bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical properties of low density polyethylene/ZnO nanocomposites: The effect of thermal treatments
Authors: Tjong S. C. , Liang G. D. , Bao S. P. 
Published: July 2006

AbstractLow density polyethylene (LDPE)/ZnO nanocomposites were prepared by melt compounding followed by annealing or quenching treatment. Electrical properties of the thermally treated nanocomposites were investigated. The results showed that thermal treatments exerted a pronounced effect on the electrical properties of LDPE/ZnO nanocomposites. The dielectric constant of annealed LDPE/ZnO nanocomposites at various ZnO contents was higher than that of quenched nanocomposites. In sharp contrast, the resistivity of annealed LDPE/ZnO nanocomposites was considerably lower than that of quenched samples. The frequency dependence of dielectric constant was much pronounced for both the annealed and quenched LDPE/ZnO nanocomposites associated with the formation of ZnO network as the ZnO volume content reached 52 vol %. The structure–property relationship of the nanocomposites is discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1436–1444, 2006
Some laws of a lignin plasticization
Authors: Bouajila J. , Dole P. , Joly C. , Limare A. 
Published: July 2006

AbstractA comparison of the plasticizing efficiency of a series of molecules introduced in dry and hydrated Kraft lignin demonstrated that the plasticization mechanisms are different before and after sorption site saturation. Lignins were plasticized in two steps and glass transition decrease was determined from DSC measurements. “Specific sorption plasticizers,” such as water, are very efficient in low content because of their functionality and accessibility to sorption sites. The plasticizing efficiency does not depend on the solubility parameter, and is well quantified, considering the molar concentration of donor/acceptor functions. After saturation of sorption sites (in wet conditions), the plasticizing efficiency depends on the solubility parameter, which should be close to that of the polymer matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1445–1451, 2006
Effects of arm number on the properties of transparent elastomers prepared from styrene–butadiene block copolymer
Authors: Ma Rui , Zhang Zhenjun , Zhang Lina 
Published: July 2006

AbstractA series of the SBS transparent elastomers were prepared from star‐shaped SBS having different arm number by solution‐casting. Their structure and physical properties were characterized by scanning electron microscope, ultraviolet spectrometer, wide‐angle X‐ray diffractometer, differential scanning calorimetry, dynamic mechanical thermal analysis, tensile testing, and contact angle measurements. The results revealed that the miscibility, optical transparence (Tr), tensile strength (σb), elongation at break (εb), and elasticity at low temperature of the star SBS increased with an increase of arm number. The six‐arm SBS having relatively high molecular weight exhibited a simultaneous enhancement of Tr (90% at 800 nm), σb (6.0 Mpa), and εb (1260%). This indicated that the SBS materials having six arms had higher transparence and elasticity than others. Moreover, the water contact angle on surface of the star‐shaped SBS film increased with an increase of arm number that is enhancement of hydrophobicity. Therefore, the relatively high arm number and molecular weight played an important role in the improvement of the miscibility and properties of the SBS sheets as a result of the compacted architecture of the hyperbranched molecules. This work provides a convenient way to obtain materials with both high transparence and elasticity by increasing the arm number. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 729–736, 2006
Two‐step consecutive reaction model and kinetic parameters relevant to the decomposition of Chinese forest fuels
Authors: Chen Haixiang , Liu Naian , Fan Weicheng 
Published: July 2006

AbstractDecomposition of some Chinese forest fuels has been studied by means of nonisothermal thermogravimetric analysis in oxidative and inert atmosphere at low heating rates. A comparison between thermogravimetric curves obtained in air and nitrogen shows that the existence of oxygen enhances the decomposition rate and changes the mechanisms of thermal degradation. After the water evaporation, two well‐defined decomposition stages have been observed in thermogravimetric curves obtained in air, which correspond to oxidative degradation of main components and oxidation of char formed. A kinetic model named “two‐step consecutive reaction model” is developed to describe the thermal degradation process of these materials in air, and there is a good agreement between the experimental and calculated thermogravimetric and derivative thermogravimetric curves. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 571–576, 2006
Effect of maleated polypropylene as coupling agent for polypropylene composites reinforced with hemp strands
Authors: Mutjé P. , Vallejos M. E. , Gironès J. , Vilaseca F. , López A. , López J. P. , Méndez J. A. 
Published: July 2006

