bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on antioxidants. III. 2[(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)methylene]hydrazine carbothioamide as a melt stabilizer for unstabilized polypropylene
Authors: Raja A. R. , Pendyala V. N. S. , Xavier S. F. , Shah A. C. , Nair K. B. 
Published: April 2003

AbstractPolypropylene's high processing temperatures initiate thermal oxidative degradation and loss of physical properties. Antioxidants protect polymers through the severe conditions of processing and fabrication and also through end use. Small amounts of antioxidants like 2,6‐di‐tert‐butyl‐4‐methylphenol and 2[(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)methylenel]‐hydrazine carbothioamide are shown to be effective in protecting isotactic polypropylene (IPP) against thermooxidative degradation. 2[3,5‐Di‐tert‐butyl‐4‐hydroxyphenyl)‐methylene]hydrazine carbothioamide was melt compounded with IPP using a twin screw extruder. The melt flow index of the extruded sample was measured. The extruded granules were injection molded to get specimens suitable for testing mechanical properties, such as heat deflection temperature, Izod impact strength, tensile strength, tensile modulus, flexural strength, and flexural modulus. 2[(3,5‐Di‐tert‐butyl‐4‐hydroxyphenyl)methylene]hydrazine carbothioamide was found to be an effective melt stabilizer for unstabilized polypropylene. © 1995 John Wiley & Sons, Inc.
Surface analysis of PP/EVA blends modified with amino acids for biomedical applications
Authors: Schroeder K. , Klee D. , Höcker H. , Leute A. , Benninghoven A. , Mittermayer C. 
Published: April 2003

AbstractThe copolymers poly(propylene‐co‐ethylene) (PP/E) and poly(ethylene‐co‐vinyl acetate) (EVA) and blends of these were modified to develop an artificial matrix which promotes the growth of endothelial cells. Covalent immobilization of amino acids or sequences of adhesion glycoproteins should trigger the formation of an endothelial cell monolayer onto the polymeric surface. Reactive functional groups were generated by saponifying the ester groups of the EVA component. Esterification with oxalylic or malonic dichlorides in the gas phase yielded the required monoesters and gave the best results for further immobilization of amino acids, while reaction with α,ω‐dicarboxylic acid dichlorides in solution led to diester formation. Subsequently, various protected amino acids were immobilized via the carbodiimide method. Surface analytical methods like infrared spectroscopy using at tenuated total reflection (IR‐ATR), X‐ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) were used to prove the modification steps. The analytical results confirmed covalent side‐chain generation in the upper surface region. © 1995 John Wiley & Sons, Inc.
Basic kinetic model for the reaction yielding linear polyurethanes. II
Authors: Król Piotr , Gawdzik Andrzej 
Published: April 2003

AbstractOn the basis of the gradual polyaddition kinetic model developed earlier, an attempt was made to provide a generalized mathematical model for the set of reactions yielding linear polyurethanes. The model is a system of first‐order ordinary differential equations. It was assumed at the present stage of this model that the rate constants for the reaction considered do not change. The model developed was then solved numerically. Average molecular weight of the polymer and composition data for oligomers were calculated for a constant volume batch reactor and varied process parameters. The GPC method, which was tested for model urethane oligomers, was employed to verify the model developed. The reaction of 2,4‐TDI with 1,4‐butanediol proceeding in a solution was investigated. It was concluded that the model was applicable to a limited degree in describing the linear polyurethane manufacturing process which is more complex. However, it was suggested that the algorithms adopted could be utilized in developing further models which could assume changing rate constants for the polymer chain growth reactions. © 1995 John Wiley & Sons, Inc.
Viscometric and conductometric studies of poly(vinyl alcohol)‐g‐polyacrylamide composites
Authors: Kaur Inderjeet , Maheshwari Savita , Gupta Anita , Misra B. N. 
Published: April 2003

