bluuebunny/crossref_metadata_2025 huggingface dataset:
Syntheses of hydroxypropyl methylcellulose phthalate hydrogels in Na2CO3 aqueous solutions with electron‐beam irradiation
Authors: Xu Ling , Nagasawa Naotsugu , Yoshii Fumio , Kume Tamikazu
Published: June 2003

Novel cellulose ether hydrogels were prepared by the radiation‐induced crosslinking of hydroxypropyl methylcellulose phthalate (HPMCP) in a solution of Na2CO3. The effects of several factors, such as the HPMCP concentration, Na2CO3 concentration, absorbed dose, and dose rate, on the crosslinking of HPMCP were investigated in detail. An increase in the HPMCP concentration resulted in an increasing content of the gel fraction, and this meant that the crosslinking probability increased as well. Na2CO3 was essential for dissolving HPMCP in water, and a 4–5% Na2CO3 aqueous solution was optimal for the crosslinking of HPMCP. The dose rate also affected the radiation crosslinking of HPMCP; hydrogels with higher gel fractions and transparency could be formed at lower dose rates. The ratio of degradation to crosslinking of the gel was calculated according to the Charlesby–Rosiak equation, and it showed good agreement with the experimental results. Some important properties, such as the swelling kinetics, ion and ionic strength dependence, and pH dependence, of the HPMCP hydrogels were also investigated. The HPMCP hydrogels possessed excellent swelling rates and swelling ratios in some solvents, such as water and methanol, with a high hydrogen‐bonding parameter. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2123–2130, 2003
Effect of reaction kinetics of polymer electrolyte on the ion‐conductive behavior for poly(oligo oxyethylene methacrylate)–LiTFSI mixtures
Authors: Kwak Gun‐Ho , Tominaga Yoichi , Asai Shigeo , Sumita Masao
Published: June 2003

The effect of the reaction kinetics on the ionic conductivity for a comblike‐type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and 1H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (Tg), spin–spin relaxation time (T2), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH3 showed maximum ionic conductivity, σi, two to three times higher in magnitude than that of the σi of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003
Synthesis and characterization of novel copper/polyaniline nanocomposite and application as a catalyst in the Wacker oxidation reaction
Authors: Athawale Anjali A. , Bhagwat S. V.
Published: June 2003

Copper nanoclusters were synthesized by a chemical reduction of an aqueous copper salt solution by sodium borohydride. A polyaniline nanocomposite containing copper nanoclusters was prepared by polymerizing a monomer aniline hydrochloride solution containing the copper nanoclusters using ammonium persulfate as an oxidizing agent. The synthesized nanocomposite was characterized using various techniques such as UV‐visible spectroscopy, FTIR spectroscopy, X‐ray diffraction (XRD), and transmission electron microscopy (TEM). The presence of copper was confirmed by XRD and the size of the copper clusters was found to be ∼53 nm, which is in good agreement with that obtained from the TEM. The synthesized nanocomposite was used to serve as a catalyst in a Wacker oxidation reaction for the conversion of 1‐decene to 2‐decanone in the presence of molecular oxygen. The formation of 2‐decanone was confirmed using GC‐MS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2412–2417, 2003
Effect of nitrocellulose on the properties of PU–NC semi‐IPN wood coatings
Authors: Lu Kun‐Tsung , Liu Cheng‐Tzu , Lee Hong‐Lin
Published: June 2003

Wood coatings of PU–NC semi‐interpenetrating polymer networks (semi‐IPNs), made from blown castor oil (BCO), aromatic polyisocyanate (PTDI), and nitrocellulose (NC), were prepared by sequential polymerization method. To investigate the effects of NC on the properties of PU–NC semi‐IPNs wood coatings, three different viscosities of NC (½‐sec, ¼‐sec, and
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‐sec), and a PU catalyst [dibutyltin dilaurate (DBTDL)] were synthesized in this study. The results revealed that the PU–NC semi‐IPNs with ½‐sec NC‐containing coating had the shortest drying time, and their films had the best tensile strength, elongation at break, lightfastness, and solvent resistance. Dynamic mechanical analysis showed that PU–NC semi‐IPNs with ½‐sec NC or
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‐sec NC had good interpenetration between PU and NC, whereas PU–NC semi‐IPNs with ¼‐sec NC had a slight separation phase between PU and NC. In both PU–NC semi‐IPNs with ¼‐sec NC and those with \documentclass{article}\pagestyle{empty}\begin{document}${1\over 16}$\end{document}
‐sec NC, the addition of 0.2% DBTDL could effectively reduce the drying time of the coating and improve the film properties, including tensile strength, elongation at break, and lightfastness. In addition, the miscibility of PU and NC was examined in PU–NC semi‐IPNs with ¼‐sec NC. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2157–2162, 2003
Mobility and solubility of antioxidants and oxygen in glassy polymers. I. Concentration and temperature dependence of antioxidant sorption
Authors: Boersma Arjen
Published: June 2003

