chloride (IPC) and terephthaloyl chloride (TPC). Co-poly(ether ether ketone amide)s were also synthesized by employing various mole proportions of IPC and TPC with diamine (XIV). These poly(ether ether ketone amide)s were characterized by FTIR, solubility, inherent viscosity, TGA, DSC, and XRD. Inherent viscosities of these poly(ether ether ketone amide)s were in the range of 0.41–0.52 dL/g in DMAc, indicating the formation of moderate to high molecular weight of polymers. Poly(ether ether ketone amide)s showed good solubility in polar aprotic solvents such as N,N-dimethyl acetamide (DMAc), N-methyl 2-pyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide. These poly(ether ether ketone amide)s had glass transition temperatures, as determined by DSC, in the range of 252–302 °C. These polymers showed similar decomposition patterns and had no weight loss below 335 °C, and temperatures for 10% weight loss (T10) were in the range of 397–406 °C, indicating that these polymers showed good thermal stability.

    更新日期:2020-01-04
  • PAMAM dendrimer-based macromolecules and their potential applications: recent advances in theoretical studies
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-03
    S. Mahmood Fatemi, Seyed Jamilaldin Fatemi, Zeynab Abbasi

    Abstract The dendrimer has a high degree of geometric symmetry, a precise and controllable molecular size, a large number of surface-active functional groups, a rich cavity inside the molecule, and a controlled molecular chain growth. The unique structural properties of the above-mentioned macromolecules have made it a research hot spot in many fields. Molecular simulation technology, as a new scientific research method, plays an important role in the basic theory and applied research of dendrimers. This paper reviews the basic progress of molecular simulation technology in the field of dendrimers in recent years, including the application of dendrimers in medicine, DNA, pharmaceutical carriers, proteins, amino acids, and so on.

    更新日期:2020-01-04
  • Fabrication of microcomposites based on silk sericin and monetite for bone tissue engineering
    Polym. Bull. (IF 1.858) Pub Date : 2019-04-01
    S. Weslen Vedakumari, R. Jayalakshmi, C. G. Sanjayan, B. Jayavardhini, K. Arya, R. Murugesan

    In the present study, silk sericin–monetite microcomposites (SS–MM) were prepared using a simple and cost-effective method. Hemolytic assay was performed to determine the blood compatibility of SS–MM. MTT assay was carried out using MG-63 osteoblasts, to determine the cytocompatibility and proliferative efficacy of SS–MM. Alkaline phosphatase activity was studied to examine the osteogenic potency of the prepared microcomposites. The results obtained showed that the SS–MM can be effectively used as a bone graft for tissue engineering applications.

    更新日期:2020-01-04
  • Modern biopolyamide-based materials: synthesis and modification
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-09
    Paulina Radzik, Agnieszka Leszczyńska, Krzysztof Pielichowski

    The wider use of renewable feedstock in structural applications, where high mechanical performance is required, can be achieved by the application of recently developed engineering biopolymers and their further modification by micro- and nanoparticles. In this review, we present the current state of the art of biopolyamide materials for structural and functional applications. The overview includes all stages of the manufacturing—from the synthesis of building blocks, through the synthesis of polymers and its physical modification, with special emphasis on the properties of the obtained engineering biocomposites as a final product of modern polymer technology. In the first part, the synthetic routes of bio-derived counterparts of common polyamides as well as specialty polymers with functional properties arising from the complex structure of biochemicals were exemplified. The development of environmentally friendly composites and nanocomposites based on biopolyamides and natural fillers, such as plant fibers or cellulosic nanofibers, was of particular interest due to preserved sustainable character of such materials.

    更新日期:2020-01-04
  • Study of hybrid alginate/gelatin hydrogel-incorporated niosomal Aloe vera capable of sustained release of Aloe vera as potential skin wound dressing
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-27
    Arezoo Dadashzadeh, Rana Imani, Saeid Moghassemi, Kobra Omidfar, Nabiollah Abolfathi

