bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and thermal properties of poly(urethane‐imide)
Authors: Jiang Bibiao , Hao Jianjun , Wang Wenyun , Jiang Luxia , Cai Xinxian 
Published: August 2002

AbstractThe synthesis and thermal properties of thermoplastic poly(urethane‐imide) (PUI) resins were studied. Model reaction studies on the reactions of 4,4′‐diphenylcarbamatodiphenylmethane and 4,4′‐diisocyanatodiphenylmethane with phthalic anhydride were performed. We found that the reaction of anhydrides with urethane groups could take place under certain reaction conditions. According to the model reaction studies, N‐2‐methyl‐pyrrolidone was employed as a solvent, and no catalyst was used in the polymerization. To restrain the side reaction of anhydrides with urethane groups, we adopted a two‐step chain‐extending procedure in a chain‐extending reaction. The inherent viscosity of PUI was 0.83–0.99 dL/g. The prepared polymers not only exhibited improved solubility in organic solvents but also formed flexible films. Thermogravimetric analysis showed that PUI exhibited a two‐step thermal weight‐loss pattern. The first step of the thermal degradation of PUI was attributed to the thermooxidizing cleavage of weak and labile linkage, such as urethane groups, isopropylidene, and methylene, except for imide rings. The polymer inherent viscosity decreased sharply during the first step of thermal degradation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 773–781, 2001
Specific interactions in 4‐hydroxybenzoic acid/poly(2‐vinylpyridine)/poly(N‐vinyl‐2‐pyrrolidone) blends
Authors: Li Xue‐Dong , Goh S. H. 
Published: August 2002

AbstractThe specific interactions in ternary 4‐hydroxybenzoic acid (HBA)/poly(2‐vinylpyridine) (P2VPy)/poly(N‐vinyl‐2‐pyrrolidone) (PVP) blends were studied by differential scanning calorimetry, Fourier transform infrared (FTIR) spectroscopy, and electron microscopy. FTIR study shows the existence of hydrogen‐bonding interactions between HBA and P2VPy as well as PVP. The addition of a sufficiently large amount of HBA produces a blend showing one glass‐transition temperature (Tg). Microscopic study shows a drastic reduction in domain size in single‐Tg blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 901–907, 2001
Stress development in drying coatings
Authors: Lei H. , Payne J. A. , McCormick A. V. , Francis L. F. , Gerberich W. W. , Scriven L. E. 
Published: August 2002

AbstractAs a solvent‐cast polymeric coating dries, each part reaches a concentration at which it solidifies and develops elastic modulus. Thereafter, as further solvent departs, that part shrinks out‐of‐plane, but not in‐plane, if the coating adheres to its substrate. Hence, it develops in‐plane elastic stress. If the stress grows large enough, the stress‐free state may yield, which reduces the final stress level. A theoretical model of diffusion and mass transfer, large shrinkage‐induced deformation, and elastic stress, together with yielding and postyielding viscous deformation, was developed to predict stress evolution in one‐dimensional drying of polymer coatings. Concentration varies only perpendicularly to the substrate, the coating shrinks only in that direction, and the stress varies only in that direction but is in‐plane isotropic. The predictions are compared with measurements of evolving stress in various solvent‐cast polymer coatings and aqueous gelatin coatings by a cantilever‐deflection method. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1000–1013, 2001
Thermal and dynamic mechanical properties of γ‐ray‐cured poly(methyl methacrylate) used as a dental‐base material
Authors: Usanmaz Ali , Eser Özlem , Doğan Arife 
Published: August 2002

AbstractIn this study, γ rays were used for the first time to cure dental‐base material. The effect of the radiation dose on the thermal and rheological properties of poly(methyl methacrylate) (PMMA) used as a dental‐base material was investigated. The commercial powder and liquid material (heat‐curing‐grade) were mixed and polymerized at 60 and 70°C in a constant‐temperature water bath for 30 min and then were cured by γ rays, with total doses of 7.5, 15, 22.5, 30, 45, 52.5, 360, and 2160 krad. For each sample, the viscosity‐average molecular weights were measured, and no significant differences were observed of total dose on molecular weights. A thermal investigation with differential scanning calorimetry showed an exothermic peak in the thermograms of samples that were not completely polymerized and crosslinked. The rheological nature of the samples was studied with dynamic mechanical analysis. A comparison of properties of γ‐ray‐cured samples and those cured by other methods revealed γ curing to be a superior method for producing high‐molecular‐weight homogenous polymers with low porosity and crosslinking. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1291–1296, 2001
Characterization of glow‐discharge–treated cellulose acetate membrane surfaces for single‐layer enzyme electrode studies
Authors: Biederman Hynek , Boyaci Ismail H. , Bilkova Petra , Slavinska Danka , Mutlu Selma , Zemek Josef , Trchova Miroslava , Klimovic Josef , Mutlu Mehmet 
Published: August 2002

