bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of gamma‐radiation on a water‐insoluble arabinoxylan
Authors: Ebringerová Anna , Pružinec Jozef , Kačuráková Marta , Hromádková Zdenka 
Published: April 2003

AbstractThe effect of gamma radiation on a water‐insoluble L‐arabino‐D‐xylan has been studied by functional group and structural analysis using chemical methods and IR spectroscopy, by sugar composition analysis, and by viscosity measurements. The gamma irradiation has been shown to modify both sugar components of the arabinoxylan, accompanied by cleavage of the glycosidic linkages, depolymerization, and sugar decomposition, depending on the applied radiation dose, thus increasing the molecular and chemical heterogeneity of the polysaccharide.
Preparation and properties of graft copolymers of vinyl chloride on atactic polypropylene
Authors: Schellenberg J. , Hamann B. 
Published: April 2003

AbstractThe possible uses of atactic polypropylene as the basis of grafting for the preparation of graft polymers of vinyl chloride are studied. Graft parameters and glass transition temperatures of the graft products obtained are specified at different compositions of the graft products. After blending the graft products with pure poly(vinyl chloride) or ABS/poly(vinyl chloride) blends, some application‐related properties are discussed with respect to the grafting degree and the amount of graft product contained.
Solution processing of composite fibers containing rodlike and thermoplastic polymers
Authors: Gabriel Carmen A. , Farris J. , Malone Michael F. 
Published: April 2003

AbstractThe solution processing and mechanical properties made from blends of the rodlike polymer poly(p‐phenylene benzobisthiazole) with either poly(ether ether ketone) or nylon 6,6 is described. The concentration dependence of the isotropic‐nematic phase transition for solutions of these polymers in methane sulfonic acid is in qualitative agreement with a theory of Flory. The mechanical properties of fibers that were wet spun from isotropic solutions of poly(ether ether ketone) and poly(p‐phenylene benzobisthiazole) are very sensitive to the concentration of the spinning solution. Fibers spun at concentrations near the isotropic‐nematic phase boundary have poor mechanical properties, resulting from phase separation during coagulation. However, when the solution concentration is significantly below the critical value, stiff and strong fibers are produced. In contrast, when nylon 6,6 is used as the thermoplastic component, the mechanical properties are good and are insensitive to the solution concentration. We attribute the solution concentration effects to two factors. The first is the difference in the solubility of poly(ether ether ketone) and nylon 6,6 in methane sulfonic acid‐water mixtures. The second is the connectivity of the nematic phase, which also depends on concentration and has a major impact on the mechanical properties of the resulting fiber.
Loop polymerization of vinyl acetate
Authors: Bataille P. , Dalpé J. F. 
Published: April 2003

AbstractThe emulsion polymerization of vinyl acetate was studied using a loop reactor. The results were compared with some earlier work done in a batch reactor. A parallel was drawn with the results obtained with a tubular loop reactor and with a continuous reactor using styrene as monomer. The same phenomena of the optimum conversion peak with styrene at the laminar turbulent flow transition zone also occurred for the vinyl acetate. The peak obtained in this case was, however, broader and in the lower turbulent zone. The effect of the surfactant concentration on the broadness of the peak is discussed.
Effect of γ‐irradiation and temperature on the structure of metal chloride‐treated poly(vinyl alcohol)
Authors: Rabie S. M. , Abdel‐Hakeem Nagwa , Moharram M. A. 
Published: April 2003

AbstractThe infrared and ultraviolet spectra of poly(vinyl alcohol) (PVA) treated with ferric chloride and zinc chloride were recorded. Careful examination of the infrared spectra revealed that these treatments cause significant changes in the crystallinity of PVA, particularly in the case of the treatment with ZnCl2. The results showed that exposure of untreated and FeCl3‐treated PVA to 12 or 28 Mrads results in no observable changes in their ultraviolet and infrared spectral features, whereas exposure of ZnCl2‐treated PVA at the same dosages, results in the appearance of an absorption band at 1595 cm−1 corresponding to β‐diketone groups. It was also found that γ‐irradiation of ZnCl2‐treated PVA produces a remarkable change in its crystallinity. Moreover, the effect of heat on the spectral features of the ZnCl2‐treated PVA was discussed. It was found that the treatment of PVA with ZnCl2 helps in oxidative degradation of PVA.
Surface analysis by ESCA of sulfite post‐treated CTMP
Authors: Barry A. O. , Koran Z. , Kaliaguine S. 
Published: April 2003

