International Journal of Polymer Science The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Viscosity Measurements of Dilute Poly(2-ethyl-2-oxazoline) Aqueous Solutions Near Theta Temperature Analyzed within the Joint Rouse-Zimm Model Tue, 03 Mar 2015 14:12:56 +0000 The steady-state shear viscosity of low-concentrated Poly(2-ethyl-2-oxazoline) (PEOX) aqueous solutions is measured near the presumed theta temperature using the falling ball viscometry technique. The experimental data are analyzed within the model that joins the Rouse and Zimm bead-spring theories of the polymer dynamics at the theta condition, which means that the polymer coils are considered to be partially permeable to the solvent. The polymer characteristics thus depend on the draining parameter h that is related to the strength of the hydrodynamic interaction between the polymer segments. The Huggins coefficient was found to be 0.418 at the temperature 20°C, as predicted by the theory. This value corresponds to h = 2.92, contrary to the usual assumption of the infinite h. This result indicates that the theta temperature for the PEOX water solutions is 20°C rather than 25°C in the previous studies. The experimental intrinsic viscosity is well described coming from the Arrhenius equation for the shear viscosity. Jana Tóthová, Katarína Paulovičová, and Vladimír Lisý Copyright © 2015 Jana Tóthová et al. All rights reserved. Recycling of Waste Streams of the Biotechnological Poly(hydroxyalkanoate) Production by Haloferax mediterranei on Whey Tue, 03 Mar 2015 11:59:39 +0000 For manufacturing “bioplastics” such as poly(hydroxyalkanoates) (PHA), the combination of utilization of inexpensive carbon sources with the application of robust microbial production strains is considered a decisive step to make this process more cost-efficient and sustainable. PHA production based on surplus whey from dairy industry was accomplished by the extremely halophile archaeon Haloferax mediterranei. After fermentative production of PHA-rich biomass and the subsequent cell harvest and downstream processing for PHA recovery, environmentally hazardous, highly saline residues, namely spent fermentation broth and cell debris, remain as residues. These waste streams were used for recycling experiments to assess their recyclability in subsequent production processes. It was demonstrated that spent fermentation broth can be used to replace a considerable part of fresh saline fermentation medium in subsequent production processes. In addition, 29% of the expensive yeast extract, needed as nitrogen and phosphate source for efficient cultivation of the microorganism, can be replaced by cell debris from prior cultivations. The presented study provides strategies to combine the reduction of costs for biomediated PHA production with minimizing ecological risks by recycling precarious waste streams. Overall, the presented work shall contribute to the quick economic success of these promising biomaterials. Martin Koller Copyright © 2015 Martin Koller. All rights reserved. Comparative Analysis of the Effect of Organoclay, Boron Nitride, and Fluoropolymer on the Rheology and Instabilities in the Extrusion of High Density Polyethylene Sat, 28 Feb 2015 10:04:08 +0000 The effect of different processing additives on the extrusion instabilities of high density polyethylene (HDPE) was investigated. The concentration of each processing additive was fixed at 0.05 wt%. Organoclay, boron nitride, and fluoropolymer reduced transient shear and extensional viscosities of HDPE melt. Drop in extrusion pressure occurred during the extrusion experiment. The initial loss of glossiness in HDPE was restored with the addition of these additives. However, the fluoropolymer did not succeed in eliminating the stick-slip fracture. Despite the inclusion of the processing additives, gross-melt fracture in HDPE reappeared at apparent shear rate of 141 s−1. Both moment and distortion factor methods of analyses were employed and their findings support the observed visual trends of the extrudate surface. The quantifying tools indicated that combined organoclay and fluoropolymer reduced the pressure fluctuations and its performance surpassed that of