International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Thiomers: A Blessing to Evaluating Era of Pharmaceuticals Sun, 05 Jul 2015 10:51:55 +0000 Thiomers are the polymers modified for the mucoadhesive properties and other additive properties by incorporating thiol moieties in the backbone of the unmodified polymeric chain by substitution reactions or simple oxidation reactions. Drugs that are less soluble and permeable can be complexed with thiomers for their increased absorption through the mucosal membranes by increase in contact time and prolonged stay in body due to mucoadhesion. Immobilization of thiol group therefore increases the mucoadhesive properties of the modified polymer by 2–140-folds. The prepared thiomers are characterized and made stable by different techniques. Thiomers also give the controlled delivery of the active pharmaceutical ingredients in the body. Different polymers that are modified by thiolation are chitosan, polyacrylic acid, sodium alginate, sodium carboxy methyl cellulose, guar gum, and so forth. Thiomeric formulations are a challenge to deliver drugs with low therapeutic compatibility. Micro- and nanopreparations containing thiomers can be prepared by different techniques such as covalent crosslinking, in situ gelation, radical emulsion polymerization, and emulsification. Nowadays thiomers have wide range of applications as a promising pharmaceutical excipient in the evaluating era of pharmaceutical technology. Muhammad Hanif, Muhammad Zaman, and Sundas Qureshi Copyright © 2015 Muhammad Hanif et al. All rights reserved. Tensile Behavior of Polyetheretherketone over a Wide Range of Strain Rates Thu, 25 Jun 2015 05:57:20 +0000 Polyetheretherketone (PEEK) is used in several engineering applications where it has to bear impact loads. Nevertheless, the tensile behavior has only been studied in the quasi-static range of loading rates. To address the lack of data in the impact strain rate range, the tensile mechanical behavior of PEEK is investigated at room temperature over a large range of strain rates (from 0.001 to 1000/s). The macroscopic volume change is studied under uniaxial tension using digital image correlation (DIC) method, showing a significant dilatation that reaches 16% at a logarithmic axial strain of 40%. The true stress-strain behavior is therefore established based on the measured volume change. Elsewhere, the yield stress shows a significant sensitivity to strain rate. Besides, a new constitutive equation is proposed to take into account the increase in strain rate sensitivity at high strain rates. It assumes an apparent activation volume which decreases as the strain rate increases. The new constitutive equation gives similar results when compared to the Ree-Eyring equation. However, only three material constants are to be identified and are physically interpreted. Zakaria El-Qoubaa and Ramzi Othman Copyright © 2015 Zakaria El-Qoubaa and Ramzi Othman. All rights reserved. Keggin-Type Heteropolyacid for Ring-Opening Polymerization of Cyclohexene Oxide: Molecular Weight Control Mon, 22 Jun 2015 06:02:20 +0000 Polymerization of 1,2-cyclohexene oxide (CHO) in dichloromethane was catalyzed by 12-tungstophosphoric acid (H3PW12O40·13H2O) as a super solid acid. The effect of polymerization parameters such as reaction time, temperature, and catalyst amount was investigated. The effect of acetic anhydride as a ring-opening agent was also investigated. The resulting poly(1,2-cyclohexene oxide) (PCHO) was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1HNMR), gel-permeation chromatography (GPC), and differential scanning calorimetry (DSC). It has been found that the PCHO prepared over H3PW12O40·13H2O has a stereoregularity higher than that prepared over clay and Aluminium alkoxide catalysts. The value obtained is due to the microstructure but not to molecular weight. The yield and the molecular weight of the polymer depend strongly on the reaction conditions. Molecular weights can be readily controlled by changing reaction temperature, reaction time, and catalyst amount. Contrary to most polymerization reactions, the molecular weight increases with the temperature increase. Addition of acetic anhydride to the reaction medium increased the yield threefold. Ahmed Aouissi, Zeid Abdullah Al-Othman, and Abdurrahman Salhabi Copyright © 2015 Ahmed Aouissi et al. All rights reserved. Sulfated Alkyl Glucopyranans with Potent Antiviral Activity Synthesized by Ring-Opening Copolymerization of Anhydroglucose and Alkyl Anhydroglucose Monomers Wed, 17 Jun 2015 11:06:28 +0000 Sulfated glucopyranans having long alkyl groups were prepared by the ring-opening copolymerization of benzylated 1,6-anhydroglucopyranose with 3-O-octadecyl 1,6-anhydro-β-D-glucopyranose monomers, and subsequent deprotection and sulfation. Water-soluble sulfated glucopyranans with 2.8 and 4.7 