International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Incorporation of Amphipathic Diblock Copolymer in Lipid Bilayer for Improving pH Responsiveness Wed, 04 May 2016 14:26:19 +0000 Diblock copolymers (mPEG-b-PDPA), which were designed to possess pH-sensitivity as well as amphipathy, were used as an intelligent lock in the liposomal membrane. The so-called pH-sensitive liposomes were prepared by simple mixing of the synthesized mPEG-b-PDPA with phospholipids and cholesterol. Fluorescence polarization at pH 7.4 showed that the membrane stability of the hybrid liposome was significantly increased compared with the pure liposome. Therefore, in the neutral environment, the leakage of doxorubicin (DOX) was inhibited. However, when pH decreased to 6.0, DOX release rate increased by 60% due to the escape of copolymer. The effects of the membrane composition and the PDPA segment length on bilayer membrane functions were investigated. These results revealed that the synthesized copolymers increased the difference in DOX cumulative release between pH 7.4 and 6.0, that is, improved the pH-controllability of the drug release from hybrid liposomes. Tian Xia, Weiju Hao, Yazhuo Shang, Shouhong Xu, and Honglai Liu Copyright © 2016 Tian Xia et al. All rights reserved. Biodegradable Polymers for Medical Applications Thu, 28 Apr 2016 14:08:44 +0000 Anezka Lengalova, Alenka Vesel, Yakai Feng, and Vitor Sencadas Copyright © 2016 Anezka Lengalova et al. All rights reserved. Electrospun PEDOT:PSS/PVP Nanofibers for CO Gas Sensing with Quartz Crystal Microbalance Technique Wed, 27 Apr 2016 13:53:39 +0000 Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyvinylpyrrolidone (PEDOT:PSS/PVP) composite nanofibers were successfully fabricated via electrospinning and used as a quartz crystal microbalance (QCM) sensor for detecting CO gas. The electrical property of individual PEDOT:PSS/PVP nanofibers was characterized and the room temperature resistivity was at the magnitude of 105 Ω·m. The QCM sensor based on PEDOT:PSS/PVP nanofibers was sensitive to low concentration (5–50 ppm) CO. In the range of 5–50 ppm CO, the relationship between the response of PEDOT:PSS nanofibers and the CO concentration was linear. Nevertheless, when the concentration exceeded 50 ppm, the adsorption of the nanofiber membrane for CO gas reached saturation and the resonant frequency range had no change. Therefore, the results open an approach to create electrospun PEDOT:PSS/PVP for gas sensing applications. Hong-Di Zhang, Xu Yan, Zhi-Hua Zhang, Gu-Feng Yu, Wen-Peng Han, Jun-Cheng Zhang, and Yun-Ze Long Copyright © 2016 Hong-Di Zhang et al. All rights reserved. Impact of Block Length and Temperature over Self-Assembling Behavior of Block Copolymers Sun, 24 Apr 2016 11:49:04 +0000 Self-assembling behavior of block copolymers having water-soluble portion as one of the blocks plays key role in the properties and applications of the copolymers. Therefore, we have synthesized block copolymers of different block length and investigated their self-assembling behavior with reference to concentration and temperature using surface tension and conductance measurement techniques. The results obtained through both techniques concluded that critical micelles concentration (CMC) was decreased from 0.100 to 0.078 g/dL with the increase in length of water insoluble block and 0.100 to 0.068 g/dL for the increased temperature. was also decreased with the increase in temperature of the system, concluding that the micellization process was encouraged with the increase in temperature and block length. However, values were highest for short block length copolymer. The surface excess concentration obtained from surface tension data concluded that it was highest for short block length and vice versa and was increased with the increase in temperature of the system. However, the minimum area per molecule was largest for highest molecular weight copolymers or having longest water insoluble block and decreases with the increase in temperature. Samia A. Kosa, Laila M. Al-Harbi, Musa Kaleem Baloch, Irfan Ullah, and Elsayed H. El-Mossalamy Copyright © 2016 Samia A. Kosa et al. All rights reserved. Schizophyllum commune Lipase Production on Pretreated Sugarcane Bagasse and Its Effectiveness Wed, 20 Apr 2016 10:29:59 +0000 Schizophyllum commune UTARA1 was used for lipase production under solid state fermentation (SSF) of sugarcane bagasse (SB) impregnated with used cooking oil medium. Pretreatments of steam, microwave, hydrochloric acid (HCl), sodium hydroxide (NaOH), and their combinations, such as steam-assisted HCl, steam-assisted NaOH, microwave-assisted HCl, and microwave-assisted NaOH, on the milled SB, were done prior to SSF to investigate their effects on lipase