bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of the enzymatic degradation of poly(vinyl acetate) in solution
Authors: Chattopadhyay Sujay , Madras Giridhar 
Published: June 2003

AbstractThe enzymatic degradability of poly(vinyl acetate) was investigated in toluene solutions at various temperatures with hog pancreas lipase. The polymer degraded by specific scission to yield oligomeric products with a molecular weight of 700. Continuous distribution kinetics were used to determine the rate coefficients. The variation of the rate coefficients with the temperature indicated an optimum at 55°C. The p‐toluene sulfonic acid catalyzed degradation of poly(vinyl acetate) was also investigated. The degradation mechanism was random chain scission, and the energy of activation for degradation was determined from the variation of the rate coefficients with the temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2579–2582, 2003
Durable and regenerable antimicrobial textiles: Synthesis and applications of 3‐methylol‐2,2,5,5‐tetramethyl‐imidazolidin‐4‐one (MTMIO)
Authors: Qian Lei , Sun Gang 
Published: June 2003

AbstractA new precursor of halamine compounds, 3‐methylol‐2,2,5,5‐tetramethylimidazolidin‐4‐one (MTMIO), was synthesized by methylolation of 2,2,5,5‐tetramethylimidazolidin‐4‐one (TMIO) and characterized by 1H‐NMR and FTIR. By chemically reacting MTMIO with cellulose, TMIO rings were successfully grafted onto cellulose‐containing fabrics. After a subsequent chlorination, the treated fabrics were converted to halamine structures, which then demonstrated effective antibacterial efficacy. As expected, the halamine structure generated from TMIO is much more stable, and therefore, the biocidal functions of the finished materials are more durable. The results indicated that this halamine structure could survive repeated home laundering and would require less frequent chlorine recharging to maintain the biocidal properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2418–2425, 2003
Degradation and stabilization of cosmetic polyetherurethane in alcoholic solution
Authors: Kim Young Shin , Park Jae Hyung , Bae You Han 
Published: June 2003

AbstractA polyetherurethane (PEU) was synthesized for potential cosmetic applications by coupling poly(tetramethylene oxide) (PTMO, Mn = 2000 g mol−1) and poly(ethylene oxide) (PEO, Mn = 2000 g mol−1) with 4,4′‐diphenylmethane diisocyanate (MDI), without using a chain extender. The PEU polymer, synthesized with PEO and PTMO in the ratio of 1:3 by weight, was soluble in ethanol–water mixed solvents. The solution formed a thin film in situ on the skin by coating, which was flexible and elastomeric with appropriate skin adhesiveness. However, PEU was susceptible to degradation when it was exposed to an ethanol–water (80/20 v/v %) mixed solvent and stored in an air‐filled and sealed bottle at 60°C for 4 weeks. These conditions resulted in deterioration of PEU molecular weight (Mn), viscosity, and mechanical properties. Peak analysis of the Fourier transform infrared spectrum of the aged PEU revealed that >97% of the urethane carbonyl bonds remained, whereas ether bonds were significantly reduced (∼82% of initial value). The degraded PEU contained ester bonds, which were confirmed by proton and carbon‐13 nuclear magnetic resonance spectroscopy. This observation suggests that oxidative chain cleavage rather than hydrolysis was the dominant reaction in the degradation process. Two approaches were adopted to minimize oxidative degradation of PEU dissolved in an ethanol–water (80/20 v/v %) mixed solvent; they were, applying a nitrogen environment and adding an antioxidant (1.8 wt % dry PEU). The results indicate that reduction of oxidative degradation produced a synergistic effect. Vitamin E was a more effective antioxidant than butylated hydroxytoluene (BHT), which is a typical antioxidant for commercial polyurethanes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2270–2276, 2003
Novel preparation of poly(propylene)–layered silicate nanocomposites
Authors: Tang Yong , Hu Yuan , Wang Shaofeng , Gui Zhou , Chen Zuyao , Fan Weicheng 
Published: June 2003

