International Journal of Polymer Science The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. (Bio)degradable Ionomeric Polyurethanes Based on Xanthan: Synthesis, Properties, and Structure Sun, 24 Sep 2017 07:08:42 +0000 New (bio)degradable environmentally friendly film-forming ionomeric polyurethanes (IPU) based on renewable biotechnological polysaccharide xanthan (Xa) have been obtained. The influence of the component composition on the colloidal-chemical and physic-mechanical properties of IPU/Xa and based films, as well as the change of their properties under the influence of environmental factors, have been studied. The results of IR-, PMS-, DMA-, and X-ray scattering study indicate that incorporation of Xa into the polyurethane chain initiates the formation of a new polymer structure different from the structure of the pure IPU (matrix): an amorphous polymer-polymer microdomain has occurred as a result of the chemical interaction of Xa and IPU. It predetermines the degradation of the IPU/Xa films as a whole, unlike the mixed polymer systems, and plays a key role in the improvement of material performance. The results of acid, alkaline hydrolysis, and incubation into the soil indicate the increase of the intensity of degradation processes occurring in the IPU/Xa in comparison with the pure IPU. It has been shown that the introduction of Xa not only imparts the biodegradability property to polyurethane, but also improves the mechanical properties. T. V. Travinskaya, A. N. Brykova, Yu. V. Savelyev, N. V. Babkina, and V. I. Shtompel Copyright © 2017 T. V. Travinskaya et al. All rights reserved. Structural Foams of Biobased Isosorbide-Containing Copolycarbonate Wed, 20 Sep 2017 08:08:55 +0000 Isosorbide-containing copolycarbonate (Bio-PC) is a partly biobased alternative to conventional bisphenol A (BPA) based polycarbonate (PC). Conventional PC is widely used in polymer processing technologies including thermoplastic foaming such as foam injection molding. At present, no detailed data is available concerning the foam injection molding behavior and foam properties of Bio-PC. This contribution provides first results on injection-molded foams based on isosorbide-containing PC. The structural foams were produced by using an endothermic chemical blowing agent (CBA) masterbatch and the low pressure foam injection molding method. The influence of weight reduction and blowing agent concentration on general foam properties such as density, morphology, and mechanical properties was studied. The test specimens consist of a foam core in the center and compact symmetrical shell layers on the sides. The thickness of the foam core increases with increasing weight reduction irrespective of the CBA concentration. The specific (mechanical) bending properties are significantly improved and the specific tensile properties can almost be maintained while reducing the density of the injection-molded parts. Stefan Zepnik, Daniel Sander, Stephan Kabasci, and Christian Hopmann Copyright © 2017 Stefan Zepnik et al. All rights reserved. Thermoplastic Cassava Starch-PVA Composite Films with Cellulose Nanofibers from Oil Palm Empty Fruit Bunches as Reinforcement Agent Wed, 20 Sep 2017 00:00:00 +0000 Thermoplastic starch-polyvinyl alcohol composite films were prepared by casting method with cellulose nanofibers as reinforcement agent and glycerol as plasticizer. The obtained cellulose nanofibers with a diameter of  nm were isolated from oil palm empty fruit bunches (OPEFBs) by mechanical treatment. The addition of cellulose nanofibers until 3 wt% increased tensile strength and crystallinity of the composite films. In contrast, it decreased their elongation at break and water vapor transmission rate. Meanwhile, the addition of glycerol increased elongation at break and water vapor transmission rate of film matrix but lowers tensile strength of composite films. Farah Fahma, Sugiarto, Titi Candra Sunarti, Sabrina Manora Indriyani, and Nurmalisa Lisdayana Copyright © 2017 Farah Fahma et al. All rights reserved. Efficacy Study of Carrageenan as an Alternative Infused Material (Filler) in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Porous 3D Scaffold Wed, 20 Sep 2017 00:00:00 +0000 Polymeric porous 3D scaffold plays an important role in culturing mammalian cells as ex vivo model. However, the scaffold used is ineffective due to its structural and cell acceptability weaknesses. Therefore, this research attempts to overcome the weaknesses by using carrageenan from red seaweed Kappaphycus alvarezii as an alternative infused material (filler) of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) porous 3D scaffold. The 3D scaffold was conventionally fabricated using the solvent-casting particulate-leaching (SCPL) method. Carrageenan was later infused into 3D porous scaffolds under vacuum pressure and freeze-drying process. Five carrageenan concentrations were prepared and its physicochemical properties such as pH and viscosity were carried out on each concentration to determine the best solutions to produce a new composite 3D structure. The preliminary result shows that carrageenan concentrations of 2, 4, and 6% (w/v) were considered the best solutions for the infusion process due to its stable rheology properties. The pH and viscosity profiles of three selected carrageenan solutions were exhibited in the range of 9.00–9.20 and 0.047–1.144 Pa·s, respectively. Moreover, the incorporated carrageenan gel fraction was in the range of 4.30% to 14.95% (w/w) which was determined by gravimetric analysis and