    Abstract Nowadays, wound dressings serve as advanced skin products, which mainly aim to accelerate the wound healing process. The wound dressings with a potential of localized and prolonged release of therapeutic agents have attracted tremendous attention. In this study, synthesis of a sustained release of niosomal Aloe vera (AV) loaded in alginate/gelatin (AG) hybrid hydrogel is aimed at improving skin regeneration as wound dressing. For this purpose, AV-loaded niosomes are synthesized and incorporated in the hybrid AG hydrogel. The size and polydispersity index (PdI) of niosomes, AV entrapment efficacy and AV in vitro release are characterized. In addition, the hydrogel characteristic, such as swelling ratio, degradation behavior and mechanical property, are studied. MTT assay is utilized to evaluate the effect of AV incorporation and release on the proliferation of fibroblast cells. Results demonstrate that size, PdI and EE% of AV-loaded niosomes are 270.080 nm, 0.108 and 42.039 ± 4.090%, respectively, and in vitro release of AV is about 20% after 7 days. AG hybrid hydrogel loaded by niosomal AV shows an extended sustained release manner, where its swelling ratio and percentage of degradation are 60 wt% after 72 h and 70 wt% after 6 days, respectively. The average Young’s modulus of the hybrid hydrogel is measured around 12.64 ± 1.3 kPa, which seems suitable as a wound dressing. Finally, MTT assay confesses an increased fibroblast proliferation in the presence of AV, particularly in the niosomal AV-loaded hydrogel. Concludingly, alginate/gelation hybrid hydrogel incorporated with niosomal AV, with sustained release potential can be suggested as a promising candidate for wound dressing applications. Graphical abstract

    更新日期:2020-01-04
  • Poly( p -phenylenediamine)-based nanocomposites with metal oxide nanoparticle for optoelectronic and magneto-optic application
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-29
    Sudhir Kumar, Shyamal Baruah, Amrit Puzari

    Abstract Use of inorganic nanoparticles for the development of high-performance polymer nanocomposites is a common practice in polymer nanotechnology, because the decrease in particle size to smaller scale greatly influences the optical and magnetic characteristics of the resulting materials. In this work, synthesis and characterization of polymeric nanocomposites based on poly(p-phenylenediamine) and metal oxide nanoparticle are described. ZnO, Fe3O4 and TiO2 nanoparticles are used for the synthesis of the nanocomposites. In situ chemical oxidative polymerization method is employed in the presence of hydrogen peroxide as oxidant and cis-bis-glycinato copper (II) monohydrate as catalyst. Structural characterization is performed with FTIR, UV–Vis spectroscopy, thermogravimetric analysis, X-ray diffraction and also transmission electron microscopy. Morphological analysis reveals amorphous to semicrystalline nature of the polymer nanocomposites. Thermal characterization indicates the stability up to a temperature of 150 °C. Electrical conductivity is found in the range 10−10 S/cm for the polymer and 10−7 S/cm for the polymer nanocomposites, which falls in the range of semiconducting materials. Study of magnetic properties using vibrating sample magnetometer (VSM) technique reveals that Fe3O4 nanocomposite exhibits enhanced soft magnetic properties as it is clear from the coercivity, retentivity, magnetization and moment. Thus these polymeric nanocomposites are expected to find application in magneto-optic field as well as in organic light-emitting devices.

    更新日期:2020-01-04
  • A detailed comparative study on electrical and photovoltaic characteristics of Al/p-Si photodiodes with coumarin-doped PVA interfacial layer: the effect of doping concentration
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-11
    Selçuk Demirezen, Seçkin Altındal Yerişkin

    In this study, three different poly(vinyl alcohol) (PVA) films doped with weight percentages of 0.05, 0.10 and 0.20 coumarin were coated on p-Si wafer via spin-coating method for the purpose of investigating the interaction of coumarin dopant with polymer host at molecular level. Therefore, metal–polymer–semiconductor (MPS) structures were formed and their current–voltage (I–V) and admittance measurements were taken to compare the main electrical parameters of the MPS structures with different film thicknesses. The values of ideality factor (n), barrier height (Φb), rectification ratio (RR = IF/IR), series resistance (Rs) and energy-dependent profiles of surface states (Nss) were calculated using the forward bias I–V data. There exists increasing trend for Nss values from mid-gap energy of Si toward the bottom of conductance band. The highest values of RR and photosensitivity (Iphoto/Idark) were found as 4.62 × 104 at ± 4 V for the MPS structure with 0.10 wt% coumarin doping level, respectively. The photoresponse of the structures was also analyzed using \(I_{\text{ph}} = AP^{m}\) relation, and the value of m was obtained from the slope of ln(Iph)–Ln(P) plot for each diode as 1.48, 1.27 and 1.57, respectively. Experimental results suggest that 0.10% coumarin-doped PVA caused MPS structure to reveal better performance considering higher RR and lowest Nss, and so it can be considered as an alternative interfacial layer material for replacing traditional insulators.

