bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of water on the oxygen barrier properties of poly(ethylene terephthalate) and polylactide films
Authors: Auras Rafael , Harte Bruce , Selke Susan 
Published: March 2004

AbstractThe aim of this work was to study the variations in the oxygen diffusion, solubility, and permeability coefficients of polylactide (PLA) films at different temperatures (5, 23, and 40°C) and water activities (0–0.9). The results were compared with the oxygen diffusion, solubility, and permeability coefficients obtained for poly(ethylene terephthalate) (PET) films under the same experimental conditions. The water sorption isotherm for PLA films was also determined. Diffusion coefficients were determined with the half‐sorption time method. Also, a consistency test for continuous‐flow permeability experimental data was run to obtain the diffusion coefficient with the lowest experimental error and to confirm that oxygen underwent Fickian diffusion in the PLA films. The permeability coefficients were obtained from steady‐state permeability experiments. The results indicated that the PLA films absorbed very low amounts of water, and no significant variation of the absorbed water with the temperature was found. The oxygen permeability coefficients obtained for PLA films (2–12 × 10−18 kg m/m2 s Pa) were higher than those obtained for PET films (1–6 × 10−19 kg m/m2 s Pa) at different temperatures and water activities. Moreover, the permeability coefficients for PLA and PET films did not change significantly with changes in the water activity at temperatures lower than 23°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1790–1803, 2004
Water‐swelling elastomer prepared by in situ formed lithium acrylate in chlorinated polyethylene
Authors: Ren Wentan , Peng Zonglin , Zhang Yong , Zhang Yinxi 
Published: March 2004

AbstractLithium acrylate (LiAA) was in situ prepared in a chlorinated polyethylene (CPE) matrix through the neutralization of lithium hydroxide (LiOH) and acrylic acid (AA) during mixing. The obtained compounds were vulcanized with dicumyl peroxide (DCP). The in situ preparation and polymerization of LiAA were characterized with Fourier transform infrared spectrometry. The crosslink density analysis results indicated that the CPE/LiAA vulcanizates contained both covalent bonds and ionic bonds. The effects of the DCP and LiAA contents on the mechanical properties and water‐swelling properties of the CPE/LiAA vulcanizates were studied. The relationship between the LiOH/AA molar ratio and the properties of the CPE/LiAA vulcanizates was investigated. The results showed that LiAA could improve the mechanical and water‐swelling properties of CPE/LiAA vulcanizates, providing a new approach to the preparation of water‐swelling elastomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1804–1812, 2004
Effect of surfactant systems on the water sensitivity of latex films
Authors: Butler Lauren N. , Fellows Christopher M. , Gilbert Robert G. 
Published: March 2004

AbstractThe effects of three different types of surfactant systems (ionic, polymeric, and electrosteric stabilizers) on the water sensitivity of poly(butyl acrylate‐co‐methyl methacrylate) latex films was examined. The water sensitivity was found to be strongly dependent on the surfactant system used in their preparation. A number of factors, such as the surfactant mobility and crystallinity and surfactant/polymer polarity appeared to affect the water uptake of the films. Highly mobile and crystallizable surfactants yielded high water sensitivity for films containing ionic surfactants, whereas the surfactant polarity had a greater effect on latices stabilized by polymeric surfactants, with the more hydrophilic systems providing greater water uptake. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1813–1823, 2004
Homopolymerization and copolymerization of tert‐butyl methacrylate and norbornene with nickel‐based methylaluminoxane catalysts
Authors: Huang Chih‐Feng , Wang Shih‐Kai , Kuo Shiao‐Wei , Huang Wu‐Jang , Chang Feng‐Chih 
Published: March 2004