AbstractPoly(vinyl alcohol)‐g‐polyacrylamide composites have been prepared by γ‐radiation‐initiated polymerization of acrylamide (AAm) in the presence of poly(vinyl alcohol) (PVA) in aqueous medium by the mutual method in air. Percentage conversion of AAm has been studied as a function of total dose, monomer concentration, and amount of water. Optimum conditions leading to maximum percent conversion of the monomer to give the composite have been evaluated. The products of polymerization of AAm in the presence of PVA consisted of unreacted PVA, the graft copolymer, PVA‐g‐PAAm, and the homopolymer polyacrylamide, PAAm, and this mixture is referred to as PVA‐g‐PAAm composite. AAm was also polymerized in the absence of PVA under similar conditions, and optimum conditions leading to maximum conversion of AAm to PAAm have been evaluated. A comparative study of the polyelectrolytic behavior of PVA, PAAm, and the composite has been made by viscometric and conductometric methods. © 1995 John Wiley & Sons, Inc.
Synthesis of highly crosslinked porous copolymers of methacrylic ester of p,p′‐dihydroxydiphenylpropane diglicydyl ether and divinylbenzene
Authors: Matynia Tadeusz , Gawdzik Barbara 
Published: April 2003

AbstractNarrow disperse porous particles were formed by emulsion polymerization of two tetrafunctional monomers in the presence of the diluent mixture: n‐decanol and toluene. One monomer was divinylbenzene while the second was synthesized by the reaction between methacrylic acid and p,p′‐dihydroxydiphenylpropane diglicydyl ether. In order to obtain chromatographic packings of different polarities copolymers of the following molar ratio of monomers, 0.2 : 0.8, 0.5, 0.5, and 0.8 : 0.2, were synthesized. Porous structures of the obtained copolymers were studied by BET and EC methods. © 1995 John Wiley & Sons, Inc.
Low‐speed tack measurements of fluids and inks
Authors: Phillips J. C. , Chiang A. C. 
Published: April 2003

AbstractLow‐speed tack measurements (≈ 0.1–6.0 rad/s or ≈ 1–57 RPM) have been determined for polymeric‐based solution inks and oil‐based dispersion inks, tripropylene glycol (TPG), Igepal (I‐530), and N‐350 (viscosity calibration standard) fluids using a metal roller/incline method. The inks and fluids were tested under “unaged” or reference conditions at 25°C. The inks were “aged” at 70°C and, subsequently, tack measurements were made at 25°C. The tack (Ti) and angular speed (Wi) for the inks were empirically fitted as functions of incline angle (α) and “aged” time, tcd. A correlation was also made for tack and percent weight change, ΔWi. Other factors, such as viscosity, surface tension, humidity, and “aging” temperature, Tcd, were also found to affect the magnitude and variation of tack. Additionally, the results suggest that low‐speed tack measurements are quite useful for selecting solution inks containing polymeric substances that possess the desirable spreading, mixing, and pressing properties in high‐speed/high‐volume printing and the component compatibility necessary for long‐term performance. © 1995 John Wiley & Sons, Inc.
A study on the tribological behavior of polyethylene. II. Effects of operating conditions on the friction behavior of polyethylene
Authors: Wang Qi , Kong Xiangan , Zhu Lushan , Zhe Ji , Fan Ying 
Published: April 2003

AbstractIn this article, the effects of the operating conditions, i.e., load, oscillation speed, temperature, and contact modes on the friction behavior of polyethylene were studied through the SRV vibration friction test machine, the MHK‐500 friction and wear test machine, as well as an on‐line temperature testing device. The experimental results showed that the friction coefficient μ of polyethylene increases with increase of the oscillation frequency and amplitude, the speed, and PV value, while load has a quite complex impact on μ; suitable choice of load could reduce μ and smoothen the friction process. Contact modes of friction pairs have considerable effects on μ, because all the real contact area of the friction assembly, the pressure, the indentation of surface asperities, as well as the temperature rise and distribution in the contact region are related to contact modes. Temperature is a key factor determining the viscoelastic properties of polyethylene, and therefore has great effect on μ. On‐line temperature testing offers a way to reveal the relations between temperature and the friction behavior of polyethylene. All the results obtained provide the basic data for establishing mathematical models and computational simulation methods to describe and study the tribological behavior of some polymer materials. © 1995 John Wiley & Sons, Inc.
NMR characterization of styrene–divinylbenzene gel beads in swollen state using chloroform as probe
Authors: Ogino Kenji , Sato Hisaya 
Published: April 2003