AbstractCellulose acetate membranes (CA) were modified by means of plasma polymerization of ethylene diamine (EDA) and n‐butylamine (n‐BA). The motivation for this work was the application of a modified membrane for the single‐layer enzyme electrode. A tubular reactor with the external radiofrequency (13.56 MHz) excitation was used. Surface modification was performed at 5, 10, and 15 W power (at 27 Pa working pressure) for 5, 10, 15 min. Modified surfaces were characterized in detail by FTIR–ATR, XPS (ESCA), contact angle, and enzyme immobilization activity. The best treatment results were obtained for EDA with 5 W and 30 min and 15 W and 10 min. These results are discussed using surface analysis data. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1341–1352, 2001
Surface modification of polypropylene membrane by low‐temperature plasma treatment
Authors: Kang Min Soo , Chun Baehyuck , Kim Sung Soo 
Published: August 2002

AbstractMicroporous polypropylene membranes were low temperature plasma treated with acrylic acid and allylamine. Parameters of plasma treatment were examined and optimized for the enhancement of membrane performance properties. Excess power damaged the membrane surface and excess monomer flow rate increased the reactor pressure to interfere with the glow discharge. Longer plasma treatment time resulted in even more plasma coating and micropore blocking. The contact angle with water decreased and wettabilities increased with the increase of plasma treatment time. Deposition of the plasma polymer on the membrane surface was confirmed by FTIR/ATR spectra of the treated surface. In determining the flux, the hydrophilicity of the surface played a role as important as that of the micropore size. Adequate plasma treatment could enhance both water flux and solute removal efficiency. Results from the BSA (bovine serum albumin) solution test confirmed that fouling was greatly reduced after the plasma treatment. The BSA solution flux through the plasma‐treated membranes depended on pH, whereas pH variation had no serious effects on the untreated membrane. Modification of the surface charge by the plasma treatment should exert a substantial influence on the adsorption and removal of BSA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1555–1566, 2001
Preparation and characterization of pyrrole/aniline copolymer nanofibrils using the template‐synthesis method
Authors: Li Xiaohong , Zhang Xiaogang , Li Hulin 
Published: August 2002

AbstractCopolymer nanofibrils composed of pyrrole and aniline had been prepared by synthesizing the desired polymer within the pores of microporous anodic aluminum oxide (AAO) template membrane. To analyze their structure and properties, FTIR spectra were taken and thermogravimetric analysis (TGA) was applied. Also, the copolymer nanofibrils were photographed under scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for microstructure analysis, and the conductivities were obtained by the four‐probe method. The result of SEM and TEM revealed that the obtained copolymer nanofibrils had uniform and well‐aligned array, and their diameter and length can be controlled by changing the aspect ratios of the AAO membrane. The result of IR spectrometry and TGA indicated that both polypyrrole and polyaniline were involved in the copolymer. The obtained nanofibrils were identified to be copolymer rather than composite. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3002–3007, 2001
Preparation and evaluation of some water‐soluble polyester surfactants
Authors: Azab M. M. , Bader S. K. , Shaaban A. F. 
Published: August 2002

AbstractA novel series of water‐soluble polyester surfactants were prepared by the polymerization of bis‐1,4‐(dicarboxymethoxy) benzene, maleic anhydride, and oxypropylated 1,4‐butane diol (IP1–IP5) or oxypropylated 1,6‐hexane diol (IIP1–IIP5). The unique structural features of these surfactants were confirmed by IR and 1H‐NMR spectra. These water‐soluble polyester surfactants exhibited excellent surface tension, interfacial tension, low foaming, good emulsifier capability, and good biodegradability in river water, solubilization, wetting, and dispersant properties for applied dyes. The antimicrobial and antifungal properties of the prepared polyester surfactants were measured and found to be highly active. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3413–3424, 2001
Immobilization of yeast alcohol dehydrogenase by entrapment and covalent binding to polymeric supports
Authors: Soni Sunil , Desai J. D. , Devi Surekha 
Published: August 2002