AbstractThe homopolymerization and copolymerization of tert‐butyl methacrylate (tBMA) and norbornene (NB) with nickel(II) acetylacetonate in combination with methylaluminoxane were systematically investigated. This catalytic system showed high activity toward the homopolymerization of both NB and tBMA. For these copolymerizations, activity was gradually lost with an addition of tBMA to NB or of NB to tBMA. This result was qualitatively explained with the trigger coordination mechanism. Furthermore, the determination of the reactivity ratios indicated a significantly higher reactivity for NB than for tBMA (rNB = 4.14 and rtBMA = 0.097), and this was interpreted by the coordination mechanism. The synthesized acrylate/NB copolymers exhibited glass‐transition temperatures of 100–250°C. The absence of crystallinity and the homogeneous repartition of the monomer units along the main chain yielded products with high transparency and high stability © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1824–1833, 2004
Supercritical CO2 assisted processing of polystyrene/nylon 1212 blends and CO2‐induced epitaxy on nylon 1212
Authors: Chang Yuning , Xu Qun , Han Buxing , Wang Yudong , Liu Minying , Zhao Qingxiang 
Published: March 2004

AbstractPolystyrene/nylon 1212 blends were prepared with supercritical CO2 as the substrate swelling agent and monomer/initiator carrier. Original nylon 1212 and blends were characterized with differential scanning calorimetry (DSC), polarizing microscopy, wide‐angle X‐ray diffraction, and scanning electron microscopy (SEM). A novel phenomenon, CO2‐induced epitaxy, was discovered, and its mechanism was deduced. Thermal analysis performed with DSC indicated that the polystyrene/nylon 1212 blends had thermal stability superior to that of virgin nylon 1212. The DSC and SEM measurements indicated that incorporated polystyrene could notably improve the mechanical performance of nylon 1212. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2023–2029, 2004
Miniemulsion polymerization of styrene with polymeric costabilizers
Authors: Chern Chorng‐Shyan , Lin Chi‐Han 
Published: March 2004

AbstractThe polymeric costabilizers poly(stearyl methacrylate‐co‐2‐hydroxyethylmethacrylate) (PSH) and poly(lauryl methacrylate‐co‐2‐hydroxyethylmethacrylate) (PLH), composed of a hydrophilic backbone and several hydrophobic alkyl (stearyl or lauryl) side chains, were prepared by the free‐radical copolymerization of stearyl methacrylate (SMA) or lauryl methacrylate (LMA) with 2‐hydroxyethylmethacrylate and evaluated in the miniemulsion polymerization of styrene (ST). For comparison, the reactive costabilizers SMA and LMA were also included in this work. The hydrophobicity of costabilizers in increasing order was PLH < PSH < LMA < SMA. Only a small amount of these comb‐like copolymers was capable of producing kinetically stable ST emulsion droplets. The more hydrophobic the costabilizer was, the more effective was the costabilizer in the retardation of Ostwald ripening. About 30–40% of the monomer droplets were successfully converted into latex particles during the polymerization. The degree of monomer droplet nucleation increased with increasing hydrophobicity of the costabilizer. The formation of particle nuclei in the continuous aqueous phase played a crucial role in the polymerization kinetics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1961–1969, 2004
Synthesis and characterization of polyurethane foam matrices for the support of granular adsorbent materials
Authors: Pinto Moisés L. , Pires João , Carvalho Ana P. , Bordado João C. M. , De Carvalho Manuela B. 
Published: March 2004

AbstractPolyurethane foams with different formulations were synthesized and characterized for use as supporting matrices of granular solid adsorbents. The open cell content, specific gravity, thermal stability, and hydrophobicity were determined and related to the formulation composition. The synthesized foams had open cell contents of 88.1–98.5% and specific gravity values of 120–28 kg m−3. The thermal stability of the prepared foams was influenced mainly by the water content and the type of isocyanate used. The hydrophobicity was assessed by an analysis of the water adsorption isotherms determined on selected foams, and a correlation between these results and the formulation of the foams was attempted. Two types of activated carbons were supported in a polyurethane matrix. The adsorption characteristics evaluated before and after the supporting procedure, by nitrogen adsorption, revealed that there was only a moderate surface area reduction of 15–20%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2045–2053, 2004
Fiber formation and physical properties of chitosan fiber crosslinked by epichlorohydrin in a wet spinning system: The effect of the concentration of the crosslinking agent epichlorohydrin
Authors: Lee Shin‐Hee , Park Soo‐Young , Choi Jae‐Hong 
Published: March 2004

