International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Polymeric Scaffolds for Tissue Engineering Wed, 20 Aug 2014 10:32:04 +0000 Xiaoming Li, Tsukasa Akasaka, and Nicholas Dunne Copyright © 2014 Xiaoming Li et al. All rights reserved. Study of Natural and Accelerated Weathering on Mechanical Properties of Antioxidants Modified Low Density Polyethylene Films for Greenhouse Wed, 20 Aug 2014 09:17:35 +0000 Natural and accelerated weatherings were studied to inspect the effect of antioxidants to protect low-density polyethylene (LDPE) films for commercial application as greenhouse covering materials in Saudi Arabia. In this investigation, six different formulations of LDPE film with incorporation of antioxidants were prepared and compared with neat LDPE. The samples were extruded and blown into a film using twin-screw extruder and film blowing machine. The LDPE films were exposed for outdoor weathering in Riyadh during the period of 90 days (mid of June to mid of September) while the accelerated tests were performed by Weather-Ometer. The film having 0.2 wt% Alkanox-240 (AN-0.2) stabilizers showed the highest tensile strength among all samples during natural and 100-hour accelerated weathering (10.9 MPa and 21.8 MPa, resp.). The best elongation at break was witnessed in 0.2% Good-rite antioxidants which were 64% in natural weathering; however, 0.5% Good-rite antioxidants showed 232% in accelerated weathering. The film having 0.5 wt% Good-rite 3114 (GR-0.5) antioxidant could withstand 70 days during natural exposure before the tensile strength values were reduced to 2/3rd of the initial. The present study suggested that the addition of antioxidants Good-rite, Anox, and Alkanox can improve the mechanical strength, film’s life, effectiveness, and stability and they are suitable to be incorporated in LDPE for commercial greenhouse films. Othman Al Othman, Shan Faiz, and Muhammad Abduh Tuasikal Copyright © 2014 Othman Al Othman et al. All rights reserved. Wood-Reinforced Polyphthalamide Resins: MultiFunctional Composite Coating for Metal Substrates Wed, 20 Aug 2014 08:55:32 +0000 Protective layers were deposited on aluminum substrates by dipping them inside a fluidized bed (FB) of wood and polyphthalamide powders. The experimental investigation looked into the influence of the main process parameters (number and composition of superimposed layers, heating temperature, and dipping time) on the visual appearance, scratch adhesion, wear resistance, and thermal insulation of the resulting coatings. Micromechanical and tribological responses of the coatings were significantly improved by the effect of the wooden particles dispersed inside the polyphthalamide binder. An improvement of the thermal insulation was also achieved whatever the setting of the process parameters. Further, the coatings displayed good adhesion to the substrate and wear endurance. M. Barletta, G. Rubino, V. Tagliaferri, F. Trovalusci, and S. Vesco Copyright © 2014 M. Barletta et al. All rights reserved. Electrical Signal Guided Ibuprofen Release from Electrodeposited Chitosan Hydrogel Tue, 19 Aug 2014 13:09:56 +0000 Electrical signal guided drug release from conductive surface provides a simple and straightforward way for advanced drug delivery. In this study, we investigated the ibuprofen release from electrodeposited chitosan hydrogel by applying electrical signals. Specifically, chitosan hydrogel was electrodeposited on titanium plate and used as a matrix for ibuprofen load and release. The release of ibuprofen from the chitosan hydrogel on titanium plate was pH sensitive. By applying a positive or negative electrical potential, the release rate of ibuprofen from the electrodeposited chitosan can be facilely controlled. Thus, coupling chitosan electrodeposition and electrical signal control spurs new possibilities for biopolymeric coating and drug elution on conductive implants. Youyu Liu, Kun Yan, Guoxia Jiang, Yuan Xiong, Yumin Du, and Xiaowen Shi Copyright © 2014 Youyu Liu et al. All rights reserved. Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry Tue, 19 Aug 2014 06:03:28 +0000 Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP) and Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC) was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA) random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-MMA)-block-PPEGMA block copolymers by using ATRP, followed by a modification step on the hydroxyl side groups of HEMA via Steglich esterification to afford propargyl side-functional polymer, alkyne-P(HEMA-co-MMA)-block-PPEGMA. Finally, click coupling between side-chain acetylene functionalities and 2,3,4,5,6-pentafluorobenzyl azide yielded fluorinated amphiphilic block copolymers. The obtained polymers were structurally characterized by 1H-NMR, 19F-NMR, FT-IR, and GPC. Their thermal characterizations were performed using DSC and TGA. Fatime Eren Erol, Deniz Sinirlioglu, Sedat Cosgun, and Ali Ekrem Muftuoglu Copyright © 2014 Fatime Eren Erol et al. All rights reserved. Copolymer SJ-1 as a Fluid Loss Additive for Drilling Fluid with High Content of Salt and Calcium Mon, 18 Aug 2014 05:50:05 +0000 A ternary copolymer of 2-acrylamide-2-methyl propane sulfonic acid (AMPS), acrylamide (AM), and allyl alcohol polyoxyethylene ether (APEG) with a side chain polyoxyethylene ether SJ-1 were designed and synthesized in this work. Good temperature resistance and salt tolerance of “” of AMPS, strong absorption ability of “amino-group” of AM, and good hydrability of side chain polyoxyethylene ether of APEG provide SJ-1 excellent properties as a fluid loss additive. The chemical structure of ternary copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The molecular weight and its distribution were determined by gel permeation chromatography (GPC). The API fluid loss of drilling fluid decreased gradually with the increasing concentration of NaCl and CaCl2 in the mud system. SJ-1 was applied well in the drilling fluid even at a high temperature of 220°C. Results of zeta potential of modified drilling fluid showed the dispersion stability of drilling fluid system. Scanning electron microscopy (SEM) analysis showed the microstructure of the surface of the filter cake obtained from the drilling fluid modified by SJ-1. Hongping Quan, Huan Li, Zhiyu Huang, Tailiang Zhang, and Shanshan Dai Copyright © 2014 Hongping Quan et al. All rights reserved. Study on Compatibility of Polymer Hydrodynamic Size and Pore Throat Size for Honggang Reservoir Mon, 11 Aug 2014 12:43:03 +0000 Long core flow experiment was conducted to study problems like excessive injection pressure and effective lag of oil wells during the polymer flooding in Honggang reservoir in Jilin oilfield. According to the changes in viscosity and hydrodynamic dimensions before and after polymer solution was injected into porous media, the compatibility of polymer hydrodynamic dimension and the pore throat size was studied in this experiment. On the basis of the median of radius R of pore throats in rocks with different permeability, dynamic light scattering method (DLS) was adopted to measure the hydrodynamic size Rh of polymer solution with different molecular weights. The results state that three kinds of 1500 mg/L concentration polymer solution with 2000 × 104, 1500 × 104, and 1000 × 104 molecular weight matched well with the pore throat in rocks with permeability of 300 mD, 180 mD, and 75 mD in sequence. In this case, the ratios of core pore throat radius median to the size of polymer molecular clew are 6.16, 5.74, and 6.04. For Honggang oil reservoir in Jilin, when that ratio ranges from 5.5 to 6.0, the compatibility of polymer and the pore structure will be relatively better. Dan-Dan Yin, Yi-Qiang Li, Bingchun Chen, Hui Zhang, Bin Liu, Qingle Chang, and Yanyue Li Copyright © 2014 Dan-Dan Yin et al. All rights reserved. Biosynthesis of Xanthan Gum from Fermenting Shrimp Shell: Yield and Apparent Viscosity Sun, 10 Aug 2014 12:26:45 +0000 With the aim of producing xanthan gum, the effects of an aqueous shrimp shell extract (SSAE) as the source of carbon and nitrogen on the yield and apparent viscosity of the gums produced by fermentation using three native strains of Xanthomonas campestris were studied. It was found that the SSAE contained 89.75% moisture, 0.054% ash, 8.069% protein, 0.787 lipids, and 1.337% carbohydrates. Media containing different concentrations of SSAE and supplemented with urea (0.01%) and phosphate (0.1%) were fermented in a shaker, and the results obtained were compared with those obtained from sucrose (control) with the same supplementation and fermentation conditions. Strain 1182 showed the highest yield (4.64 g·L−1) and viscosity (48.53 mPa·s), from the medium containing 10% (w/v) of SSAE. These values were higher than those obtained from the control medium containing sucrose. Shrimp shell is a low cost residue that can be bioconverted into products of high added value such as xanthan gum. Larissa Alves de Sousa Costa, Márcio Inomata Campos, Janice Izabel Druzian, Ana Maria de Oliveira, and Enio Nazaré de Oliveira Junior Copyright © 2014 Larissa Alves de Sousa Costa et al. All rights reserved. Molecular Dynamics Simulation of Chain Folding for Polyethylene Subjected to Vibration Excitation Tue, 05 Aug 2014 00:00:00 +0000 We propose a molecular dynamics method with vibration excitation, named as VEMD, to investigate the vibration effect on chain folding for polymer molecule. The VEMD method is based on the introduction of periodic force, the amplitude and frequency of which can be adjusted, and the method was applied to the folding simulation of a polyethylene chain. Simulation results show that the vibration excitation significantly affects the folding of the polyethylene, and frequency and amplitude of the vibration excitation play key roles in VEMD. Different frequencies and amplitudes will determine how and to what extent does the vibration excitation affect the folding process of the polyethylene structure. Junfeng Gu, Xue Wang, Jinying Wu, and Xicheng Wang Copyright © 2014 Junfeng Gu et al. All rights reserved. Synthesis and Characterization of Imide Containing Hybrid Epoxy Resin with Improved Mechanical and Thermal Properties Thu, 24 Jul 2014 00:00:00 +0000 Phosphorous containing amine, tripropyldiamine phosphine oxide (TPDAP), and hybrid monomer 4-(N-phthalimidophenyl) glycidylether (PPGE) were synthesized and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis (EDX). PPGE was incorporated in bisphenol A epoxy resin (BPA) in various concentrations (5% to 20%), based on a weight percentage of BPA resin. Curing was carried out with the stoichiometric amount of TPDAP and 1,3-propanediamine (PDA) to result in cross-link network. Various mechanical, chemical, thermal, and flame retardant properties of modified and unmodified epoxy resin were studied. The coatings obtained with the addition of PPGE were found to have improved properties as compared with those of the unmodified resin. Coatings with 15% loading of PPGE showed improved flame retardant and mechanical properties with stable thermal behaviour. U. G. Rane, A. A. Sabnis, and V. V. Shertukde Copyright © 2014 U. G. Rane et al. All rights reserved. Physicochemical Characterization of Thermally Treated Chitosans and Chitosans Obtained by Alkaline Deacetylation Tue, 22 Jul 2014 07:48:53 +0000 The thermal depolymerization of chitosan and alkaline deacetylation of chitin were characterized by measurement of viscosity, gel permeation chromatography (GPC), potentiometric titration (PT), and proton nuclear magnetic resonance spectroscopy ( NMR). The depolymerization rates (DR) measured by kinematic viscosity (KV), apparent viscosity (AV), and GPC (Mw) until 4 h of treatment were , , and %  and for 5 to 10 h of treatment they decreased slowly to produce of , , and % . The mole fraction of N-acetylglucosamine residues of chitosans was not modified after 10 h of thermal treatment at 100°C. The initial values of chitosan without any treatment were and and of chitosan treated for 10 h were and . The variables used to characterize the depolymerization process showed a good correlation. Six hours of thermal treatment as sufficient to obtain chitosans with a molar mass 90% smaller than that of the control chitosan without treatment. Ana Maria de Oliveira, Telma Teixeira Franco, and Enio Nazaré de Oliveira Junior Copyright © 2014 Ana Maria de Oliveira et al. All rights reserved. Using Polymeric Scaffolds for Vascular Tissue Engineering Mon, 21 Jul 2014 00:00:00 +0000 With the high occurrence of cardiovascular disease and increasing numbers of patients requiring vascular access, there is a significant need for small-diameter (<6 mm inner diameter) vascular graft that can provide long-term patency. Despite the technological improvements, restenosis and graft thrombosis continue to hamper the success of the implants. Vascular tissue engineering is a new field that has undergone enormous growth over the last decade and has proposed valid solutions for blood vessels repair. The goal of vascular tissue engineering is to produce neovessels and neoorgan tissue from autologous cells using a biodegradable polymer as a scaffold. The most important advantage of tissue-engineered implants is that these tissues can grow, remodel, rebuild, and respond to injury. This review describes the development of polymeric materials over the years and current tissue engineering strategies for the improvement of vascular conduits. Alida Abruzzo, Calogero Fiorica, Vincenzo Davide Palumbo, Roberta Altomare, Giuseppe Damiano, Maria Concetta Gioviale, Giovanni Tomasello, Mariano Licciardi, Fabio Salvatore