bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graft copolymerization of vinyl monomers with modified cotton. II. Grafting of acrylonitrile and methyl methacrylate on acetylated cotton
Authors: Hebeish A. , Kantouch A. , El‐Rafie M. H. 
Published: April 2003

AbstractCe(IV)‐induced polymerization of acrylonitrile and methyl methacrylate with acetylated cotton having different acetyl contents was investigated. The extent of interaction between the cotton and monomer is dependent upon the acetyl content of the former as well as on the reaction conditions. Increasing the acetyl content caused a significant decrease in the graft yield. Increasing the acrylonitrile concentration was accompanied by a substantial increase in the graft yields. The same effect was found with the initiator up to a certain concentration, but beyond it there was a reversal. The rate of grafting increased by rising the temperature and follow the order 60° > 40° > 30°C. The Ce(IV) consumption during grafting is greater than that consumed during oxidation. The consumption of Ce(IV) by the cellulosic materials was favorably influenced by the concentrations of monomer and initiator, time, and temperature. Rates of grafting and Ce(IV) consumption during oxidation of acetylated cottons having different acetyl contents strongly support the postulated mechanism of grafting using the Ce(IV)–cellulose redox system. Ce(IV) oxidation had practically no effect on the acetyl groups (expressed as per cent combined acetic acid) of the modified cotton.
The thermal analysis of polymers. V. Effects of crosslinking and hard block crystallinity on the mechanical behavior of polyurethane elastomers
Authors: Miller Gerald W. 
Published: April 2003

AbstractLinear expansion measurements have been used to correlated the degree of molecular ordering of a polyurethane elastomer with the increase in hard block content. The lower the value of the linear coefficient of expansion, αL, the higher the degree of molecular fit. The soft block exerts the major influence on the coefficient of expansion below its fusion temperature (45°C), and the value usually decreases as the hard block content increases. Extenstion with aromatic diols causes the αL to decreases at 100°C as the hard block content increases. Crosslinking a urethane prepolymer with triol increases the expansivity over the diol‐extended elastomer. Keeping the NCO/OH ratio in the range 0.975 to 1.06 causes the lowest coefficient of expansion. For elastomers of low crystallinity, no correlation can be made between hard block content and enthalpy.
Concept of secondary heterogeneous structure of long‐chain branched polyethylene
Authors: Fujiki Tokio 
Published: April 2003

AbstractThe mechanism of formation of surface roughness and extrusion swelling of the extrudate and the steady‐shear viscous flow behavior in the region of high shear rate for branched polymers were investigated using two low‐density polyethylenes and their sheared samples. These two polyethylenes varied in their degree of branching, molecular weight, and molecular weight distribution but were similar in their melt flow index. The effect of molecular parameters, especially long‐chain branching, on viscoelastic properties in the molten state was also considered. Samples of various degree of shearing level were prepared by passing them repeatedly through an extruder. Results of intrinsic viscometry, gel permeation chromatography, and infrared spectroscopy of the original and the sheared samples indicate that no appreciable variation between them takes place in the molecular parameters during the process of extrusion shearing. Both surface roughness and extrusion swelling of the extrudate diminish with increase in the extent of shear. The extrusion shearing affects the surface roughness and extrusion swelling of the extrudate as well as the capillary entrance effect more markedly for the highly branched polymers with considerably higher molecular weight than for the less branched species with bell‐type molecular weight distribution. These results demonstrate that heterogeneity becomes more conspicuous with the degree of long‐chain branching level, and therefore the role of long‐chain branching in the development of the heterogeneity is particularly important. It is suggested that the secondary heterogeneous structure arises through phase separation or from the heterogeneous formation of strongly entangled network at the branching point of the long‐chain branching in the manufacturing process of the low‐density polyethylene and that its presence causes the distinctive viscoelastic properties of long‐chain branched polymer melts.
Film formation from polymer dispersions
Authors: Bertha S. L. , Ikeda R. M. 
Published: April 2003

AbstractThe coalescence of a poly(vinylidene chloride/methyl acrylate/acrylic acid) latex was found to occur only above the Tg. The various theories of film formation from polymer dispersions attribute latex coalescence to three types of forces: the pressure due to the polymer–air interface, the pressure due to a polymer–water interface, and the pressure due to capillary action. Analysis of the forces indicates that none are sufficient to cause coalescence below Tg while any, or all, may cause coalescence above Tg.
Characterization of ethylene–propylene rubber and ethylene–propylene–diene rubber networks
Authors: Hassan A. M. , Ray L. N. 
Published: April 2003