dye staining method (visual assessment). The well-infused carrageenan 3D scaffold was further characterized based on its internal morphology and degradability study. The vertical cross-sections of the scaffolds revealed homogeneous accumulation of dried gelatinous carrageenan which was covered throughout its pores wall. The degradation rate () of the carrageenan infused 3D scaffold was between (mg/day) and (mg/day). The higher the carrageenan concentration used, the faster the degradation rate occurring (). The 3D infused scaffold of 4% (w/v) carrageenan concentration (S2) produced a moderate degradation rate of (mg/day) with a sustained structural integrity up to 28 days. The carrageenan infused scaffold of 4% (w/v) was demonstrated to be the best 3D structure for a long-term cell culture (>2 weeks). In conclusion, the usage of carrageenan as a composite material exhibits its great potential to be used in tissue engineering application and 3D cell culture model. Nor Syamimi Che Johari, Syazwan Aizad, and Saiful Irwan Zubairi Copyright © 2017 Nor Syamimi Che Johari et al. All rights reserved. Photoresist Removal Using H Radicals Generated by Iridium Hot-Wire Catalyst Tue, 19 Sep 2017 07:22:14 +0000 We examined an environmentally friendly photoresist removal method using H radicals produced by decomposing hydrogen on a hot iridium catalyst. We examined the relationship between photoresist removal rate and its surface temperature using thin film interference and the removal properties using H radicals produced by the Ir catalyst. Decomposition behavior at polymer surface by radicals may be analyzed in further detail from the aspect of kinetics. Additionally, we investigated the oxygen addition effects on the removal rate. The photoresist removal rate increased with the oxygen additive amount and then decreased more gradually than in the case of using W filament. The increasing behavior was similar but there was a large difference between W and Ir catalyst in the decreasing behavior. Masashi Yamamoto, Shiro Nagaoka, Hironobu Umemoto, Keisuke Ohdaira, Takashi Nishiyama, and Hideo Horibe Copyright © 2017 Masashi Yamamoto et al. All rights reserved. Bioactive 3D-Shaped Wound Dressings Synthesized from Bacterial Cellulose: Effect on Cell Adhesion of Polyvinyl Alcohol Integrated In Situ Mon, 18 Sep 2017 10:19:58 +0000 We investigated wound dressing composites comprising fibrils of bacterial cellulose (BC) grown by fermentation in the presence of polyvinyl alcohol (PVA) followed by physical crosslinking. The reference biointerface, neat BC, favoured adhesion of fibroblasts owing to size exclusion effects. Furthermore, it resisted migration across the biomaterial. Such effects were minimized in the case of PVA/BC membranes. Therefore, the latter are suggested in cases where cell adhesion is to be avoided, for instance, in the design of interactive wound dressings with facile exudate control. The bioactivity and other properties of the membranes were related to their morphology and structure and considered those of collagen fibres. Bioactive materials were produced by simple 3D templating of BC during growth and proposed for burn and skin ulcer treatment. Marlon Osorio, Jorge Velásquez-Cock, Luz Marina Restrepo, Robín Zuluaga, Piedad Gañán, Orlando J. Rojas, Isabel Ortiz-Trujillo, and Cristina Castro Copyright © 2017 Marlon Osorio et al. All rights reserved. Enhancement of Mechanical and Thermal Properties of Poly(L-lactide) Nanocomposites Filled with Synthetic Layered Compounds Sun, 17 Sep 2017 00:00:00 +0000 The effects of a layered double hydroxide (LDH) (Zn/Al palmitate) and two layered hydroxide salts (LHS), intercalated with the anion salicylate or palmitate, on the properties of poly(L-lactide) (PLLA) nanocomposites were investigated. PLLA and the nanocomposites were synthesized by ring opening polymerization of the cyclic dimer of lactic acid (lactide), using tin(II) 2-ethylhexanoate (stannous octanoate) as catalyst. PLLA nanocomposites containing two different fillers concentrations (1 wt% and 2 wt%) were produced. Compared to PLLA, almost all the nanocomposites exhibited an enhancement on thermal resistance. The sample containing 1 wt% of Zn/Al palmitate exhibited a decomposition temperature 51°C higher than neat polymer. Results of flexural properties demonstrated that the nanocomposites containing Zn/Al palmitate displayed the highest values of maximum flexural stress and elongation at break. The sample with 2 wt% of this filler revealed values of maximum flexural stress and strain at break, 15% and 157%, respectively, higher than PLLA. Contrary to PLLA, which only exhibited break point, this nanocomposite showed a less fragile behavior, as a yield point was observed. In this case, it was possible to promote a higher flexibility without reducing the flexural stress, revealing an advantage of the Zn/Al palmitate under the plasticizers that have been used so far for PLLA. Telma Nogueira Caio, Núria Gonçalves, Fernando Wypych, and Liliane Maria Ferrareso Lona Copyright © 2017 Telma Nogueira Caio et al. All rights reserved. Genome Structure of Bacillus cereus tsu1 and Genes Involved in Cellulose Degradation and Poly-3-Hydroxybutyrate Synthesis Sun, 10 Sep 2017 00:00:00 +0000 In previous work, we reported on the isolation and genome sequence analysis of Bacillus cereus strain tsu1 NCBI accession number JPYN00000000. The 36 scaffolds in the assembled tsu1 genome were all aligned with B. cereus B4264 genome with variations. Genes encoding for xylanase and cellulase and the cluster