production via SSF. The highest lipase activity among the pretreated SB was 0.200 U/, using steam-assisted HCl treated SB, which is lower than the lipase activity produced from the untreated SB, which was 0.413 U/. Scanning Electron Microscope (SEM) imaging showed significant rupture of the SB structure after steam-assisted-HCl pretreatments where the thin walls of the SB pith were wrinkled and collapsed, with no distinctive cell wall structure. The HCl pretreated SB gave the highest crystallinity index (CrI), 91.43%, compared to the untreated, 61.90%. Conversely, microwave and NaOH pretreatments reduced the CrI, which were 46.15% and 43.36%, respectively. In this study, the results obtained indicated that pretreated SB did not improve the lipase production of Schizophyllum commune UTARA1 under SSF. Yew Chee Kam, Siew Ling Hii, Cheryl Yan-Yi Sim, and Lisa Gaik Ai Ong Copyright © 2016 Yew Chee Kam et al. All rights reserved. Cell Adhesion on Polycaprolactone Modified by Plasma Treatment Tue, 19 Apr 2016 10:27:11 +0000 We have investigated the influence of various plasma treatments of electrospun polycaprolactone (PCL) scaffolds on the adhesion and proliferation of human umbilical endothelial cells (HUVEC). The PCL scaffolds were treated in plasmas created in O2, NH3 or SO2 gas at identical conditions. Surface functionalization of plasma-treated samples was determined using X-ray photoelectron spectroscopy. Cell adhesion and morphology were investigated by scanning electron microscopy and the influence of plasma treatment on cell adhesion and viability was evaluated with cell viability assay (MTT assay). The results showed the highest metabolic activity of HUVEC on PCL samples treated with O2 and NH3 plasma. Accordingly, the cells reflected the best adhesion and morphology on O2 and NH3 plasma-treated PCL samples already at 3 h. Moreover, treatment with O2 and NH3 plasma even stimulated endothelial cell proliferation on PCL surfaces by 60% as measured at 24 h, showing significant improvement in endothelialization of this material. Contrarily, SO2 plasma appeared to be less promising in comparison with O2 and NH3 plasma; however, it was still better than without any plasma treatment. Thus, our results importantly contribute to the biocompatibility improvement of the PCL polymer, commonly used for scaffolds in tissue engineering. Nina Recek, Matic Resnik, Helena Motaln, Tamara Lah-Turnšek, Robin Augustine, Nandakumar Kalarikkal, Sabu Thomas, and Miran Mozetič Copyright © 2016 Nina Recek et al. All rights reserved. Bonding Characteristics of Macrosynthetic Fiber in Latex-Modified Fiber-Reinforced Cement Composites as a Function of Carbon Nanotube Content Tue, 19 Apr 2016 08:27:44 +0000 The effect of carbon nanotube content (0, 0.5, 1.0, 1.5, and 2.0% of the cement weight) on the bonding properties of macrosynthetic fiber in latex-modified hybrid fiber cement-based composites (LMHFRCCs) was evaluated. The slump value, compressive strength, and bonding strength were measured for each LMHFRCC. As the carbon nanotube content increased to 1.5%, the bonding properties of the macrosynthetic fiber improved. However, the bonding performance deteriorated at a carbon nanotube content of 2.0%. A decrease in the fluidity of the mix negatively affected the dispersion of the nanotubes in the LMHFRCCs. The addition of carbon nanotubes also affected the relative bonding strength independently of the improvement in compressive strength. Microscopic analysis of the macrosynthetic fiber surfaces was used to understand changes in the bonding behavior. Ji-Hong Jean, Chan Yu, and Chan-Gi Park Copyright © 2016 Ji-Hong Jean et al. All rights reserved. Alginate Production from Alternative Carbon Sources and Use of Polymer Based Adsorbent in Heavy Metal Removal Wed, 06 Apr 2016 12:40:16 +0000 Alginate is a biopolymer composed of mannuronic and guluronic acids. It is harvested from marine brown algae; however, alginate can also be synthesized by some bacterial species, namely, Azotobacter and Pseudomonas. Use of pure carbohydrate sources for bacterial alginate production increases its cost and limits the chance of the polymer in the industrial market. In order to reduce the cost of bacterial alginate production, molasses, maltose, and starch were utilized as alternative low cost carbon sources in this study. Results were promising in the case of molasses with the maximum 4.67 g/L of alginate production. Alginates were rich in mannuronic acid during early fermentation independent of the carbon sources while the highest guluronic acid content was obtained as 68% in the case of maltose. The polymer was then combined with clinoptilolite, which is a natural zeolite, to remove copper from a synthetic wastewater. Alginate-clinoptilolite beads