International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Synthesis of Well-Defined Three-Arm Star-Branched Polystyrene through Arm-First Coupling Approach by Atom Transfer Radical Polymerization Thu, 22 Jan 2015 13:32:16 +0000 Here we describe a simple route to synthesize three-arm star-branched polystyrene. Atom transfer radical polymerization technique has been utilized to yield branched polystyrene involving Williamson coupling strategy. Initially a linear polymeric chain of predetermined molecular weight has been synthesized which is further end-functionalized into a primary alkyl bromide moiety, a prime requisition for Williamson reaction. The end-functionalized polymer is then coupled using 1,1,1-tris(4-hydroxyphenyl)ethane, a trifunctional core molecule, to give well-defined triple-arm star-branched polystyrene. Syed Shahabuddin, Fatem Hamime Ismail, Sharifah Mohamad, and Norazilawati Muhamad Sarih Copyright © 2015 Syed Shahabuddin et al. All rights reserved. Synthesis and Optical Performances of a Waterborne Polyurethane-Based Polymeric Dye Wed, 21 Jan 2015 12:43:08 +0000 A waterborne polyurethane-based polymeric dye (WPU-CFBB) was synthesized by anchoring 1, 4-bis(methylamino)anthraquinone (CFBB) to waterborne polyurethane chains. The number molecular weight, glass transition temperature, and average emulsion particle size for the polymeric dye were determined, respectively. This polymeric dye exhibited intriguing optical behaviors. The polymeric dye engendered two new absorption bands centered at about 520 nm and 760 nm if compared with CFBB in UV-vis spectra. The 760 nm peak showed hypsochromic shift with the decrease of average particle sizes. The polymeric dye dramatically demonstrated both hypsochromic and bathochromic effects with increasing temperature. The fluorescence intensity of the polymeric dye was much higher than that of CFBB. It was found that the fluorescence intensities would be enhanced from 20°C to 40°C and then decline from 40°C to 90°C. The fluorescence of the polymeric dye emulsion was very stable and was not sensitive to quenchers. Xianhai Hu, Xingyuan Zhang, and Jin Liu Copyright © 2015 Xianhai Hu et al. All rights reserved. Synthesis of New Thiophene Derivatives and Their Use as Photostabilizers for Rigid Poly(vinyl chloride) Tue, 13 Jan 2015 05:51:46 +0000 Five new thiophenes, namely, N-[(3-bromo-2-methylthiophen-5-yl)methylene]-4-methoxyaniline (4a), N-[(3-bromo-2-methylthiophen-5-yl)methylene]-3,4-dimethoxyaniline (4b), N-[(3-bromo-2-methylthiophen-5-yl)methylene]-3,4-dimethylaniline (4c), 3-[(3-bromo-2-methylthiophen-5-yl)methyleneamino]-2-methylquinazolin-4(3H)-one (4d), and 3-[(3-bromo-2-methylthiophen-5-yl)methyleneamino]-2-isopropylquinazolin-4(3H)-one (4e), have been synthesized. All of these materials brought about a reduction in the level of photodegradation of poly(vinyl chloride) (PVC) films containing the synthesized thiophenes (0.5%; by weight). The results obtained showed that the extent of photostabilization of PVC in the presence of an additive was in the order 4e > 4d > 4b > 4a > 4c. For the most favorable additive (4e), the rate of appearance of infrared absorption bands of degradation products was reduced by around two-thirds, while the quantum yield of chain scission was calculated to be reduced by a factor of more than one thousand. It is suggested that the additives may help stabilize PVC by direct absorption of UV radiation and dissipation of the energy as heat or that electrostatic attraction between the additives and PVC may assist transfer of energy from excited state PVC to the additive, from where it can be dissipated. Asim A. Balakit, Ahmed Ahmed, Gamal A. El-Hiti, Keith Smith, and Emad Yousif Copyright © 2015 Asim A. Balakit et al. All rights reserved. Chemical Functionalization and Characterization of Cellulose Extracted from Wheat Straw Using Acid Hydrolysis Methodologies Tue, 06 Jan 2015 06:47:34 +0000 The nonuniform distribution of cellulose into many composite materials is attributed to the hydrogen bonding observed by the three hydroxyl groups located on each glucose monomer. As an alternative, chemical functionalization is performed to disrupt the strong hydrogen bonding behavior without significant altering of the chemical structure or lowering of the thermal