bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aqueous dispersion of polyurethane anionomers from H12MDI/IPDI, PCL, BD, and DMPA
Authors: Kim B. K. , Kim T. K. , Jeong H. M. 
Published: April 2003

AbstractPolyurethane anionomer dispersions were prepared from hydrogenated diphenylmethane diisocyanate (H12MDI) or isophorone diisocyanate (JPDI), poly(caprolactone) (PCL) diol, 1,4‐butane diol (BD), and dimethylolpropionic acid (DMPA). Upon neutralization of the DMPA with triethylamine (TEA), the NCO‐terminated polyurethane (PU) ionomers were self‐emulsified by adding water, followed by chain extension using triethylenetetramine (TETA) in aqueous media. Polyurethanes from H12MDI showed coarser dispersion and better tensile properties over those from IPDI. Polyurethanes prepared by the one‐shot method had better dispersion and tensile properties over those by the two‐shot method. When some of the PCL diol was replaced by DMPA or BD, tensile strength increased and ductility decreased due mainly to the increased chain rigidity and intermolecular forces. © 1994 John Wiley & Sons, Inc.
Catalyzed hydrolysis of polyethylene terephthalate melts
Authors: Campanelli J. R. , Cooper D. G. , Kamal M. R. 
Published: April 2003

AbstractThe effect of zinc catalysts on the hydrolytic depolymerization of polyethylene terephthalate (PET) melts in excess water was studied using a 2‐L stirred pressure reactor at temperatures of 250, 265, and 280°C. The main products of the reaction were found to be terephthalic acid, ethylene glycol, and diethylene glycol. Rate constants were calculated from initial rate data at each temperature and found to be about 20% greater than the corresponding rate constants for uncatalyzed hydrolysis. The catalytic effect of zinc, as well as sodium, salts is attributed to the electrolytic destabilization of the polymer‐water interface during hydrolysis. The depolymerization rate data at 265°C were found to fit a kinetic model proposed earlier for the uncatalysed hydrolysis of PET. The effect of zinc and sodium salts on the activation energy of hydrolysis, or on the formation of ethylene glycol monomer is unclear. © 1994 John Wiley & Sons, Inc.
Cardanyl acrylate/methacrylate based cross‐linked copolymers as novel supports: Synthesis and characterization
Authors: John George , Thomas Shali K. , Pillai C. K. S. 
Published: April 2003

AbstractCardanyl acrylate/methacrylate on suspension polymerization with methyl methacrylate, styrene, and acrylonitrile yielded copolymer beads. The beads were almost uniform in size and cross‐linked in nature. The copolymers synthesized were characterized by infrared, thermogravimetric analysis, scanning electron and optical microscopy, and swelling studies. © 1994 John Wiley & Sons, Inc.
Interpenetrating polymer networks based on thermoplastic polyurethanes (TPUS) and cis‐1,4‐polyisoprene
Authors: Mishra V. , Murphy C. J. , Sperling L. H. 
Published: April 2003

AbstractSemi‐interpenetrating polymer networks based on two elastomers, cis‐1,4‐polyisoprene (PI) and thermoplastic polyurethane elastomers (TPUs) were prepared in varying compositions. The PI component was cross‐linked using peroxide initiators. Modulus and mechanical properties were investigated as a function of composition and temperature. Slight synergisms were observed in mechanical properties, particularly for compositions containing 10% PI by weight. Little or no molecular mixing is shown by differential scanning calorimetry (DSC) for these two‐phase materials. © 1994 John Wiley & Sons, Inc.
The effect of interfacial microstructure on the interfacial strength of glass fiber/polypropylene resin composites
Authors: Moon Chang‐Kwon 
Published: April 2003

AbstractIn this study, a new method to form resin droplets on fibers has been developed, and samples for the single fiber pull‐out test were prepared using this method. The effects of microstructure of polypropylene (PP) resin and the microstructure of interface between the glass fiber and PP resin on the interfacial strength have been investigated. In addition, the influence of the microstructure of the interface on the interfacial strength of glass fiberreinforced PP composites have been discussed. It has been found that in the pull‐out test, the transcrystallinity formed at the interface between the glass fiber and PP resin improved the interfacial strength when no spherulites developed in the PP matrix. On the other hand, it has been found that when the spherulites were well developed in the PP matrix, the transcrystallinity formed at the interface reduced the interfacial strength. Finally, rapid cooling has been shown to improve the interfacial strength between the fiber and resin in the crystalline polymer matrix composites. © 1994 John Wiley & Sons, Inc.
The use of GPC coupled with a multiangle laser light scattering photometer for the characterization of polymers. On the determination of molecular weight, size and branching
Authors: Podzimek S. 
Published: April 2003

