bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of residual acidic groups in several poly(N‐alkyl methacrylate)s using photophysical and photochemical probes
Authors: Christoff M. , Yamaki S. B. , De Oliveira M. G. , Atvars T. D. Z. 
Published: February 2004

AbstractThis work describes three different methods for detecting acidic groups copolymerized in poly(methyl methacrylate), poly(ethyl methacrylate), and poly(n‐butyl methacrylate) chains using molecular spectroscopy. The first was based on the shift of the tautomeric equilibrium of 4‐dimethylaminoazobenzene by acidic groups that modify the absorption band in the UV/vis spectra. We also show that the acidic groups present in the polymer influenced the anti‐syn photoisomerization reaction of this dye. Further, a mercury–dithizonate complex was completely bleached when sorbed in poly(n‐alkyl methacrylate) matrices containing acidic groups. Finally, Nile Blue A was used as a spectrophotometric probe to quantify the amount of acidic groups in these polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 830–838, 2004
Binary blends based on poly(N‐isopropylacrylamide): Miscibility studies with PVA, PVP, and PAA
Authors: Mano Valdir , Ribeiro E Silva Maria Elisa Scarpelli , Barbani Niccoletta , Giusti Paolo 
Published: February 2004

AbstractBlends of poly(vinyl alcohol) (PVA), poly(acrylic acid), (PAA), and poly(vinyl pyrrolidone) (PVP), with poly(N‐isopropylacrylamide) (PNIPAM), were prepared by casting from aqueous solutions. Mechanical properties of PNIPAM/PVA blends were analyzed by stress–strain tests. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were employed to analyze the miscibility between the polymeric pairs. The results revealed that PNIPAM is not miscible with PVA and PVP in the whole range of composition. On the other hand, PNIPAM interacts strongly with PAA forming interpolymer complex due to the formation of cooperative hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 743–748, 2004
Effect of maleic acid content on network structure and swelling properties of poly(N‐isopropylacrylamide‐co‐maleic acid) polyelectrolyte hydrogels
Authors: Çaykara Tuncer 
Published: February 2004

AbstractHydrogels were prepared by γ‐ray–induced polymerization in aqueous solution of N‐isopropylacrylamide (NIPA) and of NIPA with three different charge densities, that is, maleic acid (MA) as a comonomer. The swelling behaviors of these hydrogels were analyzed in buffer solutions at various pH and temperature ranges. The equilibrium swelling ratios were relatively high and sensitive to pH and temperature. The polymer–solvent interaction parameter (χ) and the molecular weight between crosslinks (Mc) of P(NIPA/MA) polyelectrolyte hydrogels were calculated from swelling studies in buffer solutions at various pH values and related to MA content. A kinetic study of the absorption determined the transport mechanism as a non‐Fickian type diffusion. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 763–769, 2004
Isothermal crystallization kinetics of polypropylene by differential scanning calorimetry. I. Experimental conditions
Authors: Hernández‐Sánchez Fernando , del Castillo Luis F. , Vera‐Graziano Ricardo 
Published: February 2004

AbstractReliable isothermal crystallization kinetic studies can be achieved by differential scanning calorimetric techniques only under restricted conditions. In the case of isotactic polypropylene, our results indicate that those conditions are met in the range of 3°C below the isothermal crystallization temperature Tc. Experimentally, it is only in this range when the complete crystallization peak can be registered by the DSC and depicted in a thermogram. Just around this temperature interval, the Avrami exponent n = 3 for bulk crystallization, whereas for any other test the isothermal temperature Tit, nonisothermal conditions prevail and the Avrami exponent deviates from the expected value. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 970–978, 2004
Kinetic analysis of poly(N‐isopropylacrylamide‐co‐dimethylaminoethyl methacrylate) microgel latex formation
Authors: Zhang Y. , Zha L. S. , Fu S. K. 
Published: February 2004