stability. In this report, we use wheat straw as the biomass source for the extraction of cellulose and, subsequently, chemical modification via the Albright-Goldman and Jones oxidation reactions. X-ray diffraction analyses reveal that upon oxidation a slight change in the cellulose polymorphic structure (CI to CII) can be observed when compared to its unmodified counterpart. Scanning electron microscopy analyses show that the oxidized cellulose structure exhibits fiber-like crystals with lengths and diameters on the micrometer scale. Thermal analyses (differential scanning calorimetry and thermogravimetric analysis) show an increase in the thermal stability for the modified cellulose at extremely high temperatures (>300°C). Chemar J. Huntley, Kristy D. Crews, and Michael L. Curry Copyright © 2015 Chemar J. Huntley et al. All rights reserved. Mechanical Properties of Membranes of Poly(L-co-DL-lactic acid) with Poly(caprolactone triol) and Study In Vivo Wed, 31 Dec 2014 09:48:03 +0000 There is increasing interest in aliphatic polyesters from lactones and lactides because of their biodegradability and biocompatibility. Among these compounds, poly(lactide), and poly(glycolide), poly(-caprolactone) and their copolymers are especially interesting because of their potential applications as biomedical materials. The aim of this study was to examine the properties of membranes of poly(L-co-D,L lactic acid) (PLDLA) with poly(caprolactone triol) (PCL-T) obtained by solvent evaporation. The blends were characterized by differential scanning calorimetry, dynamic mechanical analysis, Fourier transform infrared spectroscopy, and tensile strength tests. Based on the results of in vitro studies, PLDLA/PCL-T blends of 100/0 and 90/10 were implanted in subcutaneous tissue of Wistar rats for 1, 3, 7, 15, and 60 days to evaluate their biocompatibility. Histological analysis indicated that, although PCL-T-containing membranes caused a more prominent inflammatory reaction in the initial time intervals, by 60 days after implantation, the material was surrounded by dense, organized collagen with almost no inflammatory infiltrate. Marcia Adriana Tomaz Duarte, Adriana Cristina Motta, and Eliana Aparecida de Rezende Duek Copyright © 2014 Marcia Adriana Tomaz Duarte et al. All rights reserved. Correlation of Processing, Inner Structure, and Part Properties of Injection Moulded Thin-Wall Parts on Example of Polyamide 66 Sun, 21 Dec 2014 06:28:13 +0000 In micro- and thin-wall injection moulding the process conditions affect the developed internal structures and thus the resulting part properties. This paper investigates exemplarily on polyamide 66 the interactions of different cooling conditions on the morphological and crystalline structures. The investigations reveal that a slow cooling rate of the melt results in a homogeneous morphology and a higher degree of crystallinity and also a favoured crystalline structure. Consequently, the dielectric behaviour and light transmitting part properties are affected. Dietmar Drummer and Steve Meister Copyright © 2014 Dietmar Drummer and Steve Meister. All rights reserved. Influence of Thickness on the Holographic Parameters of H-PDLC Materials Mon, 15 Dec 2014 00:10:30 +0000 For photopolymers the compound concentrations and final thickness of the sample should be known in order to model hologram formation and introduce the reaction-diffusion kinetics of the monomer-polymer system. In principle the cell thickness can be controlled by bead spacers between the two pieces of ITO glass. In this paper we report a study of the influence of thickness on the holographic properties of this type of materials. To fit the physical and optical thickness of the samples we used the rigorous coupled wave analysis assuming an exponential decay in the refractive index modulation. S. Gallego, M. Ortuño, A. Márquez, R. Fernández, M. L. Álvarez, A. Beléndez, and I. Pascual Copyright © 2014 S. Gallego et al. All rights reserved. Diffractive Optical Elements with a Large Angle of Operation Recorded in Acrylamide Based Photopolymer on Flexible Substrates Thu, 11 Dec 2014 12:28:34 +0000 A holographic device characterised by a large angular range of operation is under development. The aim of this study is to increase the angular working range of the diffractive lens by