were efficiently adsorbed copper up to 131.6 mg Cu2+/g adsorbent at pH 4.5 according to the Langmuir isotherm model. Çiğdem Kıvılcımdan Moral and Merve Yıldız Copyright © 2016 Çiğdem Kıvılcımdan Moral and Merve Yıldız. All rights reserved. Mechanical Properties of Oil Palm Shell Composites Wed, 06 Apr 2016 11:35:03 +0000 The mechanical properties of oil palm shell (OPS) composites were investigated with different volume fraction of OPS such as 0%, 10%, 20%, and 30% using unsaturated polyester (UPE) as a matrix. The results presented that the tensile strength and tensile modulus of the UPE/OPS composites increased as the OPS loading increased. The highest tensile modulus of UPE/OPS was obtained at 30 vol% of OPS with the value of 8.50 GPa. The tensile strength of the composites was 1.15, 1.17, and 1.18 times higher than the pure UPE matrix for 10, 20, and 30 vol% of OPS, respectively. The FTIR spectra showed the change of functional group of composites with different volume fractions of OPS. SEM analysis shows the filler pull-out present in the composites which proved the poor filler-matrix interfacial bonding. J. Sahari and M. A. Maleque Copyright © 2016 J. Sahari and M. A. Maleque. All rights reserved. Fabrication of Hyaluronan-Poly(vinylphosphonic acid)-Chitosan Hydrogel for Wound Healing Application Wed, 06 Apr 2016 06:20:59 +0000 A new hydrogel made of hyaluronan, poly(vinylphosphonic acid), and chitosan (HA/PVPA/CS hydrogel) was fabricated and characterized to be used for skin wound healing application. Firstly, the component ratio of hydrogel was studied to optimize the reaction effectiveness. Next, its microstructure was observed by light microscope. The chemical interaction in hydrogel was evaluated by nuclear magnetic resonance spectroscopy and Fourier transform-infrared spectroscopy. Then, a study on its degradation rate was performed. After that, antibacterial activity of the hydrogel was examined by agar diffusion method. Finally, in vivo study was performed to evaluate hydrogel’s biocompatibility. The results showed that the optimized hydrogel had a three-dimensional highly porous structure with the pore size ranging from about 25 µm to less than 125 µm. Besides, with a degradation time of two weeks, it could give enough time for the formation of extracellular matrix framework during remodeling stages. Furthermore, the antibacterial test showed that hydrogel has antimicrobial activity against E. coli. Finally, in vivo study indicated that the hydrogel was not rejected by the immune system and could enhance wound healing process. Overall, HA/PVPA/CS hydrogel was successfully fabricated and results implied its potential for wound healing applications. Dang Hoang Phuc, Nguyen Thi Hiep, Do Ngoc Phuc Chau, Nguyen Thi Thu Hoai, Huynh Chan Khon, Vo Van Toi, Nguyen Dai Hai, and Bui Chi Bao Copyright © 2016 Dang Hoang Phuc et al. All rights reserved. Phase Characterization of Cucumber Growth: A Chemical Gel Model Tue, 05 Apr 2016 14:02:40 +0000 Cucumber grows with complex phenomena by changing its volume and shape, which is not fully investigated and challenges agriculture and food safety industry. In order to understand the mechanism and to characterize the growth process, the cucumber is modeled as a hydrogel in swelling and its development is studied in both preharvest and postharvest stages. Based on thermodynamics, constitutive equations, incorporating biological quantities, are established. The growth behavior of cucumber follows the classic theory of continuous or discontinuous phase transition. The mechanism of bulged tail in cucumber is interpreted by phase coexistence and characterized by critical conditions. Conclusions are given for advances in food engineering and novel fabrication techniques in mechanical biology. Bo Li, Xuejing Liu, and Junshi Zhang Copyright © 2016 Bo Li et al. All rights reserved. Preparation and Characterization of Irinotecan Loaded Cross-Linked Bovine Serum Albumin Beads for Liver Cancer Chemoembolization Therapy Wed, 30 Mar 2016 16:26:15 +0000 In this paper, a novel temporary embolization agent for transarterial chemoembolization of liver cancer was developed and tested. The Irinotecan loaded bovine serum albumin (BSA) beads were tried to be used as embolic agent of liver cancer therapy. BSA beads were prepared by a water-in-oil emulsion solvent diffusion method in soya oil and Span 85 was used as the emulsifier. The obtained BSA beads were able to swell 2.37-fold comparing to dried beads. Depending on the equilibrium swelling process, the Irinotecan was loaded with 9.8% total drug concentration and tested. In vitro drug release studies showed that a burst release of Irinotecan was achieved. Eventually BSA beads were completely degraded in a few weeks. CCK-8 