AbstractHandsheets of post‐treated chemithermomechanical pulps (CTMP) and a sample of Whatman paper no. 1 were analyzed using an ESCA spectrometer. All of these samples revealed the presence of the C1, C2, and C3 components in the carbon (1s) peak and the O2 component in the oxygen (1s) peak; the O1 peak component which was present in the other samples was missing from the Whatman paper. Pulp sulfonation produced a reduction in C1 representing the group of carbon not bonded to oxygen, and an increase in C2 with C3 remaining relatively constant. These changes imply reductions in lignin and extractives and a corresponding increase in cellulose content on the fiber surface. Extrapolation of the C1, C2, C1/C2, and O/C curves of CTMP to zero percent sulfonation yielded the same values as those obtained for pure TMP. ESCA analysis allows us to monitor the increase of sulfur content as a function of sulfonation in accordance with results obtained from bulk pulp sulfonate content titration.
Interaction of some solutes with certain cationic polymers and its effect on film permeability
Authors: Okor R. S. 
Published: April 2003

AbstractPermeabilities of cast films of certain cationic acrylate methacrylate copolymers have been determined using a double (donor and acceptor) compartment cell. Permeation rates of urea (nonionic permeant) and sodium chloride (ionic permeant) were determined as functions of the polymer cation content. A decrease in film permeability accompanied the decrease in polymer cation content generally; the change was more marked with sodium chloride compared with urea. The films were also generally more permeable to urea; the difference increased at lower polymer cation content to about 400‐fold. While urea promoted film swelling, sodium chloride decreased it. Electron micrographs of the film section displayed compact skin zones which must be swelled to allow solute permeation. Asymmetry characterized the flux, the film lower surface (in contact with the mold during casting) being more permeable than its upper surface. This effect was more pronounced when sodium chloride was used as permeant.
Studies on adhesive monomers for teeth. V. Influence of substituents in methacrylamide derivatives
Authors: Kitoh Shinya , Miyake Mikio , Hayashi Satoshi , Kurita Keisuke 
Published: April 2003

AbstractIn order to shed light on the relationship of monomer structure and adhesiveness to tooth enamel, methacrylamides having various substituents were synthesized and evaluated as dental adhesives. Among 17 methacrylamides synthesized here, those having N‐m‐ and N‐p‐carbethoxyphenyl, N‐p‐fluorophenyl, and N‐3‐carboxycyclohexyl groups showed adhesive tensile strength of more than 100 kg/cm2 with minimal drops in strength on standing, indicating high potentials as novel adhesives. It was also confirmed that a carboxyl group enhances adhesive tensile strength peculiarly regardless of skeletal structures.
Effects of resole phenol adhesives on the crystallinity of cellulose
Authors: So Solomon , Teh J. W. , Rudin Alfred , Tchir William J. , Fyfe Colin A. 
Published: April 2003

AbstractResole phenolic resins are widely used for gluing wood structures. Solid state 13C‐NMR and wide angle X‐ray scattering experiments show that a typical resole adhesive disrupts some of the crystallinity of the cellulose. Several explanations are offered for this observation. It is possible that this effect is connected with the adhesive action of the phenolic polymer. If this is so, then measurements of the type described here could be used to understand the adhesion better and to develop better wood glues.
Hydrolytic degradation of melt‐extruded fibers from poly(β‐propiolactone)
Authors: Mathisen Torbjörn , Albertsson Ann‐Christine 
Published: April 2003

Abstractβ‐Propiolactone was polymerized in bulk at 5°C using pyridine as initiator. The melt spun fibers were drawn at 50°C and subjected to degradation, which was monitored by mechanical, thermal, and molecular weight measurements. The hydrolytic degradation of poly(β‐propiolactone) fibers has been investigated in a buffered salt solution (pH 7.2) maintained at 37°C. The degradation was found to be very rapid during the first 90 days of immersion, with respect to mechanical properties and the weight average molecular weight. Between 90 and 180 days there were no significant changes in the mechanical properties which, however, rapidly decreased thereafter and finally reached zero at 240 days. The crystallinity seemed to increase in a linear fashion, during the same period, from about 55 to 70%.
Synthesis of bioactive 2,2‐dichloropropionic acid esters of carboxymethyl cellulose and investigations on their release behavior
Authors: Schnabelrauch Matthias , Geschwend Günter , Klemm Dieter 
Published: April 2003