Sorption experiments have been conducted at temperatures between 65 and 135°C using five phenolic antioxidants in polycarbonate at different antioxidant concentrations. A model based on the free volume was used to predict the mobility of the additives. In this model, the ratio of the specific volume of a jumping unit to the free volume available in the polymer determines the diffusion behavior of the additives. It was found that the mobility of the antioxidant was predicted accurately using literature and experimental data on the free volume in polycarbonate. Furthermore, the solubility of the antioxidants was predicted very well, based on thermodynamic considerations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2163–2178, 2003
Synthesis and solution properties of single‐chain microgels from poly(N‐isopropylacrylamide) copolymer
Authors: Zhou Nan , Ni Jian , Yan Xiaohu , Wang Zhiliu , Cheng Rongshi
Published: June 2003

“Single‐chain” microgels were synthesized successfully from the cross‐linkable poly(N‐isopropylacrylamide) (PNIPAM) copolymer. This type of microgel has the exact chemical structure, molecular weight and molecular weight distribution of its precursor. It provides a direct way to compare the properties of linear polymers with those of their networks. The viscosity properties show that the microgels have lower critical solution temperatures (LCST) that are even higher than those of the corresponding linear copolymers. This can be attributed to the crosslinking points, which retard the change of the conformation of the network chains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2179–2183, 2003
Effect of epoxy resin on morphology and physical properties of PVC/organophilic montmorillonite nanocomposites
Authors: Wan Chaoying , Qiao Xiuying , Zhang Yong , Zhang Yinxi
Published: June 2003

Poly(vinyl chloride)/organophilic montmorillonite (PVC/OMMT) nanocomposites were prepared by means of melt blending. A liquid epoxy resin was used to aid PVC chains in intercalating into silicate layers. The effects of the preparation methods and epoxy resin contents on the melt intercalation of PVC were investigated. The morphology development, mechanical properties and optical properties of the PVC/OMMT composites were tested as functions of epoxy resin content and OMMT content. Wide‐angle X‐ray diffraction, transmission electron microscopy and scanning electron microscopy were used to characterize the morphology of the resulting composites. After being pretreated by the epoxy resin, the OMMT layers were largely intercalated into the PVC matrix, and even exfoliated at high epoxy resin content. The addition of epoxy resin led to a decrease in optical clarity of the composites but improved the processing stability, as indicated by yellowness index and haze measurement. However, the optical clarity of the composites containing 4 phr of epoxy resin (PVC/E‐OMMT) was improved by increasing the OMMT content, as shown by light transmission. Both the tensile strength and notched Izod impact strength of the PVC/E‐OMMT composites reached their maximum values when the OMMT content was 0.5 phr and the epoxy resin content was 2 phr. With further increase of the OMMT content and the epoxy resin content, the tensile strength decreased but was still higher than that of original PVC. The method of addition of epoxy resin had little effect on the physical properties but mainly influenced the morphology of PVC/OMMT nanocomposites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2184–2191, 2003
Kinetics of the enzymatic degradation of poly(vinyl acetate) in solution
Authors: Chattopadhyay Sujay , Madras Giridhar
Published: June 2003

The 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

A 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

A 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

We 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

The 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

The 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

NiCl2 (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

To 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

Nonisothermal 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

The 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

A 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

In 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

Nonisothermal 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

Conductive 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

The 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

Graft 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

Poly(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

Impact 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
Properties of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)
Authors: Kim Seon Jeong , Park Sang Jun , Chung Taek Dong , An Kay Hyeok , Kim Sun I.
Published: June 2003

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) and poly(N‐isopropylacrylamide) were prepared by the sequential‐IPN method. The IPN hydrogels were analyzed for sorption behavior of water at 35°C and at a relative humidity of 95% using a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used for the quantitative determination of the amounts of freezing and nonfreezing water. Free water contents in the IPN hydrogel of IPN1, IPN2, and IPN3 were 45.8, 37.9 and 33.1% in pure water, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2041–2045, 2003
Properties of EVM vulcanizates reinforced by in situ prepared sodium methacrylate
Authors: Du Aihua , Peng Zonglin , Zhang Yong , Zhang Yinxi
Published: June 2003