assay demonstrated that BSA beads showed no cytotoxicity against human umbilical vein endothelial cells, and the Irinotecan loaded BSA beads showed comparable cytotoxicity against Hep G2, a human liver carcinoma cell line, as the traditional Irinotecan. In a rabbit model, it was found that BSA beads can successfully be transferred to liver and provide occlusion of small arteries. The present investigation suggested that the BSA beads are promising drug carriers and can potentially be used as temporary embolization agents in interventional oncology. Jin Yan, Fei Wang, Jun Chen, Tao Liu, and Tao Zhang Copyright © 2016 Jin Yan et al. All rights reserved. Effect of Heat Assisted Bath Sonication on the Mechanical and Thermal Deformation Behaviours of Graphene Nanoplatelets Filled Epoxy Polymer Composites Mon, 28 Mar 2016 10:26:53 +0000 Graphene nanoplatelets (GNP) filled epoxy composites ranged from 0.2 to 5 vol.% were prepared in this study using simple heat assisted bath sonication for better GNP dispersion and exfoliation. The effects of GNP filler loading via heat assisted bath sonication on the mechanical properties and thermal deformation behaviour were investigated. Improvements on flexural strength and fracture toughness up to 0.4 vol.% filler loading were recorded. Further addition of GNP filler loading shows a deteriorating behaviour on the mechanical properties on the composites. The bulk electrical conductivity of the epoxy composites is greatly improved with the addition of GNP filler loading up to 1 vol.%. The thermal expansion of epoxy composites is reduced with the addition of GNP; however poor thermal stability of the composites is observed. Jin-Luen Phua, Pei-Leng Teh, Supri Abdul Ghani, and Cheow-Keat Yeoh Copyright © 2016 Jin-Luen Phua et al. All rights reserved. Preparation and Property of Xylan/Poly(Methacrylic Acid) Semi-Interpenetrating Network Hydrogel Sun, 27 Mar 2016 13:55:22 +0000 Xylan/poly(methacrylic acid) semi-interpenetrating network hydrogels were synthesized, and these hydrogels were fabricated using various ratios of xylan and methacrylic acid and cross-linked by N,N′-methylenebisacrylamide. The chemical structure and morphology of the prepared hydrogels were characterized by FT-IR spectroscopy and SEM analysis. The porous structure of the prepared hydrogels was found, and the interconnected porous channels increased when the content of xylan was increased in the hydrogels. The hydrogels presented excellent pH sensitivity and swelling reversibility. The dynamic swelling kinetics were also studied, and all obtained results indicated that the prepared xylan/poly(methacrylic acid) semi-IPN hydrogel could be used in biomedical fields, especially for drug release. Xiao-Feng Sun, Yang Feng, Xiaodi Shi, and Yaxiong Wang Copyright © 2016 Xiao-Feng Sun et al. All rights reserved. The Effect of Customized Woven and Stacked Layer Orientation on Tensile and Flexural Properties of Woven Kenaf Fibre Reinforced Epoxy Composites Sun, 27 Mar 2016 12:39:07 +0000 The synthetic fibres have created some issues including risk of inhalation during fabrication process, renewability, biodegradability, and recyclability in composites industry. The usage of biocomposites as a replacement to synthetic fibres is beginning to be widespread. However, it is noted that lesser attention has been devoted to evaluating the mechanical properties of woven kenaf composites at various woven and stacked layer orientation. Thus, the research objective is to identify the effect of woven and stacked layer orientation on tensile and flexural properties of kenaf composites. Two types of fibre orientation are employed; type A contains a higher yarn density and type B contains a low yarn density. The tensile and flexural tests are conducted to analyze the mechanical properties of woven kenaf fibre composites and compare them to random chopped kenaf composites. The fracture interface between fibre and matrix epoxy is further investigated via scanning electron microscope. Type A kenaf improved up to 199% and 177% as compared to random chopped kenaf for flexural strength and tensile strength, respectively. Scanning electron microscopy analysis shows that resin matrix is properly induced into kenaf fibre gap hence giving additional strength to woven kenaf as compared to random chopped kenaf. A. Hamdan, F. Mustapha, K. A. Ahmad, A. S. Mohd Rafie, M. R. Ishak, and A. E. Ismail Copyright © 2016 A. Hamdan et al. All rights reserved. Effect of Wood Fillers on the Viscoelastic and Thermophysical Properties of HDPE-Wood Composite Wed, 23 Mar 2016 10:25:21 +0000 Wood polymer composites (WPC) have well proven their applicability in several fields of the plasturgy sector, due to their aesthetics and low maintenance costs. However, for