bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wood adhesives based on lignin wastes: Influence of the carbohydrates in the polymerization of spent sulfite liquor
Authors: Calvé L. , Fréchet J. M. J. 
Published: April 2003

AbstractThe influence of carbohydrates on the thermosetting properties of ammonium‐spent sulfite liquor (NH4SSL) was studied using various fractions of the liquor obtained by ultrafiltration. While a low molecular weight carbohydrate‐rich fraction thermoset readily, a higher molecular weight sugar‐free fraction failed to thermoset. Optimum results in the use of NH4SSL as a binder for wood particles were obtained by adjusting the carbohydrate to lignin ratio through addition of carbohydrates to the liquor. Similarly, several sugars used alone as binders without addition of lignin gave satisfactory results at slightly higher press temperatures. A study of various sugars and similar molecules in the binding of wood particles suggested that a combination of ene‐aldehyde or ketoalcohol functionalities was likely to produce good results. Condensations involving sugars were affected by such variables as carbohydrate chain length, moisture content, acid catalysis, and press temperature.
Solid state C‐13 NMR studies of a potential crosslinking agent for aliphatic polyester–urethane block copolymers
Authors: Cholli Ashok , Koenig Jack , Sun Tong , Zhou Hanxin 
Published: April 2003

AbstractSolid state C‐13 NMR was used to characterize the complex of diphenylmethane 4,4′‐diisocyanate (MDI) with acetone oxime as a potential crosslinking agent (PCA) for the aliphatic polyester–urethane block copolymers. The formation of MDI from the PCA was followed by heating the sample at 150°C. The active hydrogen atoms on the hard segments of the block copolymers can be made to react with the diisocyanate groups of the regenerated MDI from the PCA at the elevated temperature for the crosslinking. The regeneration ofNCO groups is also noted by the appearance of the 2270 cm−1 band in the FT‐IR spectrum of the heat treated PCA.
Mechanical properties of products of thermocatalytic and radiolytic styrene–acrylonitrile copolymerization
Authors: Gadalla Ahmed M. , Derini Mohamed A. E. 
Published: April 2003

AbstractThe mechanical properties of styrene (S)–acrylonitrile (AN) mixtures, ranging from 20 to 80 wt % S, polymerized by thermocatalytic and radiolytic techniques were studied. Maximum compressive and tensile strength was obtained for the mixture containing 60 wt % styrene. The hardness increased with styrene concentration up to 40 wt % and then remained nearly constant. Radiolytic copolymerization gave stronger copolymers than thermal copolymerization since irradiation enhances crosslinking. For the same composition, as the dose increases, the strength increases to a maximum and then decreases due to competing rates of crosslinking and degradation.
Grafting of poly(acrylic acid) onto polyethylene filament and its distribution
Authors: Kaji Kanako 
Published: April 2003

AbstractRadiation‐induced simultaneous grafting of acrylic acid onto high density polyethylene filament is carried out with aqueous solution of acrylic acid in the absence and presence of ethylene dichloride. Distribution of grafted poly(acrylic acid) is studied by two methods. One is optical microscopic investigation of cross sections of dyed filament, and the other is electron probe microscopy of acrylic acid graft filament after conversion to calcium acrylate. Qualitative study with WAXS is also carried out. Grafting begins from the surface or periphery and proceeds, with sharp boundary, to the core. The reaction takes place only in the amorphous part of polyethylene. The percent graft in the grafted part is homogeneous and rather high from the beginning of the reaction; it is true that additional grafting to the already grafted part takes place, but it is not so noticeable.
Crosslinking of poly(ethylene glycol) with divalent metal salts of mono(hydroxyethyl) phthalate, anhydride, and bisepoxide
Authors: Matsuda Hideaki , Miyoshi Noriyuki 
Published: April 2003