AbstractWe used a novel approach to prepare poly(propylene)–clay nanocomposite starting from pristine montmorillonite and reactive compatibilizer hexadecyl trimethyl ammonium bromide. The nanocomposite structure was revealed by X‐ray diffraction and high‐resolution electronic microscopy. The thermal properties of the nanocomposite were investigated by thermogravimetric analysis. An increase of thermal stability was observed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2586–2588, 2003
Determination of the diffusion coefficients of organic solvents in polyepichlorohydrin: A comparative study of inverse gas chromatography and sorption methods
Authors: Etxabarren C. , Iriarte M. , Etxeberria A. , Uriarte C. , Iruin J. J. 
Published: June 2003

AbstractThe diffusivity of organic solvents in polyepichlorohydrin was studied with two different experimental setups: inverse gas chromatography (IGC) with packed columns and sorption measurements in gravimetric experiments monitored in a Cahn electrobalance. The aim of this work was to test the possibility of solving an inherent problem in the data reduction of IGC measurements, that is, the necessity of characterizing the morphology of the polymer coated on the support (usually given in the so‐called geometric factor of the column). Temperatures between 35 and 65°C were used in the IGC experiments, whereas the sorption measurements were performed between 30 and 40°C. Glass beads were used as supports in IGC for obtaining data concerning the variation of the plate height with the average gas velocity, with which the use of the Van Deemter equation allowed the determination of the diffusion coefficient if the geometric factor was known. In the sorption experiments, the diffusion coefficients at different penetrant activities were directly measured. For their extrapolation within the same concentration range used for IGC (infinite dilution of the penetrant), the theoretical model of Vrentas and Duda was used. By a combination of sorption and IGC experiments, the geometric factor of an IGC column could be adjusted, and this allowed the determination of the diffusion parameters of any other solvent in the same column. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2216–2223, 2003
Phase behavior, density, and crystallization of polyethylene in n‐pentane and in n‐pentane/CO2 at high pressures
Authors: Zhang Wei , Dindar Cigdem , Bayraktar Zeynep , Kiran Erdogan 
Published: June 2003

AbstractThe phase behavior and volumetric properties of polyethylene (PE) in solutions of n‐pentane and n‐pentane/CO2 were studied in a temperature (T) range of 370–440 K at pressures up to 60 MPa. Measurements were conducted with a variable‐volume view‐cell system equipped with optical sensors to monitor the changes in the transmitted light intensity as the P or the T of the system was changed. Lower‐critical‐solution‐temperature‐type behavior was observed for all of the liquid–liquid (L–L) phase boundaries, which shifted to higher pressures in solutions containing CO2. The solid–fluid (S–F) phase boundaries were investigated over a P range of 8–54 MPa and took place in a narrow T range, from 374 to 378 K in this P interval. The S–F phase boundary showed a unique feature in that the demixing temperatures showed both increasing and decreasing trends with P depending on the P range. This was observed in both the PE/n‐pentane and PE/n‐pentane/CO2 mixtures. The density of these solutions were measured as a function of P at selected temperatures or as a function of T at selected pressures that corresponded to the paths followed in approaching the phase boundaries (S–F or L–L) starting from a homogeneous one‐phase condition. The data showed a smooth variation of the overall mixture density along these paths. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2201–2209, 2003
Polycondensation between p‐dibromobenzene and m‐dibromobenzene
Authors: Wu Biyao , Yamamoto Takakazu 
Published: June 2003

AbstractNiCl2 (bpy)‐catalyzed polycondensation between p‐dibromobenzene and m‐dibromobenzene was carried out under various conditions. With the polycondensation, a series of copolymers with number‐average molecular weights of 2400 (by gel permeation chromatography with polystyrene standards) was formed, and some samples had good solubility in organic solvents. The IR spectra and the ultraviolet spectra measured in a tetrahydrofuran (THF) solution of the copolymer showed that there were p‐phenylene and m‐phenylene units in the copolymer. According to analyses with differential scanning calorimetry, thermogravimetric analysis, and X‐rays, with an increasing molar ratio of m‐phenyl units in the copolymer, the glass‐transition temperature, the temperature of viscous flow, and the crystallizability of the polyphenylene copolymer decreased. The fluorescence spectra of the copolymer measured in a THF solution showed an emission maximum at 373–376 nm, whereas the maximum shifted to 436.6 nm for the film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2210–2215, 2003
Effect of monomethyl itaconate‐grafted HDPE and EPR on the compatibility and properties of HDPE–EPR blends
Authors: López‐Manchado M. A. , Yazdani‐Pedram M. , Retuert J. , Quijada R. 
Published: June 2003