AbstractPolymer bound bioactive agents are prepared by linking 2,2‐dichloropropionic acid to the hydroxyl groups of carboxymethyl cellulose (CMC) and enzymatically cleavable CMC networks, and to the carboxyl groups of CMC via enzymatically cleavable spacer units using a simple as well as effective CMC activation procedure. The hydrolytic release of the bioactive agent is mainly dependent on the hydrophilicity of the CMC esters. In the case of polymers containing enzymatically cleavable structural units the release can be accelerated by addition of esterases.
Polyesters containing sulfur. I. Products of melt polycondensation of diphenylmethane‐4,4′‐di(methylthioacetic acid) with some diols
Authors: Kultys Anna , Podkoscielny Wawrzyniec 
Published: April 2003

AbstractSeveral new polyesters containing sulfur in the main chain were obtained by melt polycondensation of diphenylmethane‐4,4′‐di(methylthioacetic acid) with ethanediol, 1,3‐propane diol, 1,4‐butanediol, 1,5‐pentenediol, 1,6‐hexanediol, 1,2‐propanediol, and 2,2′‐oxydiethanol. The structure of all polyesters was determined from elemental analysis and infrared (IR) spectra. Yield, reduced viscosity, molecular weight, and softening temperature for reaction products have been found. Initial decomposition and initial intensive decomposition temperature were defined from the curves of thermogravimetric analysis.
Grafting of the acrylic acid on poly(ethylene terephthalate)
Authors: Osipenko I. F. , Martinovicz V. I. 
Published: April 2003

AbstractA study has been made of the effect of solvent nature, concentrations of monomer, initiator and homopolymerization inhibitors, and initial polymer structure on the modification of poly(ethylene terephthalate) (PET) films and fibers by grafting the acrylic acid (AA). AA grafting initiated by radicals formed from thermal decomposition of benzoyl peroxide. It has been established that preswelling of PET in dichloroethane leads to changes in its sorption–diffusion properties and favors an increase in the degree of grafting. Addition of the Fe(II), Ni(II), and Cu(II) salts to AA solution decreased homopolymer yield. The studied process of grafting can be described by equations of diffusion kinetics. Distribution of the poly(acrylic acid) (PAA) over the cross section of samples and a number of physical and chemical properties depend also on conditions of performing the graft polymerization.
Crosslinking studies of polyether–ester‐based polyurethane systems
Authors: Kothandaraman H. , Venkatarao K. , Thanoo B. Chithambara 
Published: April 2003

AbstractEther‐ and ester‐based prepolymeric diols suitable for polyurethane elastomer formation were prepared from polyoxytetramethyleneglycol and polyoxytetramethylene–oxypropyleneglycol with dicarboxylic acids like adipic acid, maleicacid, and phthalic acid. Crosslinked polyurethane elastomers were prepared from these prepolymers using various concentrations of trimethylolpropane as a crosslinker and toluenediisocyanate as the curing agent. Crosslinked polyurethanes were also prepared by a method taking excess toluenedisocyanate other than that of the stochiometric requirement and curing it at a comparatively higher temperature. The data on mechanical properties of these elastomers show that both methods of crosslinking in polyurethane imparts a similar effect on mechanical properties.
Preparation of hydrogel beads from crosslinked poly(methyl methacrylate) microspheres by alkaline hydrolysis
Authors: Thanoo B. Chithambara , Jayakrishnan A. 
Published: April 2003

AbstractPoly(methyl methacrylate)/(PMMA) microspheres crosslinked with various concentrations of ethylene glycol dimethacrylate (EGDM) were prepared by a suspension polymerization procedure. They were subjected to alkaline hydrolysis in ethylene glycol at high temperature (> 175°C), resulting in the rapid conversion of methacrylate ester functions to methacrylic acid, while retaining the spherical shape of the microspheres intact. The method provides a novel approach to obtain smooth, nearly perfect spherical, mechanically strong, high water‐absorbing hydrogel beads from crosslinked PMMA. The reaction has been found to be considerably faster than many of the hydrolysis procedures reported previously. The effect of concentration of alkali, particle size, crosslinking density, and reaction time on the extent of hydrolysis has been investigated to a limited extent.
Evaluation of some side effects from the use of formaldehyde scavengers
Authors: Vail Sidney L. , Beck Keith R. 
Published: April 2003