Palumbo, Gaetano Giammona, and Attilio Ignazio Lo Monte Copyright © 2014 Alida Abruzzo et al. All rights reserved. Influence of Organoboron Compounds on Ethylene Polymerization Using Cp2ZrCl2/MAO as Catalyst System Tue, 15 Jul 2014 10:23:14 +0000 Organoboron compounds of nonionic and ionic nature, tris(pentafluorophenyl)borane, and N,N-dimethylanilinium tetra(pentafluorophenyl)borate were evaluated to act in conjunction with MAO as activators on ethylene polymerization by using the catalyst Cp2ZrCl2. A decrease on the catalytic activity was observed in both cases in relation with a reference polyethylene which was synthesized in absence of any organoboron compound. An increase on the crystallinity degree and molecular weight, as well as an improvement in thermal and dynamic-mechanical properties, was observed in polyethylenes synthetized in presence of tris(pentafluorophenyl)borane. A low density polyethylene with improved thermal stability was obtained when N,N-dimethylanilinium tetra(pentafluorophenyl)borate was employed as activator. Luis Alexandro Valencia López, Francisco Javier Enríquez-Medrano, Ricardo Mendoza Carrizales, Florentino Soriano Corral, Adali Castañeda Facio, and Ramón Enrique Díaz de León Gómez Copyright © 2014 Luis Alexandro Valencia López et al. All rights reserved. Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid) Tue, 15 Jul 2014 00:00:00 +0000 Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC), scanning electron microscope (SEM), instron tensile tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA. Xingxun Liu, Tongxin Wang, Laurence C. Chow, Mingshu Yang, and James W. Mitchell Copyright © 2014 Xingxun Liu et al. All rights reserved. Utilization of Zinc Dust for a Core Monomer 2-Bromo-3-hexylthien-5-ylzinc Bromide: Its Synthesis and Application for the Preparation of Regioregular Poly(3-hexylthiophene) Wed, 09 Jul 2014 08:44:55 +0000 The oxidative insertion of readily available zinc dust into the carbon-bromine bond of 2,5-dibromo-3-hexylthiophene was efficiently achieved to provide 2-bromo-3-hexylthien-5-ylzinc bromide (I), which was utilized for the preparation of highly regioregular poly(3-hexylthiophene) (P3HT) in the presence of catalytic amounts of Ni-catalyst. Seung-Hoi Kim Copyright © 2014 Seung-Hoi Kim. All rights reserved. The Development of Biomimetic Spherical Hydroxyapatite/Polyamide 66 Biocomposites as Bone Repair Materials Sun, 06 Jul 2014 00:00:00 +0000 A novel biomedical material composed of spherical hydroxyapatite (s-HA) and polyamide 66 (PA) biocomposite (s-HA/PA) was prepared, and its composition, mechanical properties, and cytocompatibility were characterized and evaluated. The results showed that HA distributed uniformly in the s-HA/PA matrix. Strong molecule interactions and chemical bonds were presented between the s-HA and PA in the composites confirmed by IR and XRD. The composite had excellent compressive strength in the range between 95 and 132 MPa, close to that of natural bone. In vitro experiments showed the s-HA/PA composite could improve cell growth, proliferation, and differentiation. Therefore, the developed s-HA/PA composites in this study might be used for tissue engineering and bone repair. Xuesong Zhang, Ming Lu, Yan Wang, Xiaojing Su, and Xuelian Zhang Copyright © 2014 Xuesong Zhang et al. All rights reserved. Facile Synthesis of Magnetic Copolymer Microspheres Based on Poly(glycidyl methacrylate-co-N-isopropylacrylamide)/Fe3O4 by Suspension Photopolymerization Thu, 03 Jul 2014 11:16:06 +0000 Magnetic copolymer based on poly(glycidyl methacrylate-co-N-isopropylacrylamide) microspheres was prepared by 2,2-dimethoxy-2-phenylacetophenone- (DMPP-) photo initiated and poly(vinyl alcohol)- (PVA-) stabilized single step suspension photopolymerization. The effect of chemical interaction, morphology, and thermal properties by adding 0.1% w/v Fe3O4 in the copolymer was investigated. Infrared analysis (FTIR) showed that (C=C) band disappeared after copolymerization, indicating that the magnetic copolymer microspheres were successfully synthesized and two important bands at 908 cm−1 and 1550 cm−1 appear. These are associated with the epoxy group stretching of GMA and secondary amide (N–H/C–H) deformation vibration of NIPAAm in magnetic microspheres. The X-ray diffraction (XRD) result proved the incorporation of Fe3O4 nanoparticles with copolymer microspheres as peak of Fe3O4 was observed. Morphology study revealed that magnetic copolymer exhibited uniform spheres and smoother appearance when entrapped with Fe3O4 nanoparticles. The