Ethylene–vinyl acetate copolymer (EVM) vulcanizates with good mechanical properties and high transparency were obtained using sodium methacrylate (NaMAA) as a reinforcing agent. Sodium methacrylate was in situ prepared through the neutralization of sodium hydroxide (NaOH) and methacrylic acid (MAA) in an EVM and used to reinforce the EVM cured by dicumyl peroxide (DCP). Different factors such as the DCP content, NaMAA content, and the mol ratio of NaOH/MAA were included to study their effects on the mechanical properties, optical properties, stress‐relaxation behavior, and crosslink structure of the EVM vulcanizates. The rheological behavior of the EVM compounds was also investigated and compared with that of the high abrasion furnace carbon black (HAF)/EVM compounds. The experimental results show that with an increase of the NaMAA content the curing rate index (CR) of the EVM compounds is greatly speeded up, while the Mooney viscosities of the compounds remain nearly unchanged. The mechanical properties and optical properties of the NaMAA‐reinforced EVM vulcanizates depend on the NaMAA content and the mol ratio of NaOH/MAA. The formulation of DCP of 3 phr and a NaOH/MAA mol ratio of 1.0 is recommended for the EVM vulcanizate with high mechanical properties. At a given NaOH/MAA mol ratio of 1.0, all the EVM vulcanizates are transparent and the light transmission is over 76% in the NaMAA content range of 10–50 phr. The NaMAA/EVM vulcanizates show faster stress relaxation and more obvious stress‐softening effects than those of the HAF/EVM vulcanizates. Crosslink density analysis indicated that the EVM vulcanizates contain both covalent and ionic bonds. The ionic crosslink densities greatly increase with an increasing NaMAA content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2192–2200, 2003
Studies on second harmonic generation efficiency by a series of chiral polyesters
Authors: Philip Biju , Sreekumar K.
Published: June 2003

A series of optically active main‐chain polyesters were synthesized by high‐temperature polycondensation from biphenolic azo chromophores, (2R,3R)‐(+)‐diethyl tartrate and terephthaloyl chloride. The polyesters showed glass transition temperatures in the range of 100–135°C and were thermally stable to 350°C. The second harmonic generation efficiency of the polyesters was studied by the powder method and as thin films with 2‐methyl‐4‐nitroaniline as a reference. The SHG efficiency of the polymers was compared with that of low molecular weight chromophores. The polymers with chiral units showed good second harmonic generation efficiency. The SH signal also showed good temporal stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 11: 2468–2473, 2003
Chemically treated hard gelatin capsules for colon‐targeted drug delivery: A novel approach
Authors: Bajpai S. K. , Bajpai M. , Dengre R.
Published: June 2003

Hard gelatin capsules, containing riboflavin‐loaded poly (N‐viny1–2‐pyrrolidone)‐polyacrylamide cylindrical hydrogels, were modified chemically by treating with an aqueous formaldehyde solution for the purpose of delayed release of drug along the gastrointestinal tract. The tdis (disintegration time) of capsules was studied as a function of concentration of formaldehyde solution and the treatment time. The dynamic release of vitamin B2 was studied as a function of crosslinking ratio of the hydrogels. The device studied seems to have potential to be used for colon‐targeted drug delivery. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2277–2282, 2003
Barrier properties of a thermotropic liquid‐crystalline polymer
Authors: Ramathal Hansel , Lawal Adeniyi
Published: June 2003

A developmental thermotropic liquid‐crystalline polymer (TLCP) made by Eastman (trade name LN001) was used for barrier property studies. This material is a highly aromatic TLCP with a Tm of 332°C. A permeability study was carried out to determine the chemical resistance of the TLCP. The permeability of methanol and toluene through a membrane of the TLCP was studied using a two‐part cell and a gas chromatograph to monitor the flux. The membranes of the TLCP and LDPE (as control) were made by compression molding. Both solvents had higher permeability through LDPE than TLCP and that of toluene was higher than that of methanol. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2457–2463, 2003
Electrotransport of organic electrolytes through 2‐(dimethylamino)ethyl methacrylate–grafted polyethylene films and their separation and concentration
Authors: Yamada Kazunori , Taki Takayuki , Sato Kimihito , Hirata Mitsuo
Published: June 2003

