bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionic graft copolymerization. VII. Ionic graft copolymerization of β‐propiolactone onto the trunk polymers containing pyridine, amide, sulfonyl chloride, and carboxylic acid anhydride groups
Authors: Shiota Tetsuya , Hayashi Koichiro , Okamura Seizo 
Published: April 2003

AbstractThe graft copolymerization of β‐propiolactone (βPL) onto the various trunk polymers containing polar substituents such as pyridine, amide, sulfonyl chloride, and carboxylic acid anhydride groups was carried out. In the grafting onto the basic trunk polymer containing 4‐vinylpyriding units, two kinds of grafting mechanism are supposed. In the case of rigorously dried trunk polymer, the polymerization is initiated by betaine and proceeds with higher grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency in the presence of some amount of water. With acidic trunk polymer containing sulfonyl chloride groups, no graft copolymer was produced. The grafting efficiency of βPL onto the amphoteric trunk polymer containing acrylamide units was found to be between those of basic and acidic trunk polymer. In addition, the grafting by means of ionic copolymerization of βPL with maleic anhydride units contained in trunk polymer proceeded with very high grafting efficiency.
X‐ray studies on cellophane1
Authors: Venkateswaran A. 
Published: April 2003

AbstractX‐Ray diffractograms of cellophane showed a considerable variation in the intensity corresponding to the 101, 101, and 002 planes. Applications of generally accepted procedures for estimating crystalline content in cellulosic materials yields varying results for crystallimity in cellophane. It is concluded that such procedures are not applicable to cellophane used in this study.
Voids as a source of haze in weathered poly(2,2,4,4‐tetramethyl‐1,3‐cyclobutylene carbonate)
Authors: Niegisch W. D. 
Published: April 2003

AbstractLong‐term weathering studies of the subject transparent thermoplastic polymer revealed that sheets extruded from pristine resine gradually became hazy. Electron microscopy of fracture surfaces showed that minute voids were created during outdoor exposure. By the application of the Mie light scattering theory, it was possible to calculate that the average void size was 4 × 103 Å and that the concentration of voids numbered about 106/mm3. Yet the total void volume of the poorest sample, which had a haze value of 26%, was less than 0.05%. The average void size decreased over a three‐year period, but the concentration increased with exposure. A mechanism of void formation was formulated based on photo‐induced moleculàr degradation. Chemical evidence suggests that molecular degradation occurs by complete unzippering of a molecule, resulting in the formation of carbon dioxide and 2,2,4‐trimethylpentene‐3‐al. The aldehyde is believed to plasticize the polymer in the vicinity of a growing void and the carbon dioxide acts as a blowing agent, therby generating a void. Simultaneously, free radicals formed during molecular decomposition initiate further degradation of neighboring molecules. The propensity of this resin to haze can be effectively overcome by suitable cleanup and stabilization procedures.
Environmental stress relaxation studies of polymers: Effect of temperature on polyethylene‐benzene system
Authors: Nisizawa M. 
Published: April 2003

AbstractThe method of stress relaxation has been used to study the effect of temperature on the stress decay behavior in the system of polyethylene–benzene. The behavior of stress decay in the polyethylene under benzene at various temperatures was observed and the activation energy of polyethylene–benzene system was obtained.
The study of polymers by high‐temperature ATR spectroscopy
Authors: Fujimoto K. , Wataya K. 
Published: April 2003

AbstractA new high‐temperature attenuated total reflectance apparatus (HATR) was constructed and used at different temperatures for making infrared measurements on the same liquid or solid sample. It was found that this method was applicable to the continuous quantitative analysis of changes occurring during chemical reactions such as polymerization, isomerization, and crosslinking. In the bulk polymerization of styrene, the process of monomer consumption could be followed progressively. In the crosslinking reaction of high cis‐polybutadiene by sulfur‐accelerator or peroxide crosslinking systems, the decrease of cis content and its partial isomerization to trans structure was measured. Furthermore, in the crosslinking reaction of ethylene–propylene terpolymers (EPDM), the consumption of double bonds was observed over the course of the reaction with both sulfur‐accelerator and peroxide crosslinking systems. The effect was greatest in the case of methylenenorbornene‐type EPDM.
On the degree of crystallinity in jute and mesta fibers in different states of purifications and moisture conditions
Authors: Ray P. K. 
Published: April 2003