lowest percentage of Fe3O4 nanoparticles leached from the copolymer microspheres was obtained at pH 7. Finally, thermal property of the copolymer microspheres was improved by adding a small amount of Fe3O4 nanoparticles that has been shown from the thermogram. Siti Zulaikha Mazlan, Faszly Rahim, and Sharina Abu Hanifah Copyright © 2014 Siti Zulaikha Mazlan et al. All rights reserved. Surface-Coated Polylactide Fiber Meshes as Tissue Engineering Matrices with Enhanced Cell Integration Properties Sun, 15 Jun 2014 07:34:02 +0000 Poly(L-lactide-co-D/L-lactide)-based fiber meshes resembling structural features of the native extracellular matrix have been prepared by electrospinning. Subsequent coating of the electrospun fibers with an ultrathin plasma-polymerized allylamine (PPAAm) layer after appropriate preactivation with continuous O2/Ar plasma changed the hydrophobic nature of the polylactide surface into a hydrophilic polymer network and provided positively charged amino groups on the fiber surface able to interact with negatively charged pericellular matrix components. In vitro cell experiments using different human cell types (epithelial origin: gingiva and uroepithelium; bone cells: osteoblasts) revealed that the PPAAm-activated surfaces promoted the occupancy of the meshes by cells accompanied by improved initial cell spreading. This nanolayer is stable in its cell adhesive characteristics also after γ-sterilization. An in vivo study in a rat intramuscular implantation model demonstrated that the local inflammatory tissue response did not differ between PPAAm-coated and untreated polylactide meshes. Matthias Schnabelrauch, Ralf Wyrwa, Henrike Rebl, Claudia Bergemann, Birgit Finke, Michael Schlosser, Uwe Walschus, Silke Lucke, Klaus-Dieter Weltmann, and J. Barbara Nebe Copyright © 2014 Matthias Schnabelrauch et al. All rights reserved. Chemical Polymerization Kinetics of Poly-O-Phenylenediamine and Characterization of the Obtained Polymer in Aqueous Hydrochloric Acid Solution Using K2Cr2O7 as Oxidizing Agent Thu, 12 Jun 2014 09:13:34 +0000 The oxidative chemical polymerization of o-phenylenediamine (OPDA) was studied in hydrochloric acid solution using potassium dichromate as oxidant at 5°C. The effects of potassium dichromate, hydrochloric acid, and monomer concentrations on the polymerization reaction were investigated. The order of reaction with respect to potassium dichromate, hydrochloric acid, and monomer concentration was found to be 1.011, 0.954, and 1.045, respectively. Also, the effect of temperature on the polymerization rate was studied and the apparent activation energy of the polymerization reaction was found to be 63.658 kJ/mol. The obtained polymer was characterized using XPS, IR, UV-visible, and elemental analysis. The surface morphology of the obtained polymers was characterized by X-ray diffraction and transmission electron microscopy (TEM). The TGA analysis was used to confirm the proposed structure and number of water molecules in each polymeric chain unit. The ac conductivity of (POPDA) was investigated as a function of frequency and temperature. The ac conductivity was interpreted as a power law of frequency. The frequency exponent (s) was found to be less than unity and decreased with the increase of temperature, which confirms that the correlated barrier hopping model was the dominant charge transport mechanism. S. M. Sayyah, A. B. Khaliel, Ahmed A. Aboud, and S. M. Mohamed Copyright © 2014 S. M. Sayyah et al. All rights reserved. Interaction of Refractory Dibenzothiophenes and Polymerizable Structures Thu, 12 Jun 2014 00:00:00 +0000 We carried out first principles calculations to show that polymerizable structures containing hydroxyl (alcoholic chain) and amino groups are suitable to form stable complexes with dibenzothiophene (DBT) and its alkyl derivates. These sulfur pollutants are very difficult to eliminate through traditional catalytic processes. Spontaneous and exothermic interactions at 0 K primarily occur through the formation of stable complexes of organosulfur molecules with monomeric structures by hydrogen bonds. The bonds are formed between the sulfur atom and the hydrogen of the hydroxyl group; additional hydrogen bonds are formed between the hydrogen atoms of the organosulfur molecule and the nitrogen atoms of the monomers. We vary the number of methylene groups in the alcoholic chain containing the hydroxyl group of the monomer and find that the monomeric structure with four methylene groups has the best selectivity towards the interaction