Organic electrolytes with negatively chargeable functional groups such as benzoic acid (BA, weak acid), benzenesulfonic acid (BSA, strong acid), and p‐aminobenzoic acid (p‐ABA, ampholyte) were concentrated through polyethylene (PE) films photografted with 2‐(dimethylamino)ethyl methacrylate (DMAEMA) by electrotransport. The permeabilities of DMAEMA‐grafted PE (PE‐g‐PDMAEMA) films to BA and BSA were considerably increased by the application of direct current at pH 6. BA and BSA could be selectively permeated from the respective binary BA/phenyl‐1,2‐ethandiol (PhED, neutral) and BSA/PhED mixtures by making use of the difference in their permeabilities. In addition, BSA was selectively permeated from the binary BSA/BA mixtures. The organic electrolytes mentioned above were transported against their concentration gradient toward the anode side and their degrees of concentration went up to 90% by the continuous application of direct current. The degrees of concentration for organic electrolytes obtained by electrotransport in this study were slightly higher than those obtained by the uphill transport using the pH difference across the PE‐g‐PDMAEMA film, and the concentration time was considerably shortened. It was made clear that the electrotransport through the PE‐g‐PDMAEMA films is one of the effective techniques to selectively separate or concentrate organic electrolytes with negatively chargeable functional groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2535–2544, 2003
Study of high thermal conductive epoxy resins containing controlled high‐order structures
Authors: Akatsuka Masaki , Takezawa Yoshitaka
Published: June 2003

Heat is transported by phonons through dielectric solids such as ceramics and organic insulating resins. Especially in organic insulating resins, phonons scatter intensely mainly by their amorphous structure, which affects their thermal conductivities, usually 1 to 3 orders lower than those of ceramics and metals. Here, we show that by the thermosetting resin system with a crystal‐like structure that is microscopic anisotropy, the thermal conductivities of the resin themselves can be improved while keeping their macroscopic isotropy. We studied four kinds of diepoxy monomers with a biphenyl group or two phenyl benzoate groups as mesogens, and cured them thermally with an aromatic diamine curing agent. These thermal conductivities were maximally 5 times higher than that of conventional epoxy resins because mesogens were highly ordered to form crystal‐like structures to suppress phonon scattering. We also succeeded in the direct confirmation of the existence of crystal‐like structures in the epoxy resins by TEM observation. These results suggest a novel strategy to improve thermal conductivities of insulating resins themselves by controlling the high‐order structures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2464–2467, 2003
Electron spin resonance spectroscopy study on reduction of constrained‐geometry catalyst systems
Authors: Ye Zhibin , Wang Wen‐Jun , Zhu Shiping
Published: June 2003

The reduction of a constrained‐geometry catalyst (CGCTiMe2) activated with a series of cocatalysts, including modified methylaluminoxane (MMAO), tris(pentafluorophenyl) borane [B(C6F5)3], and combined B(C6F5)3/MMAO, was experimentally investigated using an on‐line electron spin resonance spectroscopy (ESR) technique. The effects of the solvent type, cocatalyst/catalyst ratio, and temperature on the reduction were examined. In the CGCTiMe2/MMAO system, increasing the Al/Ti molar ratio from 20 to 250 significantly increased the Ti(III) content. Adding trimethylaluminum to the system lowered the Ti(III) content. Three trivalent Ti species, Ti(a) (g = 1.972), Ti(b) [g = 1.992, α(H) = 7.4 G], and Ti(c) (g = 1.995), were observed. In the CGCMe2/B(C6F5)3 system, only one trivalent Ti species (g = 1.988) was observed. The CGCTiMe2/B(C6F5)3 system was more stable to reduction than the CGCTiMe2/MMAO system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2474–2482, 2003
Synthesis of 1‐Methyl‐5‐(pyrazol‐3‐ and ‐5‐yl‐ and 1, 2, 4‐triazol‐3‐ and 5‐yl)‐1, 2, 3, 6‐tetrahydropyridine Derivatives and Their Evaluation as Muscarinic Receptor Ligands
Authors: Del Giudice Maria Rosaria , Mustazza Carlo , Borioni Anna , Gatta Franco , Tayebati Khosrow , Amenta Francesco , Tucci Paolo , Pieretti Stefano
Published: June 2003