mol% of 3-O-octadecyl group and lower molecular weights of = 2.5 × 103–5.1 × 103 have potent anti-HIV activity at 0.05–1.25 μg/mL, even though sulfated polysaccharides with molecular weights below = 6 × 103 had low anti-HIV activity. The interaction with poly-L-lysine as a model compound of proteins was analyzed by SPR, DSL, and zeta potential, indicating that the sulfated 3-O-octadecyl glucopyranans had high association and low dissociation rate constants, and the particle size increased after addition of poly-L-lysine. The anti-HIV activity was induced by electrostatic interaction between sulfate groups and amino groups of poly-L-lysine and by the synergistic effect of the hydrophobic long alkyl chain and hydrophilic sulfated group. Shiming Bai, Davaanyam Budragchaa, Shuqin Han, Taisei Kanamoto, Hideki Nakashima, and Takashi Yoshida Copyright © 2015 Shiming Bai et al. All rights reserved. Chemical and Enzymatic Hydrolysis of Polyurethane/Polylactide Blends Sun, 14 Jun 2015 08:00:44 +0000 Polyether-esterurethanes containing synthetic poly[(R,S)-3-hydroxybutyrate] (R,S-PHB) and polyoxytetramethylenediol in soft segments and polyesterurethanes with poly(ε-caprolactone) and poly[(R,S)-3-hydroxybutyrate] were blended with poly([D,L]-lactide) (PLA). The products were tested in terms of their oil and water absorption. Oil sorption tests of polyether-esterurethane revealed their higher response in comparison to polyesterurethanes. Blending of polyether-esterurethanes with PLA caused the increase of oil sorption. The highest water sorption was observed for blends of polyether-esterurethane, obtained with 10% of R,S-PHB in soft segments. The samples mass of polyurethanes and their blends were almost not changed after incubation in phosphate buffer and trypsin and lipase solutions. Nevertheless the molecular weight of polymers was significantly reduced after degradation. It was especially visible in case of incubation of samples in phosphate buffer what suggested the chemical hydrolysis of polymer chains. The changes of surface of polyurethanes and their blends, after incubation in both enzymatic solutions, indicated on enzymatic degradation, which had been started despite the lack of mass lost. Polyurethanes and their blends, contained more R,S-PHB in soft segments, were degraded faster. Joanna Brzeska, Aleksandra Heimowska, Wanda Sikorska, Lidia Jasińska-Walc, Marek Kowalczuk, and Maria Rutkowska Copyright © 2015 Joanna Brzeska et al. All rights reserved. Interaction Studies between Newly Synthesized Photosensitive Polymer and Ionic Liquids Wed, 10 Jun 2015 13:37:46 +0000 In this information age, different kinds of photosensitive materials have been used in the manufacture of information storage devices. But these photosensitive materials have the bane of low diffraction efficiency. In order to solve this problem, we have synthesized a novel photosensitive polymer from epoxy-based azopolymers (with three types of azochromophores). Furthermore, we have studied the interaction between this newly synthesized azopolymer and ionic liquids (ILs). For this purpose, we have used the ammonium and imidazolium families of ILs, such as diethylammonium dihydrogen phosphate (DEAP), tributylammonium methyl sulfate (TBMS), triethylammonium 4-aminotoluene-3-sulfonic acid (TASA), and 1-methylimidazolium chloride ([Mim]Cl). To investigate the molecular interaction between azopolymer and ILs, we have used the following spectroscopic methods of analysis: UV-visible spectroscopy, photoluminescence (PL) spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), and confocal Raman spectroscopy. In this study, we have developed new photosensitive materials by combining polymer with ILs. In Tae Kim, Gi-Chung Kwon, Eun Ha Choi, Seung-Hyun Lee, Young Sun Kim, Jong Hyun Kim, Ju Hyon Cha, Sung Ho Kim, and Pankaj Attri Copyright © 2015 In Tae Kim et al. All rights reserved. Flame-Retardant and Thermal Degradation Mechanism of Caged Phosphate Charring Agent with Melamine Pyrophosphate for Polypropylene Tue, 09 Jun 2015 16:28:01 +0000 An efficient caged phosphate charring agent named PEPA was synthesized and combined with melamine pyrophosphate (MPP) to flame-retard polypropylene (PP). The effects of MPP/PEPA on the flame retardancy and thermal degradation of PP were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimetric test (CCT), and thermogravimetric analysis (TGA). It was found that PEPA showed an outstanding synergistic effect with MPP in flame retardant PP. When the content of PEPA was 13.3 wt% and MPP was 6.7 wt%, the LOI value of the flame retardant PP was 33.0% and the UL-94 test was classed as a V-0 rating. Meanwhile, the peak heat release rate (PHRR), average heat release rate (AV-HRR), and average mass loss rate (AV-MLR) of the mixture were significantly reduced. The flame-retardant and thermal degradation mechanism of MPP/PEPA