with the methyl derivates with reference to the interaction with DBT. Even this study does not consider solvent and competitive adsorption effects; our results show that monomeric structures containing amino and hydroxyl groups can be used to develop adsorbents to eliminate organosulfur pollutants from oil and its derivates. Jose L. Rivera, Pedro Navarro-Santos, Roberto Guerra-Gonzalez, and Enrique Lima Copyright © 2014 Jose L. Rivera et al. All rights reserved. Nanocomposites with Liquid-Like Multiwalled Carbon Nanotubes Dispersed in Epoxy Resin without Solvent Process Wed, 11 Jun 2014 09:31:05 +0000 Liquid-like multiwall carbon nanotubes (MWNTs) were prepared with as-received carboxylic MWNTs-COOH and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO) through hydrogen bonding. The sample has liquid-like behavior above 58°C. The MWNTs content is 26.6 wt%. The liquid-like MWNTs nanofluids were incorporated into epoxy matrix with solvent-free process and dispersed well. When the liquid-like MWNTs nanofluids content is up to 1 wt%, the impact toughness of the nanocomposite is 153% higher than the pure epoxy matrix. Xi Zhang, Ya-Ping Zheng, Rui-Lu Yang, and Hai-Cheng Yang Copyright © 2014 Xi Zhang et al. All rights reserved. Effect of Polymerization Conditions on Thermal and Mechanical Properties of Ethylene/1-Butene Copolymer Made with Ziegler-Natta Catalysts Wed, 11 Jun 2014 08:59:06 +0000 The effect of polymerization conditions on thermal and mechanical properties of ethylene/1-butene copolymers synthesized through titanium-magnesium-supported Ziegler-Natta catalysts was studied. The increase in hydrogen pressure leads to a decrease in molecular weight (MW), storage modulus, and melting temperature. However, it yields an increase in molecular weight distribution (MWD), , % crystallinity, tensile modulus, yield stress, and strain at break. The effects of ethylene pressure and polymerization temperature on the copolymer MW, MWD and thermal and mechanical properties have been investigated. However, the impacts of ethylene pressure and polymerization temperature on copolymer modulus, tensile strength, % crystallinity, crystallization peak temperature, yield stress, strain at break, and yield strain are marginal. The hydrogen pressure plays a major role in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reaction. The MW is the key parameter that influences flow activation energy. However, the other mechanical, dynamic mechanical, and thermal properties not only depend on MW but are also influenced by other parameters. Mostafizur Rahaman, M. Anwar Parvez, J. B. P. Soares, and I. A. Hussein Copyright © 2014 Mostafizur Rahaman et al. All rights reserved. Safety and Efficiency of Biomimetic Nanohydroxyapatite/Polyamide 66 Composite in Rabbits and Primary Use in Anterior Cervical Discectomy and Fusion Wed, 04 Jun 2014 11:53:26 +0000 This study was conducted to validate the safety and efficiency of biomimetic nanohydroxyapatite/polyamide 66 (n-HA/PA66) composite in animal model (rabbit) and report its application in anterior cervical discectomy and fusion (ACDF) for 4, 12, and 24 weeks. N-HA/PA66 composite was implanted into one-side hind femur defects and the control defects were kept empty as blank controls. A combination of macroscopic and histomorphometric studies was performed up to 24 weeks postoperatively and compared with normal healing. 60 cervical spondylosis myelopathy and radiculopathy patients who were subjected to ACDF using n-HA/PA66 and PEEK cage were involved in this study with six-month minimum follow-up. Their radiographic (cage subsidence, fusion status, and segmental sagittal alignment (SSA)) and clinical (VAS and JOA scales) data before surgery and at each follow-up were recorded and compared. Nanohydroxyapatite/polyamide 66 composite is safe and effective in animal experiment and ACDF. Hui Xu, Yan Wang, Xiaojing Su, Xuelian Zhang, and Xuesong Zhang Copyright © 2014 Hui Xu et al. All rights reserved. Polymer Composites Reinforced by Nanotubes as Scaffolds for Tissue Engineering Sun, 01 Jun 2014 11:18:24 +0000 The interest in polymer based composites for tissue engineering applications has been increasing in recent years. Nanotubes materials, including carbon nanotubes (CNTs) and noncarbonic nanotubes, with unique electrical, mechanical, and surface properties, such as high aspect ratio, have long been recognized as effective reinforced materials for enhancing the mechanical properties of polymer matrix. This review paper is an attempt to present a coherent yet concise review