AbstractPoly(ethylene glycol)s (PEG) were crosslinked with divalent metal salts of mono(hydroxyethyl) phthalate, anhydride, and bisepoxide to give metal‐containing cured rubbers. As the anhydride, hexahydrophthalic anhydride was used, and bisphenol A diglycidyl ether was the bisepoxide used. As for the physical properties of the cured rubbers obtained, the rubbers containing Mg showed much better physical properties than those containing Ca. In addition, the rubbers with high hard block contents and high overall crosslinking densities exhibited high tensile strength and Shore A hardness, and so did the rubbers having a high degree of crystallinity of the PEG soft block. The occurrence of crystallization became easy as the soft block length became longer and the soft block content became higher, or as the crosslinking density of the hard block became lower. The PEG‐based rubbers showed much higher water absorption than the previously reported poly(propylene glycol)‐based rubbers, due to the much higher hydrophilicity of the PEG block. Resistance to chemical attack and stress–relaxation are also discussed.
Modification of epoxy polymer by plasticizing, blending, or reinforcing
Authors: Feldman D. , Blaga A. , Coriaty E. 
Published: April 2003

AbstractEpoxy polymer (EP) was modified by incorporation of DBP, PVC, PVA, and glass fiber reinforcement. The morphology of the unmodified polymer and the various blends was studied by SEM, dispersive X‐ray analysis, and DSC. Results indicated that EP and DBP are miscible in the proportions used in this work (up to 10% of DBP). PVA added to cured EP in a concentration of 10% occurs as a separate phase. The morphology of EP–PVC blends is relatively complex: EP and PVC are immiscible at low concentration of the second component (up to 10% of PVC), but become mutually and increasingly more miscible as the concentration of PVC increases. Incorporation of DBP into EP causes a marked reduction in the heat distortion temperature (HDT), whereas addition of PVC has only a moderate effect. Modified EP containing small amounts of DBP (up to 4%) has moderately lower bond strength than the unmodified polymer, as evidenced by lower ultimate tensile strength of the adhesion sandwich specimens mounted on aluminum substrate. However, as the concentration of DBP in the blend increases, the ultimate tensile strength is slightly higher than that of the unmodified EP. Blending of EP with PVC, PVA, and glass fibers has generally a detrimental effect on the ultimate tensile strength. Outdoor exposure for 100 days (between January and April) generally caused deterioration of the tensile strength of all samples. EP‐based blends containing DBP, however, had better resistance to deterioration in outdoor exposure than the other blends, including unmodified EP.
On the use of the dimethyl terephthalate/dimethyl isophthalate recrystallization residue as a raw material in the production of solid polyurethane foams with reduced flammability
Authors: Troev K. , Todorov K. , Borisov G. 
Published: April 2003

AbstractThe residue from the recrystallization of the dimethyl terephthalate/dimethyl isophthalate fraction consists mainly of the dimethyl esters of the phthalic acids (ca. 82–85%) and about 15% aldehydes. It is shown that the isophthalic fraction affords the hydroxyl group containing phosphonates on treatment with diethyl phosphite in the presence of alkaline or peroxide catalysts. The residue treated in this manner can be used for preparing oligoester alcohols and solid polyurethane foams from them with reduced flammability.
Self‐diffusion of small molecules in cellulose gels using FT‐pulsed field gradient NMR
Authors: Brown Wyn , Stilbs Peter , Lindström Tom 
Published: April 2003

AbstractTransport in cellulose gels has been studied with ethylene glycol and crown ether (15‐5) as “probes” using an NMR spin–echo technique. The cellulose content was varied in range 20–55% (w/w). The retardation of diffusion was found to be adequately described by simple first‐order expressions in concentration of cellulose.
Carboxyl‐containing polyesters and polyurethanes from dibenzyl L‐tartrate
Authors: Kuramoto Noriyuki , Sakamoto Munenori , Teshirogi Takuma , Komiyama Jiro , Iijima Toshiro 
Published: April 2003

AbstractWe have prepared polyesters from succinyl chloride, adipoly chloride, and telephthaloyl chloride with dibenzyl L‐tartrate, polyurethanes from hexamethylene diisocyanate, tolune 2,4‐diisocyanate, and methylene‐bis(4‐phenyl isocyanate) with dibenzyl L‐tartrate. The molecular weights of these polymers were generally low except for one of the polyurethanes. These polymers were reduced to give those having carboxyl side groups. Potency for inducing interferon was tested for one of the polymers. The result was not encouraging in showing low activity.
Upgrading the melt flow index to rheogram approach in the low shear rate region
Authors: Shenoy A. V. , Saini D. R. 
Published: April 2003