of genes in the poly-3-hydroxybutyrate (PHB) biosynthesis pathway were identified in tsu1 genome. The PHB accumulation in B. cereus tsu1 was initially identified using Sudan Black staining and then confirmed using high-performance liquid chromatography. Physical properties of these PHB extracts, when analyzed with Raman spectra and Fourier transform infrared spectroscopy, were found to be comparable to the standard compound. The five PHB genes in tsu1 (phaA, phaB, phaR, phaC, and phaP) were cloned and expressed with TOPO cloning, and the recombinant proteins were validated using peptide mapping of in-gel trypsin digestion followed by mass spectrometry analysis. The recombinant E. coli BL21 (DE3) (over)expressing phaC was found to accumulate PHB particles. The cellulolytic activity of tsu1 was detected using carboxymethylcellulose (CMC) plate Congo red assay and the shift towards low-molecular size forms of CMC revealed by gel permeation chromatography in CMC liquid culture and the identification of a cellulase in the secreted proteome. Hui Li, Suping Zhou, Terrance Johnson, Koen Vercruysse, Ouyang Lizhi, Parthasarathy Ranganathan, Nsoki Phambu, Alexander J. Ropelewski, and Theodore W. Thannhauser Copyright © 2017 Hui Li et al. All rights reserved. Discoloration Effects of High-Dose γ-Irradiation and Long-Term Thermal Aging of (U)HMW-PE Wed, 06 Sep 2017 00:00:00 +0000 Two polyethylene types with ultra-high (UHMW-PE) and high molecular weight (HMW-PE) used as neutron radiation shielding materials in casks for radioactive waste were irradiated with doses up to 600 kGy using a 60Co gamma source. Subsequently, thermal aging at 125°C was applied for up to one year. Degradation effects in the materials were characterized using colorimetry, UV-Vis spectroscopy, IR spectroscopy, and DSC. Both materials exhibited a yellowing upon irradiation. The discoloration of UHMW-PE disappeared again after thermal aging. Therefore, the yellowing is assumed to originate from annealable color centers in the form of free radicals that are trapped in the crystalline regions of the polymer and recombine at elevated temperatures. For the antioxidant-containing HMW-PE, yellowing was observed after both irradiation and thermal aging. The color change was correlated mainly to decomposition products of the antioxidant in addition to trapped radicals as in UHMW-PE. Additionally, black spots appeared after thermal aging of HMW-PE. Anja Kömmling, Emmanouil Chatzigiannakis, Jörg Beckmann, Volker Wachtendorf, Kerstin von der Ehe, Ulrike Braun, Matthias Jaunich, Ulrich Schade, and Dietmar Wolff Copyright © 2017 Anja Kömmling et al. All rights reserved. Joining of Incompatible Polymer Combinations by Form Fit Using the Vibration Welding Process Tue, 05 Sep 2017 00:00:00 +0000 The production of components consisting of various polymer types by welding is severely restricted and only possible for bonding compatible materials with melting points in a close range. Several modifications, such as the cross-linking of one joining partner, allow for circumventing the restrictions regarding the melting points but do not help in joining bonding incompatible materials. Investigations of dissimilar material combinations, especially from polymer-metal hybrid structures, show a high potential of connections based on form fits. Within the scope of this paper, the possibility of joining incompatible polymer combinations, such as polyamide 66 and high-density polyethylene, by micro form fit using the vibration welding process is analyzed. For this purpose, the generated bonding strength of the test specimen was determined by shear tests. Furthermore, the undercuts of the generated prestructures and the resulting bond of the test specimen were examined microscopically by computer-tomography. These investigations depict the high potential of joining incompatible polymer combinations by form fit in the vibration welding using prestructuring to generate undercuts. Michael Wolf, Tobias Kleffel, Christoph Leisen, and Dietmar Drummer Copyright © 2017 Michael Wolf et al. All rights reserved. Mechanical Property Analysis of Circular Polymer Membrane under Uniform Pressure Mon, 28 Aug 2017 00:00:00 +0000 Mechanical property analysis of circular hyperelastic polymer membrane under uniform pressure has been researched in this work. The polymer membrane material is assumed to be homogeneous and isotropic and incompressibility of materials has been considered. Based on the modified stain energy function from Gao and nonmomental theory of axial symmetry thin shell, finite deformation analysis of polymer membrane under uniform pressure has been proposed in current configuration and governing equations of polymer membrane have been achieved. By utilizing the boundary condition, theoretical results of governing equations have been obtained and vertical displacement distribution and stress distribution have been achieved. The results show that the constitutive parameter has a strengthening effect on the polymer material and the constitutive parameter plays a controlling role for the second strain invariant , which also has a strengthening effect on the polymer material. This research has revealed the deformational mechanism of polymer membrane and provided reference for the design of polymer membrane. Sang Jianbing, Li Xiang, Xing Sufang, and Wang Wenjia Copyright © 2017 Sang Jianbing et al. All rights reserved. Characterization of Alkaline Treatment and Fiber Content on the Physical, Thermal, and Mechanical Properties of Ground Coffee Waste/Oxobiodegradable