AbstractThe degree of crystallinity (DC) in different moisture conditions was studied for jute and mesta holo‐ and α‐celluloses. As in the case of raw fibers the DC was found to decrease as humidity increased, but the rate of change was diminished in the present case. The lower rate is explained on the supposition that some of the regions previously accessible to water have, after removal of lignin and hemicelluloses, assumed more ordered states and are less accessible. The DC increased as lignin and hemicelluloses were removed and tended to approach that of ramie or cotton. The crystalline structure of jute α‐celluloses was also found to be similar to that of ramie or cotton.
Cooking schedule of alkyd resin preparation. Part II. Effect of cooking schedule on molecular weight distribution of alkyd resin
Authors: Nagata Takumi 
Published: April 2003

AbstractThe effect of cooking schedule on the molecular weight distribution of an alkyd resin was investigated. At the molar ratio of 1.03/0.43/1.00 for glycerin, lauric acid, and phthalic anhydride, two kinds of alkyd resin were prepared, one by maintaining the reaction temperature at 170°C for an hour and then raising it up to 230°C (sample I), the other by raising the temperature up to 230°C at a uniform rate of 33°C per 10 min. (Sample II). Sample I and sample II were fractionated into seven or eight fractions by adding n‐heptane to 5 wt‐% toluene solution at 30°C. Acid valued, hydroxyl value, intrinsic viscosity [η], and the number‐averagè molecular weight M̄n were determined. The result showed that the molecular weight distribution curve obtained from sample I was much narrower than that from sample II. In addition, a relation was found between [η] and M̄n conforming to the equation [η] = KMα, where different values of K and α were obtained for sample I and sample II. Based on the differences in the molecular weight distribution curves and in the rate constants for the esterification reactions, glycerin/lauric acid and glycerin/phthalic anhydride at 170°C and 230°C, the mechanism of condensation reaction of short oil alkyd resin was discussed.
Compression creep behavior of a highly crosslinked plasticized polyester system
Authors: Steg I. , Katz D. 
Published: April 2003

AbstractThe influence of plasticizer addition on behavior of highly crosslinked unsaturated polyester–styrene systems was investigated by measurement of their compression creep and creep recovery at different temperatures. The correction between the observed behavior of the investigated polymeric systems and their structures was explained by assuming the presence of supermolecular structures which change in the applied field of stress at different temperatures. In a wide temperature range the plasticiezr addition shows a similar effect to that of temperature increase on creep recovery of the investigated polymers.
Rates of crystallization of copolyamides. I. Random copolymers of nylons 6 and 11
Authors: Hybart F. J. , Pepper B. 
Published: April 2003

AbstractRates and extents of crystallization of nylon 11 and nylon 6/11 copolymers have been measured by dilatometry. As the amount of copolymerization increased there was a decrease in the extent of crystallization and in the rates of crystallization for any degree of supercooling below the melt.
Grafting of acrylonitrile onto cellulose initiated by ceric ion
Authors: Rao S. Ranga , Kapur S. L. 
Published: April 2003

AbstractAcrylonitrile was grafted onto cellulose with the use of ceric salt as initiator and the grafting was found to be maximum at 0.6N acid concentration. The effect of monomer and initiator concentration on the extent of grafting was studied. A new method for quantitative estimation of extent of grafting on cellulose was developed and its validity was established. The grafted samples with 20% increase in weight were found to be highly resistant to microorganisms.
Direct preparation of porous polyethylene filters by radiation polymerization of ethylene
Authors: Okada Minoru , Takehisa Masaaki , Machi Sueo , Danno Akibumi 
Published: April 2003