was investigated by TGA, Fourier transform infrared spectroscopy (FTIR), TG-FTIR, and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDXS). It revealed that MPP/PEPA could generate the triazine oligomer and phosphorus-containing compound radicals which changed the thermal degradation behavior of PP. Meanwhile, a compact and thermostable intumescent char was formed and covered on the matrix surface to prevent PP from degrading and burning. Xuejun Lai, Jiedong Qiu, Hongqiang Li, Xingrong Zeng, Shuang Tang, Ye Chen, and Zhen Chen Copyright © 2015 Xuejun Lai et al. All rights reserved. Structure and Electrical Study of New Chemically Modified Poly(vinyl chloride) Mon, 08 Jun 2015 13:24:22 +0000 The aim of this work was to study the structural and electrical properties of a new polymer obtained by functionalization of a commercial poly(vinyl chloride) (PVC) (Mw = 48000) by grafting aminoalkyl and aminoaryl groups. Modified poly(vinyl chloride) was prepared in two steps. The structural properties of the polymer were systematically investigated by varieties of techniques as differential scanning calorimetric (DSC), thermogravimetry analysis (TG), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The electrical properties of the polymer were studied by electrochemical impedance spectroscopy (EIS). F. Ammari, M. Dardouri, M. Kahlaoui, and F. Meganem Copyright © 2015 F. Ammari et al. All rights reserved. Electrospun Fibers of Enteric Polymer for Controlled Drug Delivery Mon, 08 Jun 2015 08:51:32 +0000 The production of electrospun fibers of enteric polymer for controlled delivery of drugs represents a simple and low cost procedure with promising advantages relative to the longer therapeutic window provided by cylindrical geometry in association with intrinsic properties of pH-dependent drug carriers. In this work, we have explored the incorporation of additives (block copolymers of poly(ethylene)-b-poly(ethylene oxide)) into matrix of Eudragit L-100 and the effective action of hybrid composites on delivery of nifedipine, providing improvement in the overall process of controlled release of loaded drug. Fábia F. P. da Costa, Evando S. Araújo, Marcio L. F. Nascimento, and Helinando P. de Oliveira Copyright © 2015 Fábia F. P. da Costa et al. All rights reserved. Polymers for Cardiovascular Stent Coatings Mon, 08 Jun 2015 07:10:06 +0000 Polymers have found widespread applications in cardiology, in particular in coronary vascular intervention as stent platforms (scaffolds) and coating matrices for drug-eluting stents. Apart from permanent polymers, current research is focussing on biodegradable polymers. Since they degrade once their function is fulfilled, their use might contribute to the reduction of adverse events like in-stent restenosis, late stent-thrombosis, and hypersensitivity reactions. After reviewing current literature concerning polymers used for cardiovascular applications, this review deals with parameters of tissue and blood cell functions which should be considered to evaluate biocompatibility of stent polymers in order to enhance physiological appropriate properties. The properties of the substrate on which vascular cells are placed can have a large impact on cell morphology, differentiation, motility, and fate. Finally, methods to assess these parameters under physiological conditions will be summarized. Anne Strohbach and Raila Busch Copyright © 2015 Anne Strohbach and Raila Busch. All rights reserved. The Characterization of Fish (Tilapia) Collagen Sponge as a Biomaterial Mon, 08 Jun 2015 07:06:00 +0000 For scaffold manufacturing, the utility of bioactive natural organic materials derived from marine products is useful and indispensable as an alternative to bovine collagen. The weakest feature of fish collagen for scaffold application is its low degeneration temperature (), indicating poor stability of fish collagen in mammals in vivo. We have focused on the tropical fish tilapia as a candidate for generating a clinical scaffold. The aim of this study was to confirm the of tilapia type I atelocollagen (TAC) for biomedical application. Furthermore, the physical and structural properties were investigated and evaluated as a scaffold on a sponge form. Different concentrations {0.5%, 1.0%, and 2.0% (v/v)} of TAC solution were analyzed. Differential scanning calorimetry showed that the of TAC was 35-36°C. The scanning electron microscopy results indicated that the pore size (90–160 μm) of TAC sponges is acceptable for cell proliferation. The tensile strength of porous sponges was in the range of 0.01–0.07 MPa. These findings indicate that the TAC sponge prepared from tilapia is one of candidates as a scaffold. The 1.0% (v/v) concentration of TAC solution is especially recommended to be advantageous for preparing and handling the solution and for sponge formation. Kohei Yamamoto, Yuu Yoshizawa, Kajiro