bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and self‐assembling behaviors of biotinylated pluronic/poly(lactic acid) biocompatible block copolymers in aqueous solutions
Authors: Li Zi Ling , Xiong Xiang Yuan , Li Yu Ping , Gong Yan Chun , Gui Xing Xing , Ou‐Yang Xing , Lin Hua Sheng , Zhu Lu Juan , Xie Ji Lei 
Published: October 2009

AbstractFour kinds of Biotinylated Pluronic/PLA block copolymers were synthesized by two‐step reactions. Pluronic were firstly modified by biotin to obtain B‐Pluronic‐OH. Biotin‐Pluronic‐PLA block copolymers were then produced by ring‐opening polymerization of the monomer L‐lactide using Biotin‐Pluronic‐OH as the initiator and stannous octoate (Sn(Oct)2) as the catalyst. The self‐assembling behaviors of Biotin‐Pluronic‐PLA block copolymers in aqueous solutions were examined by fluorescence measurement, dynamic light scattering (DLS), and transmission electron microscopic (TEM) techniques. The size of Biotin‐F127‐PLA‐61, Biotin‐F87‐PLA, and Biotin‐P85‐PLA nanoparticles were determined to be 198, 229, and 257 nm, respectively, and their morphologies were found to be spherical micelles. Biotin‐F127‐PLA‐87 produces both spherical micelles and large compound micelles with the size of 127 and 906 nm. The cytotoxicity studies using human ovarian cancer cells OVCAR‐3 indicate that Biotin‐Pluronic‐PLA block copolymers have good biocompatibility. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Biosynthesis and characterization of bacteria cellulose–alginate film
Authors: Kanjanamosit Nitisak , Muangnapoh Chirakarn , Phisalaphong Muenduen 
Published: October 2009

AbstractA novel polysaccharide membrane containing alginate in bacterial cellulose matrix was synthesized by Acetobacter xylinum under static conditions using a culture medium supplementation with sodium alginate. By increasing alginate content, the bacterial cellulose–alginate (BCA) membrane was more hydrophilic and the film structure became denser with the smaller average pore size. Scanning electron microscope images displayed the deposits of alginate gel on the surfaces of the multilayer cellulose film. The declines in the tensile strength, the Young's modulus, and the elongation at break of the BCA membrane were dependent on the degree of alginate supplement. The BCA membrane showed higher water absorption capacity. The addition of alginate slightly affected the water vapor transmission rate but remarkably decreased the oxygen transmission rate of the membrane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Value‐added derivatives of soda lignin from alfa grass (Stipa tenacissima). I. Modification and characterization
Authors: Nadji H. , Bedard Y. , Benaboura A. , Rodrigue D. , Stevanovic T. , Riedl B. 
Published: October 2009

AbstractAlfa grass (Stipa tenacissima) is the only raw material for manufacturing paper pulp in Algeria, Tunisia, and Morocco. Soda lignin (SL) is obtained from black liquor (BL), a byproduct of manufacturing paper from alfa grass. This work was aimed at modifying SL and using it as a polymer lubricant. Modified SL was obtained in two steps: the precipitation of BL at pH 4 with sulfuric acid (2N) followed by the modification of SL by esterification using stearic anhydride (SA) dissolved in dioxane at 50°C for 8 h. The effects of different contents of SA on the hydrophobic properties and heat stability of modified SL were evaluated with contact angle analysis and thermogravimetric analysis. A commercial stearate used in plastic processing was chosen as the reference. Its thermal properties were ascertained with thermogravimetry, and its behavior was similar to that of the modified lignins. A structural comparison study was performed with Fourier transform infrared (FTIR) spectroscopy and solid‐state 13C‐NMR. The FTIR and 13C‐NMR results showed that there were significant differences between the main structures of SL samples reacted with 10, 30, or 100% (w/w) SA. The main part of the work consisted of modifying SL, evaluating the properties of the obtained products with respect to their use as lubricants, and comparing them to industrial lubricants. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Creep and stress relaxation modeling of vinyl ester nanocomposites reinforced by nanoclay and graphite platelets
Authors: Almagableh Ahmad , Raju Mantena P. , Alostaz Ahmed 
Published: October 2009