HDPE Biocomposites Sun, 27 Aug 2017 00:00:00 +0000 Effect of alkali treatment on ground coffee waste/oxobiodegradable HDPE (GCW/oxo-HDPE) composites was evaluated using 5%, 10%, 15%, and 20% volume fraction of GCW. The composites were characterized using structural (Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM)), thermal (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)), mechanical (tensile and impact test) properties, and water absorption. FTIR spectrum indicated the eradication of lipids, hemicellulose, lignin, and impurities after the treatments lead to an improvement of the filler/matrix interface adhesion. This is confirmed by SEM results. Degree of crystallinity index was increased by 5% after the treatment. Thermal stability for both untreated and treated GCW composites was alike. Optimum tensile result was achieved when using 10% volume fraction with enhancement of 25% for tensile strength and 24% for tensile modulus compared to untreated composite. Specific tensile strength and modulus had improved as the composite has lower density. The highest impact properties were achieved when using 15% volume fraction that lead to an improvement of 6%. Treated GCW composites show better water resistance with 57% improvement compared to the untreated ones. This lightweight and ecofriendly biocomposite has the potential in packaging, internal automotive parts, lightweight furniture, and other composite engineering applications. Ming Yee Tan, Hoo Tien Nicholas Kuan, and Meng Chuen Lee Copyright © 2017 Ming Yee Tan et al. All rights reserved. Characterization of Biobased Polyurethane Foams Employing Lignin Fractionated from Microwave Liquefied Switchgrass Thu, 24 Aug 2017 00:00:00 +0000 Lignin samples fractionated from microwave liquefied switchgrass were applied in the preparation of semirigid polyurethane (PU) foams without purification. The objective of this study was to elucidate the influence of lignin in the PU matrix on the morphological, chemical, mechanical, and thermal properties of the PU foams. The scanning electron microscopy (SEM) images revealed that lignin with 5 and 10% content in the PU foams did not influence the cell shape and size. The foam cell size became larger by increasing the lignin content to 15%. Fourier transform infrared spectroscopy (FTIR) indicated that chemical interactions occurred between the lignin hydroxyl and isocyanate revealing that lignin was well dispersed in the matrix materials. The apparent density of the foam with 10% lignin increased by 14.2% compared to the control, while the foam with 15% lignin had a decreased apparent density. The effect of lignin content on the mechanical properties was similar to that on apparent density. The lignin containing foams were much more thermally stable than the control foam as evidenced by having higher initial decomposition temperature and maximum decomposition rate temperature from the thermogravimetric analysis (TGA) profiles. Xingyan Huang, Cornelis F. De Hoop, Jiulong Xie, Chung-Yun Hse, Jinqiu Qi, and Tingxing Hu Copyright © 2017 Xingyan Huang et al. All rights reserved. Synthesis of Poly-(R-hydroxyalkanoates) by Cupriavidus necator ATCC 17699 Using Mexican Avocado (Persea americana) Oil as a Carbon Source Mon, 21 Aug 2017 00:00:00 +0000 Poly-R-hydroxyalkanoates (PHAs) are polymers produced by a vast number of bacterial species under stress conditions. PHAs exhibit different thermal and mechanical properties that depend on their molecular structure. In this work, PHAs were produced using avocado oil as the carbon source. Cupriavidus necator H16 was cultured in three-stage fermentation using fructose during the cell growth stages and avocado oil during the PHA synthesis stage. Different concentrations of avocado oil were used during the third stage to test the incorporation of various monomeric units into the PHAs. Biomass and PHA production were measured during the fermentation. DSC, FTIR, and gas chromatography analysis aided the PHA characterization. Different proportions of 3-hydroxyvalerate were present in the 3-hydroxybutyrate main chain depending on the concentration of avocado oil. The results suggest that avocado oil is a viable new substrate for PHA production. Araceli Flores-Sánchez, Ma. del Rocío López-Cuellar, Fermín Pérez-Guevara, Ulises Figueroa López, José Mauricio Martín-Bufájer, and Berenice Vergara-Porras Copyright © 2017 Araceli Flores-Sánchez et al. All rights reserved. Structural Analysis of Alkaline Pretreated Rice Straw for Ethanol Production Tue, 15 Aug 2017 00:00:00 +0000 Rice straw (RS) is an abundant, readily available agricultural waste, which shows promise as a potential feedstock for Asian ethanol production. To enhance release of glucose by enzymatic hydrolysis, RS was pretreated with aqueous ammonia (27% w/w) at two pretreatment temperatures: room temperature and 60°C. Statistical analysis indicated similarity of enzymatic glucose production at both pretreatment temperatures after 3-day incubation. Chemical composition, FTIR, and EDX analyses confirmed the retention of glucan and xylan in the pretreated solid, but significant reduction of lignin (60.7% removal) and silica. SEM analysis showed the disorganized surfaces and porosity of the pretreated RS fibers, thus improving cellulose accessibility for cellulase. The crystallinity index increased from 40.5 to 52.3%, indicating the higher exposure of cellulose. With 10% (w/v) solid loadings of pretreated RS, simultaneous saccharification and fermentation yielded a final ethanol concentration