AbstractTo improve the compatibility and properties of blends based on high‐density polyethylene (HDPE) and the ethylene–propylene copolymer (EPR), the functionalization of both through grafting with an itaconic acid derivative, monomethyl itaconate (MMI), was investigated. The grafting reaction was performed at 180°C in a Brabender Plasticorder using an initial monomer concentration of 3 phr in the case of HDPE and 5 phr in the case of EPR. 2,5‐Dimethyl‐2,5‐bis(tert‐butylperoxy)hexane was used as a radical initiator for the functionalization of HDPE and dicumyl peroxide was used as a radical initiator for the modification of EPR. The degree of grafting was 1.56% by weight for HDPE and 0.8% by weight for EPR. The effect of grafting on the processability, morphology, and thermal and mechanical properties of the blends are of particular interest. The results show that the grafting reaction increases the toughness and elongation at break of all tested blends and they retained their strength and stiffness. Moreover, the grafted polymers behaved as nucleating agents, accelerating the HDPE crystallization. These results are particularly relevant when both polymeric phases are modified. Morphological studies are in concordance with the mechanical characterization, showing a reduction of the rubber particle size and a better interfacial adhesion when both polymers are functionalized with MMI. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2239–2248, 2003
Studies on the effect of laser radiation on the thermal stability of stabilized poly(vinyl chloride)
Authors: Nouh S. A. , Radwan M. M. , Agami W. R. , Morsy M. 
Published: June 2003

AbstractNonisothermal studies were carried out using thermogravimetry (TG) and differential thermogravimetry (DTG) to obtain the activation energy of the decomposition for poly(vinyl chloride) (PVC), stabilized by ethyl, N‐phenylmaleimide, and 4‐carboxylate (ENPMC). Thermal gravitational analysis (TGA) indicated that the ENPMC–PVC samples decompose in two main breakdown stages. The effect of the addition of a stabilizer (ENPMC), with different concentrations, to PVC was studied. The results indicate that the addition of ENPMC with 0.01 g/1 g PVC enhances the thermal stability of pure PVC. Samples from 0.01 g ENPMC/1 g PVC were exposed to infrared laser radiation with energy fluency at levels between 0.95 and 8.53 J/cm2. The results of the thermal experiments indicate that the onset temperature of decomposition T0 and thermal activation energy of decomposition Ea are affected by the laser energy fluency owing to the simultaneous processes of degradation and crosslinking. The variation of transition temperatures with either the stabilizer concentration or the laser energy fluence was determined using differential thermal analysis (DTA). The results indicate that the irradiation with a laser to 7.11 J/cm2 decreases the melting temperature of the pure PVC and this is most suitable for applications requiring the molding of this polymer at lower temperatures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2249–2255, 2003
Texture and morphology of biaxially stretched poly(ethylene naphthalene‐2,6‐dicarboxylate)
Authors: Douillard A. , Hardy L. , Stevenson I. , Boiteux G. , Seytre G. , Kazmierczak T. , Galeski A. 
Published: June 2003

AbstractThe orientation of poly(ethylene naphthalene‐2,6‐dicarboxylate) (PEN) films with different morphologies were studied by wide‐angle X‐ray diffraction. Different structures were obtained by thermally treating biaxially stretched PEN samples. Virgin and thermally treated (1 h at 240, 250, and 260°C) samples of PEN bioriented films were characterized by DSC to determine the glass‐transition temperature and the crystallinity ratio. To define the orientation of crystallites in the 25 μm thick bioriented samples, pole figures were recorded for various PEN samples, as a function of their position in the transverse drawing direction. The significant result is that there is a dominant crystal population, whose c‐axis direction varies from +45° at one sample edge to −45° at the other edge, the orientation at the center being parallel to the transverse direction. There is also a secondary population, which can be seen only near the center. DSC studies also showed that by increasing the annealing temperature the crystallinity ratio was increased and pole figures showed that the texture was modified, probably because of disorientation mainly from an annealing temperature of 260°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2224–2232, 2003
Studies on syntheses and properties of episulfide‐type optical resins with high refractive index
Authors: Lü Changli , Cui Zhanchen , Wang Yongxia , Yang Bai , Shen Jiacong 
Published: June 2003