AbstractCurves of the conversion and particle size versus the time in the preparation of poly(N‐isopropylacrylamide‐co‐dimethylaminoethyl methacrylate) microgel latices by surfactant‐free emulsion polymerization were measured. The copolymerization reactions were rapid, and their rates increased with the dimethylaminoethyl methacrylate (DMAEMA) concentration in the polymerization recipe. Particle formation occurred by a homogeneous nucleation mechanism, in which DMAEMA helped to colloidally stabilize the primary particles. In addition, a strong dependence of the water‐soluble‐polymer (WSP) formation on the DMAEMA concentration was found, and the DMAEMA content in the WSP was significantly higher than that in the microgel particle. A drastic variation of the crosslinking density within the microgel particle during the polymerization process was found through a comparison of the particle size determined by quasi‐elastic light scattering with that determined by transmission electron microscopy. Finally, on the basis of these results, the mechanism of particle formation in this polymerization process was examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 839–846, 2004
Cure study of an acrylic resin to develop natural fiber composites
Authors: Behzad T. , Sain M. 
Published: February 2004

AbstractIn the present study a new environmentally friendly acrylic resin was characterized to develop a high‐performance biocomposite for future work. Differential scanning calorimetry measurements were used to determine onset of curing reaction as well as the degree of cure at a certain temperatures. Swelling equilibrium data for an acrylic resin were generally analyzed using the Flory–Rehner equation for a perfect network, to obtain a measurement of the molar mass between two crosslinks and the crosslink density of polymer, and to establish the effect of temperature and time on these parameters. The crosslink density of cured resin at 180°C and 10 min indicates the completion of a major part of the reaction under those conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 757–762, 2004
Incorporation of carbon dioxide into soybean oil and subsequent preparation and studies of nonisocyanate polyurethane networks
Authors: Tamami B. , Sohn S. , Wilkes G. L. 
Published: February 2004

AbstractEpoxidized soybean oil was effectively converted to carbonated soybean oil (CSBO) containing five‐membered cyclic carbonates by reaction with carbon dioxide in the presence of tetrabutylammonium bromide as catalyst at 110°C in high yield. CSBO could easily react with di‐ or tri‐ primary amines to give the corresponding nonisocyanate polyurethane networks (NIPUs). A model reaction between CSBO and n‐butylamine showed the effective ring opening of five‐membered cyclic carbonate moieties in the triglyceride molecules by the amine to form β‐hydroxyurethane systems. NIPUs were further characterized by the three techniques of solvent extraction, dynamical mechanical analysis, and limited tensile testing. The data from these methods confirmed the network character of all materials and also showed how the levels of extractables, Tg, and mechanical properties varied with type of amine and, in the case of ethylenediamine, the effect of stoichiometry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 883–891, 2004
Piezoelectricity of vinylidenefluoride–trifluoroethylene copolymer films in various poling conditions
Authors: Sathanon U. , Fukura S. , Sekiguchi A. , Ogino K. , Miyata S. 
Published: February 2004

AbstractPiezoelectricity of ferroelectric thin polymer films strongly depends on the poling condition. We can classify them as conventional electrical and novel nonelectrical poling. These experiments show the comparative results on piezoelectricity induced from various poling processes (i.e., electrical corona poling, nonelectrical surface‐energy poling, and a combination of both methods simultaneously in various poling conditions). The most interesting result confirmed that the piezoelectricity increased significantly when the combination poling was applied with appropriate metal substrate and temperature decreasing rate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 856–860, 2004
Physical characteristics of sweet potato pulp/polycaprolactone blends
Authors: Lee Eun‐Jung , Kweon Dong‐Keon , Koh Bong‐Kyung , Lim Seung‐Taik 
Published: February 2004

AbstractSweet potato pulp (SSP) obtained as a by‐product from starch extraction was blended with polycaprolactone (PCL) to prepare a biodegradable plastic material. In the blends, PCL was used as a reinforcing agent. The SPP/PCL blends were prepared by compression‐molding under high temperature and pressure, at different SPP/PCL ratios, and the mechanical properties of the molded specimens were tested. Matrix structure and thermal properties were measured by using a Fourier transform infrared (FTIR) spectrophotometer, scanning electron microscope (SEM), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). Mechanical properties (tensile and flexural properties) were also measured to find the most suitable ratio in a SSP/PCL blend. During compression molding of the SPP/PCL blends under high pressure and temperature, chemical reaction occurred between SPP and PCL, and thus, thermal stability and mechanical strength of the blends increased and water uptake decreased. Also, by increasing the PCL content in the blend, the matrix in the blend became more homogeneous, and consequently, mechanical strength of the molded specimen increased. At 7/3 or 6/4 weight ratio of SSP/PCL, water uptake of the molded specimen became substantially less than that at 8/2. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 861–866, 2004
Study on curing kinetics and curing mechanism of epoxy resin based on diglycidyl ether of bisphenol a and melamine phosphate
Authors: Chen Wen‐Yi , Wang Yez‐Zen , Chang Feng‐Chih 
Published: February 2004