AbstractConcentrations of methylol carbamates in several crosslinking formulations prepared from methyl carbamate and formaldehyde and with and without urea or ethyleneurea as scavengers were determined by nuclear magnetic resonance spectroscopy. The scavengers were effective in reducing the free formaldehyde in the solution, but the dimethylol methyl carbamate concentration was reduced by about 25%. Selected chemical and physical properties were obtained from cotton fabrics finished with five different formulations of known composition. Fabric strengths were improved by use of a scavenger, but some undesirable side effects were observed.
Dielectric constant, optical transmission, and thermal diffusivity monitoring of iodine‐impregnated polystyrene films
Authors: Leite N. F. , Franzan A. H. , Torres‐Filho A. , Miranda L. C. M. 
Published: April 2003

AbstractA simple method for the iodine doping of atactic polystyrene films is described. The marked changes in the physical properties of the polystyrene films, such as dielectric constant, optical absorption coefficient, and thermal diffusivity, are presented as a function of the doping time. The results show strong evidences of the onset of an order–disorder transition as a function of the doping time.
Structure investigations on drawn high‐density blown PE films
Authors: Hofmann D. , Geiss D. , Janke A. , Michler G. H. , Fiedler P. 
Published: April 2003

AbstractThe supermolecular structure of blown HDPE films, which were obtained by a combination of film blowing under a very low blowup ratio and slow takeoff velocity with subsequent uniaxial drawing, is characterized using WAXS texture and profile analysis, EM and mechanical investigations. Samples with low uniaxial drawing ratios (λ ≲ 1.5) contain low stress crystalline and transcrystalline material and show an a‐texture, while samples with higher uniaxial drawing ratios only consist of high stress crystalline material and show a c‐texture. With one exception the results of texture investigations can be related to the results of the mechanical investigations.
Studies of latex paint films exposed to aqueous SO2: pH effects
Authors: Xu J. R. , Balik C. M. 
Published: April 2003

AbstractLatex paint films containing the acid‐soluble extender calcium carbonate have been exposed to aqueous SO2 and other acidic solutions to evaluate the effects of acidic deposition at different pH values on the coatings. CaCO3 is completely removed from these films upon immersion in acidic solutions. The leaching process was monitored with weight loss and infrared measurements. The removal rate was found to be strongly dependent on pH, decreasing with increasing pH. Removal of CaCO3 occurs even for distilled water which has been allowed to equilibrate with atmospheric CO2 (pH 5.6). The removal rate seems to depend only on [H+]; the identity of the acidic anion is apparently insignificant. An empirical relation between the rate of removal and pH was formulated from the weight loss data. The analyses of the results from both weight loss and infrared methods suggested that the mechanism of removal at pH 2.0 is diffusion controlled, whereas a chemical reaction involving H+ becomes more important at higher pH values.
A consideration of secondary electron emission from organic solids
Authors: Kishimoto Yoshio , Ohshima Tsutomu , Hashimoto Masashi , Hayashi Tomonao 
Published: April 2003

AbstractThe behavior of the secondary electron emission (SEE) from organic solids has been considered. It has been shown that the maximum SEE yields of many hydrocarbon compounds exponentially depend on the extinction coefficient of secondary electron defined by the π‐electron fraction in molecule, which is correlated to Dionne's theoretical equation. The concept that the extinction coefficient of secondary electron is represented in terms of the fraction of the delocalized and low energy‐gap electron‐like π‐electron will be convenient for a rough estimation of the SEE yield of other various materials. On the other hand, a novel universal equation representing the normalized SEE yield curve has also been proposed in this paper, by which an analysis of the normalized SEE yield curves of many organic solids have been tried.
The effect of bisphenol monomer structure on the gas permeability of aromatic polycarbonates
Authors: Schmidhauser John C. , Longley Kathyrn L. 
Published: April 2003

AbstractPermeability measurements for oxygen and, to a lesser extent, carbon dioxide were carried out on a series of 24 structurally different aromatic polycarbonates. Polymers were prepared from bisphenols bearing substituents on the aromatic rings and/or the central aliphatic carbon atom. A strong correlation between monomer structure and polymer permeability was found, with gas transport rates varying by over two orders of magnitude between the most and the least permeable materials. In addition, a semilogarithmic relationship was found between oxygen transmission rates and monomer composition for two series of copolycarbonates. Of several methods explored, an excess free volume model was found best able to relate the experimental permeability values to the polymer molecular structure.
Analysis of branched poly(ethylene terephthalate)
Authors: Weisskopf Klaus 
Published: April 2003

