bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term investigation on hydrolytic degradation and morphology of poly(ethylene glycol terephthalate)‐b‐poly(butylene terephthalate) copolymer films
Authors: Zhang Aiying , Feng Zengguo , Xie Zhiguo 
Published: October 2008

AbstractPoly(ethylene glycol terephthalate)‐b‐Poly(butylene terephthalate) copolymer (PEGT‐b‐PBT) films with different copolymer compositions were incubated in phosphate buffered saline under pH 7.4 at 37°C to study hydrolytic degradation and morphology up to 300 days. With the fall of intrinsic viscosity and mass of degraded films, SEM micrographs show that a set of particular and highly interconnected porous morphologies closely related to the content of PBT hard segments in copolymer is developed. Moreover, the variation in PBT crystallinity for copolymer films with weight ratio of 70/30 fluctuates with the development of degradation profiles, and PEGT content for copolymer films with weight ratio of 80/20 and 70/30 gradually decreases. The hydrolytic experiments demonstrate that the degradation of PEGT‐b‐PBT copolymer results from the cleavage of ester bonds between hydrophilic PEG and terephthalate. At the beginning period of degradation, PEGT‐b‐PBT copolymer films follow a typical mechanism of bulk degradation, and then undergo both bulk degradation and surface erosion, all of which finally generate the particular porous morphologies for copolymer films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Controlling degradation and physical properties of chemical sand fixing agent‐poly(aspartic acid) by crosslinking density and composites
Authors: Yang Jun , Wang Fang , Tan Tianwei 
Published: October 2008

AbstractPoly(aspartic acid) (PASP) hydrogel crosslinked with 1,6‐ hexamethylene diamine was applied as sand fixing agent. The effect of crosslinking density of sand fixing agent on sand fixing property was studied. The relations between the degradation time and crosslinking density, sand fixing property, molecular weight, and mass loss were measured. It was found that the sand fixing property relied on the PASP crosslinking density and degradation time. The crust attained the maximal mechanical strength when the PASP crosslinking agent concentration was 0.0325 mol/L and the PASP hydrogel mass loss was 97.9% after 18 days. The composites added into PASP could increase mechanical property and prolong the degradation time when compared with the control. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of poly(ethylene succinate) and its copolyesters containing minor amounts of butylene succinate
Authors: Chen Chi‐He , Lu Hsin‐Ying , Chen Ming , Peng Jyun‐Siang , Tsai Chia‐Jung , Yang Chao‐Sen 
Published: October 2008

AbstractPoly(ethylene succinate) (PES) and its copolyesters that contain 7, 10, or 48 mol % butylene succinate (BS) were synthesized through a direct polycondensation reaction with titanium tetraisopropoxide as the catalyst. Measurements of intrinsic viscosity (1.08–1.27 dL/g) proved the success of the preparation of polyesters with high molecular weights. The compositions and the sequence distributions of the copolyesters were determined from 1H and 13C NMR spectra. The distributions of ethylene succinate and BS units were found to be random. Their thermal properties were elucidated using a differential scanning calorimeter (DSC) and a thermogravimetric analyzer. No significant difference exists among the thermal stabilities of these polyesters. All of the copolymers exhibit a single glass transition temperature. Wide‐angle X‐ray diffractograms (WAXD) were obtained from polyesters that were crystallized isothermally. The DSC thermograms and WAXD patterns indicate that the incorporation of BS units into PES significantly inhibits the crystallization behavior of PES. The heat of fusion of ideal PES crystals is 163 J/g, as determined by the depression of the melting point of PES crystals in acetophenone. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Hydrodynamic properties of aqueous dextran solutions
Authors: Xu Xuelin , Li Hangquan , Zhang Zhengdong , Qi Xin 
Published: October 2008

AbstractThe hydrodynamic performance of aqueous dextran solutions, including the rheological and thixotropic properties, were investigated. Three kinds of dextrans with different molecular weights were employed to examine the effects of the molecular weight, concentration, temperature, and so forth on the hydrodynamic properties of aqueous dextran solutions. The results showed that an aqueous solution of a dextran with a high molecular weight of 5.223 × 105 at a high concentration of 30 wt % had pseudoplastic properties, in contrast to the conclusions of other researchers finding that aqueous dextran solutions were Newtonian liquids. The viscosity of the aqueous dextran solutions decreased with temperature, and the activation energy was calculated to be 16,849.2 J/mol with a 10 wt % dextran (weight‐average molecular weight = 5.223 × 105) solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Investigation of styrene‐assisted free‐radical grafting of glycidyl methacrylate onto high‐density polyethylene using response surface method
Authors: Saeb M. R. , Garmabi H. 
Published: October 2008