Yanagiguchi, Takeshi Ikeda, Shizuka Yamada, and Yoshihiko Hayashi Copyright © 2015 Kohei Yamamoto et al. All rights reserved. Preparation and In Vitro Release of Drug-Loaded Microparticles for Oral Delivery Using Wholegrain Sorghum Kafirin Protein Mon, 08 Jun 2015 06:42:14 +0000 Kafirin microparticles have been proposed as an oral nutraceutical and drug delivery system. This study investigates microparticles formed with kafirin extracted from white and raw versus cooked red sorghum grains as an oral delivery system. Targeted delivery to the colon would be beneficial for medication such as prednisolone, which is used in the management of inflammatory bowel disease. Therefore, prednisolone was loaded into microparticles of kafirin from the different sources using phase separation. Differences were observed in the protein content, in vitro protein digestibility, and protein electrophoretic profile of the various sources of sorghum grains, kafirin extracts, and kafirin microparticles. For all of the formulations, the majority of the loaded prednisolone was not released in in vitro conditions simulating the upper gastrointestinal tract, indicating that most of the encapsulated drug could reach the target area of the lower gastrointestinal tract. This suggests that these kafirin microparticles may have potential as a colon-targeted nutraceutical and drug delivery system. Esther T. L. Lau, Stuart K. Johnson, Roger A. Stanley, Deirdre Mikkelsen, Zhongxiang Fang, Peter J. Halley, and Kathryn J. Steadman Copyright © 2015 Esther T. L. Lau et al. All rights reserved. Cationization of Alpha-Cellulose to Develop New Sustainable Products Thu, 04 Jun 2015 16:42:33 +0000 Papermaking has been using high quantities of retention agents, mainly cationic substances and organic compounds such as polyamines. The addition of these agents is related to economic and environmental issues, increasing contamination of the effluents. The aim of this work is to develop a cationic polymer for papermaking purposes based on the utilization of alpha-cellulose. The cationization of mercerized alpha-cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) is governed by a pseudo-second-order reaction. The initial amorphous fraction of cellulose is reacted with CHPTAC until the equilibrium value of nitrogen substitution is reached. Nitrogen is incorporated as a quaternary ammonium group in the polymer. Also, the kinetic constant increased with decreasing crystallinity index, showing the importance of the previous alkalization stage. The use of modified natural polysaccharides is a sustainable alternative to synthetic, nonbiodegradable polyelectrolytes and thus is desirable with a view to developing new products and new processes. Ana Moral, Roberto Aguado, Menta Ballesteros, and Antonio Tijero Copyright © 2015 Ana Moral et al. All rights reserved. Correlation between Cohesive Energy Density, Fractional Free Volume, and Gas Transport Properties of Poly(ethylene-co-vinyl acetate) Materials Thu, 04 Jun 2015 11:25:26 +0000 The transport properties of the poly(ethylene-co-vinyl acetate) (EVA) materials to He, N2, O2, and CO2 are correlated with two polymer molecular structure parameters, that is, cohesive energy density (CED) and fractional free volume (FFV), determined by the group contribution method. In our preceding paper, the attempt was made to approximate EVA permeability using a linear function of 1/FFV as predicted by the free volume theory. However, the deviations from this relationship appeared to be significant. In this paper, it is shown that permeation of gas molecules is controlled not only by free volume but also by the polymer cohesive energy. Moreover, the behavior of CO2 was found to differ significantly from that of other gases. In this instance, the correlation is much better when diffusivity instead of permeability is taken into account in a modified transport model. Piotr Kubica and Aleksandra Wolinska-Grabczyk Copyright © 2015 Piotr Kubica and Aleksandra Wolinska-Grabczyk. All rights reserved. The Mechanical Properties of a Poly(methyl methacrylate) Denture Base Material Modified with Dimethyl Itaconate and Di-n-butyl Itaconate Thu, 04 Jun 2015 09:00:35 +0000 This study investigates a wide range of clinically relevant mechanical properties of poly(methyl methacrylate) (PMMA) denture base materials modified with di-methyl itaconate (DMI) and di-n-butyl itaconate (DBI) in order to compare them to a commercial PMMA denture base material. The commercial denture base formulation was modified with DMI and DBI by replacing up to 10 wt% of methyl methacrylate (MMA) monomer. The specimens were prepared by standard bath curing process. The influence of the itaconate content on hardness, impact strength, tensile, and thermal and dynamic mechanical properties was investigated. It is found that the addition of di-n-alkyl itaconates