AbstractThis article discusses the viscoelastic behavior of a vinyl ester (Derakane 411‐350) reinforced with 1.25 and 2.5 wt % nanoclay and exfoliated graphite nanoplatelets during short‐term creep and relaxation tests with a dynamic mechanical analyzer. Linear viscoelastic models are generally composed of one or more elements such as dashpots and springs that represent the viscous and elastic properties. Stress relaxation data from the dynamic mechanical analyzer have been used to obtain the elastic parameters based on model constitutive equations. The standard linear solid model, which is a physical model, has been used for predicting the creep deformation behavior of the vinyl ester nanocomposites over a wide temperature range. Some correlations have been made with the mechanical model, such as the effect of temperature on the deformation behavior, which is well explained by the dashpot mechanism. At lower temperatures, higher creep compliance has been observed for the vinyl ester versus the nanocomposites, whereas at temperatures near the glass‐transition temperature of the vinyl ester, creep compliance in the nanocomposites is closer in magnitude to that for the vinyl ester. The creep response of the pure vinyl ester and its nanocomposites appears to be modeled reasonably well at temperatures lower than their glass‐transition temperatures. A comparison of the predictions and experimental data from the creep tests has demonstrated that this model can represent the long‐term deformation behavior of these nanoreinforced materials reasonably well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of the vinyl concentration on the structural and rheological characteristics of peroxide‐modified high‐density polyethylenes
Authors: Aigbodion Aireguamen I. , Ressia Jorge A. , Ciolino Andrés E. , Failla Marcelo D. , Vallés Enrique M. 
Published: October 2009

AbstractThe effect of the hydrogenation of the terminal vinyl groups on the peroxide modification and rheological properties of high‐density polyethylene (HDPE) was investigated. The aim of the study was to determine exclusively the effect of the terminal vinyl groups on the peroxide crosslinking and rheological properties of HDPE with one polymer type. This was achieved by hydrogenation of the terminal vinyl groups of a commercial HDPE to obtain an identical material from a structural point of view, which differed only in the nature of the terminal unsaturations, and the comparison of its level of peroxide crosslinking with that of the original polymer. Hydrogenated and unhydrogenated polymer samples were modified at 170°C with different amounts of organic peroxide ranging from 125 to 5000 ppm. Changes in the molecular structure were determined by Fourier transform infrared spectroscopy, size exclusion chromatography, and rheological measurements. Hydrogenation of the terminal groups of the original polymer significantly reduced the rate of modification or crosslinking. The dynamic viscosity and elasticity increased with the level of peroxide modification. Unhydrogenated samples exhibited rapid increases in viscosity and elastic modulus, whereas their hydrogenated counterparts required about 500% of the amount of peroxide needed for the unhydrogenated sample to attain similar structural changes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Electrical and thermal properties of γ‐irradiated nitrile rubber/rice husk ash composites
Authors: Mohamed Rasha M. , Radwan Reda M. , Abdel‐Aziz Mohamed M. , Khattab Magdy M. 
Published: October 2009

AbstractThe effects of both the rice husk ash (RHA) loading and fumed silica (FS) loading on the structure, thermal stability, and electrical properties of acrylonitrile–butadiene rubber (NBR) composites were studied. The filler loading were chosen to be 5 and 20 phr for RHA and 5 and 30 phr for silica. Also, the effect of the γ‐irradiation dose (25 kGy) on these parameters was investigated. The structure and thermal stability were studied with X‐ray diffraction and thermogravimetric analysis techniques. Furthermore, some electrical parameters, such as the direct‐current electrical conductivity (σdc), activation energy (Ea), dielectric constant (ϵ′), and dielectric loss (ϵ″), were determined. The incorporation of both RHA and FS resulted in improved thermal stability after γ irradiation at 25 kGy. The loading of FS on NBR was shown to decrease σdc, ϵ′, and ϵ″ and increase Ea. On the other hand, the loading of RHA showed the opposite trend. Finally, γ irradiation of NBR composites filled with both fillers decreased the values of σdc, ϵ′, and ϵ″ for all the samples, which followed the trend for the unirradiated composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Phase compatibility and barrier properties of ethylene/vinyl alcohol copolymer based hybrid materials
Authors: Nam Jae‐Do , Kim Seong Woo 
Published: October 2009