stacking three layers of high efficiency optical elements on top of each other so that light is collected (and focussed) from a broader range of angles. The angular range of each individual lens element is important, and work has already been done in an acrylamide-based photosensitive polymer to broaden the angular range of individual elements using holographic recording at a low spatial frequency. This paper reports new results on the angular selectivity of stacked diffractive lenses. A working range of 12° is achieved. The diffractive focussing elements were recorded holographically with a central spatial frequency of 300 l/mm using exposure energy of 60 mJ/cm2 at a range of recording angles. At this spatial frequency with layers of thickness 50 ± 5 µm, a diffraction efficiency of 80% and 50% was achieved in the single lens element and combined device, respectively. The optical recording process and the properties of the multilayer structure are described and discussed. Holographic recording of a single lens element is also successfully demonstrated on a flexible glass substrate (Corning(R) Willow(R) Glass) for the first time. Hoda Akbari, Izabela Naydenova, Lina Persechini, Sean M. Garner, Pat Cimo, and Suzanne Martin Copyright © 2014 Hoda Akbari et al. All rights reserved. Bioprocess Engineering Aspects of Biopolymer Production by the Cyanobacterium Spirulina Strain LEB 18 Thu, 11 Dec 2014 00:10:32 +0000 Microbial biopolymers can replace environmentally damaging plastics derived from petrochemicals. We investigated biopolymer synthesis by the cyanobacterium Spirulina strain LEB 18. Autotrophic culture used unmodified Zarrouk medium or modified Zarrouk medium in which the NaNO3 content was reduced to 0.25 g L−1 and the NaHCO3 content reduced to 8.4 g L−1 or increased to 25.2 g L−1. Heterotrophic culture used modified Zarrouk medium containing 0.25 g L−1 NaNO3 with the NaHCO3 replaced by 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1 of glucose (C6H12O6) or sodium acetate (CH3COONa). Mixotrophic culture used modified Zarrouk medium containing 0.25 g L−1 NaNO3 plus 16.8 g L−1 NaHCO3 with the addition of 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1 of glucose or sodium acetate. The highest biopolymer yield was 44% when LEB 18 was growing autotrophically in media containing 0.25 g L−1 NaNO3 and 8.4 g L−1 NaHCO3. Roberta Guimarães Martins, Igor Severo Gonçalves, Michele Greque de Morais, and Jorge Alberto Vieira Costa Copyright © 2014 Roberta Guimarães Martins et al. All rights reserved. Binary Intensity Modulation and Hybrid Ternary Modulation Applied to Multiplexing Objects Using Holographic Data Storage on a PVA/AA Photopolymer Wed, 10 Dec 2014 13:42:56 +0000 Holographic data pages were multiplexed in a polyvinyl alcohol/acrylamide photopolymer and a liquid crystal device was used to modify the object beam and store objects in the material. A peristrophic multiplexing method was used to store a large number of objects in the same spot of the material. The objects were stored using two different modulations: binary intensity modulation and hybrid ternary modulation. Moreover, the bit error rate (BER) of the images was calculated in order to compare which modulation is most appropriate to be used for holographic data storage. Elena Fernandez, Rosa Fuentes, Andrés Márquez, Augusto Beléndez, and Inmaculada Pascual Copyright © 2014 Elena Fernandez et al. All rights reserved. Numerical Model of Radical Photopolymerization Based on Interdiffusion Wed, 10 Dec 2014 13:42:00 +0000 An accurate reaction model is required to analyze the characteristics of photopolymers. For this purpose, we propose a numerical model for radical photopolymerization. In the proposed model, elementary reactions such as initiation, propagation, and termination are considered, and we assume interdiffusion for each component in the material. We analyzed the diffraction characteristics of a radical photopolymer based on the proposed interdiffusion model with the beam propagation method. Moreover, we also performed hologram-recording experiments and evaluated the diffraction characteristics of the photopolymer medium. By comparing the numerical and experimental results, medium parameters such as reaction rate and diffusion coefficient can be estimated. We confirmed