of 24.6 g/L, corresponding to 98% of maximum theoretical yield. Taken together, aqueous ammonia pretreatment is an effective method to generate highly digestible pretreated RS for bioethanol production and demonstrates potential application in biorefinery industry. Paripok Phitsuwan, Chutidet Permsriburasuk, Sirilak Baramee, Thitiporn Teeravivattanakit, and Khanok Ratanakhanokchai Copyright © 2017 Paripok Phitsuwan et al. All rights reserved. Effect of Polyvinyl Acetate Stabilization on the Swelling-Shrinkage Properties of Expansive Soil Tue, 15 Aug 2017 00:00:00 +0000 Polyvinyl acetate constitutes a class of polymers that can entirely dissolve in water to form a solution. In this study, polyvinyl acetate as a nontraditional chemical stabilizer was used in soil improvement. Laboratory tests were carried out to evaluate the effect of polyvinyl acetate on swelling-shrinkage properties of expansive soil. A series of shrink/swell tests were performed with adding polyvinyl acetate as amendment at a concentration 3 g/cm3 to four aggregate sizes in the range of 0–0.5 mm, 0.5–1 mm, 1-2 mm, and 2–5 mm and five concentrations 1.5 g/cm3, 3 g/cm3, 4.5 g/cm3, 6 g/cm3, and 9 g/cm3 to soils with aggregate size in the range of 0.5–1 mm for comparison of results with those of untreated soils. The results show that all the linear swelling ratio (LSWR) and linear shrinkage ratio (LSHR) values of the treated specimens decrease. SEM images and the test results indicate the achieved reduction in volume change of the soil tested using soil pore filling and particle encapsulation. Jin Liu, Yong Wang, Yi Lu, Qiao Feng, Faming Zhang, Changqing Qi, Jihong Wei, and Debi Prasanna Kanungo Copyright © 2017 Jin Liu et al. All rights reserved. Effect of Bolt-Hole Clearance on Bolted Connection Behavior for Pultruded Fiber-Reinforced Polymer Structural Plastic Members Sun, 06 Aug 2017 06:24:35 +0000 Bolt-hole clearance affects the failure mode on the bolted connection system of pultruded fiber-reinforced polymer plastic (PFRP) members. The various geometric parameters, such as the shape and cross-sectional area of the structural members, commonly reported in many references were used to validate the bolt-hole clearance. This study investigates the effects of the bolt-hole clearance in single-bolt connections of PFRP structural members. Single-bolt connection tests were planned using different bolt-hole clearances (e.g., tight-fit and clearances of 0.5 mm to 3.0 mm with 0.5 mm intervals) and uniaxial tension is applied on the test specimens. Most of the specimens failed in two sequential failure modes: bearing failure occurred and the shear-out failure followed. Test results on the bolt-hole clearances are compared with results in the previous research. Sang-Pyuk Woo, Sun-Hee Kim, Soon-Jong Yoon, and Wonchang Choi Copyright © 2017 Sang-Pyuk Woo et al. All rights reserved. Fabrication of Core-Shell PLGA-Chitosan Microparticles Using Electrospinning: Effects of Polymer Concentration Thu, 03 Aug 2017 10:10:54 +0000 This investigation aims to fabricate the core-shell microparticles composed of poly(lactic-co-glycolic acid) and chitosan (PLGA-CS MPs) using electrospinning. The challenge of using electrospinning is that it has many parameters which change product outcome if any single parameter is changed. However, the advantage of this system is that we can fabricate either micro/nanofibers or micro/nanoparticles. To learn about the effect of liquid concentration, the electrospinning parameters (voltage, needle sizes, distance from needle to collector, and ejection speed) were fixed while the concentration of PLGA or chitosan was varied. The results showed that PLGA microparticles can be fabricated successfully when the concentration of PLGA is smaller than 10 wt%. Presence of the chitosan shell was confirmed by zeta potential measurements, FT-IR, optical observation, and fluorescence observation. Thickness of the chitosan shell can be controlled by changing the concentration of chitosan and measured by fluorescamine labeling method. Moreover, SEM observation showed that concentration of chitosan affected the size of PLGA-CS microparticles. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay test showed that PLGA-CS microparticles possess excellent biocompatibility. Nguyen Thi Hiep, Nguyen Dai Hai, and Vo Van Toi Copyright © 2017 Nguyen Thi Hiep et al. All rights reserved. Method Validation for Progesterone Determination in Poly(methyl methacrylate) Nanoparticles Synthesized via Miniemulsion Polymerization Tue, 01 Aug 2017 09:16:50 +0000 Exogenous progesterone has several applications in human health and in veterinary medicine, especially in fixed-time artificial insemination protocol. Progesterone nanoencapsulation in biocompatible polymers, such as poly(methyl methacrylate) (PMMA), is an alternative to substitute silicone-based release device traditionally used for estrus control. Progesterone concentration inside the nanoparticles must be precisely known; for that reason, a validation methodology must be applied to ensure reliable results, suitable for nanoparticles application. In this work, an UV-Vis spectrophotometric method was validated for the determination of progesterone in PMMA nanoparticles synthesized by miniemulsion polymerization. Chloroform was used as solvent, showing selectivity to the encapsulated drug and the components of the polymeric matrix did not influence progesterone recovery. Detection and quantitation limits (DL and QL) obtained were 0.32 and 0.96 mg·L−1, respectively, and precision