AbstractThe wet spinning of chitosan fibers was studied with 2% acetic acid as the solvent, 10% aqueous sodium hydroxide as the nonsolvent, and a 4% chitosan solution as the polymer. This article describes the crosslinking of the chitosan fibers. Epichlorohydrin (ECH) was selected as a convenient base‐catalyzed crosslinking agent. The coagulation and crosslinking of the chitosan fibers occurred simultaneously in the coagulation bath. In this study, we investigated the effect of the concentration of the crosslinking agent, ECH, in the spinning dope on the structural, thermal, morphological, and mechanical properties (e.g., the tenacity, elongation, and work of rupture) of chitosan fibers. The tenacity of the chitosan fibers, especially the wet tenacity, was improved by crosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2054–2062, 2004
The role of additives in the manufacture of sheets of unsaturated polyester and postconsumer unsaturated polyester/glass fiber composites: Mechanical and dynamic mechanical properties
Authors: Pedroso A. G. , Rosa D. S. , Atvars T. D. Z. 
Published: March 2004

AbstractThe storage of postconsumer glass fiber reinforced unsaturated polyester composite impacts negatively on the environment because of the long lifetime and the volume/amount ratio of residuals, which are important aspects to be considered. Two types of additives were employed as an attempt to improve the mechanical properties of sheets manufactured with ground postconsumer glass fiber reinforced orthophthalic unsaturated polyester resin composite and virgin orthophthalic unsaturated polyester resin, a silane‐coupling agent and an organic dispersant. Flexural and impact tests, and dynamic mechanical analyses, demonstrated that the coupling agent increased the mechanical properties, while the dispersant decreased these properties, compared to material without either additive. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1834–1839, 2004
Synthesis and degradation behavior of poly(propylene carbonate) derived from carbon dioxide and propylene oxide
Authors: Du L. C. , Meng Y. Z. , Wang S. J. , Tjong S. C. 
Published: March 2004

AbstractHigh molecular weight and regular molecular structure poly(propylene carbonate) (PPC) was successfully synthesized from carbon dioxide and propylene oxide. The PPC copolymer structure was an exact alternating copolymer as evidenced by the 13C‐NMR technique. Degradative behavior of the PPC was conducted by soil burial and buffer solution immersion (pH = 6) tests, respectively. The results showed that the weight loss of soil buried in PPC films increased more slowly than that immersed in the buffer solution after 6‐month exposure. However, the weight loss of sample immersed in the buffer solution increased rapidly during the first 2 months and reached a value of 4.59%. Water sorption measurement also revealed that the PPC membranes immersed in buffer solution were more hydrophilic than those in soil burial tests. The degradation mechanism of PPC membranes was correlated with the sample morphologies, FTIR, and 1H‐NMR spectra. The SEM morphologies were consistent with the weight loss and water sorption measurements. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1840–1846, 2004
1H‐ and 13C‐NMR analyses of aqueous polyamideamine–epichlorohydrin resin solutions
Authors: Obokata Takao , Isogai Akira 
Published: March 2004

AbstractMore accurate signal assignment for 1H‐ and 13C‐NMR spectra of aqueous solutions of polyamideamine‐epichlorohydrin (PAE) resin and its related compounds was achieved by using distortionless enhancement of polarization transfer (DEPT) and C‐H correlation spectroscopy (COSY) methods. On the basis of the assignment, we developed new methods to determine the content of four‐membered azetidinium ring (AZR) and number‐average degree of polymerization (DPn) of the repeating unit of PAE by using NMR. Degree of introduction of epichlorohydrin into polyamideamine chains at the initial stage was 75–80%, and the resultant AZR content per one repeating unit in the PAE sample prepared in this study was about 72%. DPn of the initial polyamideamine was 32, and this value decreased to about 18 during the PAE preparation process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1847–1854, 2004
Friction and wear studies on nylon‐6/SiO2 nanocomposites
Authors: García Monserrat , De Rooij Matthijn , Winnubst Louis , van Zyl Werner E. , Verweij Henk 
Published: March 2004