that the interdiffusion model can reproduce the experimental results and showed that the medium parameters affect the diffraction characteristics. Shuhei Yoshida, Yosuke Takahata, Shuma Horiuchi, Hiroyuki Kurata, and Manabu Yamamoto Copyright © 2014 Shuhei Yoshida et al. All rights reserved. Experimental Conditions to Obtain Photopolymerization Induced Phase Separation Process in Liquid Crystal-Photopolymer Composite Materials under Laser Exposure Wed, 10 Dec 2014 00:10:46 +0000 We analyze the experimental conditions necessary to obtain a photopolymerization induced phase separation process inside liquid crystal-photopolymer composite materials. Composites stored for 24 hours perform poorly in hologram recording but a good result is obtained if they are used recently prepared. We use a procedure combining heat and sonication to disarrange the liquid crystal structures formed during storage of the composite. We also propose incoherent light treatment after recording the hologram in order to evaluate if the phase separation evolved correctly during hologram recording. Manuel Ortuño, Andrés Márquez, Sergi Gallego, Inmaculada Pascual, and Augusto Beléndez Copyright © 2014 Manuel Ortuño et al. All rights reserved. Polysaccharide Fibers as Matrices for Solid-Surface Fluorescence Mon, 08 Dec 2014 07:15:09 +0000 Fibers of cellulose diacetate (CDA) and chitosan (CTS) of polycationic and polybasic forms were tested as matrices for solid-surface fluorescence (SSF) of several fluorescent probes—eosin Y, trypaflavine, and pyrene. The morphology and surface potential of these matrices were examined. The influence of structural and energetic characteristics of the fibrous polysaccharide materials at SSF of the probes was shown. Fluorescence was studied in aqueous solutions of eosin Y and trypaflavine, in water-ethanolic and water-micellar surfactant media of pyrene, before and after dynamic sorption of the dyes on fibers and in the adsorbed state. The surface of CDA fiber was shown to be capable of sorbing trypaflavine from water and pyrene from water-micellar surfactant media of various types, so it can be a promising matrix for SSF of pyrene and trypaflavine and their chemical analogs. The Coulomb interactions were proposed to determine eosin Y and trypaflavine concentration on the surface of CTS matrices and the SSF of these probes. The CTS fibers were permeable to hydrophobic pyrene dissolved in an ethanol-water medium or solubilized in the micelles of ionic surfactants. Svetlana M. Rogacheva, Anna B. Shipovskaya, Anna V. Strashko, Tamara I. Gubina, Elena V. Volkova, and Andrey G. Melnikov Copyright © 2014 Svetlana M. Rogacheva et al. All rights reserved. Fully Supramolecular Polyrotaxanes as Biphase Drug Delivery Systems Tue, 02 Dec 2014 06:49:16 +0000 Pseudopolyrotaxanes (PPR) consisting of α-cyclodextrin rings and polyethylene glycol axes with end thymine groups have been synthesized and characterized successfully. Fluorescein (Fl) as a model drug was conjugated to the hydroxyl functional groups of cyclodextrin rings of PPR via ester bonds and PPR-Fl as the primary drug delivery system was obtained. Finally PPR-Fl was capped by hydrogen bonds between end thymine groups and a suitable complementary molecule such as polycitric acid, citric acid, or adenine. The aim of this work was to control the release of the fluorescein-cyclodextrin (Fl-CD) conjugates, as the secondary drug delivery systems, from PPR-Fl by controlling the noncovalent interactions between stoppers and thymine end groups. It was found that the rate of release of the Fl-CD from PPR-Fl could be controlled by pH and the ratio of citric acid or adenine to the PPR-Fl. Abdolhossien Massoudi, Mohsen Adeli, and Leila Khosravi far Copyright © 2014 Abdolhossien Massoudi et al. All rights reserved. Effect of Phosphoric Acid Concentration on the Optical Properties of Partially Phosphorylated PVA Complexes Tue, 18 Nov 2014 09:13:02 +0000 Partially phosphorylated polyvinyl alcohol (PPVA) films were prepared at five mole ratios of phosphoric acid (PA) using solution casting technique. The optical properties of the PPVA films were examined using UV-visible (UV) and photoluminescence (PL) spectroscopy. The UV absorption spectra reveal that the absorption peaks are blue-shifted with an increase in PA concentration