AbstractYeast alcohol dehydrogenase (YADH), which catalyzes oxidoreductions of a broad spectrum of substrates, was immobilized by entrapping it into a network of a poly(acrylamide‐co‐hydroxyethyl methacrylate) copolymer and was also covalently bound onto porous chitosan beads activated through glutaraldehyde. Maximum retention of YADH activity achieved was 90 and 24% for entrapment and covalent binding, respectively. The results obtained for thermal, storage, and operational stability of entrapped and covalently bound YADH were compared with free YADH. The immobilized enzyme showed improved thermal and storage stability. The immobilized enzymes also retained 50% activity after six and eight cycles. Enzyme‐catalyzed oxidation of ethanol was observed to be diffusion‐controlled through Lineweaver–Burk plots. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1299–1305, 2001
Conducting polymer composites of zinc‐filled nylon 6
Authors: Pinto Gabriel , Maidana Mónica B. 
Published: August 2002

AbstractThe present work is concerned with the effect of processing variables and filler concentration on the electrical conductivity, hardness, and density of composite materials prepared by compression molding of a mixture of zinc powder and nylon 6 powder. The electrical conductivity of the composites is <10−12 S/cm, unless the metal content reaches the percolation threshold at a volume fraction of about 0.18, beyond which the conductivity increases markedly by as much as 10 orders of magnitude. The density of the composites was measured and compared with values calculated by assuming different void levels within the samples. Furthermore, it is shown that the hardness increases with the increase of metal concentration, but for values of filler volume fraction higher than about 0.30 the hardness of samples remains almost constant. Two parameters of molding process, temperature and time, were shown to have a notable effect on the conductivity of composites, whereas pressure has no influence on this property in the pressure range considered. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1449–1454, 2001
Characterization by thermal analysis of PP with enhanced biodegradability
Authors: Contat‐Rodrigo L. , Ribes‐Greus A. , Díaz‐Calleja R. 
Published: August 2002

AbstractSamples of polypropylene (PP) filled with a biodegradable additive marketed under the Bioefect trademark, were subjected to an outdoor soil burial test for 21 months. Samples were initially characterized by thermogravimetry. The kynetics of the thermal degradation of both the carbonated chains of PP and the additive have been studied by means of the Hirata differential method and the Broido integral method. Such analysis reveals that the additive is more affected by the degradation process than the PP matrix. Changes in the morphology of the samples with the exposure time have been analyzed by Differential Scanning Calorimetry, in terms of the crystalline content of PP and its lamellar thickness distribution. The β‐ and α‐relaxation zones of the dynamic mechanical relaxation spectra of both PP and pure Bioefect have been characterized using the Fuoss‐Kirkwood equation and a deconvolution method. The analysis of the relaxation spectra shows that the interfacial and crystalline regions of the PP matrix are quite affected by the degradation process. On the other hand, it has also been found that changes in the crystallinity and the mechanical behavior of the samples take place in different stages. Such an evolution can be adequately represented by polynomial equations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2174–2184, 2001
Study on β‐cyclodextrin grafting with chitosan and slow release of its inclusion complex with radioactive iodine
Authors: Chen Shuiping , Wang Yuting 
Published: August 2002

Abstractβ‐CD‐2‐CTS was synthesized by β‐cyclodextrin reacting with p‐toluenesulfonyl chloride, then grafting with chitosan. The infrared spectra analysis and 13C NMR confirmed that β‐cyclodextrin reacted with p‐toluenesulfonyl chloride at the 2‐position carbon atom in the substituted glucose unit of β‐cyclodextrin and formed β‐CD‐2‐OTs. In the 13C NMR of β‐CD‐2‐OTs, the characteristic peak of the 2‐postion carbon atom in the substituted glucose unit of β‐cyclodextrin appeared at 78.43 ppm. β‐CD‐2‐CTS was characterized with infrared spectra analysis and X‐ray diffraction. In the infrared spectra of β‐CD‐2‐CTS, the characteristic peak of α‐pyanyl vibration of β‐CD was at 848.6 cm−1. The characteristic peak of β‐pyanyl vibration of CTS was at 894.9 cm−1. The X‐ray diffraction analysis showed that the peak at 2θ = 20° decreased greatly in β‐CD‐2‐CTS. The polymer inclusion complex of β‐CD‐2‐CTS with iodine was prepared and its inclusion ability was studied. The experimental results showed that a nice bit of iodine was included with β‐CD‐2‐CTS and formed a stable inclusion complex. After the subcutaneous implantation of the polymer inclusion complex of β‐CD‐2‐CTS with 131I2 in rats, 131I2 exhibited the property of slow release. 131I2 in the blood of rats decreased slowly. 131I2 in the blood of rats maintained approximately half of maximum for 70 days later, and maintained much higher radioactivity in the organs of rats compared to the inclusion complex of β‐CD with 131 I2, too. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2414–2421, 2001
Dynamic quenching of 5‐(2′‐ethyl‐hexyloxy)‐p‐phenylene vinylene (MEH‐PPV) by charge transfer to a C60 derivative in solution
Authors: Wang Jian , Wang Deli , Moses Daniel , Heeger Alan J. 
Published: August 2002