AbstractIn this study, the free‐radical grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene (HDPE) in the presence of styrene, as a comonomer, is investigated using a Brabender internal mixer. To optimize grafting level of GMA onto HDPE, response surface method (RSM) was exploited. Using RSM method of experimental design, it was possible to investigate the individual effects of various variables including dicumyl peroxide (DCP) concentration, GMA content, as well as reaction time, and their interactions on grafting efficiency. The fitted quadratic model obtained from statistical analysis is expressed by an approximating function to investigate the final torque as a responding variable over the experimental range of the independent variables. The grafting yield of GMA onto HDPE for the prepared samples was determined using titration/back‐titration technique and Fourier transform infrared spectroscopy (FTIR). According to the torque–time diagrams, increasing the DCP content led to an increase in GMA grafting yield. Also, it was found that the reaction time imparts minor effect on the final processing torque, and there exists an interaction between DCP and GMA content. The results of melt flow index (MFI) test showed that increasing the reaction time at constant DCP and GMA content enhances the MFI values of the samples, due to the more probability of chain scission phenomenon. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Development of antimicrobial membranes via the surface tethering of chitosan
Authors: Nigmatullin R. , Konovalova V. , Pobigay G. 
Published: October 2008

AbstractTo render the surface of ultrafiltration membranes biocidal, cellulose membranes were modified with chitosan, a naturally occurring polycationic biocide. Through the use of chitosans of different molecular weights and membranes with different pore sizes, the alteration of the morphological structure of tethered chitosan layers was achieved. The importance of such structural differences in the antimicrobial activity of the prepared membranes against gram‐positive Staphylococcus aureus and gram‐negative Escherichia coli was studied. The antimicrobial efficiency improved with the use of chitosans with higher molecular weights and membranes with smaller pore sizes. This suggested that the surface location of the grafted chitosan chains was more preferential for a higher antimicrobial activity of the surface. Membranes modified with chitosan showed higher antimicrobial efficiency against gram‐positive S. aureus than against gram‐negative E. coli. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Bulk prepolymerization of styrene in the presence of polybutadiene: Determination of grafting efficiency by size exclusion chromatography combined with a new extended model
Authors: Casis Natalia , Estenoz Diana A. , Vega Jorge R. , Meira Gregorio R. 
Published: October 2008

AbstractThe bulk prepolymerization of styrene in the presence of polybutadiene for the production of high‐impact polystyrene is analyzed and compared with an equivalent solution reaction described by Estenoz et al. in 1999. The heterogeneous model reported by Casis et al. in 2006 is extended to predict the bivariate distributions of the graft copolymer topologies; each topology is characterized by the number of trifunctional branching points per molecule. The developed model assumes polymerization in two phases and requires the adjustment of a single kinetic parameter. Grafting efficiencies determined by solvent extraction/gravimetry are compared with determinations obtained by the deconvolution of size exclusion chromatograms of the total polymer. The chromatographic technique is fast and simple, but it requires a representative polymerization/fractionation model. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Using modulated‐temperature differential scanning calorimetry to study interphases in blends of styrene–butadiene and polybutadiene rubbers filled with a silanized silica nanofiller
Authors: Ostad‐Movahed S. , Ansarifar A. , Song M. 
Published: October 2008

AbstractPolybutadiene and styrene–butadiene rubber compounds containing a high loading of a precipitated silica nanofiller were prepared. The silica surfaces were pretreated with bis(3‐triethoxysilylpropyl) tetrasulfide to prevent the silica from interfering with the reaction mechanism of sulfur cure in the rubber. The rubber compounds were mixed together for different times and at different temperatures to produce styrene–butadiene rubber/polybutadiene rubber blends. The mass fraction and composition of the interphase in the blends were subsequently determined with modulated‐temperature differential scanning calorimetry. At 60–65°C, the mass fraction of the interphase in the blend increased after the rubbers were mixed together for 10 min, and then it decreased significantly when the mixing time was increased to 20 min. When the two rubbers were mixed together for 7 min at 60–105°C, the mass fraction of the interphase in the blend increased slightly because of a higher mixing temperature. The composition of the interphase in the blend also changed with the mixing time and mixing temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Application of the group contribution approach to Nafion swelling
Authors: Randová Alena , Bartovská Lidmila , Hovorka Štěpán , Poloncarzová Magda , Kolská Zdeňka , Izák Pavel 
Published: October 2008