tests (between different analysts and equipment) indicated acceptable Relative Standard Deviations (RSD < 5%). Miniemulsion polymerization reactions were carried out producing two different morphologies: nanospheres (NS) and nanocapsules (NC), with average intensity diameters (Dz) of 150–200 nm and 240–300 nm, respectively. Polymerization gravimetric conversions obtained for both cases were higher than 95% and encapsulation efficiencies greater than 69% and 90% for the nanospheres and nanocapsules, respectively. Odinei Fogolari, Arlindo Cristiano Felippe, Fernanda Vitória Leimann, Odinei Hess Gonçalves, Claudia Sayer, and Pedro Henrique Hermes De Araújo Copyright © 2017 Odinei Fogolari et al. All rights reserved. Use of TBzTD as Noncarcinogenic Accelerator for ENR/SiO2 Nanocomposites: Cured Characteristics, Mechanical Properties, Thermal Behaviors, and Oil Resistance Mon, 31 Jul 2017 09:43:55 +0000 This study reported the use of tetrabenzylthiuram disulphide (TBzTD) as a noncarcinogenic accelerator in a traditional sulfur curing system of epoxidized natural rubber (ENR)/nanosilica (nSiO2) composites. ENR used in this work was synthesized via in situ epoxidation of natural rubber (NR) in the presence of performic acid generated from the reaction of formic acid and hydrogen peroxide at 50°C for 8 h to acquire the epoxide content of about 40 mol%. Accordingly, the resulting ENR was referred to as ENR 40. The curing characteristics, mechanical properties, thermal behaviors, dynamic mechanical properties, and oil resistance of ENR 40/nSiO2 nanocomposites filled with three loadings of nSiO2 (1, 2, and 3 parts per hundred parts of rubber) were investigated and compared with NR and neat ENR 40. The results revealed that the scorch and cure times of ENR 40/nSiO2 nanocomposites were slightly longer than those of NR but slightly shorter than those of ENR 40. The tensile properties and tear strength for both before and after aging of all ENR 40/nSiO2 nanocomposites were higher than those of ENR 40, while the glass transition temperature, storage modulus at −65°C, thermal stability, and oil resistance of ENR 40/nSiO2 nanocomposites were higher than those of NR and ENR 40. Laksamon Raksaksri, Saowaroj Chuayjuljit, Phasawat Chaiwutthinan, and Anyaporn Boonmahitthisud Copyright © 2017 Laksamon Raksaksri et al. All rights reserved. Thermal Synthesis of Polypeptides from N-Butyloxycarbonyl Oligopeptides Containing Aspartyl Residue at C-Terminus Sun, 30 Jul 2017 06:42:56 +0000 The thermal reactions of amino acids have been investigated for pure organic synthesis, materials preparation in industry, and prebiotic chemistry. N-t-Butyloxycarbonyl aspartic acid (Boc-Asp) releases 2-butene and carbon dioxide upon heating without solvents. The resulting mixture of the free molten aspartic acid was dehydrated to give peptide bonds. This study describes the thermal reactions of N-t-butyloxycarbonyl peptides (Boc-Gly-L-Asp, Boc-L-Ala-L-Asp, Boc-L-Val-L-Asp, and Boc-Gly-Gly-L-Asp) having an aspartic residue at the carboxyl terminus. The peptides were deprotected upon heating at a constant temperature between 110 and 170°C for 1 to 24 h to afford polypeptides in which the average molecular weight reached 7800. Toratane Munegumi and Takafumi Yamada Copyright © 2017 Toratane Munegumi and Takafumi Yamada. All rights reserved. Effect of Surface Modification of Palygorskite on the Properties of Polypropylene/Polypropylene-g-Maleic Anhydride/Palygorskite Nanocomposites Wed, 19 Jul 2017 00:00:00 +0000 The effect of surface modification of palygorskite (Pal) on filler dispersion and on the mechanical and thermal properties of polypropylene (PP)/polypropylene grafted maleic anhydride (PP-g-MAH)/palygorskite (Pal) nanocomposites was evaluated. A natural Pal mineral was purified and individually surface modified with hexadecyl tributyl phosphonium bromide and (3-Aminopropyl)trimethoxysilane; the pristine and modified Pals were melt-compounded with PP to produce nanocomposites using PP-g-MAH as compatibilizer. The grafting of Pal surface was verified by FT-IR and the change in surface hydrophilicity was estimated by the contact angle of sessile drops of ethylene glycol on Pal tablets. The extent of Pal dispersion and the degree of improvement in both the mechanical and thermal properties were related to the surface treatment of Pal. Modified Pals were better dispersed during melt processing and improved Young’s modulus and strength; however, maximum deformation tended to decrease. The thermal stability of PP/PP-g-MAH/Pal nanocomposites was considerably improved with the content of modified Pals. The degree of crystallinity increased with Pal content, regardless of the surface modification. Surfactant modified Pal exhibited better results in comparison with silane Pal; it is possible that longer alkyl chains from surfactant molecules promoted interactions with polymer chains, thereby improving nanofiller dispersion and enhancing the properties. David Cisneros-Rosado and Jorge Alonso Uribe-Calderon Copyright © 2017 David Cisneros-Rosado and Jorge Alonso Uribe-Calderon. All rights reserved. Facile Preparation of Biocomposite from Prawn Shell Derived Chitosan and Kaolinite-Rich Locally Available Clay Tue, 18 Jul 2017 00:00:00 +0000 A novel composite material was prepared from prawn shell derived chitosan (CHT) and locally available kaolinite-rich modified Bijoypur clay (MC) using a facile technique in which dilute acetic acid was used as a solvent for dissolving chitosan and composite fabrication whereas distilled water was used for preparing the clay dispersion. Bijoypur clay mainly consists of kaolinite clay mineral and it was modified with the dodecyl amine to make it organophilic. Morphology and properties of the composites (different weight ratio of MC and CHT) have been studied and compared with those of pure CHT and MC. Purification and modification of Bijoypur clay were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transformed infrared spectroscopy (FTIR) analyses. The fabrication of CHT-MC composites was confirmed by FTIR analysis. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to investigate the thermal stability of the composites. It was observed that dispersed clay improves the thermal stability and enhances the hardness of the matrix systematically with the increase of clay loading. In this study, a better insolubility in both acidic and alkaline media of the composites is also observed compared to pure chitosan. Shanta Biswas, Taslim U. Rashid, Abul K. Mallik, Md. Minhajul Islam, M. Nuruzzaman Khan, Papia Haque, Mala Khan, and Mohammed Mizanur Rahman Copyright © 2017 Shanta Biswas et al. All rights reserved. Flexural Behaviour of RC Beams Strengthened with Prestressed CFRP NSM Tendon Using New Prestressing System Mon, 17 Jul 2017 10:46:55 +0000 CFRP has been used mainly for strengthening of existing structures in civil engineering area. Prestressed strengthening is being studied to solve the bond failure model featuring EBR and NSMR methods. The largest disadvantage of the prestressing system is that the system cannot be removed until the filler is cured. This problem lowers the turning rate of the equipment and makes it limited to experiment, which stresses the necessity of a new prestressing system. Therefore, the present study applies a new prestressing system which reliefs the need to wait until the curing of the filler after jacking to the prestressing of NSMR and examines the effect of the prestressing size and location of the anchorage on the strengthened behaviour. The experimental results show that the crack and yield loads increase with higher level of prestress, while the ductility tends to reduce, and the anchor plate should be installed within the effective depth to minimize the occurrence of shear-induced diagonal cracks. The comparison of the experimental results and results by section analysis shows that the section analysis could predict the maximum load of the specimens strengthened by prestressed NSMR within an error between 4% and 6%. Woo-tai Jung, Jong-sup Park, Jae-yoon Kang, Moon-seoung Keum, and Young-hwan Park Copyright © 2017 Woo-tai Jung et al. All rights reserved. Molecular Dynamics Simulation to Understand the Ability of Anionic Polymers to Alter the Morphology of Calcite Mon, 17 Jul 2017 08:42:06 +0000 Molecular dynamics was utilized to investigate the ability of anionic macromolecules to drastically change the morphology of calcite in the presence of magnesium ions. Anionic poly(acrylic acid) and poly(methacrylic acid) were compared with cationic poly(ethylene imine) in their binding behavior on calcite (104) and (110) surfaces. Poly(acrylic acid) and poly(methacrylic acid) showed preferential binding on (110) with strong electrostatic attractions, whereas poly(ethylene imine) was only weakly attracted to (104). The extent of the charge imbalance on the surfaces appeared responsible for the current results, which originated from the deficient number of the coordinating oxygen atoms of carbonate around the surface calcium. The results of the current study were in accordance with the previous experimental observations, where the surfaces of calcite were elongated under the coexistence of the anionic polymers and magnesium ions. These results could be generally utilized in the polymer-controlled crystallization with broad implications in the specific interactions with crystal surfaces. Insil Choi and Il Won Kim Copyright © 2017 Insil Choi and Il Won Kim. All rights reserved. A Comparative Study of the Photodegradation of Two Series of Cyclic Olefin Copolymers Thu, 13 Jul 2017 08:12:09 +0000 A series of commercial cyclic olefin copolymers (COC), namely, ethylene-norbornene (E-NB) and ethylene-tetracyclododecene (E-TD), were processed as thin films with thicknesses of 25 μm by an extrusion process. The photodegradation of neat and formulated films with different metal stearates (Fe, Co, and Mn) was investigated using an ultraviolet (UV) light lamp (340 nm) for a period of 30 days in an accelerated weathering tester model QUV from Q-LAB according to the ASTM D 5208-01 standard practice. Changes in carbonyl index (CI) and tensile properties were used to evaluate the photodegradation of the films and other properties, such as variation by DSC, were also analyzed. The present study reveals that (E-NB) copolymers show higher sensitivity to photodegradation than (E-TD) resins, in the absence and presence of metal stearates. We also find that the Fe salt shows the highest oxidative activity. Mario H. Gutiérrez-Villarreal and Sara A. Zavala-Betancourt Copyright © 2017 Mario H. Gutiérrez-Villarreal and Sara A. Zavala-Betancourt. All rights reserved. Characterization of Extruded Poly(lactic acid)/Pecan Nutshell Biocomposites Wed, 12 Jul 2017 06:49:53 +0000 Pecan nutshells are a solid form of waste obtained from the pecan nut production and they have been explored as an inexpensive filler for incorporation by melt blending into the poly(lactic acid) (PLA) matrix. The pecan nutshells contain polyphenols, proteins, tannins, sugars, and lipids; some of