    更新日期:2020-01-04
  • Preparation of high-damping soft elastomer based on Eucommia ulmoides gum
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-11
    Feng Yang, Li Dai, Tong Liu, Jinlin Zhou, Qinghong Fang

    Abstract This paper focus on the nature of a high-damping soft elastic material based on Eucommia ulmoides gum (EUG) obtained by epoxidation of EUG first and then in situ reaction between epoxy group and sodium bisulfite. The influence of degree of modification (M mol%) and degree of sulfonation (S mol%) of the product sulfonated E. ulmoides gum (SEUG) on the melting–crystallization behavior, tensile properties and dynamic mechanical properties is analyzed mainly. The results show that M mol% is the key factor in controlling the aggregation structure and static or dynamic mechanical behavior of SEUG, while the introduced sodium bisulfite groups show strengthening and toughening effect to some extent. Besides, the SEUG with high M mol% shows dramatically high tanδ value. With M mol% increasing, the tensile strength and Shore A hardness of SEUG decrease sequentially, while the elongation at break increases visibly. SEUGs with M mol% above 20.3 display soft and elastic stress–strain behavior. At similar M mol% level, SEUG with higher S mol% shows higher tensile strength and lower elongation at break than the one with lower S mol% value. These are attributed to the transformation of the aggregate structure and the introduction of ion interaction. The maximum tanδ value of SEUG reaches up to 2.19. The removal of the restriction effect of crystal region on the molecular motion of amorphous and the increased intermolecular interaction are thought to be main causes.

    更新日期:2020-01-04
  • Chemical interactions of heparin in porous polypyrrole, an example of drug–carrier destructive interaction
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-25
    M. González-Torres, M. G. Olayo, L. M. Gómez, J. Morales, R. Olayo, R. Ramírez, F. G. Flores, M. R. Mejía-Cuero, G. J. Cruz

    Plasma polypyrrole doped with iodine (PPy/I) and heparin (Hp) has been used as drugs in different ways in the human body. In this work, Hp was inserted into porous PPy/I to prepare biocompatible mixtures to potentially release Hp into the human body. The study was focused on the absorption and chemical interaction of Hp with PPy/I to find whether their structures suffer modifications in the carrying process. The absorption was performed by cryo-lyophilization immersing Hp in water with a 10:1 polymer/drug mass ratio. Once in contact, Hp went into the pores and partially coated the PPy/I surface. IR analyses of the mixtures on the surface showed that the functional Hp groups predominated over the polymer. The chemical interaction of both components was studied by XPS analyzing the energetic distribution of their atomic 1s or 2p orbitals. The results indicated that Hp interacted chemically with PPy/I losing the highest oxidized C1s, N1s and S2p chemical states in both components, forming new reduced ones with less multiple bonds or with more hydrogenated groups. S2p states were especially modified losing the most reactive states with 6 valences to form new more stable states with 2 valences. O1s orbitals behaved differently losing the most reduced chemical states forming new oxidized ones. These modifications suggest that the chemical reactivity of this PPy/I-Hp binary system was altered reducing the therapeutic capability of both components. This kind of studies should be done in all carrier–drug combinations to evaluate the possible chemical interaction between them.

    更新日期:2020-01-04
  • Tunable wicking behavior via titanium oxide embedded in polyacrylonitrile nanofiber strings of yarn
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-19
    Seyed Abdolkarim Hosseini Ravandi, Soha Mehrara, Mehdi Sadrjahani, Akbar Khodaparast Haghi

    Abstract The effect(s) of TiO2 nanoparticles on the vertical wicking behavior observed in electrospun polyacrylonitrile (PAN) nanofiber strings of yarn was investigated in this study. The capillary flow was measured in composite nanofiber strings of yarn by means of the image analysis of the rise of colored liquid soaked up in the strings of yarn; the height of liquid rise was determined as a function of time. The kinetics of capillary rise follows the Lucas–Washburn’s equation. The results obtained from the experimental design showed that the rate coefficient of the capillary rise was influenced by TiO2 nanoparticles more than the twist level in nanofiber strings of yarn. For various hot-stretching ratios, the rate of capillary rise decreased with increasing the number of TiO2 nanoparticles and the level of yarn twist. This decreasing trend was more pronounced at higher levels of yarn twist. To find how capillary behavior changed with the release of nanoparticles, the wicking mechanisms were measured at different concentrations of TiO2 nanoparticles in capillary liquid. When TiO2 nanoparticles were used in capillary liquid, they immediately filled the spaces between nanofibers in yarn and the liquid could not rise any more. The present study indicated that the wicking behavior of composite nanofiber strings of yarn was tunable provided that appropriate constructive factors, that is to say, the number of TiO2 nanoparticles and the level of nanofiber yarn twist, were chosen.