AbstractThe fluorescence of 5‐(2′‐ethyl‐hexyloxy)‐p‐phenylene vinylene (MEH‐PPV) quenched in solution in 1,2‐dichlorobenzene by a soluble derivative of C60 [1‐(3‐methoxycarbonyl)propyl‐1‐phenyl[6,6]C61; [6,6]PCBM] is studied by changing the concentration of the quencher and by varying the temperature. For MEH‐PPV and PCBM dissolved in 1,2‐dichlorobenzene, the Stern–Volmer constant (KSV) is 2 × 103M−1. At high temperature, KSV is enhanced because thermal energy facilitates the diffusion of PCBM. The results show that dynamic quenching (rather than static quenching) is the basic mechanism. Comparison with data obtained from quenching studies of trans‐stilbene indicates that a single acceptor in contact with an MEH‐PPV macromolecule quenches the luminescence from hundreds of repeat units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2553–2557, 2001
Phase morphology of polystyrene–polyarylate block copolymer/polycarbonate blends and their application to disk substrates
Authors: Ohishi Hiroshi , Ikehara Takayuki , Nishi Toshio 
Published: August 2002

AbstractPolystyrene–polyarylate (PS–PAr) block copolymer was applied as a moldability modifier of polycarbonate (PC). From the 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) extraction results, PS–PAr block copolymer was demonstrated to copolymerize with PC via an in situ reaction between the PAr chain and PC. As a result of the chemical bonding between PS and PC chains, the PS dispersed domain in the PS–PAr block copolymer/PC blend could be reduced, on average, to a size smaller than the visible light wavelength. In particular, by adjusting PAr composition to 30 wt % in the fed PS–PAr block copolymer during the melt‐mixing process, the PS domain size was completely reduced to be smaller than the visible light wavelength. As a result the blend substrate could satisfy the transparency required for the optical disk substrate with higher memory density: homogeneity under polarizing light, clarity on the reflective plate, and transparency at 400 nm. The melt viscosity could be lowered to the equal viscosity level of PC at about 30°C higher temperature by blending PC 15 wt % with the PS–PAr block copolymer. The lowered melt viscosity could reduce the retardation in the optical disk substrate, which was equivalent to that of the PC substrate processed at 30°C higher. In addition, the PS–PAr block copolymer/PC blend could attain the exact groove transcription at 20°C lower mold temperature than that of PC as a result of the lowered elastic modulus caused by the PS‐rich phase. These features of the PS–PAr block copolymer/PC blend indicated a potential to offer an improved process window for the substrate molding. Because of its excellent transparency and a potential for processing flexibility, the PS–PAr block copolymer/PC blend would be a promising material for optical disk substrates with higher memory density. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2566–2582, 2001
Photocuring of acrylate oligomers containing pentabromo benzylacrylate as flame‐retarding monomer and properties of cured films
Authors: Imamoglu Tülin , Yagci Yusuf 
Published: August 2002

AbstractPhotocuring of formulations containing polyurethane and unsaturated polyester acrylate oligomers and a flame‐retarding (FR) monomer, that is, pentabromo benzylacrylate, with various α‐cleavage–type photoinitiators were studied. The effects of each photoinitiator on photocuring efficiency in both the presence and the absence of the FR monomer were examined. The flame retardancy and both physical and mechanical properties of the cured films were also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1181–1189, 2002
Study of stability of high‐temperature polyimides using TG/MS technique
Authors: Xie Wei , Heltsley Rebecca , Cai Xinhua , Deng Fuquan , Liu Jiemin , Lee Charles , Pan Wei‐Ping 
Published: August 2002