AbstractThe anisotropic swelling of Nafion 112 membrane in pure organic liquids was monitored by an optical method. The findings were used as a basis for application of the group contribution method to the relative expansion in equilibrium. From a total of 38 organic liquids under study, 26 were selected as an evaluational set from which the group and structural group contributions were assigned. The remaining 12 compounds were used as the testing set. Value of ±1.5% in relative expansions was determined to be the experimental error. Maximum differences between the experimental and calculated relative expansions in both sets did not exceed the value of ±3%. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structure and properties of soy protein films plasticized with hydroxyamine
Authors: Tian Huafeng , Liu Dagang , Zhang Lina 
Published: October 2008

AbstractTwo kinds of transparent films of soy protein were successfully prepared by plasticizing with diethanolamine (DEA) and triethanolamin (TEA). The films were hot pressed at 140°C and 20 MPa, and characterized with Fourier transform infrared spectroscopy, scanning electron microscope, ultraviolet–visible spectrometer, differential scanning calorimetry (DSC), thermogravimetric analysis, and tensile testing. The results indicated that films with triethanolamine plasticizers possessed better optical transmittance (more than 80% at 800 nm) than those with diethanolamine and glycerol. All of the sheets exhibited only one Tg in DSC curves. Moreover, the soy protein plastics with TEA had higher thermal stability and mechanical properties, as well as lower water uptake than those with DEA and glycerol, as a result of the strong interaction between TEA and protein molecules. The soy protein materials will be promising for the application in the fields of package and container, substituting for the nongreen polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of brush copolymers based on methoxy poly(ethylene glycol) and poly(ε‐caprolactone)
Authors: Bajgai Madhab Prasad , Aryal Santosh , Parajuli Daman Chandra , Khil Myung‐Seob , Lee Duck Rae , Kim Hak Yong 
Published: October 2008

AbstractBrush copolymers composed of methoxy poly(ethylene glycol) (MPEG) and poly(ε‐caprolactone) (PCL) have been synthesized by the ring‐opening polymerization of ε‐caprolactone initiated by hydroxyl function of thermally esterified MPEG‐citrate in presence of stannous octoate. Citric acid (CA) acts as spacer between brush‐like MPEG and the long chain of PCL. Existence of hydrophobic domains as cores of the micelles were characterized by 1H NMR spectroscopy and further confirmed with fluorescence technique using pyrene as a probe. Critical micelle concentration (CMC) of the synthesized copolymer decreased from 0.019 to 0.0031 mg/mL on increasing the fraction of PCL. Along with the physicochemical study, the brush copolymers were explored for the preparation of nanoparticles by nanoprecipitation technique. The morphology and geometry of micelles were investigated by using DLS, AFM, and TEM. Hydrodyanamic dimensions of micelles were around 118 and 178 nm with the core size of 8–10 nm, which further aggregated to form secondary micelle of 60–90 nm. Such assembled polymeric micelles with its flexible dendritic MPEG corona could hold a promise for the immobilization (encapsulation) of hydrophobic drugs and subsequently promote sustained release so that it can be a good vehicle for anti‐cancer drug deliverance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
High yield synthesis of diverse well‐defined end‐functionalized polymers by combination of anionic polymerization and “click” chemistry
Authors: Ho Chun‐Chih , Dai Chi‐An , Su Wei‐Fang 
Published: October 2008