    更新日期:2020-01-04
  • Fabrication of cellulose-mediated chitosan adsorbent beads and their surface chemical characterization
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-14
    Somayyah Abdul Munim, Muhammad Tahir Saddique, Zulfiqar Ali Raza, Muhammad Irfan Majeed

    The use of nontoxic, biodegradable and biocompatible biopolymers such as chitosan and cellulose is of considerable importance particularly in uptake of metal ions from the contaminated water systems. Current study was aimed to develop a chitosan-based biosorbent in combination with cellulose to form composite adsorbent beads. The developed composite beads were chemo-physically characterized using advanced analytical techniques of scanning electron microscope, Fourier transform infrared, x-ray diffraction and thermogravimetric analysis. The point of zero charge (PZC) of the developed beads was determined using the methods of salt addition, electrokinetic potential and the mass atitration. The average value of PZC of composite beads was found to be 7.26 using the said methods. On incorporating cellulose into chitosan, the thermal properties of the composite beads were considerably enhanced. The adsorption capacity of chitosan–cellulose beads was found to be 99.8, 79.98 and 99.10 mg/g for Ni(II), Cu(II) and Cr(III), respectively. The adsorption extent showed that the developed composite beads could be employed as adsorbent for wastewater treatment.

    更新日期:2020-01-04
  • Enhanced performance of PSF/PVP polymer membrane by silver incorporation
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-14
    Pramila Ponnaiyan, Gopalakrishnan Nammalvar

    Pure and silver (Ag) nanoparticle (0.5 wt%, 1 wt%, 2 wt%)-incorporated polysulphone/polyvinyl pyrrolidone (PSF/PVP) membranes have been prepared by phase inversion method. The effects of Ag nanoparticle incorporation on PSF/PVP polymer membrane have been studied by XRD, FE-SEM, AFM and contact angle measurement. The successful incorporation of Ag nanoparticle has been confirmed by XRD analysis. FE-SEM images showed that morphology varies with the variation in Ag concentration. The decrease in contact angle value proved that membrane surface is more hydrophilic in nature than pure PSF/PVP membrane. Enhanced mechanical and thermal behaviour has been observed by tensile test measurement and TGA, respectively. It has been also observed that permeability, salt rejection and antibacterial activity of the membrane were enhanced upon Ag incorporation in the PSF/PVP membrane. Among the Ag-incorporated membranes, 1 wt% Ag showed superior performance. The enhancement of membrane performance upon Ag incorporation has been well justified, and other features are discussed in detail.

    更新日期:2020-01-04
  • Graphene impact of the LDPE characteristics
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-30
    Maziyar Sabet, Hassan Soleimani, Seyednooroldin Hosseini

    Abstract Graphene addition to low-density polyethylene prolonged oxygen penetration in low-density polyethylene (LDPE), deferred embrittlement effect of polymeric compound, developed storage modulus, electrical conductivity and enhanced viscosity of LDPE nanocompounds. The presence of graphenes inhibited movement of polymer chains, which affected increasing toughness and capability of LDPE compounds. Continuity of carbon–carbon connection threshold of graphene compound took place with about 0.5 wt% graphene inclusion in LDPE structure. The impenetrability of oxygen over the surface of LDPE compounds achieved with 0.5 wt% graphene inclusion, which made severe perfections and decreased 37% fuel penetration if it is compared to pristine LDPE.

    更新日期:2020-01-04
  • Composites of polyethylene and layered cobalt hydroxide salts as potential ultraviolet radiation absorbers
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-16
    Neffer Arvey Gomez Gomez, Swami Arêa Maruyama, Andreas Leuteritz, Fernando Wypych

    Abstract This paper describes the synthesis of cobalt hydroxide nitrate (CoHN) and cobalt hydroxide p-aminobenzoate (CoHAB), which were dispersed in polyethylene with the objective of protecting the polymer from ultraviolet (UV) radiation degradation. First, CoHN was synthesized by urea hydrolysis in the presence of Co(II) nitrate and the intercalation of p-aminobenzoate into CoHAB was performed under hydrothermal alkaline conditions. The structure and thermal stability of the CoHN and CoHAB were characterized by several instrumental techniques. Results indicated that both fillers were dispersed in polyethylene and absorb radiation in the whole UV range, modifying the behavior of the polymer degradation under artificial weathering conditions. Graphical abstract

    更新日期:2020-01-04
  • Biodegradable and biocompatible radiopaque iodinated poly-3-hydroxy butyrate: synthesis, characterization and in vitro/in vivo X-ray visibility
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-18
    Arzu Erol, Derya B. Hazer Rosberg, Baki Hazer, Beyza S. Göncü

    Some novel radiopaque biodegradable and biocompatible iodinated polymers based on poly-3-hydroxy butyrate (PHB) were obtained. Following the attachment of diethanol amine to PHB, the hydroxyl ends were capped with 4-iodobenzoic acid and 2,3,5-tri-iodobenzoic acid. In this manner, tri-novel radiopaque polymers were obtained. The resulting polymers were structurally characterized by NMR technique. They were evaluated with respect to their possible use as radiopaque implant biomaterials indicating X-ray visibility in a noninvasive manner using routine X-ray absorption imaging techniques. These polymers exhibited good radiopacity with conventional imaging X-ray techniques in vivo. Additionally, biocompatibility of these iodinated polymers was also evaluated. There were no signs of infection or abscess formation on the surgical area. These novel radiopaque PHBs should be promising biomaterials for a new-generation radiopaque materials.