AbstractThe use of gel permeation chromatorgraphy (GPC) coupled with the multiangle laser light scattering (MALLS) detector for the determination of molecular weight and size distribution and for the identification of polymer branching is demonstrated on several examples of both organic and water souluble polymers. The influence of the second virial coefficient and the way of the light scattering data evaluation on the results obtained is shown. Measurements of the root mean square radius are presented for two series of polystyrene and polymethylmethacrylate standard, and the results are compared with the radii calculated from the Flory‐Fox equation. © 1994 John Wiley & Sons, Inc.
Phase behavior of blends of styrene/maleic anhydride copolymers
Authors: Gan P. P. , Paul D. R. 
Published: April 2003

AbstractThe phase behavior of blends of styrene/maleic anhydride copolymers (SMA) with styrene/methyl methacrylate copolymers (SMMA), styrene/acrylonitrile copolymers (SAN), tetramethyl bisphenol‐A polycarbonate (TMPC), and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) have been determined. Tentative binary interaction energies were evaluated from mapping the copolymer composition miscibility boundaries using the Flory–Huggins theory combined with the binary interaction model. Data on phase‐separation temperatures were too sparse for these systems to obtain refined estimates using the Sanchez–Lacombe theory. A negative interaction energy was obtained for the MA/AN pair; however, the MA unit showed strong repulsive interactions with all other monomer units examined here. © 1994 John Wiley & Sons, Inc.
Polymer swelling. XV. Swelling and deswelling studies of polystyrene–liquid systems in binary solutions
Authors: Errede L. A. , Hanson S. C. 
Published: April 2003

AbstractThe specific sorption capacities of poly(styrene‐co‐divinylbenzene) [i.e., (Sty)1−x (DVB)x samples for binary solutions of toluene (α = 1.98)] and a second solvent [i.e., heptane (α = <0.01), methanol (α = <0.06), acetone (α = 0.92) or chloroform (α = 3.00)] were correlated with the corresponding DVB mole fraction (x) in the sorbent polymer samples (0.01 < x < 0.11), with the volume fraction (z) of toluene in the sorbed binary liquid (which was cycled at least twice from z = 0 to z = 1 and back to z = 0 in increments of 0.1) and with the adsorption parameter (α) of the sorbed liquid. These correlations demonstrated that the sorption capacity during the initial transit from z = 0 to 1 reflects the molecular architecture in the original dry state. Once the samples have been swelled to saturation in toluene (z = 1), however, the “memory” of the former dry state is erased; thereafter the sorption capacity reflects only the architecture established in the fully swollen state, and the composition of the sorbed solution. The molecular nature of the solvent exchange processes is discussed in the text. © 1994 John Wiley & Sons, Inc.
Polysulfone membranes. V. Poly(phenyl sulfone) (Radel R)–poly(vinyl pyrrolidone) membranes
Authors: Dal‐Cin M. M. , Tam C. M. , Guiver M. D. , Tweddle T. A. 
Published: April 2003

AbstractUltrafiltration membranes were prepared from mixtures of poly(phenyl sulfone) (Radel R5000) and poly(vinyl pyrrolidone) (PVP) dissolved in 1‐methyl‐2‐pyrrolidinone (NMP). The effects of the casting solution composition on membrane performance and morphology are presented. Radel R5000 membranes showed higher productivity for a given pore size when compared to other polysulfone membranes. The biphenyl group in Radel R5000 makes it more rigid in comparison to other polysulfones. This may result in more ordered packing, which resulted in the higher productivities and smaller pore sizes observed in the membranes. © 1994 John Wiley & Sons, Inc.
Investigation on damping behavior and morphology of polyurethane/polymethacrylates and polyacrylates interpenetrating polymer networks
Authors: Chen Qingmin , Ge Hanhua , Chen Dongzhong , He Xiangdong , Yu Xuehai 
Published: April 2003