AbstractThe unified viscosity function curves proposed earlier by the authors have an inherent limitation in the low shear rate region. This limitation is the effect of using the melt flow index as a normalizing factor to obtain the coalesced curves, which itself is insensitive to molecular parameters such as molecular weight distribution. A single integral constitutive equation of the BKZ type is used to derive the viscosity function which would be useful in generating unified curves based on the melt flow index but devoid of the limitation of molecular weight distribution effects in the low shear rate region.
Crystallization of PP in PP/SEBS blends and its correlation with tensile properties
Authors: Gupta A. K. , Purwar S. N. 
Published: April 2003

AbstractCrystallization of polypropylene (PP) in the blends of PP with styrene–ethylene butylene–styrene triblock copolymer (SEBS) is studied through differential thermal analysis (DTA) and X‐ray diffraction measurements. Analysis of crystallization exotherm peaks in terms of crystallization nucleation and growth rates, crystallite size distribution, and crystallinity revealed differences in the morphology of PP component in the blend in the different regions of blend composition. Crystallinity determined by X‐ray diffraction and DTA showed identical variations with blend composition. Variations in tensile properties of these blends with blend composition are also reported. Correlations of the various tensile properties with the crystallization parameters, viz., the crystallinity and crystallite size distribution, are presented, which confirm the influence of crystallization of PP component on the tensile properties of these blends.
Compatibility of poly(ϵ‐caprolactone) (PCL) and poly(styrene‐co‐acrylonitrile) (SAN) blends. I. Blends containing SAN with 24 wt% acrylonitrile
Authors: Chiu Shao‐Cheng , Smith T. G. 
Published: April 2003

AbstractPolymer blends of poly(ϵ‐caprolactone) (PCL) and poly(styrene‐co‐acrylonitrile) (SAN), containing 24 wt % acrylonitrile (AN), were prepared, and their transition behavior was examined by thermal analysis and dynamic mechanical testing. The blends were judged to be compatible on the basis of the presence of a single, compositionally dependent glass transition. The results of thermal treatment upon blends glass transition behavior and the dependence of thermal history upon the crystallization of semicrystalline PCL were also studied. The crystallization of PCL from SAN/PCL blends was found to be retarded by the presence of SAN, and crystalline PCL was found to exist only in blends containing a high PCL concentration. Blends which do not contain crystalline PCL were transparent, and their glass transition behavior can be correlated by the Gordon–Taylor equation. Phase separation, which was characterized by lower critical solution temperature (LCST) behavior, was found to occur when blends were heated to elevated temperatures.
Method for studying orientation variations near surfaces in semicrystalline polymers
Authors: Buckley C. P. , Taylor R. J. 
Published: April 2003

AbstractThe method of grazing incidence X‐ray diffraction provides a convenient means of examining crystal orientation close to the surface of a semicrystalline polymer. Since the sampled depth is governed by the choice of X‐radiation (via its absorption coefficient) and the angle of incidence, it is under the control of the experimenter. The method was tested and shown to be valid by applying it to a crossply laminated film of oriented polyethylene, of thickness 50 μm, in which the different crystal orientations on opposite faces of the film were known. Further experiments, with two polyethylene films of 20 μm and 40 μm thickness each extruded with differing rates of cooling on each surface, demonstrated the ability of the method to resolve spatial variations of orientation on this scale arising during manufacture.
Studies on the improvement of cured two‐stage phenolics performance. III. Relation between conditions of heat treatment and properties of wood‐flour‐filled phenolics
Authors: Fukuda Akinori , Hasegawa Kiichi , Horiuchi Hikaru 
Published: April 2003

AbstractThe effect of heat treatment on the properties of cured two‐stage phenolics was studied. Samples were compression‐molded from the compound that was prepared from novolac, wood flour (100 phr), and hexamethylenetetramine (15 phr). Samples were heat‐treated in conditions of four levels for temperature (150°C, 170°C, 190°C, and 210°C) and time (4, 8, 16, and 24 h). The properties of samples heat‐treated, such as weight loss, dimensional stability, water absorption after boiling, and flexural properties were measured. The relation between the properties and the conditions of heat treatment was examined statistically. From the results, it was decided that the optimum conditions of heat treatment for practical use were: (i) to decrease water absorption and to heighten electrical resistance, 210°C, 24 h; (ii) to improve flexural properties at room temperature and at 160°C; 170°C, 8 h, and 170–190°C, 24 h, respectively. It was concluded that the decrease of water absorption of moldings was due to the increase of hydrophobic nature of wood flour included in moldings by heat treatment and that the improvement of flexural property of moldings at 160°C was due to an increase of crosslinking density by heat treatment. The reasons for the improvement of the electrical properties by heat treatment were also discussed.
Use of a microcomputer with a gas permeation apparatus
Authors: Toi Keio , Ito Tomoyasu , Shirakawa Toshiaki , Ichimura Hajime , Ikemoto Isao 
Published: April 2003