the individual additives. A. A. Adesina, M. S. Nasser, and I. A. Hussein Copyright © 2015 A. A. Adesina et al. All rights reserved. Preparation and Characterization of Biocompatible Polymer Particles as Potential Nanocarriers for Inhalation Therapy Thu, 26 Feb 2015 09:27:08 +0000 Aim. Investigation of the possibility of manufacturing biocompatible polymer particles which have the required properties for pulmonary delivery via inhalation and simultaneously act as vehicles of nanotherapeutics. Methods. Nanostructures were obtained from biocompatible polysaccharides by successive oxidation and reactive coiling in the aqueous phase. The resultant nanosuspensions of PAD (polyaldehyde dextran) and DACMC (dialdehyde carbomethylcellulose) were used as precursors in spray drying production of powders at variable process conditions. The resultant dry microparticles were characterized by SEM observations, and their properties related to delivery by inhalation were determined by laser diffraction spectrometry following the dispersion in the commercial inhaler. Finally, the possibility of the reconstitution of nanosuspensions by powders rehydration was evaluated. Results. Synthesized nanoparticles had size of 120–170 nm. Microparticles after drying had size of 0.5–5 µm and different surface morphology. Aerosolized particles obtained from powder dispersion in the inhaler had the volumetric median diameter of ~2 and ~1 µm for PAD and DACMC, respectively. Hydration of powders led to restoring the nanosuspensions with the average particle size similar to the precursor. Conclusions. PAD and DACMC can be used to obtain nanostructures which, after processing, take a form suitable for effective delivery to the lungs via inhalation. Katarzyna Jabłczyńska, Magdalena Janczewska, Aleksandra Kulikowska, and Tomasz R. Sosnowski Copyright © 2015 Katarzyna Jabłczyńska et al. All rights reserved. Rapid Fabrication of Periodic Patterns on Poly(styrene-co-acrylonitrile) Surfaces Using Direct Laser Interference Patterning Thu, 26 Feb 2015 09:10:39 +0000 Periodic microstructures in styrene-acrylonitrile (SAN) copolymers are fabricated by two-beam direct laser interference patterning using a nanosecond pulsed laser operating at a wavelength of 266 nm. The SAN copolymers are synthesized using different molar ratios (styrene to acrylonitrile) by a free radical polymerization process. The chemical composition of the copolymers and their properties are determined using Fourier transformed infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Depending on the composition of the irradiated copolymer films, with weight ratios ranging from 58 to 96.5% of styrene to acrylonitrile, different ablation behaviors are observed. The laser fluence necessary to locally ablate the copolymer is found to be dependent on the copolymer composition. Unlike other dielectric polymers, the laser irradiation produced both direct ablation of the irradiated material and collapse of the surface. It is shown that, by varying the laser fluence and the copolymer composition, the surface structure can be changed from a periodic pattern with a swelled topography to an ablated-like structure. The number of holes does not depend monotonically on the amount of PS or PAN units but shows a more complex behavior which depends on the copolymer composition and the laser fluence. Martin F. Broglia, Diego F. Acevedo, Denise Langheinrich, Heidi R. Perez-Hernandez, Cesar A. Barbero, and Andrés F. Lasagni Copyright © 2015 Martin F. Broglia et al. All rights reserved. In Situ Study of Electropolymerized Poly(3-aminobenzoic acid) Thin Film on BD-R and DVD-R Grating Substrates by Electrochemical-Transmission Surface Plasmon Resonance Spectroscopy Wed, 25 Feb 2015 11:23:23 +0000 The electropolymerization process and doping/dedoping properties of poly(3-aminobenzoic acid) (PABA) thin films on gold-coated commercial BD-R and DVD-R grating substrates were simultaneously studied by the combination of electrochemical technique and transmission surface plasmon resonance (TSPR) spectroscopy. The optical property as a function of the applied potentials and time dependence during electropolymerization were studied. The obtained TSPR wavelength