these components must be released in order to improve adhesion with a polymeric matrix. The physicochemical characterization of the extruded biocomposites of pecan nutshell powder (PNSP) at 0, 5, and 7.5% wt. with two treatments (untreated and defatted) into PLA is presented in this work. The incorporation of PNSP into the PLA matrix caused a variation in color and density and increased the water absorption. However, some mechanical and thermal parameters of the biocomposites showed a significant decrease. The morphological analysis showed good dispersion and adhesion of the PNSP to the PLA matrix. Based on the results of the characterization, biocomposites formulated with defatted PNSP have a potential to be used as sustainable fillers in PLA biocomposites. These biocomposites have a potential application as food containers, packaging trays, or disposable items. C. R. Álvarez-Chávez, D. L. Sánchez-Acosta, J. C. Encinas-Encinas, J. Esquer, P. Quintana-Owen, and T. J. Madera-Santana Copyright © 2017 C. R. Álvarez-Chávez et al. All rights reserved. Microencapsulation of Baker’s Yeast in Gellan Gum Beads Used in Repeated Cycles of Glucose Fermentation Tue, 11 Jul 2017 09:16:07 +0000 The purpose of this work is to prepare ionically cross-linked (with CaCl2) gellan particles with immobilized yeast cells for their use in repeated fermentation cycles of glucose. The study investigates the influence of ionic cross-linker concentration on the stability and physical properties of the particles obtained before extrusion and during time in the coagulation bath (the cross-linker solution with different CaCl2 concentrations). It was found that by increasing the amount of the cross-linker the degree of cross-linking in the spherical gellan matrix increases, having a direct influence on the particle morphology and swelling degree in water. These characteristics were found to be very important for diffusion of substrate, that is, the glucose, into the yeast immobilized cells and for the biocatalytic activity of the yeast immobilized cells in gellan particles. These results highlight the potential of these bioreactors to be used in repeated fermentation cycles (minimum 10) without reducing their biocatalytic activity and maintaining their productivity at similar parameters to those obtained in the free yeast fermentation. Encapsulation of Saccharomyces cerevisiae into the gellan gum beads plays a role in the effective application of immobilized yeast for the fermentation process. Camelia Elena Iurciuc (Tincu), Catalina Peptu, Alexandru Savin, Leonard-Ionuț Atanase, Kaies Souidi, Grahame Mackenzie, Patrick Martin, Gerard Riess, and Marcel Popa Copyright © 2017 Camelia Elena Iurciuc (Tincu) et al. All rights reserved. Mechanical and Thermal Properties of PLA Biocomposites Reinforced by Coir Fibers Mon, 10 Jul 2017 00:00:00 +0000 In this work, polylactic acid (PLA) biocomposites reinforced with short coir fibers were fabricated using a corotating twin-screw extruder and injection molding machine. Short coir fibers were treated by mixed solution including hydrogen peroxide and sodium hydroxide to improve the adhesion between fibers and PLA matrix. The effects of treated coir fiber content (1, 3, 5, and 7 wt%) on tensile, impact, thermal properties, and surface morphology of PLA biocomposites were investigated. The best impact strength results were obtained for 3 wt% PLA/treated coir fiber biocomposites, where the impact strength was increased by approximately 28% compared to the neat PLA. The tensile modulus of PLA biocomposites was increased by increasing the treated coir fiber content. These results were confirmed by morphological structure analysis. Differential scanning calorimetry (DSC) results demonstrated a minor effect of the treated coir fiber on thermal behavior of PLA resin. Thermogravimetry analysis (TGA) demonstrated that the thermal stability of the PLA/treated coir fiber biocomposites was reduced by the incorporation of treated coir fiber. Zhihui Sun, Li Zhang, Duoping Liang, Wei Xiao, and Jing Lin Copyright © 2017 Zhihui Sun et al. All rights reserved. Properties and Biodegradability of Thermoplastic Starch Obtained from Granular Starches Grafted with Polycaprolactone Thu, 06 Jul 2017 00:00:00 +0000 Granular starches grafted with polycaprolactone (St-g-PCL) were obtained using N-methylimidazole (NMI) as a catalyst. The effect of the starch/monomer ratio and catalyst content was studied to obtain different levels of grafted PCL. The highest grafting percentage (76%) and addition (43%) were achieved for reactions with a starch/monomer ratio of 50/50 and 25% catalyst. The grafting of PCL on the starch granule was verified by the emergence of the carbonyl group in the FTIR spectra and the increased diameter of the grafted starch granule. Thermoplastic starch from ungrafted starch (TPS) and grafted starch (TPGS) was obtained by mixing ungrafted or grafted starch granules with water, glycerol, or sorbitol in a mixer. TPS and TPGS behave as plastic materials, and their mechanical properties depend on the type of plasticizer used. Materials with glycerol as the plasticizer exhibited less rigidity. The presence of starch-g-PCL results in a dramatic increase in the elongation of the thermoplastic material. The starch present in the TPS or TPGS was completely biodegraded while the grafted PCL was partially biodegraded after the enzymatic degradation of the materials. Z. B. Cuevas-Carballo, S. Duarte-Aranda, and G. Canché-Escamilla Copyright © 2017 Z. B. Cuevas-Carballo et al. All rights reserved.