AbstractA series of novel high refractive index episulfide‐type optical resins were prepared by ring‐opening copolymerization of bis(β‐epithiopropylthioethyl) sulfide (BEPTES) with episulfide derivative of diglydicyl ether of bisphenol A (ESDGEBA) and 2,4‐tolylene diisocyanate (TDI), respectively, in the presence of triethylamine as a curing catalyst. The episulfide monomers, BEPTES and ESDGEBA, were synthesized from their corresponding epoxy compounds, respectively. The cured transparent resins exhibit high refractive index (nd> 1.63) and relatively low dispersion. The refractive index (nd) and Abbe's number (νd) of the BEPTES/ESDGEBA curing system increased linearly with the weight content of BEPTES monomer in the range from 1.633 and 34.0 for the copolymer with 10 wt % of BEPTES to 1.697 and 38.1 for the homopolymer of pure BEPTES. For the BEPTES/TDI curing system, the refractive index and Abbe's number varied linearly with the molar ratio of BEPTES to TDI from 1.652 and 28.7 to 1.669 and 34.6. High glass‐transition temperatures (Tg> 130°C) of the cured BEPTES/TDI resins were observed, which indicate that the cured BEPTES/TDI resins possess a good heat resistance. The optical, physical, and thermal properties of the episulfide‐type cured optical resins were also discussed in this study. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2426–2430, 2003
Resin‐transfer molding of natural fiber–reinforced plastic. I. Kinetic study of an unsaturated polyester resin containing an inhibitor and various promoters
Authors: Rouison David , Sain Mohini , Couturier Michel 
Published: June 2003

AbstractIn this study an autocatalytic model was used to describe the cure of a polyester system containing various promoters and an inhibitor. The effect of the initiator concentration was investigated. Isothermal DSC measurements were used to determine the kinetic parameters for the curing reaction. The rate of curing increased with increasing initiator concentration. The parameters were found to be temperature dependent. The nonlinear regression analysis showed that by fixing one parameter at a constant value the temperature dependency of the other parameters was described by simple relationships. The model was then compared to the experimental data. The reaction rate could be predicted fairly well in a wide range of temperatures. These results will be used to model the cure of this resin in a resin transfer‐molding (RTM) process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2553–2561, 2003
Nonisothermal crystallization kinetics of linear bimodal–polyethylene (LBPE) and LBPE/low‐density polyethylene blends
Authors: Gao Jungang , Yu Maoshang , Li Yanfang , Li Zhiting 
Published: June 2003

AbstractNonisothermal crystallization kinetics of linear bimodal–polyethylene (LBPE) and the blends of LBPE/low‐density polyethylene (LDPE) were studied using DSC at various scanning rates. The Avrami analysis modified by Jeziorny and a method developed by Mo were employed to describe the nonisothermal crystallization process of LBPE and LBPE/LDPE blends. The theory of Ozawa was also used to analyze the LBPE DSC data. Kinetic parameters such as, for example, the Avrami exponent (n), the kinetic crystallization rate constant (Zc), the crystallization peak temperature (Tp), and the half‐time of crystallization (t1/2) were determined at various scanning rates. The appearance of double melting peaks and double crystallization peaks in the heating and cooling DSC curves of LBPE/LDPE blends indicated that LBPE and LDPE could crystallize, respectively. As a result of these studies, the Zc of LBPE increases with the increase of cooling rates and the Tp of LBPE for LBPE/LDPE blends first increases with increasing LBPE content in the blends and reaches its maximum, then decreases as the LBPE content further increases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2431–2437, 2003
Performance stabilization of conductive polymer composites
Authors: Hou Yan Hui , Zhang Ming Qiu , Rong Min Zhi 
Published: June 2003

AbstractConductive polymer composites used as candidates for positive temperature coefficient (PTC) materials are faced with performance decay characterized by gradually increased room‐temperature resistivity and decreased PTC intensity. Considering that deterioration of the properties is mainly related to the capability of conductive networks established by conductive fillers to recover from the effect of repeated expansion/contraction in a timely manner, the present work introduces chemical bonding into the filler/matrix interphase. The experimental results indicate that in the composites consisting of conductive carbon black (CB), low‐density polyethylene (LDPE), and ethylene–vinyl acetate copolymer, CB particles can be covalently connected with LDPE through melt grafting of acrylic acid. As a result, the composites are provided with reduced room‐temperature resistivity and significantly increased PTC intensity. Compared with the composites filled with untreated CB, the present composites possess reproducible PTC behavior and demonstrate stable electrothermal output in association with negligible contact resistance at the composites/metallic electrodes contacts. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2438–2445, 2003
Binary mixtures of polyethylene and oxidized wax: Dependency of thermal and mechanical properties upon mixing procedure
Authors: Mtshali T. N. , Van Sittert C. G. C. E. , Djoković V. , Luyt A. S. 
Published: June 2003