AbstractAn ethylene/vinyl alcohol copolymer (EVOH) with superior barrier properties was used as an organic component to prepare EVOH/SiO2 hybrid materials with improved gas barrier properties with a sol–gel method. As a silane coupling agent, 3‐isocyanatopropyl triethoxysilane (IPTES) was used to promote interfacial attraction between the organic EVOH segments and the inorganic silicate network in the hybrid. The phase compatibility was evaluated by analysis of Fourier transform infrared spectroscopy and phase morphology and the optical properties of the hybrids. We confirmed that the addition of the silane coupling agent IPTES up to some level of content resulted in enhanced phase compatibility and optical transparency of the nanostructured hybrid material with a homogeneous phase morphology exhibiting no microphase separation. For the preparation of the monolayer coated film, the biaxially oriented polypropylene substrate pretreated with a corona was coated with the hybrid sols by a spin‐coating method. The oxygen permeation behavior through the coated film was examined with various contents of the silane coupling agent IPTES and inorganic silicate precursor tetraethoxyorthosilicate in the hybrid system. Consequently, it was revealed that an optimum range of IPTES and tetraethoxyorthosilicate contents was required to produce high barrier EVOH/SiO2 hybrid materials with a stable homogeneous microstructure and enhanced optical transparency. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of the thin‐film thickness and crystallization temperature on the spherulitic structure of polymer thin films
Authors: Liu Jieping , Qiao Xiaoping , He Shuangai , Cao Qikun , Wang Hui 
Published: October 2009

AbstractThe spherulitic structure and morphology of poly(3‐hydroxybutyrate) (PHB) thin films crystallized from the melt were observed with a polarizing optical microscope. Depending on the thickness of the PHB thin film and crystallization temperature, banded and nonbanded spherulites could form. Reducing the thin‐film thickness and crystallization temperature was favorable for the formation of the banded structure. The morphology transition from banded spherulites to nonbanded spherulites was related to the ratio of the crystallization rate to the diffusion rate. The formation mechanism of the banded structure was examined with the discontinuity growth theory. A depletion zone was considered to appear periodically at the crystal growth front because of the slow diffusion rate, and this may have resulted in the banded spherulites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of a photoinitiator on the photochemical stability of poly(methyl methacrylate) studied with fourier transform infrared spectroscopy
Authors: Kaczmarek Halina , Gałka Piotr , Kowalonek Jolanta 
Published: October 2009

AbstractFourier transform infrared (FTIR) spectroscopy was used to investigate the effect of a commercial photoinitiator [2,2‐dimethoxy‐2‐phenylacetophenone (DMPA); Irgacure 651, Ciba, Basel, Switzerland] incorporated into poly(methyl methacrylate) (PMMA). Pure PMMA and modified PMMA (containing 5% DMPA) films were exposed to a xenon lamp in air. Qualitative and quantitative analyses of the recorded FTIR absorption spectra were done. This allowed us to determine the differences in the course of polymer photooxidative degradation occurring in PMMA and PMMA doped with DMPA. We found that the initiator added to polymer film enhanced the efficiency of the formation of the photooxidized products containing functional groups of different types, which could be distinguished by mathematical treatment of the FTIR spectra. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Vibration damping and electrical conductivity of styrene–butyl acrylate random copolymers filled with carbon black
Authors: Shamir D. , Siegmann A. , Narkis M. 
Published: October 2009

AbstractEmulsion‐polymerized poly(styrene‐rand‐butyl acrylate) (St–BA) copolymers exhibit damping capabilities over a wide temperature range with changes in the monomer ratio. Blending copolymers of different compositions results in a multidamping peak, further widening the effective damping temperature range. Adding carbon black (CB) reduces the peak damping intensity but enhances damping at higher temperatures. The addition of dodecyl benzene sulfonic acid to an St–BA/CB aqueous dispersion improves the dispersion of CB in the polymer, reducing the percolation threshold and improving the conductivity while slightly affecting the mechanical behavior. The electrical properties of the St–BA/CB system are affected by the copolymer composition, influencing the polymer surface tension. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of poly(ϵ‐caprolactone)‐block‐poly(n‐butyl acrylate) by the combination of ring‐opening polymerization and atom transfer radical polymerization with Ti[OCH2CCl3]4 as a difunctional initiator. II. Synthesis and characterization of poly(ϵ‐caprolactone)‐block‐poly(n‐butyl acrylate) copolymers
Authors: Li Peichun , Xia Zhean , Zerroukhi Amar , Chen Jianding , Chalamet Yvan , Jeanmaire Thomas 
Published: October 2009