added to the pure PVA. The PL spectra show the presence of peaks which are characteristic of isotactic (389–398, 460–462 nm), syndiotactic (418–420 nm), and atactic (440–446 nm) configurations of the PPVA. The results also show the peak of O–P–O bonding at a wavelength range of 481–489 nm. Asmalina Mohamed Saat and Mohd Rafie Johan Copyright © 2014 Asmalina Mohamed Saat and Mohd Rafie Johan. All rights reserved. Preparation and Characterization of UV-Curable Cyclohexanone-Formaldehyde Resin and Its Cured Film Properties Tue, 11 Nov 2014 07:47:42 +0000 UV-curable cyclohexanone-formaldehyde (UVCF) resin was prepared with cyclohexanone-formaldehyde (CF) resin, isophorone diisocyanate (IPDI), and pentaerythritol triacrylate (PETA) as base substance, bridging agent, and functional monomer, respectively. The structure of UVCF was characterized by Fourier transform infrared spectroscopy (FT-IR), 1H-nuclear magnetic resonance spectroscopy (1H-NMR), and gel permeation chromatography (GPC). The viscosity and photopolymerization behavior of the UV-curable formulations were studied. The thermal stability and mechanical properties of the cured films were also investigated. The results showed that UVCF resin was successfully prepared, the number of average molecular weight was about 2010, and its molecular weight distribution index was 2.8. With the increase of UVCF resin content, the viscosity of the UV-curable formulations increased. After exposure to UV irradiation for 230 s, the photopolymerization conversion of the UV-curable formulations was above 80%. Moreover, when the UVCF content was 60%, the formulations had high photopolymerization rate, and the cured UVCF films showed good thermal stability and mechanical properties. Guang Yang, Hongqiang Li, Xuejun Lai, Yi Wang, Yifu Zhang, and Xingrong Zeng Copyright © 2014 Guang Yang et al. All rights reserved. Low Velocity Impact and Creep-Strain Behaviour of Vinyl Ester Matrix Nanocomposites Based on Layered Silicate Thu, 06 Nov 2014 11:26:03 +0000 The impact properties of neat vinyl ester and the nanocomposites were performed using a low velocity impact testing. The addition of layered silicate into the polymer matrix shows that an optimum range of nanoclay reinforcement in the vinyl ester matrix can produce enhanced load bearing and energy absorption capability compared to the neat matrix. In addition, the amount of microvoids in the nanocomposites structure influences the overall properties. Likewise, the influence of the clay addition into the neat polymer on the creep relaxation behaviour at 25°C and 60°C was studied. In both cases, the presence of the layered silicate remarkably improved the creep behaviour. The improvement of these properties can be assigned to the stiff fillers and the configurational linkage between the polymer and the layered silicate which are supported by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterisations by showing a distinct change in surface morphology associated with improved impact toughness and creep response. A. I. Alateyah, H. N. Dhakal, Z. Y. Zhang, and B. Aldousiri Copyright © 2014 A. I. Alateyah et al. All rights reserved. Application of Biodegradable Polyhydroxyalkanoates as Surgical Films for Ventral Hernia Repair in Mice Wed, 05 Nov 2014 08:35:15 +0000 The cytotoxicity and biosafety of poly-(3-hydroxybutyrate) (P3HB) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HBV) films were investigated in vitro using 3T3 fibroblast cells and in vivo through subcutaneous implantation of the film in mice. The in vitro test revealed that endotoxin-free P3HB and P3HBV films allowed cell attachment and growth. Film-soaked conditional media showed no significant inhibitory or cytotoxic effects on cell proliferation. The in vivo absorption test showed that both the P3HB and P3HBV films slowly degraded and that P3HB had a slower degradation rate than that of P3HBV. Applying a P3HB film in hernia repair demonstrated a favorable outcome: the film was able to correct the abdominal ventral hernia by inducing connective tissue and fat ingrowth and exhibited an extremely slow rate of degradation. Furthermore, the P3HB film demonstrated the advantage of lower intestinal adhesion to the ventral hernia site compared with the P3HBV and PP commercial films. Yun Chen, Ya-Hui