plasturgy applications, the characterization of viscoelastic behavior and thermomechanical and thermophysical properties of WPC with the temperature and wood filler contents is essential. Therefore, the processability of polymer composites made up with different percentage of wood particles needs a better understanding of materials behaviors in accordance with temperature and wood particles contents. To this end, a numerical analysis of the viscoelastic, mechanical, and thermophysical properties of composite composed of high density polyethylene (HDPE) reinforced with soft wood particles is evaluated. M. Tazi, M. S. Sukiman, F. Erchiqui, A. Imad, and T. Kanit Copyright © 2016 M. Tazi et al. All rights reserved. Influence of Membrane Materials and Operational Modes on the Performance of Ultrafiltration Modules for Drinking Water Treatment Tue, 22 Mar 2016 09:42:24 +0000 Polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAN) were prepared to purify micropolluted source water via a pilot-plant test. Integrative devices of in-line coagulation/ultrafiltration (UF) were proposed. Then the treatment performance, operation stability, clean methods, and fresh water recovery rate were assessed. The results showed that the membrane materials and operational modes did not result in significant difference of the removal efficiency of turbidity, , and NH4-N. The uniform distribution porosity, better hydrophilicity, and higher thermal stability of the PES membrane made its specific flux (SF) more than double those of two other membranes; in addition, the transmembrane pressure (TMP) of PES membrane appeared to be the least influenced by temperature change. The hydrophilicity of UF membrane was not a conclusive factor with the critical flux. The inside-out module with higher fouling load presented higher decay rate of SF under fixed flux operation compared with outside-in modules in single filtration duration. The way of gas washing of outside-in modules as a supplement resulted in recovery improvement. The acid-base staggered method of inside-out module to carry out chemical enhanced backwash (CEB) can effectively intensify the effects of backwashing by water. Gongduan Fan, Zhaoyue Su, Rujing Lin, Xiuyong Lin, Renxin Xu, and Wei Chen Copyright © 2016 Gongduan Fan et al. All rights reserved. Preparation and Characterization of Acrylic Primer for Concrete Substrate Application Sun, 20 Mar 2016 09:55:47 +0000 This study dealt with the properties of acrylic primer for concrete substrate using acrylic syrup, made from a methyl methacrylate monomer solution of terpolymers. Terpolymer systems consisting of methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), and methacrylic acid (MAA) with different chemical composition ratios of MMA and 2-EHA were synthesized through bulk polymerization using azobisisobutyronitrile (AIBN) as initiator. The terpolymer composition is characterized by FTIR, 1H NMR, DSC, TGA, and SEM. The glass transition temperature and the thermal stability increased with increasing amounts of MMA in the terpolymer backbone. The effect of chemical composition of terpolymers on physicomechanical properties of primer films was investigated. However, increasing the amount of MMA in terpolymer backbone increased tensile and contact angle of primer films while elongation at break, water absorption, and bond strength are decreased. In particular, the primer syrup containing 65% 2-EHA has good bonding strength with concrete substrate around 1.1 MPa. El-Sayed Negim, Nurlybayeva Aisha, Grigoriy A. Mun, Rinat Iskakov, Galiya S. Irmukhametova, and Mussylmanbek Sakhy Copyright © 2016 El-Sayed Negim et al. All rights reserved. Preparation of Nanofibers with Renewable Polymers and Their Application in Wound Dressing Thu, 17 Mar 2016 16:44:06 +0000 Renewable polymers have attracted considerable attentions in the last two decades, predominantly due to their environmentally friendly properties, renewability, good biocompatibility, biodegradability, bioactivity, and modifiability. The nanofibers prepared from the renewable polymers can combine the excellent properties of the renewable polymer and nanofiber, such as high specific surface area, high porosity, excellent performances in cell adhesion, migration, proliferation, differentiation, and the analogous physical properties of extracellular matrix. They have been widely used in the fields of wound dressing to promote the wound healing, hemostasis, skin regeneration, and treatment of diabetic ulcers. In the present review, the different methods to prepare the nanofibers from the renewable polymers were introduced. Then the recent progress on preparation and properties of the nanofibers from different renewable polymers or their composites were