    更新日期:2020-01-04
  • Role of CNT/clay hybrid on the mechanical, electrical and transport properties of NBR/NR blends
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-08
    Saliny Thomas, Jiji Abraham, Soney C. George, Sabu Thomas

    Abstract Hybrid fillers are making a remarkable improvement in the properties of polymeric systems. In the present study, the influence of hybrid of multiwalled carbon nanotube (MWCNT) and nanoclay on the mechanical, electrical and transport properties of nitrile rubber (NBR)/natural rubber (NR) blends has been investigated. Attempts were made to prepare NBR/NR/CNT/nanoclay composites on a two-roll mill and to study various mechanical properties such as tensile strength, tear resistance, abrasion loss and compression set percent. Transport, thermal and electrical properties were also investigated. By virtue of the synergism between MWCNT and nanoclay, the composites exhibited enhancement in the mechanical properties by the immobilization of rubber chains via coupling action between the filler surface and the rubber molecules. The fine and uniform dispersion of both CNT and clay in composite samples supported the observation. The hybrid filler system had a great impact on the thermal and electrical properties of the composites. Graphical abstract

    更新日期:2020-01-04
  • Effects of cooling process on the solid–liquid phase separation process in ultra-high-molecular-weight polyethylene/liquid paraffin blends
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-14
    Lei Sheng, Yanqiu Du, Hui Zhang, Zhihui Chen, Junjie Pan, Tao Wang, Xianli Huang, Jianping He

    Abstract Ultra-high-molecular-weight polyethylene (UHMWPE) microporous membrane is generally prepared by thermally induced phase separation process. The phase separation process is closely related to the cooling process in practical production. In this paper, the phase separation temperature of UHMWPE/liquid paraffin blends was explored by the hot-stage-optical device and differential scanning calorimeter (DSC), and the result showed that the temperature was about 105–125 °C. The effects of cooling condition and crystallization ability of UHMWPE on the separation process of the blends were also investigated by DSC. The results showed that the phase separation was affected by the cooling rates rather than the initial cooling temperature. And the crystallization of UHMWPE was mainly limited by the nucleating at a low cooling rate, which could form larger porous structure. In a word, it should be inspirational for the actual production of the UHMWPE microporous membrane. Graphical abstract The solid–liquid phase separation will occur in the cooling process of UHMWPE/LP blends, which is driven by the external temperature difference. It is significant to understand the phase separation process. In this paper, the effects of the melting properties and cooling condition on phase separation process were investigated, the S–L phase separation range is at 105–125 °C, and the speed of phase separation is mainly related to the external temperature difference and the UHMWPE content. It could be inspirational for actual production of the UHMWPE membrane with more uniform pore structure.

    更新日期:2020-01-04
  • The influence of 1,4-cyclohexanedicarboxylic acid on the thermal and mechanical properties of copolyamides
    Polym. Bull. (IF 1.858) Pub Date : 2019-03-16
    Chin-Wen Chen, Chiao-Wei Lin, Yu-Haw Chen, Tung-Fan Wei, Syang-Peng Rwei, Ragu Sasikumar

    The present paper describes the novel aliphatic polyamide 6 (PA6) copolyamides by the melt polymerization reaction of our newly synthesized aliphatic diamine monomer: N1,N6-Bis-(2-aminoethyl)adipamide (BAEA). The BAEA/CHDA (1,4-cyclohexanedicarboxylic acid) salt was prepared by pertinent long-chain polyamide with the cycloaliphatic ring and isolated as white solid, utterly characterized for the first time. The chemical structure of BAEA, BAEA/CHDA salt and copolyamides (PA6-BAEA/CHDA) was identified by 1H NMR and FT-IR spectroscopy. Depending on the chemical compositions, the viscosity and molecular weight of the copolyamides were in the range of 19,447–13,536 g mol−1 and 2.74–2.2 dL g−1. With increasing BAEA/CHDA salt molar ratio in the synthesized copolyamides, their melting temperatures (Tm) decreased from 212.7 to 170.4 °C, and the glass transition temperatures (Tg) increased from 60 to 89.4 °C. Besides, the as-synthesized all copolyamides possess nearly similar thermal stability (Td-50% = 439.59 − 443.38 °C) as neat PA6. Mechanical testing data revealed that with an increase in a proportion of BAEA/CHDA salt, Young’s modulus of copolyamides is increased from 698.54 to 1093.89 MPa, while the tensile strength is increased by 8.1%.