Tsai, I-Ning Chou, Sheng-Hong Tseng, and Ho-Shing Wu Copyright © 2014 Yun Chen et al. All rights reserved. Environmentally Friendly Flame-Retardant and Its Application in Rigid Polyurethane Foam Tue, 28 Oct 2014 12:00:33 +0000 A novel Flame-Retardant N-(P,P′-diphenyl) phosphorus-based-(3-triethoxysilicon) propylamine (DPTP) was synthesized in this study. The impact of DPTP on the mechanical properties, thermal stability, and flame retardancy of rigid polyurethane foam (RPUF) was studied. The addition of DPTP to RPUF can significantly reduce the undesirable thermal effects and smoke density during combustion, as well as increasing the limiting oxygen index. Compared with pure RPUF, the peak heat release rate of RPUF containing 10 phr of DPTP decreased by 39.4%, while its peak smoke production rate decreased by 49.9%. However, it was also found that the addition of DPTP reduced the compressive strength of RPUF. Yongjun Chen, Zhixin Jia, Yuanfang Luo, Demin Jia, and Bin Li Copyright © 2014 Yongjun Chen et al. All rights reserved. Laser Induced Modification of the Optical Properties of Nano-ZnO Doped PVC Films Tue, 14 Oct 2014 00:00:00 +0000 The effect of continuous CO2 laser radiation on the optical properties of pure polyvinyl chloride and doped of ZnO nanoparticles with two different concentrations (10, 15%) has been investigated. All samples were prepared using casting method at room temperature. Optical properties (absorption, transmission, absorption coefficient, extinction coefficient, refractive index, and optical conductivity) of all films after CO2 laser irradiated have been studied as a function of the wavelength in the range (200–800) nm for three energies (300, 400 and 500 mJ). It has been found that the transmission, energy gap, and refractive index increase with increasing laser energy. The values of absorption, Urbach energy, absorption coefficient, extinction coefficient, and optical conductivity were decreased. Tagreed K. Hamad, Rahimi M. Yusop, Wasan A. Al-Taa’y, Bashar Abdullah, and Emad Yousif Copyright © 2014 Tagreed K. Hamad et al. All rights reserved. Fibrous Agricultural Biomass as a Potential Source for Bioconversion to Vanillic Acid Mon, 15 Sep 2014 05:14:01 +0000 This study was conducted to assess the potential of six fibrous agricultural residues, namely, oil palm empty fruit bunch fiber (OPEFBF), coconut coir fiber (CCF), pineapple peel (PP), pineapple crown leaves (PCL), kenaf bast fiber (KBF), and kenaf core fiber (KCF), as a source of ferulic acid and phenolic compounds for bioconversion into vanillic acid. The raw samples were pretreated with organosolv (NaOH-glycerol) and alkaline treatment (NaOH), to produce phenol-rich black liquor. The finding showed that the highest amount of phenolic compounds and ferulic acid was produced from CCF and PP, respectively. This study also found that organosolv treatment was the superior method for phenolic compound extraction, whereas alkaline treatment was the selective method for lignin extraction. Vanillic acid production by Aspergillus niger I-1472 was only observed when the fermentation broth was fed with liquors from PP and PCL, possibly due to the higher levels of ferulic acid in those samples. Pei-Ling Tang, Osman Hassan, Jamaliah Md-Jahim, Wan Aida Wan Mustapha, and Mohamad Yusof Maskat Copyright © 2014 Pei-Ling Tang et al. All rights reserved. Electrospun Fibres of Polyhydroxybutyrate Synthesized by Ralstonia eutropha from Different Carbon Sources Thu, 11 Sep 2014 11:38:25 +0000 The properties of PHB may be affected by the carbon source used in its production and this may affect nanofibres made from this polymer by electrospinning. In this study, P(3-HB) was produced from glucose, rapeseed oil, and olive oil by Ralstonia eutropha H16. Cell growth and polymer production were higher in olive or rapeseed oil supplemented media compared to glucose supplemented media. FT-IR, 1H-, 13C-NMR, and ESI/MSn confirmed that the synthesized polymers were P(3-HB). SEM micrograph showed the formation of nanofibres from P(3-HB) samples with the fibre diameters dependent on the source of the carbon used in polymer synthesis and the concentration of the polymer in the electrospinning solution. GPC showed that P(3-HB) from glucose (G-PHB) had a higher molecular weight ( gmol−1) compared to