AbstractComposites of nanometer‐sized silica (SiO2) filler incorporated in nylon‐6 polymer were prepared by compression molding. Their friction and wear properties were investigated on a pin on disk tribometer by running a flat pin of steel against a composite disc. The morphologies of the composites as well as of the wear track were observed by scanning electron microscopy (SEM). The addition of 2 wt % SiO2 resulted in a friction reduction (μ) from 0.5 to 0.18 when compared with neat nylon‐6. This low silica loading led to a reduction in wear rate by a factor of 140, whereas the influence of higher silica loadings was less pronounced. The smooth morphology obtained after the wear test indicated the negligible contribution to friction of the pin to the nanocomposite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1855–1862, 2004
Synthesis and chain extension of nitroxide‐terminated styrene–maleimide copolymers
Authors: Lokaj J. , Krakovský I. , Holler P. , Hanyková L. 
Published: March 2004

AbstractThermal radical copolymerization of styrene (S) and maleimide (MI) at 125°C in diglyme in the presence of 2,2,6,6‐tetramethylpiperidin‐1‐yloxyl radical (TEMPO) was studied. Mole fractions of maleimide in the feed, FMI, varied in the range 0.1–0.9. A quasiliving reaction process proceeded yielding copolymers with a low polydispersity (Mw/Mn = 1.17–1.41). The found azeotropic composition, (FMI)A = 0.46, did not differ substantially from that (0.5) in the conventional radical S‐MI copolymerization. At a higher conversion or MI content in the feed, deactivation of the copolymer chains occurred. The obtained TEMPO‐terminated S‐MI copolymers readily initiated polymerization of styrene; chain extension of the macroinitiators took place, giving poly(S‐co‐MI)‐block‐poly(S) diblock copolymers. The synthesized copolymers containing S and MI units were characterized by elemental analysis, NMR spectroscopy, size‐exclusion chromatography, and differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1863–1868, 2004
Properties of a few aromatic poly(thioether ketones) as sulfur‐containing high‐performance polymers
Authors: Matsumura Sumiko , Kihara Nobuhiro , Takata Toshikazu 
Published: March 2004

AbstractSeveral basic physical properties of poly(thioether ketones) (PTEKs) were studied in comparison with corresponding ether analogs, poly(ether ketones) (PEKs), and various typical engineering plastics. The water absorption of PTEK (0.13%) was lower than that of the corresponding PEK (0.16%), probably because of the hydrophobic nature of the sulfide group. The dielectric breakdown strengths of PTEK and PEK were much greater than that of commercially available polymers. PTEK had higher dielectric breakdown strength than PEK. Although the volume resistivity of PEK considerably decreased after water absorption, that of PTEK remained high even after water absorption. PTEK exhibited a remarkably high refractive index (nD23 1.66). α‐Transition corresponding to Tg was observed at a high temperature (PTEK‐1, 235°C; PTEK‐2, 269°C) in the dynamic mechanical analysis. Young's modulus and tensile strength of PTEK were comparable to those of commercial high‐performance polymers. PTEK also exhibited excellent flame resistance. Although the linear thermal expansion coefficient of PTEK was greater than that of PEEK, it was still within a practically acceptable level. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1869–1874, 2004
Modeling of polyurethane foam formation
Authors: Tesser R. , Di Serio M. , Sclafani A. , Santacesaria E. 
Published: March 2004

AbstractPolymeric foams are widely used both as structural and as thermal insulating material. Few detailed data about the process of foam growth are reported in the literature, especially for recently developed polyurethane formulations that involve the use of a volatile organic compound instead of the banned chlorofluorocarbons (CFCs). In this work, a dedicated device was realized that allows experimental data collection for polymeric foams growth in terms of temperature and density profiles. For modeling and simulation purposes, a model reported in the literature was modified by improving, in particular, the description of the vapor–liquid phase equilibrium for the system blowing agent/polymer mixture. Simulation of the collected experimental data was performed by this model after the determination of the kinetic parameters for the occurring reaction between polyol and isocyanate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1875–1886, 2004
Comparison between titanium tetrabutoxide and a new commercial titanium dioxide based catalyst used for the synthesis of poly(ethylene terephthalate)
Authors: Finelli Lara , Lorenzetti Cesare , Messori Massimo , Sisti Laura , Vannini Micaela 
Published: March 2004