AbstractStyrene—divinylbenzene copolymer gel beads in a swollen state were characterized with a proton nuclear magnetic resonance spectroscopy (1H‐NMR) using chloroform as a probe. The signal of chloroform was observed as doublet peaks and the peak at higher magnetic field was assigned to chloroform inside the gel beads and the other at lower magnetic field to one outside the gel beads. NMR parameters such as signal chemical shift, intensity, line width, and shape were investigated in relation to the characteristics of gel beads such as the swelling ratio, the diameter, pore size, and crosslinking density. The relative intensity of the signal due to chloroform inside the gel beads increased with the amount of diluent used in preparation of the beads. With the decrease of the diameter of the beads, two signals became closer, because the rate of exchange between the solvent molecules inside and outside increased. The pore size also influenced the shape of the doublet peaks. As the pore size increased, the two peaks overlapped due to the decrease of the portion of chloroform that interacts with the polymer matrix. The crosslinking density did not influence the peak shape although the dynamics of chloroform were affected by the crosslinking density. © 1995 John Wiley & Sons, Inc.
Studies of rigid poly(vinyl chloride) (PVC) compounds. II. Determination of the fusion level
Authors: Chen C. H. , Wesson R. D. , Collier J. R. , Lo Y. W. 
Published: April 2003

AbstractRigid poly(vinyl chloride) (PVC) compounds were prepared in a Haake torque rheometer using various blending conditions. The fusion levels of processed compounds were evaluated by a capillary rheometer and differential scanning calorimetry (DSC), based on the entrance pressure drop and the heat of fusion, respectively. S‐shaped fusion curves were obtained. Starting temperature of the mixer, rotor speed, and totalized torque are the three major factors that affect the fusion level of PVC compounds blended in the Haake torque rheometer. All three parameters have a significant effect; however, totalized torque has the greatest effect and this can be characterized using a torque rheometer. Both capillary rheological and DSC thermal analysis can be applied to determine the fusion level of a PVC compound. The morphological changes of the various fusion processes were characterized by scanning electron microscopy (SEM). © 1995 John Wiley & Sons, Inc.
Studies of rigid poly(vinyl chloride) (PVC) compounds. III. Correlation of compounding energy with fusion level
Authors: Chen C. H. , Wesson R. D. , Collier J. R. , Lo Y. W. 
Published: April 2003

AbstractThe major contributors to the compounding energy of a poly(vinyl chloride) (PVC) sample in the Haake torque rheometer are starting temperature, rotor speed, and totalized torque. In this study, the compounding energy was calculated by using an energy balance in the internal mixer reported by Pedersen. The fusion levels of the PVC samples, which were prepared in the Haake torque rheometer at various blending conditions (starting temperature = variable, rotor speed = 60 rpm, and totalized torque = 10 kg‐m‐min), were determined by DSC and a capillary rheometer. The compounding energy was then correlated with the fusion level. The simple total energy balance can be applied to correlate the compounding energy with the fusion level of the PVC compound prepared in the Haake torque rheometer. © 1995 John Wiley & Sons, Inc.
Synthesis, structure, and properties of poly(dimethylsiloxane) networks reinforced by in situ‐precipitated silica–titania, silica–zirconia, and silica–alumina mixed oxides
Authors: Wen Jianye , Mark James E. 
Published: April 2003

AbstractSeveral novel fillers, specifically silica–titania, silica–zirconia, and silica–alumina mixed oxides, have been successfully precipitated into poly(dimethylsiloxane) (PDMS) networks using a sol‐gel approach. The resulting filled networks were found to have very good mechanical properties. In comparison with networks filled only with silica, these materials had good extensibilities as well as high strengths. Filler particle diameters were generally several hundred angstroms, but were found to decrease with increase in crosslink density of the networks. The distributions of particle size were relatively narrow, and there was very little particle aggregation. The presence of in situ silica–titania and silica–zirconia mixed oxides can also increase the onset temperature for degradation of the PDMS. © 1995 John Wiley & Sons, Inc.
Modeling and design of an industrial dryer with convective and radiant heating
Authors: Cairncross R. A. , Jeyadev S. , Dunham R. F. , Evans K. , Francis L. F. , Scriven L. E. 
Published: April 2003