P(3-HB) from rapeseed (R-PHB) and olive (O-PHB) oil. Differential scanning calorimetry (DSC) showed that the crystallinity of the electrospun polymers reduces with decreasing polymer concentration with R-PHB having lower crystallinity at all concentrations used. These observation shows that more PHB yield can be obtained using either rapeseed or olive oil compared to glucose with glucose producing polymers of higher molecular weight. It also show that electrospinning could be used to reduce the crystallinity of PHB fibres. Victor U. Irorere, Soroosh Bagheriasl, Mark Blevins, Iwona Kwiecień, Artemis Stamboulis, and Iza Radecka Copyright © 2014 Victor U. Irorere et al. All rights reserved. Synthesis and Characterization of Metal Sulfides Nanoparticles/Poly(methyl methacrylate) Nanocomposites Sun, 07 Sep 2014 06:17:34 +0000 Metal sulfides nanoparticles in poly(methyl methacrylate) matrices were prepared and characterized by infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, scanning electron microscope (SEM), and transmission electron microscope (TEM). The FTIR confirms the dispersion of the nanoparticles in PMMA matrices with the C=O and C–O–C bonds of the PMMA shifting slightly which may be attributed to the interactions between the nanoparticles and PMMA. The ZnS nanoparticles in PMMA have average crystallite sizes of 4–7 nm while the CdS has particle size of 10 nm and HgS has crystallite sizes of 8–20 nm. The increasing order of particle sizes as calculated from the XRD is ZnS/PMMAHgS/PMMACdS/PMMA and ranges from 1.02 to 1.35 nm. These calculated particle sizes are smaller than the values obtained from TEM. Peter A. Ajibade and Johannes Z. Mbese Copyright © 2014 Peter A. Ajibade and Johannes Z. Mbese. All rights reserved. Enhancement of Lignin Biopolymer Isolation from Hybrid Poplar by Organosolv Pretreatments Thu, 28 Aug 2014 11:42:49 +0000 Lignocellulosic biomass is an abundant renewable resource that has the potential to displace petroleum in the production of biomaterials and biofuels. In the present study, the fractionation of different lignin biopolymers from hybrid poplar based on organosolv pretreatments using 80% aqueous methanol, ethanol, 1-propanol, and 1-butanol at 220°C for 30 min was investigated. The isolated lignin fractions were characterized by Fourier transform infrared spectroscopy (FT-IR), high-performance anion exchange chromatography (HPAEC), 2D nuclear magnetic resonance (2D NMR), and thermogravimetric analysis (TGA). The results showed that the lignin fraction obtained with aqueous ethanol (EOL) possessed the highest yield and the strongest thermal stability compared with other lignin fractions. In addition, other lignin fractions were almost absent of neutral sugars (1.16–1.46%) though lignin preparation extracted with 1-butanol (BOL) was incongruent (7.53%). 2D HSQC spectra analysis revealed that the four lignin fractions mainly consisted of -O-4′ linkages combined with small amounts of - and -5′ linkages. Furthermore, substitution of in -O-4′ substructures had occurred due to the effects of dissolvent during the autocatalyzed alcohol organosolv pretreatments. Therefore, aqueous ethanol was found to be the most promising alcoholic organic solvent compared with other alcohols to be used in noncatalyzed processes for the pretreatment of lignocellulosic biomass in biorefinery. Miao Wu, Jinhui Pang, Xueming Zhang, and Runcang Sun Copyright © 2014 Miao Wu et al. All rights reserved. An Environmentally Friendly Process for the Preparation of UHMWPE As-Spun Fibres Thu, 28 Aug 2014 00:00:00 +0000 The extrusion of ultra high molecular weight polyethylene (UHMWPE) fibres cannot be achieved by conventional extrusion processes due to its very high melt viscosity. To overcome this limitation, UHMWPE is first dissolved in a petrochemical to form a gel before extrusion. The petrochemicals used to dissolve the polymer then need to be removed using other chemicals making the process unfriendly to the environment. This article is focused on finding an environmentally friendly, natural solution to replace these chemicals and altering the process to potentially reduce the process cost. Abdul Waqar Rajput, Anwar ul Aleem, and Farooq Ahmed Arain Copyright © 2014 Abdul Waqar Rajput et al. 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.