A series of 1‐methyl‐5‐(pyrazol‐3‐ and ‐5‐yl‐ and 1, 2, 4‐triazol‐3‐ and 5‐yl)‐1, 2, 3, 6‐tetrahydropyridine derivatives structurally related to arecoline were synthesized and evaluated on M1, M2, and M3 muscarinic receptors using [3H] pirenzepine and [3H] NMS as ligands. The binding affinity depended on the position and size of the substituents. The most interesting compounds were further evaluated in functional studies on isolated organs and in vivo for cholinergic side effects. Compounds 5l and 6i good M1 and M3 antagonistic properties in vitro and were devoid of cholinergic side effects in vivo.
Synthesis of 2‐Methylsulfanyl‐1H‐imidazoles as Novel Non‐nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
Authors: Loksha Yasser M. , El‐Badawi Mahmoud A. , El‐Barbary Ahmed A. , Pedersen Erik B. , Nielsen Claus
Published: June 2003

α‐Aminoketone hydrochlorides 2a—d were synthesized by Dakin‐West reaction from L‐phenylalanine and L‐cyclohexylalanine followed by hydrolysis in acidic medium. Treatment of 2a—d with aqueous potassium thiocyanate afforded 1, 3‐imidazole‐2‐thiones 3a—d which were alkylated with methyl iodide to give 2‐methylsulfanyl‐1H‐imidazoles 4a—d with 4‐benzyl/4‐cyclohexylmethyl and 5‐ethyl/5‐isopropyl substituents. Coupling of 4a—d with ethoxymethyl chloride or benzyloxymethyl chloride furnished N‐1 5a—d and N‐3 6a—h alkylated products. The synthesised compounds were tested for their activity against HIV‐1. The most active compounds have a cyclohexylmethyl group in the 5‐position of 6 and showed an activity against HIV‐1 comparable to the activity of Nevirapine.
Synthesis and Cytotoxicity of Substituted Ethyl 2‐Phenacyl‐3‐phenylpyrrole‐4‐carboxylates
Authors: Evans Michael A. , Smith Daniel C. , Holub Justin M. , Argenti Anthony , Hoff Mafoloe , Dalglish Gerard A. , Wilson Donna L. , Taylor Brett M. , Berkowitz Joshua D. , Burnham Bruce S. , Krumpe Keith , Gupton John T. , Scarlett Tanya C. , Durham, Jr Richard W. , Hall Iris H.
Published: June 2003

The substituted ethyl‐2‐phenacyl‐3‐phenylpyrrole‐4‐carboxylates were synthesized by a condensation of a beta‐chloroenal and an alpha‐aminoketone under neutral conditions. They proved to be potent cytotoxic agents against the growth of murine L1210 and P388 leukemias and human HL‐60 promyelocytic leukemia, HuT‐78 lymphoma, and HeLa‐S3 uterine carcinoma. Selective compounds were active against the growth of Tmolt3 and Tmolt4 leukemias and THP‐1 acute monocytic leukemia, liver Hepe‐2, ovary 1‐A9, ileum HCT‐8 adenocarcinoma, and osteosarcoma HSO. A mode of action study in HL‐60 cells demonstrated that DNA and protein syntheses were inhibited after 60[TH]min at 100[TH]μM. DNA and RNA polymerases, PRPP‐amido transferase, dihydrofolate reductase, thymidylate synthase, and TMP kinase activities were interfered with by the agent with reduction of d[NTP] pools. Nonspecific interaction with the bases of DNA and cross‐linking of the DNA may play a role in the mode of action of these carboxylates.
Bioelectromagnetics in morphogenesis
Authors: Levin Michael
Published: June 2003

Understanding the factors that allow biological systems to reliably self‐assemble consistent, highly complex, four dimensional patterns on many scales is crucial for the biomedicine of cancer, regeneration, and birth defects. The role of chemical signaling factors in controlling embryonic morphogenesis has been a central focus in modern developmental biology. While the role of tensile forces is also beginning to be appreciated, another major aspect of physics remains largely neglected by molecular embryology: electromagnetic fields and radiations. The continued progress of molecular approaches to understanding biological form and function in the post genome era now requires the merging of genetics with functional understanding of biophysics and physiology in vivo. The literature contains much data hinting at an important role for bioelectromagnetic phenomena as a mediator of morphogenetic information in many contexts relevant to embryonic development. This review attempts to highlight briefly some of the most promising (and often underappreciated) findings that are of high relevance for understanding the biophysical factors mediating morphogenetic signals in biological systems. These data originate from contexts including embryonic development, neoplasm, and regeneration. Bioelectromagnetics 24:295‐315, 2003. © 2003 Wiley‐Liss, Inc.