AbstractIndustrial equipment for drying polymeric coatings normally consists of a series of zones, each with a controlled temperature and airflow. Drying of a polymer–solvent solution is strongly affected by the variation of diffusivity, solvent vapor pressure, and solvent activity with temperature and composition. The equations of mass transfer by diffusion and of heat transfer by conduction and radiation describe changes in composition and temperature within the shrinking coating. This system of equations is solved by Galerkin's method with finite element basis functions. The boundary conditions on dryer airflow and temperature change at the entrance to each zone. In a few test cases, the predictions show how evaporative cooling can slow drying in early zones where the coating temperature drops below the dryer temperature, whereas in later zones the coating temperature rapidly approaches the dryer temperature. Infrared heating can be used to reduce the extent of evaporative cooling. In the test cases and experiments, “blistering” occurs in later zones where high oven temperature causes the solvent partial pressure to rise; dryer parameters can be chosen to maintain solvent partial pressure just below ambient pressure in order to avoid “blistering” with least sacrifice of process speed. © 1995 John Wiley & Sons, Inc.
Preparation and properties of phenolated wood/phenol/formaldehyde cocondensed resin
Authors: Lin Lianzhen , Yoshioka Mariko , Yao Yaoguang , Shiraishi Nobuo 
Published: April 2003

AbstractA phenolated wood/phenol/formaldehyde cocondensed novolac‐type resin was prepared with a two‐stage procedure. Wood was first liquefied in the presence of phenol by using an acid catalyst to produce a phenolated wood, and after the liquefaction, formalin (i.e., formaldehyde aqueous solution) was added to conduct a cocondensation reaction for converting the remaining nonreacted phenol into resin components. It was found that this procedure can convert almost all the phenol remained after liquefaction into resin, and therefore significantly upgrades the practical value of the liquefaction technique. In addition, it can also greatly improve the thermofluidities of the phenolated wood resins and the mechanical properties of their molded products. As a result, the flow temperatures and melt viscosities of the cocondensed resins were much lower than those of the phenolated wood resins. However, these two properties were more or less similar to those of the conventional novolac resin, resulting in an excellent processability. The flexural properties of the molded products made from the cocondensed resins were much higher than those of the phenolated wood and also somewhat superior to those of the conventional novolac resin. Therefore, this preparation procedure is a prospective technique for preparing wood‐based novolac resins. © 1995 John Wiley & Sons, Inc.
Polymerization and thermal behaviors of poly[dimethyl(acrylamidopropyl)ammonium propane sulfonate] poly (DMAAPS)
Authors: Lee Wen‐Fu , Tsai Chan‐Chang 
Published: April 2003

AbstractThe conversion in the free radical polymerization of zwitterionic sulfobetaine monomer [dimethyl(acrylamidopropyl)ammonium propanesulfonate] (DMAAPS) was investigated under various conditions, such as, monomer concentration, reaction time and temperature, and various salts. The high conversion of DMAAPS monomer could be achieved under lower temperature. The conversion of DMAAPS is enhanced in the presence of various salts in aqueous solution, but is not very significant because the reactivity of DMAAPS is very rapid even at lower temperature and lower concentration of the monomer. The thermal behavior of poly(DMAAPS) was also studied under nitrogen and air atmosphere at various heating rates. The kinetic parameters such as activation energy, preexponential factor, and reaction order were determined by Ozawa's method. Thermal degradation of such a polymer occurs in two and three stages in nitrogen and air atmospheres, respectively. © 1995 John Wiley & Sons, Inc.
Epoxy resins based on bisphenol S. II. HPLC analysis
Authors: Podzimek Š. , Sýkora V. , Horálek J. , Švestka Š. 
Published: April 2003