gives homogenous blends that show decreased glass transition temperature, as well as decrease in storage modulus, ultimate tensile strength, and impact fracture resistance with increase in the itaconate content. The mean values of surface hardness show no significant change with the addition of itaconates. The magnitude of the measured values indicates that the poly(methyl methacrylate) (PMMA) denture base material modified with itaconates could be developed into a less toxic, more environmentally and patient friendly product than commercial pure PMMA denture base material. Pavle Spasojevic, Milorad Zrilic, Vesna Panic, Dragoslav Stamenkovic, Sanja Seslija, and Sava Velickovic Copyright © 2015 Pavle Spasojevic et al. All rights reserved. Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling Wed, 03 Jun 2015 07:38:24 +0000 This study focuses on how the texture of the silicone rubber material affects the distribution of microbial growth on the surface of materials used for high voltage insulation. The analysis of surface wetting properties showed that the textured surfaces provide higher receding contact angles and therefore lower contact angle hysteresis. The textured surfaces decrease the risk for dry band formation and thus preserve the electrical properties of the material due to a more homogeneous distribution of water on the surface, which, however, promotes the formation of more extensive biofilms. The samples were inoculated with fungal suspension and incubated in a microenvironment chamber simulating authentic conditions in the field. The extent and distribution of microbial growth on the textured and plane surface samples representing the different parts of the insulator housing that is shank and shed were determined by visual inspection and image analysis methods. The results showed that the microbial growth was evenly distributed on the surface of the textured samples but restricted to limited areas on the plane samples. More intensive microbial growth was determined on the textured samples representing sheds. It would therefore be preferable to use the textured surface silicone rubber for the shank of the insulator. Sevil Atarijabarzadeh, Fritjof Nilsson, Henrik Hillborg, Sigbritt Karlsson, and Emma Strömberg Copyright © 2015 Sevil Atarijabarzadeh et al. All rights reserved. Electrospun Sodium Alginate/Polyethylene Oxide Fibers and Nanocoated Yarns Sun, 31 May 2015 16:41:01 +0000 Sodium alginate (NaAlg), as a natural biopolymer, was electrospun from aqueous solution via blending with a biofriendly synthetic polymer polyethylene oxide. The morphology and chemical properties of resultant alginate-based nanofibers were characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffractometer (PXRD), and differential scanning calorimetry (DSC). At a wide voltage window (i.e., 12–24 kV), smooth and uniform nanofibers were obtained from the 5.0% concentration with the NaAlg/PEO ratio ranging from 1 : 1 to 1 : 3. The results from FTIR, PXRD, and DSC demonstrate that molecular interaction exists between these two polymers and, therefore, contributes to the alteration of crystallinity of electrospun fibers. In addition, NaAlg/PEO nanofiber-coated polylactic acid (PLA) yarns with different twist levels were also fabricated in this work. The results show that the tensile strength of the nanocoated hybrid yarn and the tensile strength of uncoated yarn increase with the twist per centimeter (TPC) up to 0.5 but decrease when TPC is further increased. The tensile properties of hybrid yarn are superior to those of the uncoated yarn. C. Hu, R. H. Gong, and F. L. Zhou Copyright © 2015 C. Hu et al. All rights reserved. Physicochemical and Antioxidant Properties of Chitosan Films Incorporated with Cinnamon Oil Thu, 28 May 2015 07:12:30 +0000 Chitosan films (CF) with cinnamon bark oil (CO) incorporated at 0% (control), 0.25%, 0.5%, and 1.0% v/v were prepared by an emulsion method. The films were characterized based on their physical properties (solubility, water vapor permeability, optical property, and microstructure) and antioxidant properties (DPPH, ABTS, and its protective effects on human erythrocytes). The results showed that the incorporation of 0.5 and 1.0% of CO into the CF significantly decreased its solubility to 22% of the control (). The water vapor permeability of the CF-CO was significantly reduced to 40% with low concentrations of CO (0.25%) incorporated into the CF. In general, the films presented a yellow coloration and an increase in transparency with the incorporation of CO into the CF. It was also observed that the incorporation of CO increased the antioxidant activity between 6.0-fold and 14.5-fold compared to the control, and the protective capacity against erythrocyte hemolysis increased by as much as 80%. Marco A. López-Mata, Saul Ruiz-Cruz, Norma Patricia Silva-Beltrán, José de Jesús