AbstractHardware and software for collecting and storing the data of gas permeation in polymer membranes from the vacuum detector and various sensors have been developed for the GP‐IB microcomputer online system. The system uses BASIC language programs. In comparison to manual inputs and calculations, the programs allow reductions in the time required for data treatment and in the standard deviation for a determination and, moreover, an improvement in the reproducibility of the results.
Dielectric and ultrasonic absorption in some linear polyamides
Authors: Aziz A. W. , Abd‐El‐Nour K. N. 
Published: April 2003

AbstractThe dielectric behavior of some linear polyamides has been studied over a frequency range from 102 to 105 Hz between 20°C and 90°C. Also the change in attenuation of longitudinal ultrasonic waves has been measured as a function of frequency and temperature. Analysis of the results shows α‐ and β‐ relaxations. The movement of amide protons involved in intermolecular hydrogen bonds is also noticed.
Structure property studies of polyester‐ and polyether‐based MDI–BD segmented polyurethanes: Effect of one‐ vs. two‐stage polymerization conditions
Authors: Abouzahr Saad , Wilkes Garth L. 
Published: April 2003

AbstractThe effect of the polymerization method (one‐or two‐stage) on the morphology and properties of specific polyether‐ and polyester‐based urethanes was studied. For the systems investigated, the polymerization technique was somewhat more influential on properties when the soft segment was a polyester than when it was a polyether. In the case of the polyester, a one‐stage process yields materials with somewhat poorer physical properties than for a two‐stage technique. This decrease in properties is attributed to a higher soft–hard segment interaction and to the higher mutual solubility of the segments that is brought about by a possible broader molecular weight distribution of hard segments produced in a one‐stage reaction. A large difference in hard segment length distribution, however, was not expected since the MDI isocyanate moieties should display equal reactivity. In the case of polyether soft segments, any effect of the polymerization method appears to be largely offset by the higher incompatibility of the hard and soft components.
Photoinduced tension of polymers
Authors: Maerov S. B. , Avakian P. , Matheson R. R. 
Published: April 2003

AbstractPhotoirradiation of polymer films at constant length induced a fast tension reduction (time scale: seconds) followed by slow tension buildup (time scale: minutes). Immediately after irradiation, fast tension buildup was followed by slow tension decay. Cycles were repeatable without significant hysteresis loss. The amplitude of both phenomena are intensity‐dependent in the ultraviolet–visible spectral regions; both phenomena are thermal rather than photochemical effects. Light‐absorbing chromophores in the polymer structure, or in additives such as dyes, lead to absorption of light and internal conversion into heat. The classical, rapid thermal expansion (or contraction) on heating (or cooling) leads to the fast relaxation (or buildup) of tension. The elastic, entropic response of the sample with its longer relasation time leads to slow buildup (or decay) of tension. Fast and slow responses are observed sequentially with film of extensively crosslinked Riston photopolymer resist or with Kapton polymide film, whereas, in experiments with latex rubber, the rubbery behavior dominates.
Dielectric and dynamic mechanical measurements of poly(4‐methyl pentene‐1)
Authors: Lee Gilbert F. , Hiltz Thomas 
Published: April 2003

AbstractThe α‐relaxation process of poly(4‐methyl pentene‐1) was studied by dielectric and dynamic mechanical means. The complex dielectric constant was determined at nine discrete frequencies from 100 to 10,000 Hz and over a temperature range of −50–90°C. The complex dynamic mechanical Young's modulus was determined over the audiofrequency range of 10–22,000 Hz and a temperature range of 21–76°C, from which a master curve was constructed. The relaxation process was studied by comparing the activation energies and width of the dispersion curves. The results of a logarithmic frequency vs. reciprocal temperature plot of the loss peak maxima show that both the dielectric and mechanical curves are roughly linear but have different slopes. From the slopes the activation energies were determined. For the dielectric data an activation energy of 39 kcal/mol was obtained, whereas for the mechanical data a value of 106 kcal/mol was found. The width of the dispersion curves was determined by using a Cole–Cole empirical fit. The width of the dielectric dispersion curve is narrower by as much as a factor of 3 than the mechanical dispersion curve. It is concluded that the energy to cause the large scale molecular motion involved in the α‐relaxation is lower when excited by an alternating electric field than by an alternating stress field. Also the number of repeat units involved is smaller in the dielectric case than in the mechanical case.
Characterization of some poly(methyl methacrylate) prepared by emulsion polymerization in presence of egyptian delta titano magnetite ore (EDTMO)
Authors: Moustafa A. B. , Sayyah S. M. , Badran A. S. , Hassanin M. S. 
Published: April 2003