AbstractTitanium‐based catalysts for poly(alkylene terephthalate) synthesis have been known for many years. Up to now, organotitanate compounds are used as catalysts on an industrial scale only for the synthesis of poly(butylene terephthalate) (PBT), poly(trimethylene terephthalate) (PTT), and related copolyesters; for poly(ethylene terephthalate) (PET), synthesis antimony‐based catalysts are preferred. In fact, in this case, titanium is known to cause undesirable discoloration. In this article, a study of PET synthesis using different concentrations of a new titanium dioxide based catalyst (C‐94), commercially available from Acordis Industrial Fibers GmbH, is carried out and compared with the results obtained with titanium tetrabutoxide (TBT) catalyst in the same experimental conditions. The solid‐state properties and composition of C‐94 was investigated by thermogravimetric analysis (TGA) coupled with mass spectroscopy and by X‐ray powder diffraction (XRD). A characterization of the polymers prepared with C‐94 and TBT is also described. The results have shown that the use of C‐94 leads to more hydrolytically stable polymers, whereas no evidence of difference in the catalytic activity, carboxyl end‐groups concentration, diethylene glycol content, and thermal properties were revealed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1887–1892, 2004
Pectin and polyacrylamide composite hydrogels: Effect of pectin on structural and dynamic mechanical properties
Authors: Liu Linshu , Cooke Peter H. , Coffin David R. , Fishman Marshall L. , Hicks Kevin B. 
Published: March 2004

AbstractComposite hydrogels of pectin and polyacrylamide were synthesized and evaluated by scanning electron microscopy, atomic force microscopy, light microscopy, and dynamic mechanical analysis. The crosslinking polymerization of acrylamide in pectin solution resulted in a composite having a macroporous pectin domain with an interstitial polyacrylamide domain. This composite had improved mechanical properties compared to those of either polymer alone, and it absorbed and retained more water than crosslinked polyacrylamide alone. Furthermore, crosslinking polymerization of acrylamide in an existing pectinate scaffold resulted in a double‐network architecture, where filamentous polyacrylamide networks penetrated through pores of the pectin scaffold. It was found that pectins dictated the features of microstructure in the composites through regulating the coordination of phase separation of the two components and water partition between the two phases. Results from this study highlight potential new uses of pectins in protecting the physical structure of environmentally sensitive polymers from mechanical damage related to freezing, lyophilization, and other conditions experienced during their use in biomedical and industrial products. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1893–1901, 2004
Synthesis and characterization of statistical copolymers of styrene and 4‐(1‐hydroxyalkyl)styrene
Authors: Nasrullah J. Mohammed , Dhamodharan R. 
Published: March 2004

AbstractA family of new polymers based on poly(4‐(1‐hydroxyalkyl)styrene), and its copolymers with styrene were synthesized and thoroughly characterized by 1H‐NMR, 13C‐NMR, FTIR, and UV spectroscopies. The chemical modification reactions of polystyrene (PS) was used as a novel method of performing the synthesis of poly(4‐(1‐hydroxyethyl‐co‐styrene)), poly(4‐(1‐hydroxypropyl‐co‐styrene)), poly(4‐(1‐hydroxybutyl‐co‐styrene)), and poly(4‐(1‐hydroxyphenylmethyl‐co‐styrene)). The novelty of this method lies in the incorporation of the desired mol % of the functional groups in polystyrene chain, to obtain random copolymers of desired composition. In preliminary testing/evaluation studies the utility and versatility of the new copolymers, which have the potential to be negative‐tone photoresist materials, were studied. Thus a few photoresist formulations based on poly(styrene‐co‐4‐(1‐hydroxyalkylstyrene)) were developed with 5 wt % of a photoacid generator. These studies suggested that the new copolymers synthesized by a simple and alternate method could have the same potential as a photoresist material when compared with the polymers synthesized by the polymerization of the corresponding functional monomer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1902–1914, 2004