AbstractIn order to prepare porous, macroscopically homogeneous filters without a separate packing process, ethylene was polymerized by radiation in glass tubes. The bulk density of the polyethylene is approximately proportional to ρ(ƒM)2I0.9t2, where ρM is average ethylene density, ƒM is average ethylene fugacity, I is radiation dose rate, and t is reaction time. The effect of the bulk density on “treatment capacity” was investigated by experiments where air samples containing 0.1 wt‐% iodine vapor were filtered. Treatment capacity is difined as that amount of air per gram of polyethylene which passes through a filter until the polyethylene reaches the break point. The treatment capacity is approximately constant at 9 × 102 cm3/g over the bulk density range from 0.03 to 0.07 g/cm3, and it is lower at the outside of this range. The pressure drop due to the polyethylene filters varies with the 2.7th power of the bulk density when the bulk density is more than 0.03 g/cm3; below 0.03 g/cm3 this exponent increases with decreasing bulk density. Because of both the necessity of high Treatment capacity and that of low pressure drop, the optimum bulk density of polyethylene in the filter is about 0.03 g/cm3.
Studies in disperse dye transfer mechanism in polyester–viscose union at elevated temperatures
Authors: Kangle P. J. 
Published: April 2003

AbstractThe thermofixation process of dyeing polyethylene terephthalate–viscose union fabric with disperse dyes has been experimentally studied with a view to understanding the phenomena of dyeing polyester blends. It is shown how the distribution of a disperse dyestuff changes on the terylene and viscose portions of a union during different stages of dyeing by the thermofixation process. Equilibrium adsorption isotherm and rate curves of adsorption of disperse dyes on the polyester portion of the union have been determined. The nature of staining of the viscose portion of the union with different disperse dyes has been investigated. From the presented typical data it is possible to deduce fairly simple semiempirical rules regarding the phenomena of the thermofixation process of dyeing polyester–viscose union. It is pointed out that it is not possible to derive an exact thermodynamic theory to explain the data and describe the molecular mechanisms in such systems.
Effect of oxygen on intensity exponents of radiation‐induced polymerization rates
Authors: Tsurugi Jitsuo , Fukumoto Tsugio , Yamagami Masayuki 
Published: April 2003

AbstractGamma radiation‐induced graft polymerization to natural rubber in benzene solution (solution grafting), graft polymerization to natural rubber latex (Emulsion grafting), and emulsion polymerization of three vinyl monomers—styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN), were carried out under air atmosphere to compare the radiation intensity exponent of each polymerization rate under air atmosphere with that under nitrogen atmosphere or under vacuum. The intensity exponents of the solution grafting both under air atmosphere and under exclusion of air were found to be numerals near one half. This indicates prevailing normal radical mechanism. However, the intensity exponents of the emulsion grafting under air atmosphere were found to be 0.94, 1.00, and 0.82 for St, MMA, and AN, respectively, and those of the emulsion polymerization under air atmosphere, 0.16 and 0.15 for St and MMA, respectively, although those of both emulsion grafting and emulsion polymerization under exclusion of air were found to be numerals near to one half except for that of emulsion polymerization of AN. For emulsion grafting, the initiating species is considered to be trunk polymer radical but the terminating species is assumed to be the radical(s) produced in the water phase in the presence of oxygen. For emulsion polymerization, both initiating and terminating species are assumed to be the radical(s) produced in the water phase in the presence of oxygen.
The influence of intermolecular hydrogen bonding on the flow behavior of polymer melts
Authors: Blyler L. L. , Haas T. W. 
Published: April 2003

AbstractThe influence of hydrogen bonding on the flow behavior of polymer melts at high shear rate has been investigated using a capillary extrusion rheometer. The systems studied were copolymers of ethylene and acrylic or methacrylic acid. Hydrogen bonding was found to substantially enhance both flow activation energy and viscosity level, as well as the degree of dependence of viscosity on rate of shear. It was also found that hydrogen bonding does not influence the critical shear stress for onset of “melt fracture.” The data support the view that hydrogen bonds act effectively as temporary (quasi‐) crosslinks during the short time scales of deformation involved in flow at high shear rates.
Abrasion resistance of pre‐stressed and stressed rubber vulcanizates
Authors: Lambert D. H. , Boonstra B. B. 
Published: April 2003

AbstractThe abrasion resistance of carbon black‐reinforced SBR‐1500 vulcanizates has been shown to be drastically reduced by the application of tensile strain during the abrasion process. Pre‐stressing of similar vulcanizates, however, has no effect upon the abrasion resistance.
The analysis of polyurethane foams II. Chemical constitution of the polymer
Authors: Dawson B. , Hopkins S. , Sewell P. R. 
Published: April 2003