AbstractThe emulsion polymerization of methyl methacrylate was studied in water using potassium persulphate as initiator and dedocyl–benzene sodium sulphonate as emulsifying agent at 85°C. The effect of Egyptian delta titano magnetite ore (EDTMO) upon the activation energy and on the mean average molecular weights of the obtained polymers was studied. It was found that the viscosity average molecular weights increase with decrease of reaction temperature and initiator concentration but increase with increase of monomer concentration in the reaction medium. Some of the polymer samples prepared in absence and in presence of some (EDTMO) were separated on tlc plates according to molecular weight in binary mixture, benzene:methanol (1:1.4 by volume) at 30°C. The tlc techniques were performed to give an idea about the molecular weight distribution of the polymer samples obtained.
Complexation of samarium ion with poly(acrylic acid) grafted onto polyethylene by radiation‐induced method
Authors: Maekawa Toshihiko , Nishide Hiroyuki , Tsuchida Eishun , Ohmichi Hideki , Okamoto Jiro 
Published: April 2003

AbstractAcrylic acid was graft‐polymerized onto polyethylene powder by preirradiation method. The grafted powder (PE‐g‐AA) rapidaly adsorbed Sm3− ion in high efficiency. The poly(acrylic acid) grafted to the surface region of PE acted as an effective chelating site for the relatively large Sm ion. The complex formation constant of Sm ion with PE‐g‐AA was much larger than those of Sm ion with poly(acrylic acid) and propionic acid and of Cu2+ ion with PE‐g‐AA.
Depolymerization of nylon 6: Some kinetic modeling aspects
Authors: Ogale Amod A. 
Published: April 2003

AbstractDepolymerization reactions of nylon 6 [poly(ϵ‐caprolactam)] have been modeled based on an existing mechanism for reversible polymerization reactions. The method of moments proposed by Min has been used together with kinetic and equilibrium constants for polymerization reactions to simulate depolymerization reactions. Simulation results thus obtained for batch and semibatch processes compare well with the corresponding experimental results.
Interactions between dyes and polyelectrolytes: Effect of polymer–polymer interactions
Authors: Petrak K. 
Published: April 2003

AbstractThe competition between methyl orange dye and various polymers [gelatin, poly(vinyl alcohol), polyacrylamide, etc.] for the binding sites on quaternized poly(1‐vinylimidazole) in aqueous solutions was studied. The method used was based on a well‐known effect of dissolved polyelectrolytes on the rate of diffusion of solutes through semipermeable membranes. The final results are expressed as the ratio of C1″(bound)/C1′(bound), where C1″(bound) is the amount of the solute adsorbed to a mixture of two polymers and C1(bound) is the amount of solute bound to a single polymer. In the case of quaternized poly(1‐vinylimidazole) it was found that as much as 15% of the solute bound to the polymer can be replaced by another, “nonadsorbing” polymer.
An analysis of CSTRs in series for solution copolymerization
Authors: Rodriguez F. 
Published: April 2003

AbstractContinuous copolymerization is used in order to achieve a product of uniform composition. However, it is difficult to attain high conversions without resorting to very high residence times in a single tank. The way to avoid this is to use a series of stirred reactors with addition of one comonomer and initiator to each one after the first. The allowable half‐life of the initator is a function of the residence time. When all the reactors are equal in volume so that the residence time is the same in each, it can be shown that the incremental conversion in each successive reactor must decrease in a well‐ordered manner. As a specific example, a copolymerization is postulated with total polymer concentration restricted to the region where viscosity is manageable with conventional mixing equipment. Under these conditions the relative reactivity ratios are presumed to be constant and temperature can be held within narrow bounds.