scan spectra after electropolymerization showed that the maximum wavelength slightly shifted to longer wavelength indicating the increase of film thickness. In addition, the change during construction of PABA-based immunosensor for label-free detection of human immunoglobulin G can be observed. Saengrawee Sriwichai, Akira Baba, Sukon Phanichphant, Kazunari Shinbo, Keizo Kato, and Futao Kaneko Copyright © 2015 Saengrawee Sriwichai et al. All rights reserved. Preparation of Chloro Penta Amine Cobalt(III) Chloride and Study of Its Influence on the Structural and Some Optical Properties of Polyvinyl Acetate Sun, 15 Feb 2015 11:27:45 +0000 Chloro penta amine cobalt(III) cloride [Co(NH3)5Cl]Cl2 was prepared and then characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The obtained results indicated the formation of orthorhombic [Co(NH3)5Cl]Cl2 nanoparticles of ≈28.75 nm size. Polymeric films based on polyvinyl acetate (PVAc) doped with chloro penta amine cobalt(III) cloride [Co(NH3)5Cl]Cl2 in different weight percent ratios were prepared using the solvent cast technique. The complexation of the additive with the polymer was confirmed by FTIR and SEM studies. The XRD pattern revealed that the amorphousicity of PVAc polymer matrix increased with raising the [Co(NH3)5Cl]Cl2 content. Parameters such as extinction coefficient, refractive index, real and imaginary parts, and optical conductivity were studied by using the absorbance and measurements from computerized UV-visible spectrophotometer in the spectral range 190–800 nm. This study showed that the optical properties of PVAc were affected by the doping of [Co(NH3)5Cl]Cl2 where the absorption increased by leveling up [Co(NH3)5Cl]Cl2 concentration. The nature of electronic transition from valence band to conduction band was determined and the energy band gaps of the composite films samples were estimated by UV-visible spectrum. It was observed that the optical conductivity increased with photon energy and with the increase of [Co(NH3)5Cl]Cl2 concentration. Nada K. Abbas, Majeed Ali Habeeb, and Alaa J. Kadham Algidsawi Copyright © 2015 Nada K. Abbas et al. All rights reserved. Nanosuspension: An Emerging Trend for Bioavailability Enhancement of Etodolac Thu, 12 Feb 2015 09:05:22 +0000 Etodolac (ET) (poorly soluble drug) nanosuspensions were prepared by both pH shift method and antisolvent techniques in order to increase its dissolution rate. Various stabilizers were used, namely, Tween 20 and 80, HPMC, PVP K44, PVA, PEG 400, NaCMC, and β-cyclodextrin. The prepared nanosuspensions were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) and evaluated for their particle size, particle size distribution, and in vitro dissolution rate. In general, it was found that the antisolvent method for the preparation of ET nanosuspensions reduced the drug particle size to a higher extent compared to the pH shift method. The dissolution rate of ET in distilled water was markedly enhanced in the nanosized system, as more than 65% of drug dissolved in 10 min from all the nanosuspension formulations except F5 (stabilized with PVP K44) and F8 (stabilized with Tween 20), as compared to less than 20% of crude drug. Nanoparticles prepared by antisolvent method using Tween 80 as a stabilizer were selected for further in vivo study. The in vivo test demonstrated that nanoparticles of ET were well absorbed with a percentage drug absorption value 2.7 times more than that of micrometric size of crude ET. Samar A. Afifi, Maha A. Hassan, Ali S. Abdelhameed, and Kadria A. Elkhodairy Copyright © 2015 Samar A. Afifi et al. All rights reserved. Development of Cutaneous Bioadhesive Ureasil-Polyether Hybrid Films Wed, 11 Feb 2015 13:57:16 +0000 The hydrolysis and condensation reactions involved in synthesis of ureasil-polyether films influence the film formation time and the number of chemical groups able to form hydrogen bonds, responsible for the bioadhesion, with the biological substrate. The objective of this work was to study the influence of the use of an acid catalyst (hydrochloric acid) and a basic catalyst (ammonium fluoride) in the hydrolysis and condensation reactions on the time formation and bioadhesion of ureasil-polyether