AbstractEfforts have been made to establish the chemical constitution of water‐blown polyurethane foams. Specific reagents have been used to indicate the presence of biuret or allophanate linkages. Partial hydrolysis techniques have been used to degrade foams selectively and hence isolate parts of the chain network. These methods yield information which is not satisfactorily obtained from the examination of undegraded polymer and which is not available after total degradation. It has been shown that polyureatype linkages are present in the chain network of both polyester and polyether foams.
Glass‐rubber transition behavior and compatibility of polymer pairs: Poly(ethyl acrylate) and poly(methyl methacrylate)
Authors: Sperling L. H. , Taylor D. W. , Kirkpatrick M. L. , George H. F. , Bardman D. R. 
Published: April 2003

AbstractA series of interpenetrating polymer networks were prepared containing PMMA and PEA as their two components. Corresponding telomer mixtures and random copolymers were also prepared for comparison purposes. The glass‐rubber transition studies were made via shear modulus and dilatometric measurements. The results indicate one very broad transition for the IPN's rather than two transitions expected for incompatible polymer pairs. An interpretation based on the compatibility or near‐compatibility of the PEA/PMMA pair is offered.
Some rheological properties of molten polytetrafluoroethylene
Authors: Ajroldi G. , Garbuglio C. , Ragazzini M. 
Published: April 2003

AbstractMeasurements of melt viscosity on samples of polytetrafluoroethylene of different molecular weight were carried out at 360°C by means of tensile creep tests in the linear viscoelasticity range. The apparent activation energy for viscous flow in the range between 330° and 380°C was estimated to be 20 kcal/mole. A value of about 7,500 was also determined for the average molecular weight between entanglement points (Me), from the equilibrium compliance (De). Melt viscosity data were compared with zero strength time (ZST) values and a linear correlation was found on a bilogarithmic scale. The dependence of ZST on the applied stress and temperature was also studied and the results are discussed on the basis of Bueche's theory on the creep at rupture above the glass transition temperature.
Amorphous state transitions in butadiene–acrylonitrile copolymers
Authors: Geiszler W. A. , Koutsky J. A. , Dibenedetto A. T. 
Published: April 2003

AbstractDifferential thermal analysis, creep measurements, and gas permeation rates are used to confirm the existence of a transition zone in three butadiene acrylonitrile copolymers in a temperature region that starts at roughly 15° to 25°C above the main glass transition temperatures of the copolymers and extends over a broad temperature range. The change appears to be slightly endothermic and softens the copolymers upon heating. It is speculated that the copolymers are in a mesomorphic state above their main glass temperature in which there is either a degree of ordering or a low‐grade crystallinity of polybutadiene units along the copolymer chains. It is not until the copolymers are 50° to 75°C above their main glass temperature that they become truly amorphous.
Distribution of internal flaws in acrylic fibers
Authors: Thorne D. J. 
Published: April 2003

AbstractOptical microscopy has been used to illustrate various types of discontinuities, or flaws found within acrylic polymer fibers and to determine the distribution of such internal flaws along the length of the fiber. Flaws are comprised of particulate inclusions and voids. The internal flaw distributions approximate a Poisson type for point flaws, but significant variation is found in mean flaw concentrations from 0.03 to 2.3 flaws/mm. Both flaw concentration and flaw‐free length distributions have been used to predict, for random selection of test lengths, the probability of avoiding a flaw with respect to gauge length (P versus Lg plots).
The thermal stabilization of polyethylene sulfide
Authors: Lee T. C. P. , Wragg R. T. 
Published: April 2003