    更新日期:2020-01-04
  • A semi-empirical model for thermal conductivity of polymer nanocomposites containing carbon nanotubes
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-02
    M. Safi, M. K. Hassanzadeh-Aghdam, M. J. Mahmoodi

    Abstract A new version of the semi-empirical Halpin–Tsai (H–T) model is presented to evaluate the effective thermal conductivity of general carbon nanotubes (CNTs)-reinforced polymer nanocomposites. The model captures the influences of the CNTs alignment, random orientation, aggregation, waviness, length, diameter and the CNT/polymer interfacial thermal resistance parameters. In order to verify the suitability of the new H–T model, the numerically calculated thermal conductivities are compared with existing experimentally measured ones. An excellent predictability is found of the modified H–T model over a wide range of the tests. The consideration of the CNT waviness and the interfacial thermal resistance parameters is seriously essential for a more realistic prediction in all conditions. For aligned CNT-reinforced polymer nanocomposites, considering the alignment factor seems to be very important. Moreover, in the case of well-dispersed CNTs into the matrix, it is necessary to incorporate the CNT random orientation parameter. Additionally, when CNTs are not well dispersed, the CNT aggregation and random orientation parameters must be incorporated in the analysis. The effects of the CNT volume fraction, length, diameter and non-straight shape on the nanocomposite thermal conducting behavior are estimated in details. The results clearly expose that it is needed to eliminate the aggregation, use the straight CNTs and form a strong interface if the full potential of CNT reinforcement is to be realized. Finally, the thermal conductivities of CNT-shape-memory polymer nanocomposites at different temperatures are obtained.

    更新日期:2020-01-02
  • Epoxidized soybean oil toughened recycled blends: a new method for the toughening of recycled polymers employing renewable resources
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-01
    Sunil S. Suresh, Smita Mohanty, Sanjay K. Nayak

    Abstract The enhancements in the properties of the recycled blends are concerned as the major highlight in the field of polymer recycling and technology. The materials containing polar functional groups are generally employed for enhancing the mechanical and thermal properties of the recycled blends. In this study, epoxidized soybean oil (ESBO), a bio-derived material, was considered as the toughening agent for the modification of the recycled blends made of poly(vinyl chloride) and poly(methyl methacrylate). A series of concentrations (3–12 wt%) of ESBO have been incorporated into the recycled blend matrix via the melt blending method. Further, the formulated recycled blends were analysed for their mechanical, rheological, thermal, flammability and morphological characteristics. Among them, the modified blend with 9% ESBO has been indicated a significant improvement in the fracture toughness parameters. The scanning electron micrographs are clearly indicating the changes in the microstructural properties of the recycled blend after the integration of ESBO. Moreover, dynamic mechanical analysis indicated changes in the glass transition values which resulted from the improved interfacial adhesions and compatibility of the recycled blend matrix.

    更新日期:2020-01-01
  • Synthesis and characterization of an aromatic diamine and its polyimides containing asymmetric large side groups
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-01
    Chenyi Wang, Bin Yu, Cairong Jiang, Xiaoyan Zhao, Jian Li, Qiang Ren

    A novel aromatic diamine monomer with asymmetric large side group: 4-(2,4,6-trimethyl)phenoxy-1,3-diaminobenzene, was synthesized by a two-step organic reaction. The monomer was separately subjected to a one-step high-temperature polycondensation reaction with three commercial aromatic dianhydrides to obtain a series of polyimides. Their structures and properties were characterized and studied by FTIR, NMR, UV, TGA, DSC, etc. The obtained polyimides showed excellent solubility not only in high-boiling solvents such as NMP, DMAc, and DMF, but also in low-boiling solvents such as CHCl3 and CH2Cl2. Their tensile strength was in the range of 76.9–93.5 MPa, the elongation at break was between 4.8% and 7.3%, and the modulus of elasticity was in the range of 1.6–1.8 GPa. The obtained films exhibited good optical transparency, and the representative polyimide derived from 4,4′-oxydiphthalic dianhydride exhibited a light transmittance of more than 83% at a wavelength of 450 nm. Moreover, these polyimides also possessed good thermal properties. Their glass transition temperatures are between 285 °C and 345 °C, and the 10% weight loss temperature in air and nitrogen is above 463 °C, showing excellent thermal properties.