AbstractThe curing kinetics of the diglycidyl ether of bisphenol A/melamine phosphate (DGEBA/MP) was analyzed by the DSC technique. The Kissinger and Flynn–Wall–Ozawa methods were applied to determine the dynamic kinetics of the DGEBA/MP system. The activation energies obtained by these two methods were 83.9 and 85.6 kJ/mol, respectively. An autocatalytic equation was applied to determine the isothermal curing kinetics of the DGEBA/MP system. The DGEBA/MP system exhibits autocatalytic behavior in the isothermal curing procedure, whose kinetics fits well with the autocatalytic mechanism. The obtained isothermal curing activation energy of the DGEBA/MP system was 110.0 kJ/mol. The curing mechanism of DGEBA with melamine phosphate was investigated using FTIR, 13C solid‐state NMR, and 31P solid‐state NMR. It involved an epoxide–amine reaction, etherification of phosphoric acid and epoxy, dehydration, and thermal oxidation of the hydroxyl group of the DGEBA/MP system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 892–900, 2004
Active control on molecular conformations and tensile properties of spider silk
Authors: Pan Z. J. , Li C. P. , Xu Q. 
Published: February 2004

AbstractThe mechanical properties of spider dragline silk vary with the spinning conditions, and molecular conformation is one of the important factors for the strength and strain of materials. Four kinds of Araneus ventricosus spider dragline silk fibers, measured by Raman microscopic spectrometry, were produced under different conditions: (1) reeled at the rate of 2 cm/s; (2) secreted by a dropping spider from a 100‐cm‐high table; (3) spun by spiders raised in two different containers. The Raman spectra of these fibers showed that the spinning method and growing environment of spiders had evident influences on the molecular conformations and tensile properties of dragline silk, and the dragline silk obtained from a dropping spider contained the greatest number of molecules with highly oriented β‐sheet structures and gave higher stress/strain values. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 901–905, 2004
The tribological behavior of micrometer and nanometer TiO2 particle‐filled poly(phthalazine ether sulfone ketone) composites
Authors: Shao Xin , Liu Weimin , Xue Qunji 
Published: February 2004

AbstractMicrometer and nanometer TiO2 particle‐filled poly(phthalazine ether sulfone ketone) (PPESK) composites with various filler volume fractions from 0.5 to 7.5 vol % were prepared by heating compression molding. The friction and wear behaviors of the PPESK composites were evaluated using the block‐on‐ring test rig by sliding PPESK‐based composite blocks against a mild carbon steel ring under dry friction conditions. The wear debris and the worn surfaces of the PPESK composites filled with micrometer and nanometer TiO2 particles were investigated by using a scanning electron microscope (SEM), while the structures of PPESK composites and wear debris were analyzed with IR spectra. Experimental results show that antiwear properties of the PPESK composites can be improved greatly by filling nanometer TiO2 particles, and the friction coefficient decreases when the filler volume fraction is below 2.5%, but when the filler volume fraction is above 2.5% the friction coefficient increases gradually with increasing filler volume fraction. In the case of micrometer TiO2 filler, wear rates increase with increasing filler volume fractions under identical test conditions, and the friction coefficients are less sensitive to the filler volume fraction. It was also found that the wear mechanism of micrometer TiO2 particle‐filled PPESK is mainly severe adhesion and abrasive wear, while that of nanometer TiO2 particle‐filled PPESK is mainly slight abrasive wear. In the former case, there are no transfer film formed on the surface of the counterpart steel, and wear debris are in the form of long and large ribbon. While in the latter case, the wear debris was granule and their size was about 10 μm. In case of 1 vol % nanometer TiO2 particle‐filled PPESK composites, the transfer film was fairly thinner and smoother, and the transfer film provided better coverage on the surface of steel ring, while that of 7.5 vol % was thicker and discrete. These account for the different friction and wear behavior of micrometer and nanometer TiO2 particle‐filled PPESK composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 906–914, 2004
Experimental and simulation studies on molecular transport of substituted monocyclic aromatic liquids into fluoropolymer sheet membranes: Liquid structure–diffusion, –sorption, and –permeation relationships
Authors: Aminabhavi Tejraj M. , Naidu B. Vijaya Kumar 
Published: February 2004