AbstractThree types of bisphenol S (BS) based epoxy resins prepared by reaction of BS or a mixture of BS and bisphenol A (BA) with an excess of epichlorohydrin in alkaline medium or by thermal treatment of BS with diglycidyl ether of bisphenol A (DGEBA) were analyzed by reversed‐phase high‐performance liquid chromatography (HPLC). Some components present in the reaction products were identified by analogy with BA based epoxies, combination of semipreparative HPLC with IR and NMR spectroscopy, and derivatization of resins with HCl or NaOH. © 1995 John Wiley & Sons, Inc.
Liquid crystalline aromatic polyesters formed with terephthalic acid, phenyl hydroquinone, and napthalene or anthracene diols
Authors: Khan Nazir , Bashir Zahir , Price Duncan M. 
Published: April 2003

AbstractThe synthesis and characterization of aromatic copolyesters containing terephthalic acid and phenyl hydroquinone as the major constituents and either 1,4‐napthalene diol or 1,4‐anthracene diol as the minority comonomer is described. Both polymers melted in the vicinity of 300°C, giving birefringent fluids. Optical microscopy showed Schlieren textures consisting predominantly of inversion walls characteristic of the nematic phase. The clearing temperature was in the vicinity of 460°C, but was accompanied by charring. DSC experiments showed a high glass transition temperature of 130–160°C for both polymers. Crystalnematic and nematic‐isotropic endotherms were observed on heating; however, degradation took place near the isotropization temperature. Thus, on cooling, the sequence was reversible only if the previous heating was beyond the crystal‐nematic but below the isotropization temperature. The polymers were stable in terms of gross weight loss until about 450°C, though there were indications that crosslinking occurred above about 400°C over a short period of time. The polymers formed low‐viscosity injection‐molding compounds, but to use them effectively, it would require mold‐gate designs that reduce the “jetting” tendency for liquid crystal polymer melts, which result in weld lines. © 1995 John Wiley & Sons, Inc.
Synthesis and evaluation of positive‐acting photosensitive polyimides with phenol moiety
Authors: Oba Masayuki , Kawamonzen Yoshiaki 
Published: April 2003

AbstractNovel positive‐acting photosensitive polyimide resists (1) developable with an alkaline aqueous solution were prepared. The resists consisted of a naphthoquinone diazide (NQ) and a polyamic acid bearing hydroxyphenyl groups (PA). The hydroxyphenyl moieties are newly incorporated by adding 2‐N,N‐dimethylaminoethyl‐3‐hydroxybenzoate (m‐PEA) or 2‐N,N‐dimethylaminoethyl‐4‐hydroxybenzoate (p‐PEA) to the polyamic acid, through ionic interaction between the carboxylic acid and the amine. The NQ acts as a solution inhibitor for the PA by the interaction with the hydroxyphenyl moiety. This system is similar to that of phenol‐novolac resin/NQ resists currently conducted in the fabrication of the Large Scale Integrated circuit (LSI). The resist (1) is exposed to a G‐line and is developed with tetramethylammonium hydroxide aqueous solution to provide fine patterns, proving that the (1) is compatible with LSI‐production lines currently applied. A novel polyamic acid‐curing mechanism found in the course of this study is also reported. © 1995 John Wiley & Sons, Inc.
ESR studies of chemically modified and photocrosslinked poly(vinyl alcohol) gels
Authors: Uhlich Thomas , Ulbricht Mathias , Tomaschewski Georg , Stösser Reinhard 
Published: April 2003

AbstractThe hydrophilicity of poly(vinyl alcohol) (PVA) was lowered by acetalization with propionic aldehyde. After UV irradiation of pendent styrylpyridinium groups, these prepolymers form networks of different hydrophobicity depending on the degree of acetaization. PVA films containing different amounts of propionic acetals were doped with 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl. Then, the ESR spectra of the spin probe entrapped in the polymeric network were monitored while allowing different solvents to diffuse into the polymer. The rate of spin probe mobilization depends on the hydrophilicity/hydrophobicity of both the polymer network and the solvent. However, the modified polymers, even the more hydrophobic ones, are hydrophilic in comparison to “really” hydrophobic polymers. This is probably caused by the character of the parent polymer (PVA), unreacted hydroxy groups. S++uiations of the ESR spectra have shown that in polymers with a higher degree of acetalization domains of different hydrophobicity are built in which the spin probes have a different mobility. © 1995 John Wiley & Sons, Inc.