AbstractWell‐defined poly(methyl methacrylate) (Mn = 3630 g mol−1, PDI = 1.06) with a primary benzylic bromide prepared using anionic polymerization was successfully transformed into diverse end‐functionalities (ω‐carboxyl, ω‐hydroxy, ω‐methyl‐vinyl, ω‐trimethylsilane, and ω‐glycidyl‐ether) via “click” reaction. The bromine end‐terminated poly(methyl methacrylate) was first substituted by an azide function and sequentially was reacted with various functional alkynes (propiolic acid, propargyl alcohol, 2‐methyl‐1‐buten‐3‐yne, propargyl trimethylsilane, and propargyl glycidylether). In all the cases, 1H‐NMR, 13C NMR, FT‐IR, and GPC measurements show qualitative and quantitative transformation of the chain‐end poly(methyl methacrylate) into the desired functionalities with high conversion (above 99%). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Novel biodegradable amphiphilic poly(ε‐caprolactone)/poly(N‐vinylpyrrolidone) blends via successive in situ polymerizations
Authors: Xing Zhimin , Xie Tingxiu , Yang Guisheng 
Published: October 2008

AbstractIn this study, biodegradable blends of poly(ε‐caprolactone) (PCL) and poly(N‐vinylpyrrolidone) (PVP) were prepared by a new strategy in the following steps: (1) free radical polymerization of N‐vinyl‐2‐pyrrolidone (NVP) in ε‐caprolactone (CL); (2) ring‐opening polymerization of ε‐caprolactone in the presence of PVP to obtain the target blends. The structure of the blends was confirmed by FTIR and 1H NMR, and the molecular weight of PCL and PVP were determined by GPC. SEM study revealed that this polymerization method could decrease the disperse phase size and improve the interphase when compared with solution‐blending method. The phase inversion occurred when PVP content was 15–20 wt %. Subsequently, the PCL sphere dispersed in PVP matrix and its size decreased with the increase of PVP content. The contact angle results showed that PVP has a profound effect on hydrophilic properties of PCL/PVP blends. PCL/PVP blends are believed to be promising for drug delivery, cell therapy, and other biomedical applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparison of micelles formed by amphiphilic poly(ethylene glycol)‐b‐poly(trimethylene carbonate) star block copolymers
Authors: Kim Byung Soo , Oh Jae Min , Cho Jae Song , Lee Sang Hyo , Lee Bong , Khang Gilson , Lee Hai Bang , Kim Moon Suk 
Published: October 2008

AbstractIn this article, we describe the synthesis and solution properties of PEG‐b‐PTMC star block copolymers via ring‐opening polymerization (ROP) of trimethylene carbonate (TMC) monomer initiated at the hydroxyl end group of the core PEG using HCl Et2O as a monomer activator. The ROP of TMC was performed to synthesize PEG‐b‐PTMC star block copolymers with one, two, four, and eight arms. The PEG‐b‐PTMC star block copolymers with same ratio of between hydrophobic PTMC and hydrophilic PEG segments were obtained in quantitative yield and exhibited monomodal GPC curves. The amphiphilic PEG‐b‐PTMC star block copolymers formed spherical micelles with a core–shell structure in an aqueous phase. The mean hydrodynamic diameters of the micelles increased from 17 to 194 nm with increasing arm number. As arm number increased, the critical micelle concentration (CMC) of the PEG‐b‐PTMC star block copolymers increased from 3.1 × 10−3 to 21.1 × 10−3 mg/mL but the partition equilibrium constant, which is an indicator of the hydrophobicity of the micelles of the PEG‐b‐PTMC star block copolymers in aqueous media, decreased from 4.44 × 104 to 1.34 × 104. In conclusion, we confirmed that the PEG‐b‐PTMC star block copolymers form micelles and, hence, may be potential hydrophobic drug delivery vehicles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polypropylene cellulose‐based composites: The effect of bagasse reinforcement and polybutadiene isocyanate treatment on the mechanical properties
Authors: Ashori Alireza , Nourbakhsh Amir 
Published: October 2008

AbstractUsing bagasse fiber as the reinforcing filler and polypropylene as the thermoplastic matrix polymer, a reinforced composite was prepared, and its mechanical properties examined as a function of the amount of compatibilizing agents used. In the sample preparation, four levels of fiber loading (10, 20, 30, and 40 wt %), three levels of polybutadiene isocyanate (PBNCO) content (0, 2, and 4 wt %) and two levels of maleated polypropylenes (MAPP) content (0 and 3 wt %) as compatibilizing agents were used. The tensile properties of the composites improved as the fiber loading and the compatibilizing agents increased, but the impact strength was significantly decreased. The mechanical study revealed that the positive effect of compatibilizing agents on interfacial bonding. The composites treated with PBNCO showed superior tensile and impact properties than those without treatment. The findings indicated that bagasse as agro‐waste material is a valuable renewable natural resource for composite production and could be utilized as a substitute for wood in composite industries. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Magnetic and optical properties of poly(vinylidene difluoride)/Fe3O4 nanocomposite prepared by coprecipitation approach
Authors: Xu Chunhua , Ouyang Chunfa , Jia Runping , Li Yongsheng , Wang Xia 
Published: October 2008