Ornelas-Paz, Víctor Manuel Ocaño-Higuera, Francisco Rodríguez-Félix, Luis A. Cira-Chávez, C. L. Del-Toro-Sánchez, and Keiko Shirai Copyright © 2015 Marco A. López-Mata et al. All rights reserved. Evaluation of Different Analysis Methods for the Encapsulation Efficiency of Amylose Inclusion Compound Wed, 27 May 2015 11:38:40 +0000 Recently amylose has drawn much attention as a potential vehicle for the nanoencapsulation of different flavor molecules, and the encapsulation efficiency of the complex is an important index for the evaluation of its embedding effect. In this study, three different methods for assessing encapsulation efficiency of amylose-flavor complexes were compared. We chose heptanol and menthone as the flavor molecules, as both of them exhibit a typical odor. The complexes were prepared by the melting method, and their structures were characterized by XRD. In addition, the encapsulation efficiency was determined by thermal gravimetric analysis (TGA), potentiometric titration (PT), and headspace solid phase microextraction gas chromatography (HS-SPME-GC), respectively. The results showed that PT results were within the reported literature range while HS-SPME-GC seemed to overestimate the results and TGA results were the lowest. What is more, the operations of TGA and PT were relatively simple and the results were reproducible, while the HS-SPME-GC method displayed excellent high sensitivity. Therefore, PT method is the best method for assessing encapsulation efficiency of amylose-flavor complexes. Tao Feng, Fangfang Liu, Xu Wang, Haining Zhuang, Ran Ye, Zhiwei Rong, and Yi Liu Copyright © 2015 Tao Feng et al. All rights reserved. Kinetics of Phase Transformation of Indium in the Presence of Polytetrafluoroethylene: Implications for DSC Measurements on Polymers and Their Composites Mon, 25 May 2015 09:38:39 +0000 The present work focuses on the influence, at nominal constant temperatures, of an inert polymer on the crystallization kinetics of a highly conductive metal as indium (In) to show not only that the presence of a polymer allows obtaining information on the In crystallization directly from differential scanning calorimeter (DSC) curves, but also that appropriate corrections of thermal measurements on low conductivity samples are needed. Maria Raimo Copyright © 2015 Maria Raimo. All rights reserved. Copolymerization of Tris(methoxyethoxy)vinyl Silane with N-Vinyl Pyrrolidone: Synthesis, Characterization, and Reactivity Relationships Mon, 25 May 2015 06:33:17 +0000 Copolymer of tris(methoxyethoxy)vinyl silane (TMEVS) with N-vinyl pyrrolidone (NVP) was synthesized by free radical polymerization in dry benzene at 70°C using benzoyl peroxide (BPO) as initiator. The copolymer was characterized by viscometer, FTIR, and 1H-NMR and its thermal properties were studied by DSC and TGA. The copolymer composition was determined by elemental analysis. The monomer reactivity ratios were calculated by linearization methods proposed by Fineman-Ross and Kelen-Tudos. The intersection method was proposed by Mayo-Lewis and nonlinear method was proposed by curve-fitting procedure. The microstructure of copolymer and sequence distribution of monomers in the copolymer were calculated by statistical method. Ameen Hadi Mohammed, Mansor Bin Ahmad, and Kamyar Shameli Copyright © 2015 Ameen Hadi Mohammed et al. All rights reserved. Improved Thrombin Hemostat Using the Cross-Linked Gelatin by Microbial Transglutaminase Thu, 21 May 2015 07:28:16 +0000 It is well known that the thrombin obtained from animal is available in clinical treatment, which plays an important role in hemostasis and the treatment of hemorrhagic diseases. However, how to achieve complete hemostasis in 2 min is still a challenge. In this report, the thrombin hemostatic has been improved using the cross-linked gelatin by microbial transglutaminase, and its efficacy was demonstrated by the vitro experiment. Compared with the traditional thrombin hemostatic the clotting time with the improved hemostat is significantly shorter. It may rapidly stop blood loss, which would provide a simple, safe, and cost-effective surgical sealant. Tengfei Yu, Yuepeng Guan, Xia Xie, Yaqin Huang, and Jie Tang Copyright © 2015 Tengfei Yu et al. All rights reserved. Development of a Layer-by-Layer Assembled Film on Hydrogel for Ocular Drug Delivery Wed, 20 May 2015 06:47:43 +0000 Hydrogel is a kind of attractive drug carriers because of its good biocompatibility and transparency. But traditional hydrogel showed some restrictions in its application in ocular drug delivery. A simple surface modification technique based on layer-by-layer (LbL) self-assembled multilayer for ocular drug delivery was developed in this work. Polycarboxymethyl-β-cyclodextrin (poly(CM-β-CD))/poly-l-lysine (PLL) multilayer film was designed and constructed for ocular drug delivery, since β-CD