AbstractThe kinetics and controllability of the Ti[OCH2CCl3]4‐initiated atom transfer radical polymerization (ATRP) of n‐butyl acrylate were investigated. Then, with Ti[OCH2CCl3]4 as the initiator, poly(ϵ‐caprolactone)‐block‐poly(n‐butyl acrylate) (PCL‐b‐PBA) copolymers were synthesized by the combination of the ring‐opening polymerization (ROP) of ϵ‐caprolactone and ATRP of n‐butyl acrylate. With different sequential combinations of ROP and ATRP, three routes were used to synthesize PCL‐b‐PBA copolymers. The composition characterization results demonstrated that the first‐ROP‐then‐ATRP route was most efficient; it was followed by the in situ ATRP and ROP route and then the first‐ATRP‐then‐ROP route. Furthermore, with a Haake Rheomix reactor (Thermo Electron Corp., Karlsruhe, Germany), the PCL‐b‐PBA copolymers were in situ synthesized in a poly(methyl methacrylate) matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effects of annealing (solid and melt) on the time evolution of the polymorphic structure of polyamide 6
Authors: Zhao Xiong‐Yan , Zhang Bing‐Zhu 
Published: October 2009

AbstractTo understand whether and how the thermal history, especially the melting annealing, affects the polymorphism and thermal property of polyamide 6 (PA6), the temperature‐modulated differential scanning calorimetry technology was used to investigate the effects of thermal histories, including annealing temperature, annealing time, and cooling rate, on the polymorphic behavior and thermal property of PA6. It was found that longer annealing time and faster cooling rate favored the formation of α crystal when PA6 samples were annealed in the solid‐state at 175°C. As the annealing temperature was elevated to 195°C, faster cooling rate also favored the formation of α crystal, whereas longer annealing time was more favorable for the formation of γ‐form crystals. When PA6 samples were annealed in the melt‐state (245°C), however, although the α crystal was dominating crystalline phase, the formation of γ crystal was greatly enhanced with increasing annealing time and cooling rate. Moreover, a small endothermic peak was observed in the low‐temperature region in PA6 samples annealed at 175°C and 195°C, which might be related to the melting of microcrystals formed in the amorphous regions during annealing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of water‐glass‐based silica aerogel powder via with and without squeezing of hydrogels
Authors: Rani T. Sobha , Subha M. C. S. , Venkata Reddy G. , Kim Yong‐Ha , Ahn Young‐Soo 
Published: October 2009

AbstractThe present article describes the synthesis of water‐glass‐based silica aerogel powder via coprecursor method, using with and without squeezing, in drying technique. The present research was aimed to develop a simple, cost‐effective, and rapid drying process, i.e., squeezing through sol–gel synthesis. The physical and textural properties of the aerogel powder synthesized with and without squeezing process via ambient pressure drying (APD) have been studied and compared. For characterization of aerogel powder, we employed Brunauer, Emmett, and Teller, Barrett‐Joyner‐Halenda, and field emission scanning electron microscope techniques. The experimental results showed that the properties of the aerogel powder obtained by squeezing are superior to those dried in a furnace one. The squeeze‐dried aerogel powder exhibited lower tapping density (0.126 g/cm3) than furnace dried. Furthermore, textural investigations revealed that the aerogel powder has high‐specific surface area (752.3 m2/g), high porosity, low shrinkage, and uniform pore size distribution, which is obtained by squeezing process via APD. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Study on mechanical properties of powder impregnated glass fiber reinforced poly(phenylene sulphide) by injection molding at various temperatures
Authors: Zhai Huan , Zhou Xiaodong , Fang Li , Lu Ai 
Published: October 2009

AbstractThe prepreg of continuous glass fiber reinforced poly(phenylene sulphide) (PPS) was prepared using the powder impregnation technique and cut into the pellets, in which the length of glass fibers was the same as the pellets. After injection molding, the mechanical properties were tested and the effects of the pellet length, fiber content, and thermal treatment on the mechanical properties at different temperatures were studied. It is found that the tensile strength and flexural strength of 6‐mm pellet sample are slightly higher than that of 3‐ and 12‐mm pellet samples. The tensile strength, flexural strength, and modulus decrease significantly with increasing the temperature. The notched Izod impact strength at 85ºC is higher than both at 25ºC and 205ºC. At 205ºC, the glass fiber reinforced PPS composites can still keep better mechanical properties. When the fiber content ranges from 0 to 50%, the mechanical properties increase with increasing the fiber contents at different temperatures, except the notched Izod impact strength do not further increase at 145 and 205ºC with raising the fiber content from 40 to 50%. Thermal treatment could improve the mechanical properties of the composites at higher serving temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effect of modified pluronic on the distribution of fillers in the polyvinyl chloride matrix
Authors: Rozik Nehad N. , Abd‐El Messieh S. L. , Abd‐El Nour K. N. 
Published: October 2009