reviewed; the application of them in the fields of wound dressing was emphasized. Ying Zhao, Yihui Qiu, Huanhuan Wang, Yu Chen, Shaohua Jin, and Shuseng Chen Copyright © 2016 Ying Zhao et al. All rights reserved. Tensile and Compressive Properties of Woven Kenaf/Glass Sandwich Hybrid Composites Thu, 17 Mar 2016 14:07:25 +0000 Monotonic (tensile and compression) properties of woven kenaf/glass reinforced unsaturated polyester sandwich hybrid composites have been experimentally investigated. Five types of composites laminates were fabricated using a combination of hand lay-up and cold press techniques, postcured for two hours at 80°C and left for 48 hours at room temperature. The hybrid composites contained fixed six layers of glass as a shell, three on each side, whereas the number of core kenaf layers was changed in three stages to get S1, S2, and S3 hybrid composites. Composites specimens with pure glass and kenaf were also fabricated for comparison. It was found that one kenaf layer replaced about 20% of total fiber weight fraction of the composite; this leads to reducing the density of final hybrid composite by 13%. Besides, in mechanical properties perspective, there are less than 1% reduction in compression strength and 40% in tensile strength when compared to pure glass composite. Generally, the results revealed that the best performance was observed in S1, which showed a good balance of all mechanical properties determined in this work. Mohaiman J. Sharba, Z. Leman, M. T. H. Sultan, M. R. Ishak, and M. A. Azmah Hanim Copyright © 2016 Mohaiman J. Sharba et al. All rights reserved. Hybrid Composites from Wheat Straw, Inorganic Filler, and Recycled Polypropylene: Morphology and Mechanical and Thermal Expansion Performance Wed, 16 Mar 2016 08:04:23 +0000 Reinforcing effect of hybrid filler including wheat straw (WS) and inorganic filler (heavy calcium carbonate, silicon dioxide, and fly ash) in recycled polypropylene (R-PP) has been investigated. The effects of individual filler (WS) and combined fillers (WS and inorganic filler) on morphological, mechanical, and thermal expansion and water absorption properties of hybrid composites were investigated. The flexural modulus and flexural strength were both reduced when reinforced with three kinds of inorganic fillers, respectively, which was possibly due to the poor interphase adhesion as observed in SEM. The high surface energy of heavy calcium carbonate due to its high acidic character provides an opportunity of better PP-heavy calcium carbonate interfacial interactions compared to PP-straw, PP-fly ash, and PP-SiO2 interface. The water absorption at saturation increased markedly by introduction of WS in it. The hybrid composites from WS and inorganic fillers showed better water absorption compared to those WS/PP composites. The thermal expansion of composites decreased with the increase of WS loading. Heavy calcium and SiO2 can obviously reduce the LCTE value of composite. At the 25% inorganic filler content, composites had the smallest LCTE values. Min Yu, Runzhou Huang, Chunxia He, Qinglin Wu, and Xueni Zhao Copyright © 2016 Min Yu et al. All rights reserved. Synthesis of High cis-1,4-BR with Neodymium for the Manufacture of Tires Tue, 15 Mar 2016 12:41:04 +0000 The salt of neodymium has been widely used in industrial polymerization of 1,3-butadiene. We used the ternary catalytic system neodymium versatate/diethylaluminum chloride/triisobutylaluminum (NdV3/DEAC/TIBA) with 0.5 mM NdV3/100 g Bd, NdV3 : DEAC = 1 : 9 mol : mol, and TIBA = 25, 50, 100, and 200 mM. The number-average molecular weight (Mn), weight-average molecular weight (Mw), and polydispersity index (PDI) were analyzed by GPC; the rheological properties were analyzed by DMA. The formulations were prepared with carbon black (IRB6) as reinforcing filler and the mechanical properties were compared to behavior of the different elastomeric compounds. The elastomeric compounds were characterized by their rheological properties, tensile strength, abrasion resistance, tear strength, permanent set, resilience, and fatigue properties. The high cis-1,4 polybutadiene (high cis-1,4-BR) was obtained with a percentage of cis-1,4 ≥97%. The weight-average molecular weight (Mw) was from 150 × 103 to 900 × 103 g/mol and polydispersity index (PDI) was from 3.1 to 5.1. This work is based on evaluation of the effect of the catalyst system on the final properties of the synthesized polybutadiene. Maria Leonor Méndez-Hernández, José Luis Rivera-Armenta, Ulises Páramo-García, Sergio Corona Galvan, Ricardo García-Alamilla, and Beatriz Adriana Salazar-Cruz Copyright © 2016 Maria Leonor Méndez-Hernández et al. All rights reserved. Polymers from Biomass: Characterization, Modification, Degradation, and Applications