AbstractThe present study reports an investigation on the molecular transport of 10 monocyclic aromatic liquids (benzene, chlorobenzene, 1,2‐dichlorobenzene, bromobenzene, toluene,p‐xylene, trimethylbenzene, ethylbenzene, methoxybenzene, and ethoxybenzene) at 40 and 50°C through sheet polymeric membranes (FLS‐2650) using a sorption gravimetric technique. Diffusion and permeation coefficients of these liquids were calculated from the sorption data using Fick's diffusion equation. Sorption results were analyzed typically in the case of benzene and chlorobenzene to compute the concentration profiles at different depths along the thickness direction of the sheet membranes and at different time intervals by solving the Fick's equation under appropriate boundary conditions, based on the numerical simulation method developed in “C” language using a finite‐difference method. Transport results were analyzed to establish the relationships between the penetrating liquid structures with diffusion, permeation, and sorption data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 991–996, 2004
Electrical behavior of chitosan and poly(hydroxyethyl methacrylate) hydrogel in the contact system
Authors: Kim Seon Jeong , Kim Han Il , Shin Su Ryon , Kim Sun I. 
Published: February 2004

AbstractSemi‐interpenetrating polymer networks (semi‐IPNs), as polymer hydrogels composed of chitosan and poly(hydroxyethyl methacrylate) (PHEMA), exhibiting electrical‐sensitive behavior, were prepared. The swelling behavior of the chitosan/PHEMA hydrogels was studied by immersing the gels in various concentrations of aqueous NaCl solution. The electrical responses of the semi‐IPN hydrogel, in applied electric fields, were also investigated. When the semi‐IPN hydrogels were swollen, where one electrode was placed in contact with the gel and the other fixed 30 mm apart from one, they exhibited bending behavior on the application of an electric field on a contact system. The electroresponsive behavior of the present semi‐IPN was also affected by the electrolyte concentration of the external solution. The semi‐IPN also showed various degrees of increased bending behavior depending on the electric stimulus. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 915–919, 2004
Water‐swelling behavior of hydrophobic porous copolymer resins composed of two kinds of crosslinkers
Authors: Zhao Xin , Wang Xunhua , Yan Jun 
Published: February 2004

AbstractHydrophobic, but water‐swellable, porous copolymer resins composed of divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDM) or ethylene glycol diacrylate (EGDA) were prepared by using purified DVB (98.8%) in the presence of toluene as porogen. The EGDM/DVB resins thus obtained, whose polarity was nearly identical to that of the resins based on DVB and methyl methacrylate (MMA) at the same DVB levels, were water‐swellable by direct contact with water up to a DVB content of 64%, whereas the latter did not swell in water at any DVB levels. EGDA is also hydrophobic, but with a polarity greater than that of EGDM. As a result, the EGDA/DVB resins were more water swellable than EGDM/DVB resins, and could also be prepared as water‐swellable materials by using technical DVB (79.3%), besides the use of the purified DVB. All these results were explained on the basis of the network rigidity (crosslinking density) and the polymer polarity of the resins that were formed in the presence of a well‐solvating porogenic solvent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 997–1004, 2004
Permselectivity of polyamide composite membrane modified by solvent
Authors: Cai Bang‐Xiao 
Published: February 2004