on the mechanical and biocompatibility properties of CNTs and noncarbonic nanotubes/polymer composites, such as Boron nitride nanotubes (BNNTs) and Tungsten disulfide nanotubes (WSNTs) reinforced polymer composites which are used as scaffolds for tissue engineering. We also introduced different preparation methods of CNTs/polymer composites, such as in situ polymerization, solution mixing, melt blending, and latex technology, each of them has its own advantages. Wei Wang, Susan Liao, Ming Liu, Qian Zhao, and Yuhe Zhu Copyright © 2014 Wei Wang et al. All rights reserved. Using Rutile TiO2 Nanoparticles Reinforcing High Density Polyethylene Resin Tue, 27 May 2014 11:10:51 +0000 The TiO2 nanoparticles were used as a reinforcement to prepare nanocomposites with high density polyethylene (HDPE) by melt blending process. The original TiO2 (ORT) was modified by 3-glycidoxypropyltrimethoxysilane (GPMS) to improve the dispersion into HDPE matrix. The FT-IR spectroscopy and FESEM micrographs of modified TiO2 (GRT) demonstrated that GPMS successfully grafted with TiO2 nanoparticles. The tensile test of HDPE/ORT and HDPE/GRT nanocomposites with various contents of dispersive particles indicated that the tensile strength and Young’s modulus of HDPE/GRT nanocomposites are superior to the values of original HDPE and HDPE/ORT nanocomposites. At 1 wt.% of GRT, the mechanical properties of nanocomposites were optimal. In DSC and TGA analyses, with the presence of GRT in the nanocomposites, the thermal stability significantly increased in comparison with pure HDPE and HDPE/ORT nanocomposites. The better dispersion of GRT in polymer matrix as shown in FESEM images demonstrated the higher mechanical properties of HDPE/GRT nanocomposites to HDPE/ORT nanocomposites. Vu Manh Tuan, Da Woon Jeong, Ho Joon Yoon, SangYong Kang, Nguyen Vu Giang, Thai Hoang, Tran Ich Thinh, and Myung Yul Kim Copyright © 2014 Vu Manh Tuan et al. All rights reserved. Molecular Modeling of Acidic Treated PSTM-3T Polymer for Removal of Heavy Metal Ions by Experimental and Computational Studies Mon, 26 May 2014 00:00:00 +0000 The synthesized poly[N,N′-bis(3-silsesquioxanilpropyl)-thiocarbamide] (PSTM-3T) was used and the surface morphology and microstructure of it were analyzed by scanning electron microscopy with energy dispersive spectrometer (SEM/EDS). The molecular structure change of the PSTM-3T polymer of the PSTM-3T after treatment by acidic solution with different pHs was revealed using FT-IR experiments and ab initio calculations with density functional theory method. The sorption efficiency of the heavy metal ions depends on the molecular structure change of PSTM-3T after treatment of different pH aqueous solutions. After the treatment of acidic solution (pH = 2) of PSTM-3T, the polymer formed the tautomer state to increase the sorption efficiency for chromate ion. For the increment of pH value for acidic solution, the PSTM-3T polymer was dissociated to increase the sorption efficiency for copper ion. Natsagdorj Narantsogt, Gunchin Burmaa, Adiya Perlee-Oidov, Nyamdorj Shurkhuu, and Namsrai Javkhlantugs Copyright © 2014 Natsagdorj Narantsogt et al. All rights reserved. Coupling Metallic Nanostructures to Thermally Responsive Polymers Allows the Development of Intelligent Responsive Membranes Thu, 22 May 2014 10:42:44 +0000 Development of porous membranes capable of controlling flow or changing their permeability to specific chemical entities, in response to small changes in environmental stimuli, is an area of appealing research, since these membranes present a wide variety of applications. The synthesis of these membranes has been mainly approached through grafting of environmentally responsive polymers to the surface walls of polymeric porous membranes. This synergizes the chemical stability and mechanical strength of the polymer membrane with the fast response times of the bonded polymer chains. Therefore, different composite membranes capable of changing their effective pore size with environmental triggers have been developed. A recent interest has been the development of porous membranes responsive to light, since these can achieve rapid, remote, noninvasive, and localized flow control. This work describes the synthesis pathway to construct intelligent optothermally responsive membranes. The method followed involved the grafting of optothermally responsive polymer-metal nanoparticle nanocomposites to polycarbonate track-etched porous membranes (PCTEPMs). The nanoparticles coupled to the polymer grafts serve as the optothermal