AbstractSimultaneous Interpenetrating Networks (SINs) were synthesized based on polyepichlorohydrin glycol (PECG), toluene diiocyanate (TDI), and trihydroxymethyl propane (TMP) as network I; and methyl methacrylate (MMA), ethyl methacrylate (EMA), methyl acrylate (MA), ethyl acrylate (EA), and ethyleneglycol dimethylacrylate (EGLM), respectively as network II. Damping behavior of the SINs was studied by a dynamic viscoelastometer. It was found that loss factor, tan δ, of PU/PEMA and PU/PEA is much higher than that of PU/PMMA and PU/PMA. The present authors consider that the length of pendant groups has an influence on the height of tan δ in the interpenetrating structure. Transmission electron microscopy (TEM) photos show that the SINs possess multiphase structures. These two networks are dispersed in a system microheterogeneously. © 1994 John Wiley & Sons, Inc.
Radiation vulcanization of hydrogenated acrylonitrile butadiene rubber (HNBR)
Authors: Zhao Wenwei , Yu Li , Zhong Xiaoguang , Zhang Yuefang , Sun Jiazhen 
Published: April 2003

AbstractRaw polymer and compound of hydrogenated acrylonitrile butadiene rubber (HNBR) were subjected to γ‐ray irradiation. Crosslinking was found to be the main chemical reaction induced by irradiation; the ratio of chain scission to crosslinking as well as the does at which gelation occurred were determined from gel content measurements to be 0.41 and 3.8 Mrad, respectively. The excellent hot‐air and oil‐resistant properties should be retained because no formation of double bonds or changing of the nitrile groups were observed with in the optimum dose range. Desired mechanical properties of the vulcanizate may be conveniently obtained by controlling the radiation dose. © 1994 John Wiley & Sons, Inc.
A new technique for preparing monodisperse polymer particles. II. Phase separation mechanisms
Authors: Hou Wei‐Hsin , Lobuglio Thomas M. 
Published: April 2003

AbstractNylon 6 polymer particles with a narrow‐size distribution are made by phase separation of different concentrations of polymer solutions. At concentrations above 0.15 wt %, the diameter of the precipitated particles increases linearly with the increasing of polymer concentration. The experimental results suggest that coagulation plays an important role in particle growth during the propagation stage. A mechanism is proposed for the formation of monodisperse polymer particles during phase separation. The uniformity of the precipitated nylon 6 particles decreases when the cooling process is slowered. The surface morphologies of the nylon 6 particles are controlled by changing the drying conditions. © 1994 John Wiley & Sons, Inc.
Kinetic and catalytic aspects in melt transesterification of dimethyl terephthalate with ethylene glycol
Authors: Santacesaria E. , Trulli F. , Minervini L. , Di Serio M. , Tesser R. , Contessa S. 
Published: April 2003

AbstractThe kinetics of melt transesterification of dimethyl terephthalate with ethylene glycol in the presence of zinc acetate as catalyst has been studied in semibatch conditions. We observed that this reaction occurs with the formation of many oligomers characterized from the terminal groups of the chains that can be hydroxyl–hydroxyl, methyl–hydroxyl or methyl–methyl. Experimental runs have been performed at different temperatures, initial reagents ratios, and catalyst concentrations, following the amount of methanol released during the time as well as the concentration of any kind of oligomer. All the oligomers have been identified and determined by HPLC analysis. A classic Kinetic model based on a complex reaction scheme containing four or five reaction sequences has been developed.The scheme with four sequences foresees 24 oligomeric species involved in 58 different reactions, while the scheme with five sequences has 48 oligomeric species involved in 228 reactions. Despite the large number of oligomers and occurring reactions, only two kinetic parameters and two equilibrium constants are necessary to simulate the kinetic behaviour of all the oligomers. A kinetic constant is related to the reaction of a methyl group with a hydroxyl of ethylene glycol, while the other corresponds to the reaction of a methyl group with a hydroxyl in a chain. Both kinetic constants show an activation energy of about 15 kcal/mol. We observed a nonlinear correlation between activity and catalyst concentration and interpreted this fact by assuming two different catalytic activity levels for a dissociated and an undissociated zinc ionic couple, respectively. © 1994 John Wiley & Sons, Inc.
Oxidation of poly(1‐trimethylsilyl‐1‐propyne)
Authors: Nagai Kazukiyo , Nakagawa Tsutomu 
Published: April 2003