AbstractPoly(ethylene terephthalate) modified with 1,1,1‐trishydroxymethyl propane (THP) and pentaerythritol was analyzed with respect to branching by combined GPC/viscometry measurements. The average effective functionality of the branching molecules was calculated and compared with the theoretically attainable functionality, thus permitting one to distinguish between different branching theories. Maximum effectiveness was achieved only at low concentrations of the modifiers added. Pentaerythritol and THP were found equivalent in the ratio 1 : 3, estimated from their influence on the polydispersities of the branched polyester. It was shown that apparent molecular weights obtained from GPC calibration with linear standards can be converted by correction factors. The resulting molecular weight averages of the branched PET samples were in a good agreement with those from the GPC/viscometry iteration procedure.
Effect of temperature on gas permeation of polymer blends. I. Poly(ethylene oxide)/copolyester–polyurethane
Authors: Qipeng Guo , Hechang Xu , Dezhu Ma 
Published: April 2003

AbstractThe transport behavior of H2, N2, and CO2, was studied for blends of poly(ethylene oxide) (PEO) with a copolyester–polyurethane (PU) at various temperatures from 20 to 80°C. It was found that there was an abrupt change in slope or discontinuity around the melting point of PEO in Arrhenius plot of the permeability vs. temperature. The relationships between the logarithms of gas permeability and blend composition were strongly dependent on the temperature and showed very different shapes at temperature below and above the melting point of PEO. The activation energy of gas permeation for the blends had different values below and above the melting temperature of PEO.
Determination of additives in biomer and lycra spandex by pyrolysis tandem mass spectrometry and time temperature resolved pyrolysis mass spectrometry
Authors: Richards Joseph M. , McClennen William H. , Meuzelaar Henk L. C. 
Published: April 2003

AbstractPyrolysis mass spectrometry (Py‐MS), time/temperature resolved Py‐MS (TTR‐Py‐MS), and pyrolysis tandem mass spectrometry (Py‐MS/MS) were used to determine the structure of an additive present in Biomer and Lycra Spandex. The additive was found to form a second phase in the polymer matrix which was insoulble in N,N′‐dimethylacetamide. This insoluble portion (7% by weight) was separated by centrifugation. The structure of this additive is proposed to be poly(2‐diisopropyl amino ethyl methacrylate)(DPA‐EMA). The additive is present as a stabilizer for UV radiation and chloride and hypochlorite ion attack. A chloride containing compound of similar structure (2‐diisopropyl amino ethyl chloride) (CAS No. 96‐79‐7) is also detected. This chloride‐containing compound may be formed by reaction of the polymeric additive with chloride ions during storage or pyrolysis.
Capillary flow properties of thermotropic hydroxypropylcelluloses
Authors: Fujiyama Mitsuyoshi 
Published: April 2003

AbstractThe influences of molecular weight, temperature, and shear rate on the capillary flow properties of thermotropic hydroxypropycelluloses have been studied. The crystalline/liquid crystalline transition temperature and the temperatures at which the liquid crystalline/isotropic transition begins and ends are higher as the molecular weight is higher. The flow curves show yield stresses and, contrary to general thermoplastic resins, the slope of log(viscosity)–log(shear rate) curve decreases as the shear rate increases. This tendency is more notable as the molecular weight is higher. The temperature change of the viscosity shows a minimum and the minimum moves to a higher temperature with increasing shear rate. The moving rate is higher as the molecular weight is higher. This is because the molecular orientation of the isotropic phase increases with increasing shear rate. Contrary to general thermoplastic resins, the molecular weight dependence of the viscosity increases with increasing shear rate. The yield stress is higher as the molecular weight is higher and shows a minimum at 200–210°C. The molecular weight dependence of the entrance pressure loss is higher than that of the viscosity. The end correction coefficients of the hydroxypropylcelluloses are very much higher than those of general thermoplastic resins: They exceed 50 in some cases. The temperature change of the end correction coefficient shows a maximum and the temperature at the maximum is higher as the molecular weight is higher. The die swell ratio shows a minimum at 180–220°C at low shear rates and the minimum swell ratio is lower than unity in some cases. The die swell ratio is higher as the molecular weight is increased.