energy converters to achieve optical switching of the pores. The results of the paper show that grafting of the polymer and in situ synthesis of the metallic particles can be easily achieved. In addition, the composite membranes allow fast and reversible switching of the pores using both light and heat permitting control of fluid flow. J. Rubén Morones-Ramírez Copyright © 2014 J. Rubén Morones-Ramírez. All rights reserved. Rheological Properties of Hydrophobically Associative Copolymers Prepared in a Mixed Micellar Method Based on Methacryloxyethyl-dimethyl Cetyl Ammonium Chloride as Surfmer Thu, 15 May 2014 11:09:41 +0000 A novel cationic surfmer, methacryloxyethyl-dimethyl cetyl ammonium chloride (DMDCC), is synthesized. The micellar properties, including critical micelle concentration and aggregation number, of DMDCC-SDS mixed micelle system are studied using conductivity measurement and a steady-state fluorescence technique. A series of water-soluble associative copolymers with acrylamide and DMDCC are prepared using the mixed micellar polymerization. Compared to conventional micellar polymerization, this new method could not only reasonably adjust the length of the hydrophobic microblock, that is, , but also sharply reduce the amount of surfactant. Their rheological properties related to hydrophobic microblock and stickers are studied by the combination of steady flow and linear viscoelasticity experiments. The results indicate that both the hydrophobic content and, especially the length of the hydrophobic microblock are the dominating factors effecting the intermolecular hydrophobic association. The presence of salt influences the dynamics of copolymers, resulting in the variation of solution characters. Viscosity measurement indicates that mixed micelles between the copolymer chain and SDS molecules serving as junction bridges for transitional network remarkably enhance the viscosity. Moreover, the microscopic structures of copolymers at different experimental conditions are conducted by ESEM. This method gives us an insight into the preparation of hydrophobically associative water-soluble copolymers by cationic surfmer-anionic surfactant mixed micellar polymerization with good performance. Rui Liu, WanFen Pu, Hu Jia, XiaoPei Shang, Yue Pan, and ZhaoPeng Yan Copyright © 2014 Rui Liu et al. All rights reserved. Preparation and Characterization of Polymer Electrolyte of Glycidyl Methacrylate-Methyl Methacrylate-LiClO4 Plasticized with Ethylene Carbonate Wed, 14 May 2014 09:39:47 +0000 In the present investigation, we study the properties of the plasticized polyglycidyl methacrylate P(GMA) copolymerized with polymethyl methacrylate P(MMA)-LiClO4 polymer electrolyte prepared by solution casting technique. The electrolyte was characterized using impedance spectroscopy (EIS), Fourier transforms infrared (FTIR), cyclic voltammetry (CV), and X-ray diffraction (XRD). The conductivity was improved from  S cm−1 to  S cm−1 upon the addition of 25 wt.% LiClO4 salt into P(GMA-MMA). The conductivity was improved from  S cm−1 to  S cm−1 upon the addition of 80 wt.% EC into P(GMA-MMA)-LiClO4 The band that belongs to C–O–C is shifted farther than the band of C=O upon the addition of LiClO4 into P(GMA-MMA). The band of C–O–C stretching is shifted to lower wavenumber upon the addition of EC into P(GMA-MMA)-LiClO4. Upon the addition of EC into P(GMA-co-MMA), the intensity of the peaks decreases, implying the amorphous nature of the electrolyte increases with the concentration of the plasticizer. The electrolyte is electrochemically stable at 3.8 V, making it suitable for dye-sensitized solar cell application. M. Imperiyka, A. Ahmad, S. A. Hanifah, and M. Y. A. Rahman Copyright © 2014 M. Imperiyka et al. All rights reserved. 1-Butyl-3-methylimidazolium Salts as New Catalysts to Produce Epoxy-anhydride Polymers with Improved Properties Tue, 13 May 2014 12:05:43 +0000 We report the curing process of epoxy oligomers by using isomethyltetrahydrophthalic anhydride catalyzed with 1-butyl-3-methylimidazolium salts. Catalytic action has been ascertained to be dependent on the nature of anion. Salts with and anions appeared to be most active. Formation of salt adducts with epoxy resin and anhydride is shown. Polymers having higher values of strength and glass transition temperature—as compared with similar epoxy systems cured in the presence of tertiary amines as catalysts—are prepared. Mikhail S. Fedoseev, Matvey S. Gruzdev, and Lubov F. Derzhavinskaya Copyright © 2014 Mikhail S. Fedoseev et al. All rights reserved.