AbstractAsymmetric reverse osmosis (RO) polyamide (PA) composite membrane may be modified by means of a solvent‐processing technique into pervaporation (PV) membrane for separating organic aqueous solution. Formic acid, acetic acid, phosphoric acid, hydrochloric acid, phenol, and so forth, better solvents for PA, were selected as the modifying agents in this study. The effect of the modifying conditions (type and concentration of the modifying agent, processing time of membrane in liquid medium) on the sorption of modified membranes was investigated. After the PA composite membrane was treated with 8 wt % acetic acid for 1 h, the swelling rate for water (Sw) increased, whereas that for isopropanol (SIPA) decreased, compared with that of the nonmodified membrane. The difference between Sw and SIPA of the membrane treated with acetic acid was greater than that with other modifying agents. The separation factor and flux of the modified membrane were correspondingly maximal when it was used in a PV separating isopropanol aqueous solution. The contact of solvent molecules in liquid medium with polymer chains in the PA membrane and the intranodular chains in the PA membrane tending to diffuse by reptation toward the solvent molecules were the principal causes leading to a change of structure of asymmetric PA composite membrane. The mechanism of changing membrane structure by means of the solvent‐processing technique may better interpret the modification of PA composite RO membrane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1005–1010, 2004
Effect of process variables on bulk development of air‐textured poly(trimethylene terephthalate) bulk continuous filaments
Authors: Chuah Hoe H. 
Published: February 2004

AbstractBulk development of air‐textured poly(trimethylene terephthalate) (PTT) bulk continuous filaments was studied by varying two texturing parameters, yarn preheating and texturing hot air temperatures. The yarns were subsequently heat treated from 80 to 160°C. Bulk was found to go through a maximum with increasing heat‐treatment temperature because of two competing mechanisms. Upon heat treatment, the fiber shrunk and developed bulk; heat treatment also simultaneously induced structural reorganization through annealing and stabilized the fiber against shrinkage. When the later mechanism became dominant, bulk development decreased with further increase of heat‐treatment temperature. The temperature at which the maximum occurred increased when the yarn preheating or texturing air temperatures were increased. Depending on the extent of annealing and structural reorganization during yarn preheating and during texturing, fibers with equivalent bulk measured at a single temperature did not behave the same way over a range of heat‐treatment temperatures. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1011–1017, 2004
A novel dendritic acrylate oligomer: Synthesis and UV curable properties
Authors: Xu Dong‐Mei , Zhang Ke‐Da , Zhu Xiu‐Lin 
Published: February 2004

AbstractAn dendritic acrylate oligomer with eight double bonds (DAO) was synthesized by Michael addition reaction of ethylene diamine (EDA) and trimethylolpropane triacrylate (TMPTA) under mild conditions, and was easily separated from the reaction system with methanol. The structure of DAO was characterized by IR, 1H‐NMR, and elemental analysis. DAO is UV curable oligomer with low viscosity and high curing speed. Its viscosity was 10.85% of that of the linear acrylic oligomers with similar molecule weight (EBECRYL Resin 285). With Darocure 1173 as the photoinitiator, the curing speed of DAO was respectively 7.5 and 10.3 times higher than that of EBECRYL Resin 605 and EBECRYL Resin 285. Furthermore, the effect of the photoinitiator and active diluent on curing speed of DAO UV curing system was studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1018–1022, 2004
Cure characteristics and mechanical properties of short nylon fiber‐reinforced nitrile rubber composites
Authors: Rajesh C. , Unnikrishnan G. , Purushothaman E. , Thomas Sabu 
Published: February 2004

AbstractAcrylonitrile butadiene rubber (NBR)‐based composites were prepared by incorporating short nylon fibers of different lengths and concentration into the matrix using a two‐roll mixing mill according to a base formulation. The curing characteristics of the samples were studied. The influence of fiber length, loading, and rubber crosslinking systems on the properties of the composites was analyzed. Surface morphology of the composites has been studied using Scanning Electron Microscopy (SEM). Addition of nylon fiber to NBR offers good reinforcement, and causes improvement in mechanical properties. A fiber length of 6 mm was found to be optimum for the best balance of properties. It has been found that at higher fiber loadings, composites show brittle‐type behavior. Composites vulcanized by the dicumyl peroxide (DCP) system were found to have better mechanical properties than that by the sulfur system. The swelling behavior of the composites in N,N‐dimethyl formamide has been analyzed for the swelling coefficient values. Composites vulcanized in the DCP system were found to have higher rubber volume fraction than that in the sulfur system, which indicates better rubber–fiber interaction in the former. The crosslink densities of various composites were also compared. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1023–1030, 2004