AbstractNew composites based on poly(propylene) as polymer matrix and hemp strands as natural reinforcement have been developed by injection‐molding. The materials were previously mixed in a two roll mill to induce the dispersion of the fiber inside the polymer. To improve the adhesion between both components, maleated poly(propylene) was added as coupling agent, at 4% wt/wt with respect to hemp strands. The addition of this amount of this coupling agent to the formulation modified with 40 wt % of hemp strands increases the ultimate tensile strength (σt) and flexural strength (σf) up to 49 and 38%, respectively, compared with the composite without coupling agent. The interaction between the surface of hemp strands and the coupling agent was determined by FT‐IR spectroscopy assuming that a covalent bond was established, avoiding the adverse effect of the poor compatibility at the interface for this kind of composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 833–840, 2006
Melt grafting of poly(ethylene‐vinyl acetate) copolymer with maleic anhydride
Authors: Yin Jun , Zhang Jun , Yao Yu 
Published: July 2006

AbstractPoly(ethylene‐vinyl acetate) (EVA) copolymer was melt grafted with maleic anhydride (MAH) in a twin screw extruder in the presence of peroxide. It is confirmed that MAH has been melt grafted on the backbone of EVA by FTIR using the method of hydrolysis. The NMR analysis suggests that the grafting reaction occurs on the tertiary carbon of main chain of EVA other than the methyl moiety of vinyl acetate (VA) group. The incorporation of VA groups onto the matrix shows a competitive effect on the grafting. The existence of VA groups promotes the extent of MAH graft onto EVA; nevertheless, it also weakens the crystallizability of main chain. When the content of peroxide initiator is 0.1 wt % based on the polymer matrix, the grafting degree increases with increasing the concentration of monomer. When the peroxide content is higher than 0.1 wt %, side reactions such as crosslinking or disproportionation will be introduced into this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 841–846, 2006
Influence of the network structure and void content on hygrothermal stability of resol resin modified with epoxy–amine
Authors: Manfredi Liliana B. , Fraga Alicia N. , Vázquez Analía 
Published: July 2006

AbstractEpoxy–amine was blended with two resol resins to study the influence of the final network and void content on the water absorption of these systems. To characterize the network structure of the blends, infrared analyses were performed. It was observed that a diminution in the crosslink density of the network and the reaction between the epoxy and resol have been occurred. From dynamic–mechanical analyses, a diminution in the Tg value and an increment in the height of the tan δ peak with the epoxy–amine content added to the resol were observed. Thermogravimetric analysis showed that the thermal stability of the resol was reduced by the addition of epoxy–amine as well as a lesser crosslink network for the blends with higher epoxy–amine content. The maximum water uptake and the diffusion coefficient were related with the chemical structure and void content of the specimens. On one hand, the maximum water uptake was observed to depend on the void content of the blends. On the other hand, the diffusion coefficient appears to be related with the local motions of the polymeric chains and with the hydrophilic character of the materials. This behavior was observed for the two resols studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 588–597, 2006
Synthesis of thermoplastic polyurethane and its physical and shape memory properties
Authors: Wang Huei‐Hsiung , Yuen Uen‐En 
Published: July 2006

AbstractIn this article, thermoplastic polyurethane (PU) with a shape memory property was synthesized. First, the PU prepolymer was prepared by reacting poly(tetramethylene glycol) with 4,4′‐diphenylmethane diisocyanate, then extended with various extenders such as linear aliphatic 1,4‐butanediol, benzoyl‐type 4,4‐bis(4‐hydroxyhexoxy)‐isopropylane and naphthalate‐type bis(2‐phenoxyethanol)‐sulfone or naphthoxy diethanol. The experimental results showed that the tensile strength, elongation at break, and initial modulus at 300% of these copolymer films were in the range of 31–64 Mpa, 42%–614%, and 8.26–11.5 MPa, respectively. Thermal analysis showed that the glass‐transition temperature of these copolymers was in the range of −73°C to −50°C for the soft segment (Tgs) and 70°C–106°C for the hard segment (Tgh) and that the melting point was in the range of 14.6°C–24.2°C for the soft segment and 198°C–206°C for the hard segment. The extender with a benzoyl or naphthalate group was better able to promote its shape memory property than was the regular polyurethane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 607–615, 2006
Viscoelastic analysis applied to the determination of long‐term creep behavior for magnetic tape materials
Authors: Weick Brian L. 
Published: July 2006