AbstractThe influence of the preparation procedure on the thermal and mechanical properties of linear low‐density polyethylene (LLDPE)– and LDPE–oxidized wax blends was investigated. It was found that mechanically mixed blends show reduced thermal stability as well as ultimate mechanical properties (stress and strain at break) compared to that of extrusion mixed blends. However, the structure of the blend and consequently its thermal and mechanical behavior also depend on the initial morphology of polyethylene. DSC measurements show miscibility up to high wax contents in both blend types, but increasing the amount of wax in LDPE blends induces increasing crystallinity. As a result, the LDPE/wax blends show improved thermal stability of between 20 and 50°C at low wax concentrations. Although the elasticity modulus of the blends increases, increasing the amount of wax generally degrades the mechanical properties. The main reason for this is the reduced number of tie chains. Changes in the average concentration of tie chains with increasing wax content were calculated and a correlation was made with the ultimate properties of the blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2446–2456, 2003
Graft copolymerization of methyl methacrylate onto oil palm empty fruit bunch fiber using H2O2/Fe2+ as an initiator
Authors: Ibrahim Nor Azowa , Yunus Wan Md Zin Wan , Abu‐Ilaiwi Faraj A. , Rahman Mohd Zaki Ab , Bin Ahmad Mansor , Dahlan Khairul Zaman M. 
Published: June 2003

AbstractGraft copolymerization of methyl methacrylate (MMA) onto oil palm empty fruit bunch fiber (OPEFB) was successfully carried out in aqueous medium using hydrogen peroxide as an initiator. Results from the investigation of the optimum conditions for grafting are presented. Maximum percentage of grafting was achieved when the amount of initiator, cocatalyst, and nitric acid were 5.877 × 10−3 mol, 2.63 × 10−4 mol, and 3.24 × 10−3 mol, respectively. The optimum reaction temperature was 50°C and the reaction period was 120 min. The highest percentage of grafting and grafting efficiency were 220 and 47%, respectively, under optimum conditions. The grafted copolymer was characterized by FTIR spectroscopy and scanning electron microscopy. The presence of a band at 1730 cm−1 provides strong evidence of grafting. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2233–2238, 2003
Synthesis and characterization of poly(methyl methacrylate)/montmorillonite nanocomposites by in situ bulk polymerization
Authors: Xie Tingxiu , Yang Guisheng , Fang Xiaoping , Ou Yuchun 
Published: June 2003

AbstractPoly(methyl methacrylate)/montmorillonite (MMT) nanocomposites were prepared by in situ bulk polymerization. The results showed that the silicone coupling agent affected the structure and properties of hybrid materials. XRD analysis showed that the dispersion of clay in nanocomposites with silicone‐modified organophilic MMT was more ordered than that in nanocomposites with unmodified organophilic MMT. The glass transition temperature (Tg) of the nanocomposites was 6–15°C higher and the thermal decomposition temperature (Td) was 100–120°C higher than those of pure PMMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2256–2260, 2003
Impact performance of laminates made of syntactic foam and glass fiber reinforced epoxy as protective materials
Authors: Kim Ho Sung , Mitchell Calvin 
Published: June 2003

AbstractImpact performance of two‐dimensional quasi‐isotropic laminates subjected to impact loading with flat‐ended impactors has been studied in terms of impact stress, strain rate, and volume fraction of laminae. A simple model was formulated to predict impact stress within an elastic limit as a function of volume fractions of laminae. Individual impact parameters for syntactic foam and fiber‐reinforced epoxy were experimentally obtained at impact energy levels of 0.54 and 0.87 Joule, and used to predict impact stress of the laminates made of the same materials. A reasonable agreement between predictions and experimental results were found. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2306–2310, 2003