AbstractThe oxidative stability of the carbon fiber‐reinforced composite of polyimide was examined, in real time, using the evolved gas analysis techniques. Off‐gas degradation products suggested the onset temperature for chain scissions to be fairly low at about 190–220°C. Based on the off‐gas products present and the trend of their release, the composite degradation mechanism appeared to be similar between 190 and 371°C, thereby marking 371°C to be the highest accelerated aging temperature for its long‐term lifetime prediction. Beyond 371°C, different degradation mechanisms would apply. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1219–1227, 2002
Study of the synthesis of chitosan derivatives containing benzo‐21‐crown‐7 and their adsorption properties for metal ions
Authors: Tang Xin‐Hu , Tan Shu‐Ying , Wang Yu‐Ting 
Published: August 2002

AbstractThree new chitosan crown ethers, N‐Schiff base‐type chitosan crown ethers (I, III), and N‐secondary amino type chitosan crown ether (II) were prepared. N‐Schiff base‐type chitosan crown ethers (I, III) were synthesized by the reaction of 4′‐formylbenzo‐21‐crown‐7 with chitosan or crosslinked chitosan. N‐Secondary amino type chitosan‐crown ether (II) was prepared through the reaction of N‐Schiff base type chitosan crown ether (I) with sodium brohydride. Their structures were characterized by elemental analysis, infrared spectra analysis, X‐ray diffraction analysis, and solid‐state 13C NMR analysis. In the infrared spectra, characteristic peaks of CN stretch vibration appeared at 1636 cm−1 for I and 1652 cm−1 for II; characteristic peaks of NH stretch vibration appeared at 1570 cm−1 in II. The X‐ray diffraction analysis showed that the peaks at 2θ = 10° and 28° disappeared in chitosan derivatives I and III, respectively; the peak at 2θ = 10° disappeared and the peak at 2θ = 28° decreased in chitosan‐crown ether II; and the peak at 2θ = 20° decreased in all chitosan derivatives. In the solid‐state 13C NMR, characteristic aromatic carbon appeared at 129 ppm in all chitosan derivatives, and the characteristic peaks of carbon in CN groups appeared at 151 ppm in chitosan crown ethers I and III. The adsorption and selectivity properties of I, II, and III for Pd2+, Au3+, Pt4+, Ag+, Cu2+, and Hg2+ were studied. Experimental results showed these adsorbents not only had good adsorption capacities for noble metal ions Pd2+, Au3+, Pt4+, and Ag+, but also high selectivity for the adsorption of Pd2+ with the coexistence of Cu2+ and Hg2+. Chitosan‐crown ether II only adsorbs Hg2+ and does not adsorbs Cu2+ in an aqueous system containing Pd2+, Cu2+, and Hg2+. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1886–1891, 2002
From an environmental policy towards a sustainable tourism industry. The Albanian case
Authors: Santoro Lezzi Cecilia 
Published: August 2002

AbstractAlbania possesses enormous potential in terms of environment resources, which could play a leading role in the economic reconstruction of the country. A great heritage of environmental resources, as well as of historical and archaeological sites, occurs along the coasts, which could allow a substantial development in the sector of tourism. Among the many priorities facing this emerging country, a valorization of the coastline may reveal that it represents one of the country's greatest resources, even if, at the moment, it shows signs of degradation and pollution. Copyright © 2001 John Wiley & Sons, Ltd.
Expression of bone morphogenetic protein‐5 gene during chick heart development: Possible roles in valvuloseptal endocardial cushion formation
Authors: Yamagishi Toshiyuki , Nakajima Yuji , Nishimatsu Shin‐Ichiro , Nohno Tsutomu , Ando Katsumi , Nakamura Hiroaki 
Published: August 2002

AbstractThe bone morphogenetic protein (BMP) family, comprising multifunctional peptide growth factors, regulates many developmental processes in a variety of tissues. We examined the spatiotemporal expression of BMP5 by in situ hybridization in chick embryonic hearts from stages 5 to 33. The BMP5 gene was first expressed in the endoderm underlying the precardiac mesoderm at stages 5 to 8. Thereafter, BMP5 expression was restricted to the myocardium of the atrioventricular (AV) canal and outflow tract (OT) regions, where the valvuloseptal endocardial cushion tissue is induced. These results suggest that BMP5 may play important roles not only in myocardial differentiation, but also in the formation and maintenance of endocardial cushion tissue. Anat Rec 264:313–316, 2001. © 2001 Wiley‐Liss, Inc.