showed good drug delivery property. The properties such as the contact angle and transparency varied a little with the deposition of poly(CM-β-CD)/PLL multilayer. Orfloxacin and puerarin were loaded into multilayer during the self-assembly procedure by two methods, which were tracked by the largest drug absorbance of UV spectrum. The loaded drug amount by incorporating drugs into poly(CM-β-CD) solution was larger than that by incorporating drugs into PLL solution. The loaded drug in the multilayer could gradually be released from multilayer in some period either for orfloxacin or for puerarin. The drug release behavior was influenced by drug loading method and pH value of released medium. Moreover, the balanced released drug amount by incorporating drugs into poly(CM-β-CD) solution is much smaller than that by incorporating drugs into PLL solution. Pin Chen, Xin Wang, Yan Dong, and Xiaohong Hu Copyright © 2015 Pin Chen et al. All rights reserved. End-Group Evaluation of HEMA Initiated Poly(-caprolactone) Macromonomers via Enzymatic Ring-Opening Polymerization Tue, 19 May 2015 13:47:45 +0000 Poly(ε-caprolactone) (PCL) macromonomers comprising acrylate end-functionality were synthesized via enzymatic ring-opening polymerization (eROP) by utilizing commercially available Candida antarctica Lipase B (CALB), Novozyme-435. 2-Hydroxyethyl methacrylate (HEMA) was purposed to be the nucleophilic initiator in eROP. The side reactions generated due to the cleavage of ester bonds in HEMA and the growing polymer chains were investigated through altering polymerization period, initiator concentration, temperature, and enzyme concentration. 1H NMR evaluations showed that minimum quantities of side reactions were in lower temperatures, initiator concentration, enzyme concentration, and lower monomer conversions. Gel permeation chromatography (GPC) results revealed that lower polydispersity along with number-average molecular weight of end-functionalized PCL macromonomers was obtained depending on higher initiator/monomer ratios, lower temperature (60°C), enzyme concentration (100 mg), and/or polymerization time (2 h). Furthermore, 0.1 HEMA/ε-caprolactone (CL) ratio had higher molecular weight than 0.5 HEMA/CL ratio, while keeping a close value of methacrylate transfer, total methacrylate end-groups, and lower polyester transfer. N. Ugur Kaya and Y. Avcibasi Guvenilir Copyright © 2015 N. Ugur Kaya and Y. Avcibasi Guvenilir. All rights reserved. Characterization and Cell Culture of a Grafted Chitosan Scaffold for Tissue Engineering Tue, 19 May 2015 11:36:50 +0000 Poly(vinyl alcohol) (PVA) was grafted to chitosan to form a porous scaffold. The PVA-g-chitosan 3D scaffold was then observed by Fourier transform infrared spectroscopy (FT-IR). The water absorbency of PVA-g-chitosan was increased 370% by grafting. Scanning electron microscope (SEM) observations of the material revealed that the 3D scaffold is highly porous when formed using a homogenizer at 300 rpm. Compression testing demonstrated that as the amount of chitosan increases, the strength of the 3D scaffold strength reached showed that, by increasing the amount of chitosan, the strength of the 3D scaffold could be increased to 16 × 10−1 MPa. Over 35 days of enzymatic degradation, the 3D scaffold was degraded by various enzymes at rates of up to 10%. In vitro tests showed good cell proliferation and growth in the 3D scaffold. Wen-Chuan Hsieh, Jiun-Jia Liau, and Yi-Jhong Li Copyright © 2015 Wen-Chuan Hsieh et al. All rights reserved. Microstructure, Mechanical, and Biological Properties of Porous Poly(vinylidene fluoride) Scaffolds Fabricated by Selective Laser Sintering Mon, 18 May 2015 15:01:30 +0000 Porous poly(vinylidene fluoride) (PVDF) scaffolds were prepared by selective laser sintering. The effects of laser energy density, ranging from 0.66 to 2.16 J/mm2, on microstructure and mechanical properties were investigated. At low energy density levels, PVDF particles could fuse well and the structure becomes dense with the increase of the energy density. Smoke and defects (such as holes) were observed when the energy density increased above 1.56 J/mm2 which indicated decomposition of the PVDF powder. The scaffolds appeared to be light yellow and there was a reduction in tensile strength. The fabricated scaffolds were immersed into simulated body fluid for different time to evaluate biostability. In addition, MG63 cells were seeded and cultured for different days on the scaffolds. The testing results showed that the cells grew and spread well, indicating that PVDF scaffolds had good biocompatibility. Wei Huang, Pei Feng, Chengde Gao, Xiong Shuai, Tao Xiao, Cijun Shuai, and Shuping Peng Copyright © 2015 Wei Huang et al. All rights reserved. Effect of Particle Size of Additives on the Flammability and Mechanical Properties of Intumescent Flame Retarded Polypropylene