AbstractThe oxidation of poly(1‐trimethylsilyl‐1‐propyne) (PMSP) proceeded normally in air at room temperature and under mild thermal conditions. Two different bands assigned to the carbonyl groups on a side chain and on a decomposed chain end were found in the IR spectra of the oxidized PMSP membrane. However, no band assigned to a hydroxyl group was observed. An allyl‐type methyl group of the PMSP was mainly autooxidized without a decrease in molecular weight at room temperature. Only the former band assigned to the carbonyl groups appeared and it had a shoulder peak. In the case of mild thermal oxidation, the decomposition started in the backbone chain and both bands appeared. When the thermal oxidation proceeded further, all bonds were broken and various carbonyl and siloxane bonds were then randomly produced. © 1994 John Wiley & Sons, Inc.
Effect of surface‐modifying macromolecules and solvent evaporation time on the performance of polyethersulfone membranes for the separation of chloroform/water mixtures by pervaporation
Authors: Fang Yi , Pham Vu Anh , Matsuura Takeshi , Santerre J. P. , Narbaitz Roberto M. 
Published: April 2003

AbstractPolyethersulfone (PES) membranes using different evaporation periods were fabricated by the phase‐inversion method. Pervaporation experiments were conducted for chloroform/water mixtures to determine the selectivity of the PES membranes. It was found that chloroform could be concentrated in the permeate from chloroform/water binary feed mixtures by PES membranes prepared using longer evaporation periods, and that the selectivity of PES membranes in pervaporation could be reversed by shorter evaporation periods. This study also showed that by adding surface‐modifying macromolecules (SMM) up to 1 wt % into the casting solution, chloroform enrichment in the permeate could be increased by 50%. Chloroform enrichment increased with increasing SMM concentration until an optimal value, after which the enrichment decreased. © 1994 John Wiley & Sons, Inc.
Properties of highly water‐absorptive hydroxyethylcellulose graft copolymers: Viscoelasticity and moisture sorption
Authors: Miyata Namiko , Yokoyama Miyuki , Sakata Isao 
Published: April 2003

AbstractThe viscoelasticity of the hydrogels, the moisture sorption, and the characteristics of the sorbed water of highly water‐absorptive hydroxyethylcellulose (HEC) graft copolymers [e.g., HEC graft copolymers containing partially hydrolyzed polyacrylamide (HEC‐P‐Hyd‐PAM), etc.] were investigated in comparison with commercial absorbents. The viscosity (η) and the rigidity (G) of the dispersions of their hydrogels were, respectively, proportional to the second to the sixth powers and the fifth to the seventh powers of their concentrations (η = KC2–6 and G = K′C5–7). With respect to the characteristics of the sorbed water, the conductivity of 0.1 N KCI in the hydrogels of the HEC water, absorbents was about 11.8 mS/cm, which was almost the same as that of 0.1 N KCI in pure water, and the water absorbency of dry matter (soybean seeds) in their hydrogels was almost the same as that in pure water. These results suggest that most of the sorbed water in the HEC super water absorbents behaves like free water. The maximum volume of sorbed moisture in a monolayer fashion (Vm) of HEC‐P‐Hyd‐PAM analyzed using the Brunauer‐Emmett‐Teller equation was about 0.21 g/g (1.2 mol water/polymer repeat unit), and there was no cluster water at 92% relative humidity or below as a result of applying the cluster function concept. © 1995 John Wiley & Sons, Inc.
Carbodiimide catalysis in cross‐linking of cotton cellulose with 1,2,3,4‐butanetetracarboxylic acid
Authors: Choi Hyung‐Min , Mahmood Tariq , Li Jiang Dong , Schlup John 
Published: April 2003

AbstractThis study examined carbodiimde catalysis (cyanamide, dicyandiamide, disodium cyanamide) in the cross‐linking of cotton cellulose with 1,2,3,4‐butanetetracarboxylic acid (BTCA). Considerable improvement in the smooth drying appearance of the treated cotton substantiated the fact that cellulose cross‐linking has been achieved by BTCA in the presence of carbodiimide. Bath pH was a very important factor in determining the performance properties of the treated cotton. Two possible reaction mechanisms were proposed: direct esterification and anhydride intermediate formation. Both pathways involved the formation of urea. Semiquantitative analyses of the spectra obtained by Fourier transform infrared spectroscopy revealed that the cyanamide was somewhat less effective than were dicyandiamide and sodium hypophosphite in esterification efficiency. © 1995 John Wiley & Sons, Inc.
A DSC study of the crosslinking of polychloroprene with ZnO and MgO
Authors: Mallon P. E. , McGill W. J. , Shillington D. P. 
Published: April 2003