    更新日期:2020-01-01
  • The impact of MWCNT modification on the structural performance of polymeric composite profiles
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-01
    Ali Tabatabaeian, Ahmad Reza Ghasemi

    The significant advantages of nanoparticles have motivated engineers to focus on development of structural integrity by use of these materials. This paper presents a comprehensive experimental study on the impact of nanomodification in laminated composite structures. The influence of nanomaterials on the mechanical performance is examined through the assessment of “residual stress,” “weight loss under thermal fatigue” and “delamination damage in machining operations” of glass fiber-reinforced polymer (GFRP) composites. In this case, different composite specimens were fabricated with 0% and 1% weight fraction of multi-walled carbon nanotubes (MWCNTs). Then, the slitting method as an accurate semi-destructive technique was performed to measure the non-uniform residual stresses in terms of MWCNTs content. Also, the role of MWCNTs in the weight loss of the specimens with different thicknesses under thermal fatigue was analyzed. Additionally, the rotary ultrasonic drilling technique as a high-tech drilling operation was carried out and delamination damage of the GFRPs under machining process was measured. The results indicated that the addition of 1% MWCNTs results in a decrease of 30% and 2.33% in residual stress and delamination states, respectively.

    更新日期:2020-01-01
  • Simple method to obtaining a prolonged-release system of urea based on wheat gluten: development and characterization
    Polym. Bull. (IF 1.858) Pub Date : 2020-01-01
    C. G. Barreras-Urbina, M. Plascencia-Jatomea, F. J. Wong-Corral, M. Pérez-Tello, A. I. Ledesma-Osuna, J. A. Tapia-Hernández, D. D. Castro-Enríquez, E. O. Rueda-Puente, F. Rodríguez-Félix

    Abstract Urea is one of the most widely used nitrogen fertilizers. However, it is lost to the environment via processes such as denitrification, surface runoff, volatilization, and leaching. In this paper, a novel material is reported on, with low production cost and avoiding the use of harmful solvents, with a pastille morphology developed by a simple method from a mixture of wheat gluten and urea, with potential use as a prolonged-release system of urea (PRSU). The PRSU obtained was characterized by scanning electron microscopy, kinetics of water absorption, equilibrium water content (EWC), Fourier-transform infrared (FT-IR) spectroscopy analysis, and release kinetics. The PRSU diameter was 2.46 cm, and its thickness was 0.17 cm. The PRSU showed physical and structural characteristics such as micropores and hollow fractions in its structure. In addition, the wheat gluten pastille is classified as a swelling material and demonstrated an EWC of 58.47 ± 1.50%. FT-IR analysis of the samples showed hydrogen-bond interactions between the amino and carbonyl groups in the urea and the wheat gluten proteins. Laboratory tests showed that the system can release 97% of the urea within 8–10 h. These results showed that the PRSU presents suitable characteristics for its application as a fertilization alternative for carrying out better agronomic practices.

    更新日期:2020-01-01
  • Effect of Fe 3+ –MMT nanocomposite content on thermal, mechanical and water resistance behavior of PVP/amylose films
    Polym. Bull. (IF 1.858) Pub Date : 2019-12-26
    Reza Abdollahi, Naser Sadeghpour Orang, Farhad Akbari Afkhami, Ali Akbar Khandar, Ghodrat Mahmoudi, Payam Hayati, Fedor I. Zubkov

    Novel nanocomposite films based on amylose (AM) and Fe3+–montmorillonite (Fe3+–MMT) in the matrix of poly(vinyl pyrrolidone) (PVP) were fabricated using a solution casting method. X-ray diffraction indicated that an ion exchange process occurred between Fe3+–MMT and PVP/AM. Thermogravimetric analysis and differential scanning calorimetry results hinted to PVP/AM films forming a more stable network through the dispersion of Fe3+ cations. An increase in the loading of Fe3+–MMT improved the hydrophilic properties of PVP/AM films, which lead to the high degree of resistance against the water absorption. Mechanical properties of PVP/AM films influenced by the uniform dispersion of Fe3+–MMT in the polymer network established strong covalent interactions between PVP/AM and Fe3+–MMT. This interaction not only improved the mechanical properties of the films, but also enhanced the thermal stability of them through the facilitation of the MMT dispersion within the polymer matrix.

    更新日期:2019-12-27
  • Building up of Prosopis juliflora carbon incorporated cardanol based polybenzoxazine composites with intensification of mechanical and corrosion resistance properties for adaptable applications
    Polym. Bull. (IF 1.858) Pub Date : 2019-12-23
    V. Selvaraj, T. R. Raghavarshini

    In the present work, amine-functionalized Prosopis juliflora carbon (APJC)-reinforced diphenyldiaminomethane-based cardanol benzoxazine (DDCBz) composites have been developed and characterized with a view to utilizing them for possible load-bearing and corrosion-resistant applications. Chemical structure of the DDCBz was ascertained using Fourier transform infrared, Proton nuclear magnetic resonance and Maldi mass spectroscopy. The 5 wt% APJC/DDCBz composites exhibit good hydrophobic character, thermal stability and mechanical properties compared to those of neat matrix and other wt% of APJC-reinforced composites. Similarly, glass transition temperature (Tg) and water contact angle of composites are enhanced according to their weight percentage concentration. Results from corrosion studies indicate that the mild steel specimens coated with DDCBz matrix and APJC/DDCBz composites offer enhanced corrosion resistance. Data obtained from different studies infer that the APJC-reinforced DDCBz composites possess an improved thermal stability, thermomechanical behaviour, hydrophobic characteristics and corrosion-resistant properties, which make them suitable for high-performance thermal and corrosion-resistant applications.