AbstractIt has been shown that the resistance of certain polyethylene sulfides to thermal degradation can be markedly improved by the addition of small amounts of metal dithiocarbamates, thioureas, or diphenyl acetylene together with a suitable carbodiimide. The extent of degradation, as indicated by the concurrent changes in polymer melt viscosity in the temperature range 220°–250°C, was dramatically reduced, in particular, by a stabilizer comprised of 4% hexamethylenebis(tert‐butyl)carbodiimide and 2% diphenylacetylene. At 250°C polyethylene sulfide (Dabco initiated) was stable in the melt viscometer for a period of 8–10 min and the resulting extrudate showed little sign of discoloration. The detailed mechanism of stabilizer action cannot be put forward at this stage because of uncertainty regarding the mode of polymer degradation which could occur by radical or ionic processes.
Photodegradation of nylon 66. I. Phototendering by TiO2
Authors: Taylor H. A. , Tincher W. C. , Hamner W. F. 
Published: April 2003

AbstractThe mechanism by which TiO2 exerts a phototendering effect on nylon 66 photodegradation has not been previously explained. To aid in the elucidation of this mechanism, the wavelength dependence curves of photodegradation of nylon 66 both with and without TiO2 have been accurately determined. These data, in conjunction with reflectance and phosphorescence measurements, indicate that the phototendering effect of TiO2 proceeds by a chemical rather than an energy transfer mechanism.
Properties of PVC. II. Properties of PVC compounds with solvents
Authors: Maláč J. , Altmann V. , Zelinger J. 
Published: April 2003

AbstractIt was the aim of this paper to study the influence of the solvent residues in PVC compounds on physical and mechanical properties of samples prepared from them as well as the rheologic properties of their melts. Besides tetrahydrofuran other solvents are also partly retained in PVC even after processing at higher temperatures. The properties of samples prepared from PVC compounds containing solvents depend on the solubility parameter of the solvent used. Solvents with a solubility close to that of PVC have the same effect as plasticizers. Solvents with very high solubility parameters, e.g., water, influence the flow and dynamic properties in just the opposite way than plasticizers and behave rather like fillers. A mechanism for influencing the properties of PVC by the presence of solvent residues is suggested.
The effect of phenol/formaldehyde ratio on the char yield from phenolic resins
Authors: Mitchell S. J. , Pickering R. S. , Thomas C. R. 
Published: April 2003

AbstractAn idealized mechanism for the carbonization of phenolic resins was adopted and an equation was derived for the char yield. In simplified cases this was shown to be a function giving a maximum of 67.9% at a 1:1 formaldehyde/phenol molar ratio, falling rapidly at lower and slowly at higher ratios. In experimental verification, the alkalicatalyzed reaction of phenol and formaldehyde at various molar ratios was studied and the resulting resins were characterized and carbonized. The char yields were found to correspond well with predictions, with a maximum of about 67.2% in the region of 1.1:1 formaldehyde/phenol molar ratio.
Degradation du polychlorure de vinyle preparé en presence de composes organoaluminiques
Authors: Guyot A. , Rocaniere P. , Bert M. 
Published: April 2003

AbstractLes alkylaluminium en milieu CCl4 provoquent, avec un faible rendement, la polymérisation du chlorure de vinyle et réagissent sur le polymère formé. Une réaction rapide se produit après une période d'induction de 2 heures environ, qui forme un bon catalyseur de deshydrochloruration du polymère. En l'absence de monomére, les alkylaluminum peuvent attaquer le polychlorure de vinyle, et la réaction rapide, pas toujours observée, peut ètre catalysée par les parois du réacteur. Les polymères attaqués présentent une très mauvaises tabilité thermique. Les polymères préparés avec un systéme alkylaluminum–titanate de butyle ne sont que fort peu attaqués par l'alkylaluminum et leur stabilité thermique est relativement bonne. Les résidus de titanate, lorsque leur teneur dépasse 100 ppm, inhibent l'accélération de la dégradation thermique.
Combined pyrolysis and radiochemical gas chromatography for studying the thermal degradation of epoxy resins and polyimides. I. The degradation of epoxy resins in nitrogen between 400°C and 700°C
Authors: Bishop D. P. , Smith D. A. 
Published: April 2003

AbstractThe thermal degradation of a bisphenol A‐based epoxy resin (EP 274) cured with 4,4′‐diaminodiphenyl methane (DDM) and with phthalic anhydride (PA) was studied using a radiochemical pyrolysis gas chromatography technique. Conclusive evidence for some of the degradation mechanisms of these resins was obtained by pyrolyzing samples containing various 14C‐labelled groups and analyzing the products using this method.