AbstractCreep‐compliance experiments were performed for three representative magnetic tapes. Two of these tapes used a magnetic particle (MP) coating, and one used a metal‐evaporated (ME) coating. The MP tapes used the following polyester substrates: semitensilized poly(ethylene naphthalate) (PEN) and supertensilized poly(ethylene terephthalate). The ME tape used an aromatic poly(amide) or aramid substrate. Time–temperature superposition was used to make creep‐compliance predictions at 30 and 50°C reference temperatures. Comparisons were made with dimensional stability requirements based on position error signal (PES) specifications for magnetic tape drives along with in‐cartridge creep specifications based on PES measurements. Circumferential and lateral creep strains were determined that account for storage of the tapes in a reel, and creep strains were predicted for future tapes with thinner, lower compliance coatings. A rule of mixtures method was also used to extract compliance information for individual layers of MP‐PEN tapes, and stress profiles through the thickness of the tapes were determined. Additional measurements and analyses were performed to determine the creep recovery and shrinkage characteristics for the magnetic tapes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1106–1128, 2006
Preparation and characterization of P(AN/VAC)/clay based nanocomposites
Authors: Gu Xiaohua , Xi Peng , Jia Yongtang , Liu Ting , Shen Xinyuan 
Published: July 2006

AbstractIn this article, P(AN/VAC)/clay nanocomposites were prepared by an in situ polymerization and characterized by transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. The results show that the P(AN/VAC)/clay exhibit a multilayered structure. The montmorillonite layers are totally exfoliated and distributed uniformly in the P(AN/VAC) matrix. The dimension stability and heat resistance property of P(AN/VAC)/clay are superior to those of P(AN/VAC) alone.
© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 703–706, 2006
Polyimide foams with ultralow dielectric constants
Authors: Chu Hui‐Juan , Zhu Bao‐Ku , Xu You‐Yi 
Published: July 2006

AbstractTo explore ultralow dielectric constant polyimide, the crosslinked polyimide foams (PIFs) were prepared from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), 4,4′‐oxydianiline (ODA), and 2,4,6‐triaminopyrimidine (TAP) via a poly(ester–amine salt) (PEAS) process. FTIR measurements indicated that TAP did not yield a negative effect on imidization of PEAS precursors. SEM measurement revealed the homogeneous cell structure. Through using TAP as a crosslinking monomer, the mechanical properties of PIFs could be improved in comparison with uncrosslinked BTDA/ODA based PIF. The crosslinked PIFs still exhibited excellent thermal stability with 5% weight loss temperatures higher than 520°C. In the field with frequency higher than 100 Hz, the dielectric constants of the obtained PIFs ranged from 1.77 to 2.4, and the dielectric losses were smaller than 3 × 10−2 at 25–150°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1734–1740, 2006
Cure reaction and phase separation behavior of cyanate ester‐cured epoxy/polyphenylene oxide blends
Authors: Wu Shao‐Jung 
Published: July 2006

AbstractThe cure reaction and phase separation mechanism of a cyanate ester‐cured epoxy and its blends with polyphenylene oxide (PPO) were studied. An autocatalytic mechanism was observed for the epoxy and its blends. The reaction rate of the blends was higher than that of the neat epoxy at initial stage; however, the reached conversion decreased with PPO content. FTIR analysis revealed that the cyanate functional group reactions were accelerated by adding PPO and indicated that several coreactions have occurred. This was caused by the reaction of cyanate ester with the PPO reactive chain ends. But at a later stage of cure, the reaction could not progress further due to diffusional limitation of PPO. To understand the relationship between the cure kinetics and phase separation of the blends, the morphology of the blends during cure was examined. When the homogeneous epoxy/PPO blends with low PPO content (10 phr) were cured isothermally, the blends were separated by nucleation and growth (NG) mechanism to form the PPO particle structure. But at high PPO content (30 phr), the phase separation took place via spinodal decomposition (SD). SD is favored near critical concentration and high cure rate system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1139–1145, 2006
Acrylonitrile/ammonium itaconate aqueous deposited copolymerization
Authors: Cui Chuansheng , Wang Chengguo , Zhao Yaqi 
Published: July 2006