AbstractPoly(vinylidene difluoride) (PVDF)/Fe3O4 magnetic nanocomposite was prepared by a simple coprecipitation method, and was characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), vibrating sample magnetometer (VSM), and ultraviolet visible spectroscopy (UV‐Vis). The SEM images showed that Fe3O4 nanoparticles were dispersed in the PVDF matrix as some aggregates with the sizes of 50 nm–2 μm, and the XRD curves showed the incorporation of the Fe3O4 nanoparticles in PVDF matrices and the decrease of the crystallinity of the PVDF. VSM results showed that the saturation magnetization (Ms) and remnant magnetization (Mr) of the PVDF/Fe3O4 nanocomposite increased with the increase of the Fe3O4 content, and that Ms and Mr along the parallel direction were higher than those along the perpendicular direction at the same Fe3O4 content. The coercive force (Hc) of the nanocomposite was independent of the Fe3O4 content and approximately equal along the parallel and perpendicular direction at the same Fe3O4 content. The optical band gap (Eg) of the PVDF/Fe3O4 nanocomposite was influenced by the Fe3O4 content, and decreased by 0.75 eV compared with that of pure PVDF when the Fe3O4 content was 3 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Design and Synthesis of Novel Benzopyran‐2‐one Derivatives of Expected Antimicrobial Activity through DNA Gyrase‐B Inhibition
Authors: Hassan Ghaneya S. , Farag Nahla A. , Hegazy Gehan H. , Arafa Reem K. 
Published: October 2008

AbstractIn an attempt to find a new class of antibacterial agents, we have synthesized thirty new coumarin (2H‐benzopyran‐2‐one) analogues. These derivatives include substituted azetidin‐2‐ones (β‐lactam) 3a–f, pyrrolidin‐2‐ones 4a–f, 2H‐1,3,4‐oxadiazoles 5a–f, and thiazolidin‐4‐ones 6a–f attached to 4‐phenyl‐2H‐benzopyran‐2‐one through an oxyacetamido or an oxymethyl bridge. The target compounds were synthesized starting from 2‐oxo‐4‐phenyl‐2H‐benzo[b]pyran‐7‐yl‐oxyacetic acid hydrazides 2a–f. The new compounds were evaluated as DNA gyrase‐B inhibitors through molecular modeling and docking techniques using the Molsoft ICM 3.4‐8C program. The synthesized compounds were also screened for antibacterial activity against four different species of Gram‐positive and Gram‐negative bacteria; as well as screening against C. albicans for antifungal activity. The molecular modeling data were in accordance with the antimicrobial screening results.
Synthesis of Novel Substituted 7‐(Benzylideneamino)‐4‐Methyl‐2H‐Chromen‐2‐one Derivatives as Anti‐inflammatory and Analgesic Agents
Authors: Ronad Pradeepkumar , Dharbamalla Satyanarayana , Hunshal Rajesh , Maddi Veeresh 
Published: October 2008

AbstractA series of novel Schiff' base‐containing a 7‐amino‐4‐methylcoumarin moiety have been synthesized III a–l, characterized by spectroscopic data and studied for their anti‐inflammatory and analgesic activity. The results of the anti‐inflammatory and analgesic activity evaluation of 7‐(substituted benzylideneamino)‐4‐methyl‐2H‐chromen‐2‐one derivatives III a–l proved to be comparable or more potent with respect to the reference drugs. In particular, compounds 7‐(4‐chlorobenzylideneamino)‐4‐methyl‐2H‐chromen‐2‐one III f, 7‐(2,4‐dichlorobenzylideneamino)‐4‐methyl‐2H‐chromen‐2‐one III g and 7‐(4‐bromobenzylideneamino)‐4‐methyl‐2H‐chromen‐2‐one III h exhibited potent anti‐inflammatory and analgesic activity.