    更新日期:2019-12-25
  • Effect of 60 keV argon ion implantation in Makrofol ® DE 1-1 on the optical properties
    Polym. Bull. (IF 1.858) Pub Date : 2019-12-21
    Hossam Donya, Abeer Salah

    Abstract Ion implantation in polymeric materials has recently attracted considerable attention in various technology and science fields. The effect of 60 keV low-energy and high-fluence argon ion implantation in the Makrofol® DE 1-1 polymer on the nonlinear and linear optical properties was investigated. Structural changes of the polymer were studied with Raman spectroscopy to ensure the structural modifications induced by argon ions. Linear optical parameters such as the absorption and refractive index were investigated for the ion-implanted sheets. Direct and indirect optical band gaps were observed to decrease with an increase in argon ion fluence. In addition, an increase in the optical conductivity was found with increasing number of ions implanted in the sheets. The photoluminescence (PL) measurements reveal enhanced PL intensity of higher-fluence ion implanted in contrast to the PL of lower ion implantation fluence. Additionally, nonlinear absorption and optical limiting were investigated via the Z scan technique. The implanted materials have saturable nonlinear absorption, the nonlinear absorption coefficients and the figure of merit were calculated for the investigated samples, and the results show that the implanted argon ion Makrofol is a good candidate for saturable absorbers, optoelectronic devices and medical products.

    更新日期:2019-12-22
  • Chemical modification of titanium dioxide nanoparticles with dicarboxylic acids to mediate the UV degradation in polyethylene films
    Polym. Bull. (IF 1.858) Pub Date : 2019-12-21
    D. L. Zapata-Tello, V. Escobar-Barrios, J. A. Gonzalez-Calderon, Elías Pérez

    This work deals with the study of the degradation of films made of low-density polyethylene (LDPE) by the incorporation of commercial titanium dioxide nanoparticles (TiO2 Nps). These nanoparticles were functionalized with three types of dicarboxylic acid, which have different length chain (glutaric, pimelic and azelaic acids), to improve their compatibility with LDPE. Besides, the effect of the functionalized TiO2 Nps concentration on the photodegradation, roughness, mechanical and thermal stability of the nanocomposites was evaluated. The obtained results show that the organic coating helps to passivate the photodegradation of LDPE; the longer carbon chain of the dicarboxylic acid, the higher active sites on filler/polymer interface, which inhibits photodegradation. Also, it was elucidated that calcium, from the functionalization, increased the thermal stability of the polymer nanocomposites when exposed to UV radiation. The thermal, physical (surface wear) and aesthetic (color) properties of polyethylene, with the functionalized nanoparticles, were less affected when exposed to the weather, where it is attributed to the UV photo-stabilization of the polymer. The resultant materials (LDPE with functionalized TiO2 Nps) can be used in diverse applications such as films for greenhouse and other agricultural applications, outdoor appliances (furniture and decks, for example), among others.

    更新日期:2019-12-22
  • Density functional theory calculations on the grafting copolymerization of 2-substituted aniline onto chitosan
    Polym. Bull. (IF 1.858) Pub Date : 2019-12-21
    M. S. Ibrahim, H. R. Abd El-Mageed, H. M. Abd El-Salam

    Chitosan is a biodegradable natural polymer which is safe and non-toxic and used in different applications. Grafting of chitosan with aniline derivatives is an important route to improve its properties. Chitosan has different active groups that can be blocked in the grafting process, which could be confirmed by calculation studies. The author thinks that the confirmation of chitosan active group included in the grafting by calculations is not given before. So authors give evidence to the direction of grafting and mechanism. Poly(2-methylaniline) (P2-MA), poly(2-hydroxyaniline) (P2-HA) and their copolymers are used in the present study. Quantum mechanics calculations using density functional theory were applied to study the grafting process. The obtained data reveal that grafting occurs at NH2 groups, which is less energetic (2.04). This conclusion confirms the experimental studies. Computational calculations show that the interaction between chitosan and both P2-MA and P2-HA takes place at the NH2 group of chitosan with high stabilization energy (− 1346.7746). A complete next-to-leading order (NLO) values show that the graft could be a better candidate for NLO application (42.25 kcal mol−1) global properties (hardness). Also, the grafting process gives high reactive products due to a decrease in band gap energy.

    更新日期:2019-12-21
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