AbstractAcrylonitrile/ammonium itaconate [AN/(NH4)2IA] aqueous deposited polymerizations were studied in this work. It shows that the polymerizations were influenced by various factors, especially the water solubility of AN. In the polymerization process, the system was as separated monomer and water phases, and AN transferred from monomer phase to water phase until the monomer phase disappeared. Because of the solubility of AN in water, the reactivity ratios of monomer calculated by Kelen‐Tudos method were different in various monomer contents. Although (NH4)2S2O8 was a water‐soluble initiator, there was a short amount of polymer formed in monomer phase. To inhibit the polymerization in monomer phase, two additives were used in the polymerization and experiment data indicated that the two inhibitors exert inhibitory role effectively in monomer phase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 904–908, 2006
Synthesis of fluorinated diblock copolymer by ATRP and its application of PAVAc polymerization in ScCO2
Authors: Yang Yajun , Wang Zi , Gao Yan , Liu Tao , Hu Chunpu , Dong Qingzhi 
Published: July 2006

AbstractA series of fluorinated diblock copolymers consisting of poly(styrene‐r‐acrylonitrile) (PSAN) and poly (1,1,2,2‐tetrahydroperfluorooctyl methacrylate) (PFOMA) were prepared by atom transfer radical polymerization (ATRP). The copolymers with well‐controlled molecular weight and narrow molecular weight distribution (PDI < 1.2) were characterized by 1H NMR, GPC, and FTIR. With the amphiphilic diblock copolymers as stabilizers, acrylonitrile‐vinyl acetate random copolymers were synthesized by dispersion polymerization in supercritical carbon dioxide (ScCO2). Compared with precipitation polymerization, the products prepared via dispersion polymerization possess of higher yield and higher molecular weight. In addition, via dispersion polymerization, the particle morphology of the product is spherical. And the dispersity index of the particle size distribution is very narrow. At the same reaction condition, the particle morphology of the product prepared by precipitation polymerization is irregular. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1146–1151, 2006
Plasma‐induced solid‐state polymerization modified poly(tetrafluoroethylene) membrane for pervaporation separation of aqueous alcohol mixtures
Authors: Li Chi‐Lan , Tu Chen‐Yuan , Inagaki N. , Lee Kueir‐Rarn , Lai Juin‐Yih 
Published: July 2006

AbstractAcrylamide (AAm) solid state polymerization was induced using argon plasma to improve the pervaporation performance of poly(tetrafluoroethylene) (PTFE) membranes (PTFE‐g‐PAAm) in aqueous alcohol mixtures. The surface morphology, chemical composition, and hydrophilicity changes in the PTFE and PTFE‐g‐PAAm membranes were investigated using ATR‐FTIR, SEM, AFM, X‐ray photoelectron spectroscopy, and water contact angle measurements. The surface hydrophilicity rapidly increased with increasing Ar exposure time, but decreased after longer Ar exposure time because of the degradation in the PTFE‐g‐PAAm membrane grafted layer. Compared with the hydrophilicity of the pristine PTFE membrane (water contact angle = 120°), the argon plasma induced acrylamide (AAm) solid‐state polymerization onto the PTFE surface (water contact angle = 43.3°) and effectively improved the hydrophilicity of the PTFE membrane. This value increases slowly with increasing aging time and then reaches a plateau value of about 50° after 10 days of storage under air. The pervaporation separation performances of the PTFE‐g‐PAAm membranes were higher than that of the pristine PTFE membrane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:909–919, 2006
Preparation and properties of a poly(2‐cyano‐1,4‐phenylene terephthalamide)/layered silicate nanocomposite
Authors: Park Soo‐Young , Lee Seung‐Woo , Oh Tae‐Jin 
Published: July 2006