AbstractPolychloroprene and compounds of polychloroprene with ZnO and MgO were crosslinked by heating in a DSC at a programmed rate. The reaction was stopped at points along the thermogram and the crosslink density of the compound determined. The amount of chlorine evolved during reaction was measured as ZnCl2 and/or MgCl2. Two crosslinking processes were identified, both involving reaction of the 1,2 units in the polymer chain; the first comprising a rapid crosslinking reaction that occurs prior to the isomerization of 1,2 units and the second, a much slower reaction of isomerized 1,2 units. ZnCl2, which forms during compounding and on crosslinking, catalyzes the first reaction, while ZnO promotes the allylic rearrangment of 1,2 units. MgO increases the scorch time by trapping HCl evolved during compounding, thus limiting the amount of the crosslinking catalyst (ZnCl2) formed. © 1995 John Wiley & Sons, Inc.
Lifetime prediction of polymers
Authors: Hamid S. H. , Amin M. B. 
Published: April 2003

AbstractNatural and artificially accelerated weathering trials were carried out on low‐density polyethylene samples used for agricultural and disposable purposes. Modifications in polymer characteristics were studied using Fourier transform infrared (FTIR) spectroscopy, different scanning calorimetry (DSC), gel permeation chromatography (GPC), scanning electron microscopy (SEM), and mechanical properties testing. The natural exposure trials were conducted at five geographical locations representing varying ambient temperature and humidity conditions and receiving different doses of solar radiation. The artificially accelerated exposure trials were carried out in an Atlas weatherometer for 5,000 hours, whereas the natural exposure was for 24 months. Rates of photo‐oxidative and thermal degradation have been determined by measuring the formation of non‐volatile carbonyl oxidation products which absorb in the infrared region with a maximum absorbance level at 1710cm−1. Thermal characteristics were noticed to vary in terms of the shape and size of melting peak for both the natural and artificial weathering. This implies a change in crystallinity, which has indicated an increasing trend with exposure time. The crystalline melting temperature (Tm) remains almost steady for both exposure tests. The drop in mechanical properties and the modification in polymer chain length were also monitored. The GPC analysis indicated the change in molecular weight distribution (MWD), which shows the formation of lower molecular‐weight species. Surface modifications were revealed in terms of abrasion effects apparent from SEM micrographs. A correlation between natural and artificial weathering was considered for lifetime prediction in a short exposure time. It was found that the confidence level of predicting lifetime on the basis of artificially accelerated exposure trials is dependent on many parameters, which include time, material, equipment, etc. © 1995 John Wiley & Sons, Inc.
Surface area of aqueous sodium hydroxide hydrolyzed high‐speed spun poly(ethylene terephthalate) fibers
Authors: Holmes S. A. , Zeronian S. H. 
Published: April 2003

AbstractThe specific surface area (SSA) of delustered undrawn and drawn high‐speed spun PET fibers hydrolyzed in aqueous NaOH was measured using three methods: (1) geometric, based on fiber diameter; (2) gas adsorption using N2 and the BET equation; and (3) adsorption of a nonionic surfactant. Increasing the spinning speed had little effect on the SSA of the untreated fibers, while drawing resulted in considerably larger SSA. For the hydrolyzed fibers, both adsorption methods resulted in larger SSAs than that predicted geometrically due to surface pitting. After hydrolysis, the higher spinning speed resulted in a greater increase in SSA over the untreated sample, whereas the increase in SSA was less for the drawn fibers compared to the undrawn. The kinetics of hydrolysis are also discussed. © 1995 John Wiley & Sons, Inc.
Organic polymer‐surface modified precipitated silica
Authors: Waddell Walter H. , O'Haver John H. , Evans Larry R. , Harwell Jeffrey H. 
Published: April 2003

AbstractTo improve the performance of rubber compounds using precipitated silica as a reinforcing filler, the silica surface was directly modified by (1) adsorption of a surfactant, (2) adsolubilization of an organic monomer, (3) in situ polymerization of the monomer in the surfactant bilayer, and (4) partial surfactant removal. Silica was thus surface modified with polymerized styrene, isoprene, butadiene, and copolymers. Styrene–butadiene modification afforded the most promising candidate based on evaluation in a silica‐filled model tire compound. Compound physical testing showed that cure times were decreased, and break strength, tear energy, elongation to break, and cut growth resistance were increased. Thus, surface modification of silica by the in situ polymerization of organic monomers affords unique materials useful in improving rubber cure properties and cured compound physical properties. © 1995 John Wiley & Sons, Inc.