Mon, 14 Mar 2016 06:00:49 +0000 Mukund Adsul, Deepak K. Tuli, Pratheep K. Annamalai, Dilip Depan, and Shiv Shankar Copyright © 2016 Mukund Adsul et al. All rights reserved. Influence of Textile Structure and Silica Based Finishing on Thermal Insulation Properties of Cotton Fabrics Tue, 08 Mar 2016 08:43:17 +0000 The aim of this work is to investigate the influence of weave structures and silica coatings obtained via sol-gel process on the thermal insulation properties of cotton samples. For this reason three main weave structures (plain, satin, and piqué) of cotton fabric were selected with different yarn count, threads per cm, and mass per square meter values. Thereafter, only for the plain weave, the samples were padded using silica sol formed by hydrolysis and subsequent condensation of 3-glycidoxypropyltrimethoxysilane under acidic conditions. The silanized plain weave samples were characterized by TGA and FT-IR techniques. The thermal properties were measured with a home-made apparatus in order to calculate thermal conductivity, resistance, and absorption of all the treated fabric samples. The relationship between the thermal insulation properties of the plain weave fabrics and the concentration of sol solutions has been investigated. Fabrics weave and density were found to strongly influence the thermal properties: piqué always shows the lowest values and satin shows the highest values while plain weave lies in between. The thermal properties of treated high-density cotton plain weave fabric were proved to be strongly influenced by finishing agent concentration. G. Rosace, E. Guido, C. Colleoni, and G. Barigozzi Copyright © 2016 G. Rosace et al. All rights reserved. Alginate Biosynthesis in Azotobacter vinelandii: Overview of Molecular Mechanisms in Connection with the Oxygen Availability Mon, 29 Feb 2016 13:02:44 +0000 The Gram-negative bacterium Azotobacter vinelandii can synthetize the biopolymer alginate that has material properties appropriate for plenty of applications in industry as well as in medicine. In order to settle the foundation for improving alginate production without compromising its quality, a better understanding of the polymer biosynthesis and the mechanism of regulation during fermentation processes is necessary. This knowledge is crucial for the development of novel production strategies. Here, we highlight the key aspects of alginate biosynthesis that can lead to producing an alginate with specific material properties with particular focus on the role of oxygen availability linked with the molecular mechanisms involved in the alginate production. Ivette Pacheco-Leyva, Felipe Guevara Pezoa, and Alvaro Díaz-Barrera Copyright © 2016 Ivette Pacheco-Leyva et al. All rights reserved. Utilization of Waste Clay from Boron Production in Bituminous Geosynthetic Barrier (GBR-B) Production as Landfill Liner Thu, 25 Feb 2016 13:16:03 +0000 Bituminous geomembranes, one type of geosynthetics, include a hot bituminous mixture with mineral filler and reinforcement. In this study, boron production waste clay (CW) was used as filler to produce a geosynthetic barrier with bentonite, waste tire, and bitumen. Bentonite and waste tires were used as auxiliary fillers and bitumen as the binder. CW/bitumen, CW/bentonite/bitumen, and CW/waste tire/bitumen mixtures were prepared by using a laboratory mixer at 100°C. Hot mixtures were extruded into strips by using a lab-scale corotating twin screw extruder (L/D: 40) followed by die casting (2 mm × 100 mm). Glass fleece or nonwoven polyester was used as reinforcement material and while die casting, both sides of the reinforcement materials were covered with bituminous mixture. Thickness, mass per unit area, tensile strength, elongation at yield, and hydraulic conductivity were used to characterize the geomembranes. Among all geomembranes, nonwoven polyester covered with 30% bitumen-70% boron waste clay mixture (PK-BTM30CW70) was found to be the most promising in terms of structure and mechanical behaviour. After that, consequences of its exposure to distilled water (DW), municipal solid waste landfill leachate (L-MSW), and hazardous waste landfill leachate (L-HW) were examined to use for an innovative impermeable liner on solid waste landfills. Müfide Banar, Yücel Güney, Aysun Özkan, Zerrin Günkaya, Eren Bayrakcı, and Derya Ulutaş Copyright © 2016 Müfide Banar et al. All rights reserved. Thermal, Morphological, and Biodegradability Properties of Bioplastic Fertilizer Composites Made of Oil Palm Biomass, Fertilizer, and Poly(hydroxybutyrate-co-valerate) Wed, 24 Feb 2016 13:37:49 +0000 Slow-release bioplastic fertilizer (BpF) composites were developed by processing oil palm empty fruit bunch (EFB), fertilizer, and poly(hydroxybutyrate-co-valerate) (PHBv) using