films. The toxicity of the films was evaluated. The MTT assay has shown cell viability of human skin keratinocytes higher than 70% of all analyzed materials suggesting low cytotoxicity. The bioadhesion of the films is strongly dependent on the viscosity and hydrophilic/hydrophobic balance of the polyether chains used to synthetize the hybrid molecules. The use of acid catalyst promotes the formation of less viscous films with higher bioadhesion. The hybrids formed by more hydrophilic PEO chains are more bioadherent, since they can interact more efficiently with the water present in the stratum corneum increasing the bioadhesion. Due to their low toxicity and high bioadhesion, the ureasil-PEO films obtained by using HCl as catalyst agent are good candidates for application to the skin as bioadhesive films. João Augusto Oshiro Junior, Flávia Chiva Carvalho, Christiane Pienna Soares, Marlus Chorilli, and Leila Aparecida Chiavacci Copyright © 2015 João Augusto Oshiro Junior et al. All rights reserved. Curing Kinetics of Hybrid Networks Composed of Benzoxazine and Multifunctional Novolac Epoxy Mon, 09 Feb 2015 08:03:13 +0000 A novel hybrid network composed of benzoxazines (BZ) and novolac epoxy resin (F-51) was prepared successfully. Thermal properties, curing kinetics, and decomposition process were studied using isothermal differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) in this paper. The reactive mechanism of F-51/BZ mixture system is different from the BZ homopolymers at low temperatures; two resin systems follow the autocatalytic model mainly at high temperatures. Thermogravimetric analysis indicates that F-51 can have no significant effect on thermal degradation temperatures and on increasing char yield. Wu Ke, Wang Rumin, and Zeng Jinfang Copyright © 2015 Wu Ke et al. All rights reserved. Stress Distribution of CF/EP Laminated Composites under Supercritical Conditions Sun, 08 Feb 2015 10:38:49 +0000 Enormous amounts of wastes have been produced due to extensive use of carbon fiber/epoxy resin (CF/EP) composites. The fact that the supercritical fluid can be used to recycle these composites efficiently has attracted widespread concerns. A three-dimensional model of CF/EP laminates considering the interfacial layers was established. The internal stress distribution of laminates was simulated based on a heat transfer model; and the change of shear stress with supercritical temperature and pressure was investigated. The results show that the shear stress concentration was located in the interfacial layers; the maximum shear stress can be expressed by a curve of convex parabola to the temperature; and the most serious damage occurred in interfacial layers when temperature approached the glass-transition temperature of resin. Haihong Huang, Zhenwen Li, Huanbo Cheng, and Yanzhen Yin Copyright © 2015 Haihong Huang et al. All rights reserved. The Preparation of Graphene Reinforced Poly(vinyl alcohol) Antibacterial Nanocomposite Thin Film Mon, 26 Jan 2015 13:51:35 +0000 Methylated melamine grafted polyvinyl benzylchloride (mm-g-PvBCl) was prepared which was used as additive in poly(vinyl alcohol) (PVA) and graphene nanosheets (GNs) were used to reinforce the mechanical strength. Using casting method, antimicrobial nanocomposite films were prepared with the polymeric biocide loading lever of 1 wt%, 5 wt%, and 10 wt%. Thermogravimetric analysis (TGA) characterization revealed the 2.0 wt% of graphene content in resultant nanocomposites films. XRD showed that the resultant GNs 2 theta was changed from 16.6 degree to 23.3 degree. Using Japanese Industry Standard test methods, the antimicrobial efficiency for the loading lever of 1 wt%, 5 wt%, and 10 wt% was 92.0%, 95.8%, and 97.1%, respectively, against gram negative bacteria E. coli and 92.3%, 99.6%, and 99.7%, respectively, against the gram positive S. aureus. These results indicate the prepared nanocomposite films are the promising materials for the food and drink package applications. Yuan-Cheng Cao, Wenjun Wei, Jiyan Liu, Qingliang You, Feiyan Liu, Qian Lan, Chang Zhang, Chang Liu, and Jinxing Zhao Copyright © 2015 Yuan-Cheng Cao et al. 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.