Compounds Mon, 18 May 2015 13:12:58 +0000 The effect of particle size reduction of the components of a common intumescent flame retardant system, consisting of pentaerythritol (PER) and ammonium polyphosphate (APP) in a weight ratio of 1 to 2, was investigated on the flammability and mechanical performance of flame retarded polypropylene (PP) compounds. Additives of reduced particle size were obtained by ball milling. In the case of PER, the significant reduction of particle size resulted in inferior flame retardant and mechanical performance, while the systems containing milled APP noticeably outperformed the reference intumescent system containing as-received additives. The beneficial effect of the particle size reduction of APP is explained by the better distribution of the particles in the polymer matrix and by the modified degradation mechanism which results in the formation of an effectively protecting carbonaceous foam accompanied with improved mechanical resistance. Nevertheless, 10% higher tensile strength was measured for the flame retarded PP compound when as-received APP was substituted by milled APP. Katalin Bocz, Tamás Krain, and György Marosi Copyright © 2015 Katalin Bocz et al. All rights reserved. Chemical Modifications of Starch: Microwave Effect Sun, 17 May 2015 07:56:44 +0000 This paper presents basic methods of starch chemical modification, the effect of microwave radiation on the modification process, and the physicochemical properties of starch. It has been shown that the modifications contribute to improvement of the material performance and likewise to significant improvement of its mechanical properties. As a result, more and more extensive use of starch is possible in various industries. In addition, methods of oxidized starch and starch esters preparation are discussed. Properties of microwave radiation and its impact on starch (with particular regard to modifications described in literature) are characterized. Kamila Lewicka, Przemysław Siemion, and Piotr Kurcok Copyright © 2015 Kamila Lewicka et al. All rights reserved. Potential Environmental Benefits of Ultralight Particleboards with Biobased Foam Cores Thu, 14 May 2015 13:39:10 +0000 A new generation of ultralight particleboards (ULPB) with an expanded foam core layer produced in an in-line foaming step is under development. The environmental impacts of three types of ULPB containing foam based on 100% polylactic acid (PLA), 100% expanded polystyrene, and 50% PLA/50% polymethyl methacrylate, as well as a conventional particleboard (PB), have been compared in an LCA. Two approaches were chosen for the assessment: first, the “EPD-approach” in accordance with EN 15804 for EPD of building materials and second, a holistic-approach which allows an expansion of the system boundaries in order to forecast the consequences of a broader replacement of PB with ULPB. The results show that most of the environmental impacts are related to raw materials and end-of-life stages. Both approaches show that the exchange of PB with ULPB with a foam core based on PLA leads to a reduction of greenhouse gas emissions. On the other hand, the PLA is responsible for higher ecotoxicity results in comparison to non-bio-based polymers mainly due to agricultural processes. Both approaches allowed the drafting of complementary advisories for environmental impact reduction addressed to the developers. Christelle Ganne-Chédeville and Stefan Diederichs Copyright © 2015 Christelle Ganne-Chédeville and Stefan Diederichs. All rights reserved. The Mechanical Aspects of Formation and Application of PDMS Bilayers Rolled into a Cylindrical Structure Wed, 13 May 2015 09:44:10 +0000 A polydimethylsiloxane (PDMS) film with its surface being oxidized by a plasma treatment or a UV-ozone (UVO) treatment, that is, a bilayer made of PDMS and its oxidized surface layer, is known to roll into a cylindrical structure upon exposure to the chloroform vapor due to the mismatch in the swelling ratio between PDMS and the oxidized layer by the chloroform vapor. Here we analyzed the formation of the rolled bilayer with the mechanical aspects: how the mismatch in the swelling ratio of the bilayer induces rolling of the bilayer, why any form of trigger that breaks the symmetry in the in-plane stress level is needed to roll the bilayer uniaxially, why the rolled bilayer does not unroll in the dry state when there is no more mismatch in the swelling ratio, and how the measured curvature of rolled bilayer matches well with the prediction by the theory. Moreover, for the use of the rolled bilayer as the channel of the microfluidic device, we examined whether the rolled bilayer deforms or unrolls by the flow of the aqueous solution that exerts the circumferential stress on the rolled bilayer. Dongwon Kang, Hyeonji Yu, and Jungwook Kim Copyright © 2015 Dongwon Kang et al. All rights reserved.