AbstractPluronic was modified by using maleic anhydride (MA) and was characterized by means of FTIR and 1H NMR. Polyvinyl chloride (PVC) was blended with different contents of modified pluronic (MPL). After 20% by weight MPL, no significant change was noticed in either the electrical or the mechanical properties. The addition of 10 wt % MPL to PVC loaded with different contents of titanium oxide (TiO2) and sodium bentonite was chosen to act as a dispersing agent for the two types of fillers. This result was obtained through the measurements of permittivity ε′ and dielectric loss ε″ at the frequency range (102−105 Hz) in addition to the electrical conductivity (σ). According to Arrhenius equation, the activation related to both conductivity Eσ and relaxation time Eτ in addition to the experimental σo were found to confirm the validity of compensation law for the semiconducting PVC system. The increase of ε′ and ε″ by increasing filler content in the presence of 10% MPL in comparison with those before the addition of such concentration of MPL indicates a homogenous distribution of filler in the PVC matrix. This result finds further justification through the mechanical measurements and the scanning electron micrographs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Pervaporative studies using polyimide‐filled PDMS membrane
Authors: Garg P. , Singh R. P. , Pandey L. K. , Choudhary V. 
Published: October 2009

AbstractThe application of pervaporation (PV) to the removal of volatile organic from aqueous solutions has become very interesting in the last few years. It is caused by the increasing level of compounds, such as petrochemical solvents (benzene, toluene, and xylenes) or chlorinated solvents (trichloroethylene or tetrachloroethylene), which are polluting the natural environment. In this work, effects of polyimide (PI) (prepared by direct polycondensation of dianhydride and diamine followed by thermal cyclization of polyamic acid) filler on PV properties of poly(dimethyl siloxane) (PDMS) have been studied. PDMS membrane filled with PI was used for the separation of benzene (Bz) and toluene (Tol) from the diluted aqueous solution and the results were compared with the neat PDMS membrane of similar thickness. The PDMS‐PI membrane showed normalized flux (J′) upto 1.2 kg μm/m2h for Bz and 1.48 kg μm/m2h for Tol and selectivity of organics varies from 7.3 to 3.2 for Bz and 8.9 to 2.8 for Tol with increasing concentration of organics. Concentration of PI filler in PDMS varied 5–25% w/w. PI filler increases thermal as well as mechanical stability of filled PDMS membranes. PDMS membrane filled with 25% PI was chosen for the pervaporation studies. The membranes were characterized by FTIR, thermogravimetric analyser and scanning electron microscopy. The mechanical strength of PDMS filled with 25% w/w PI (SPI‐25) membrane was found to be 2.7 MPa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Development of biosensor for phenol detection using agarose–guar gum based laccases extracted from Pleurotus ostreatus
Authors: Kushwah Brajesh Singh , Bhadauria Seema 
Published: October 2009

AbstractLaccases from Pleurotus ostreatus was extracted from the Shaken flask cultures of Pleurotus ostreatus grown at 25°C with continuous agitation (110 rpm.) in baffled 1000 mL Erlenmeyer flasks containing 200 mL medium. The basal GYP medium used for cultures contained 20 g glucose l−1, 5 g yeast extract l−1, 5 g peptone from casein l−1, and 1 g MgSO4.7H2O l−1. The pH was adjusted to 5.0 with H3PO4 before sterilization. The kinetics of oxidation reactions catalyzed by laccases was studied using 2,2′‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulphonic acid). The laccases showed lower specific activity and higher activity in nonpolar organic solvents. A biosensor using laccases was constructed for the determination of phenol. The enzyme was extracted from Pleurotus ostreatus and entrapped in agarose–guar gum composite biopolymer matrix. Phenol was determined by direct reduction of biocatalytically liberated quinone species at −0.1 V versus Ag/AgCl (3M KCl). The response was found to be linear and concentration dependent.It has a shelf life of more than 2 months when stored at 4°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010