extrusion techniques with controlled formulation and temperature. The temperature was kept at 150°C for 3 to 5 min during processing using twin-screw extruder. The PHBv lost weight gradually with the increasing temperature and its thermal degradation occurred initially at 263.4°C and reached the maximum at 300.7°C. Scanning electron microscope (SEM) images showed that the bonding of all composites created small gaps between matrices polymer and fiber because the hydrophilic characteristic of EFB fibers weakened the interfacial bonding. PHBv/EFB/NPKC2 showed faster biodegradation over PHBv/NPKC1 and PHBv/NPKC2, which was 99.35% compared to 68.66% and 90.28%, respectively. A. S. Harmaen, A. Khalina, H. Mohd Ali, and I. Nor Azowa Copyright © 2016 A. S. Harmaen et al. All rights reserved. Influence of Fiber Content on Mechanical and Morphological Properties of Woven Kenaf Reinforced PVB Film Produced Using a Hot Press Technique Tue, 23 Feb 2016 13:09:34 +0000 This work addresses the results of experimental investigation carried out on mechanical and morphological properties of plain woven kenaf fiber reinforced PVB film which was prepared by hot press technique. The composites were prepared with various fiber contents: 0%, 10%, 20%, 30%, 40%, 50%, and 60% (by weight), with the processing parameters 165°C, 20 min, and at a pressure of 8 MPa applied on the material. Tensile, flexural, and Charpy impact properties were studied as well as morphological properties of impact fracture surface. With the increase in kenaf fibers content up to 40%, the PVB composites have shown lower tensile and flexural strength accompanied with reduction in the ultimate strain of the composite. The results showed that impact properties were affected in markedly different ways by using various kenaf contents and decrease with the increase in kenaf fiber content up to 40%; however, high impact strength was observed even with 40% kenaf fiber content. Furthermore, scanning electron microscopy for impact samples was utilised to demonstrate the different failures in the fracture surfaces for various kenaf fibers contents. Suhad D. Salman, Z. Leman, M. T. H. Sultan, M. R. Ishak, and F. Cardona Copyright © 2016 Suhad D. Salman et al. All rights reserved. Moisture Sorption and Thermodynamic Properties of Wood under Dynamic Condition Tue, 23 Feb 2016 11:58:16 +0000 Thermodynamic approach is a useful method to study interactions between water and wood at molecular level. This work investigated the dynamic moisture sorption and thermodynamic properties for two thick poplar woods (Populus euramericana Cv.) subjected to sinusoidal relative humidity (RH) changes between 45% and 75% for cyclic period of 1, 6, and 24 h, at two temperatures of 25°C and 40°C. Moisture changes of the specimens were measured during the successive adsorption and desorption processes, giving the following results: (1) moisture content changed sinusoidally with the imposed RH and was inversely related to specimen thickness as well as temperature, but in a positive correlation with cyclic periods; (2) all of , , and of the adsorbed water during dynamic sorption decreased with increasing moisture content or specimen thickness and decreasing cyclic period. However, temperature had opposite effects on and . (3) Both moisture sorption hysteresis and thermodynamic sorption hysteresis could be found. The former became weak with rising temperature or thicker specimens, while the latter got clear when temperature or specimen thickness increased. Tiantian Yang and Erni Ma Copyright © 2016 Tiantian Yang and Erni Ma. All rights reserved. Effect of Sodium Salicylate on the Viscoelastic Properties and Stability of Polyacrylate-Based Hydrogels for Medical Applications Tue, 23 Feb 2016 09:27:59 +0000 Investigation was made into the effect exerted by the presence of sodium salicylate (0–2 wt.%), in Carbomer-based hydrogel systems, on processing conditions, rheological and antimicrobial properties in tests against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterial strains, and examples of yeast (Candida albicans) and mould (Aspergillus niger). In addition, the work presents an examination of long-term stability by means of aging over one year the given hydrogels at 8°C and 25°C. The results show that 0.5 wt.% NaSal demonstrated a noticeable effect on the hydrogel neutralization process, viscosity, and antimicrobial properties against all of the tested microorganisms. The long-term stability studies revealed that hydrogels can maintain antimicrobial activity as well as viscosity to a degree that would be sufficient for practical use. Zuzana Kolarova Raskova, Martina Hrabalikova, and Vladimir Sedlarik Copyright © 2016 Zuzana Kolarova Raskova et al. All rights reserved.