AbstractThe in situ polymerization method was used to prepare a poly(2‐cyano‐1,4‐phenylene terephthalamide)/layered silicate nanocomposite with organically‐modified clay (Cloisite® 30B, southern clay), which was spun into well‐oriented fibers and cast into film in the lyotropic and isotropic state, respectively. The degradation temperature of the nanocomposite (∼550°C) was similar to that of poly (2‐cyano‐1,4‐phenylene terephthalamide) and its strength (and modulus) linearly increased with the amount of the layered silicate in the nanocomposite. The intercalated structure was observed using transmission electron microscopy and X‐ray diffraction with an increase in d‐spacing of the layered silicate from 18.7 Å (the organically modified layered silicate; cliosite 30B) to 21.1 Å (nanocomposite). The layered silicate in the nanocomposite was well oriented during fiber spinning and film casting. The normal of the surface of the layered silicate was perpendicular to the fiber axis and the surface of the cast film. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 640–645, 2006
The transient nature of maximum maleic anhydride grafting of polypropylene: A mechanistic approach based on a consecutive reaction model Part 1: Batch solution process
Authors: García‐Martínez J. Ma. , Areso S. , Collar E. P. 
Published: July 2006

AbstractThis article reports the chemical modification of an atactic polypropylene performed in solution. To model the process, a Box‐Wilson experimental design was used, taking in to consideration the concentrations of maleic anhydride and dycumile peroxide, as well as reaction time, as independent variables. The dynamic character of the process is proposed on the basis of model forecasts supported by experimental results. The proposed kinetic pathway agrees with the fact that short reaction times are not only sufficient but necessary for the greatest graft yields to be attained, while preventing degradative processes in the system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1182–1190, 2006.
Acoustic attenuation characteristics of surface‐modified polymeric porous microspheres
Authors: Ng Yeap‐Hung , Hong Liang 
Published: July 2006

AbstractPorous microspheres (30–50 μm) of poly(styrene‐co‐divinylbenzene) (SD), poly(styrene‐co‐2‐hydroxyethyl acrylate‐co‐divinylbenzene) (SDH), and poly(methyl acrylate‐co‐divinylbenzene) (MD) have been synthesized as the basic unit of acoustic shielding medium. To improve their acoustic insulating property, the structural modifications involving deposition of Ni particles (d < 100 nm) by in situ reduction or electroless plating and incorporation of soft poly(ethyl acrylate) chains into SD microspheres to form a semi‐IPN have been attempted. The effect of these modifications was assessed using acoustic sources of pink/white noises and an audio band (4000–5000 Hz). Different internal porous structures of the pristine microspheres cause indistinct divergences of acoustic insulating capabilities in the pink and white noise fields. The surface metallization enhances the reflection and scattering actions but dismantle the viscoelastic absorption feature of polymer bulk. Therefore, metallization on relatively soft MD microsphere could create a better effect than on SD and SDH beads. Embedding soft poly(ethyl acrylate) into individual SD bead demonstrates a clear improvement in the sound proof performance. Additionally, the disk constituted by semi‐IPN beads displays a downshift of the panel resonance frequencies relative to the disk made of the corresponding SD beads. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1202–1212, 2006
Biodegradable studies of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone), poly(dioxanone), and poly(glycolide‐ε‐caprolactone) (Monocryl®) monofilaments
Authors: Hong Jong‐Taek , Cho Nam‐Sook , Yoon Hye‐Sung , Kim Tae‐Hun , Koh Myoung‐Seok , Kim Whan‐Gi 
Published: July 2006

AbstractThe aim of the study was to investigate the mechanical properties and biodegradability of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone) [P(TMC‐ε‐CL)‐block‐PDO] in comparison with poly(p‐dioxanone) and poly(glycolide‐ε‐caprolactone) (Monocryl®) monofilaments in vivo and in vitro. P(TMC‐ε‐CL)‐block‐PDO copolymer and poly(p‐dioxanone) were prepared by using ring‐opening polymerization reaction. The monofilament fibers were obtained using conventional melt spun methods. The physicochemical and mechanical properties, such as viscosity, molecular weight, crystallinity, and knot security, were studied. Tensile strength, breaking strength retention, and surface morphology of P(TMC‐ε‐CL)‐block‐PDO, poly(p‐dioxanone), and Monocryl monofilament fibers were studied by immersion in phosphate‐buffered distilled water (pH 7.2) at 37°C and in vivo. The implantation studies of absorbable suture strands were performed in gluteal muscle of rats. The polymers, P(TMC‐ε‐CL)‐block‐PDO, poly(p‐dioxanone), and Monocryl, were semicrystalline and showed 27, 32, and 34% crystallinity, respectively. Those mechanical properties of P(TMC‐ε‐CL)‐block‐PDO were comparatively lower than other polymers. The biodegradability of poly(dioxanone) homopolymer is much slower compared with that of two copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 737–743, 2006