AbstractThe stress–strain (S/S) and the swelling equilibrium behavior in a series of ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) networks were investigated and the results were employed to evaluate the effects of varying the cure conditions on the crosslinking efficiency in these networks. The S/S curve of completely swollen vulcanizates is in agreement with the predictions of rubber elasticity theory, while that of dry or partially swollen vulcanizates is fully described by the Mooney‐Rivlin equation. ϰ values determined in benzene were found to vary linearly with vr (vr = equilibrium volume fraction of rubber in swollen sample). Crosslinking efficiency, moles of crosslinks produced per moles of crosslinking agent used, ranges from 3.7 in peroxide‐cured EPDM (55% wt ethylene and 2.6% unsaturation) to 0.15 in similarly cured EPR (43% ethylene). Efficiency in the latter system improves to 0.6 by addition of a coagent (sulfur) to the cure formula. Crosslinking efficiency in EPDM (55% ethylene) was found to increase in the order: peroxide‐ > resin‐ > sulfur‐cured. In the EPDM sulfur vulcanizates, changing the terpolymer in the cure formula resulted in significant changes in the crosslinking efficiency.
Cavity formation on elongation in filled elastomers
Authors: Sekhar N. , Van Der Hoff B. M. E. 
Published: April 2003

AbstractExperiments were conducted on samples of crosslinked rubbers filled with poly(tetrafluoroethylene) powder or small glass beads. Volume changes on elongation were measured in a dilatometer. Slow deformation cycles showed considerable hysteresis, the volume on elongation being smaller than on contraction. There is much less hysteresis if the sample is degassed before the experiment. These observations suggest that, to a large extent, the volume of the cavities is determined by the availability of gases dissolved in the elastomer matrix. When the samples were saturated with carbon dioxide, nitrogen, and helium, it was indeed found that the degree of cavitation increased in order with the solubility of these gases.The initial rate of cavitation is high. After about 1 min, dilatation is proportional to the logarithm of time. This rate is inversely related to the solubility of the gas present.When a sample is subjected to a constant tensile stress under vacuum and the external pressure is suddenly brought to atmospheric, the elongation at first decreases due to compression of the cavities and then increases slowly as gas diffuses into them. Even unfilled compounds mixed mechanically contain submicroscopic holes. These enlarge on deformation thus causing dilatation. Only for samples prepared by evaporation from solution is there no pressure dependence of the apparent modulus.It is demonstrated that the relation between the volume of vacuum cavities and the external pressure resembles that of volume and inflation pressure of a spherical hole in an infinite elastic medium.
Necking of high‐density polyethylene
Authors: Wada Yasaku , Nakayama Akira 
Published: April 2003

AbstractNecking draw of high‐density polyethylene is studied at draw rates of 2.5 × 10−2 to 25 mm/min and at temperatures of −40° to 80°C. Effect of temperature and draw rate on necking stress is interpreted in terms of viscoelastic flow of amorphous phase accompanying orientation of crystallites. It is proved that reducibility of draw rate and temperature holds and that the reduction factor obeys approximately the Williams‐Landel‐Ferry equation. Necking stress at an extremely low draw rate, critical necking stress, is discussed in terms of the phase equilibrium under stress between two states before and after microfracture of crystallites. The theory, with some approximations, leads to the equation by Iida in which the critical necking stress is expressed by fusion parameters. The thermodynamic behavior of isothermal necking is discussed and a phenomenologic criterion for necking is presented.
The preparation and stability of snake cage membranes
Authors: Jerome R. , Desreux V. 
Published: April 2003

AbstractLinear chains of poly(methacrylic acid) have been successfully trapped in different polymeric materices of variable degree of reticulation. The length of the linear chains and the porosity of the cages are the two fundamental parameters which control the stability of the snake cage systems. The physical character of trapping in the membranes which are described in this paper is qualitatively demonstrated. The snake cage effect seems to be a very general principle of insolubilization. By this method, systems with specific exchange or absorption characteristics may be prepared.
Reactions de sulfopropylation, cyanoethylation et greffage d'acrylonitrile sur l'alcool polyvinylique et le poly[ethylene methylenebis(4‐phenyl carbamate)]
Authors: Galin J. C. 
Published: April 2003

AbstractBy using “dimsyl sodium” or sodium hydride as metallating agent, it is possible to obtain without degradation the sodium derivatives of poly(vinyl alcohol) or of polyurethanes in homogeneous solution in dimethylsulfoxide or dimethylformamide. These metallated polymers have been successfully reacted with calculated amounts of propane sultone and then of acrylonitrile to produce sulfonated, cyanoethylated, and acrylonitrile graft copolymers. The copolymers thus obtained present two characteristic properties: (1) they are anionic polyelectrolytes offering a good affinity toward cationic dyes, and (2) they are compatible, either in solution or in solid state, with acrylic and modacrylic fiber‐forming polymers.
Transport of fixed gases in radiation‐stabilized poly(vinyl chloride)
Authors: Nakagawa Tsutomu , Hopfenberg H. B. , Stannett V. 
Published: April 2003

AbstractPoly(vinyl chloride) was reacted with sodium N‐methyl dithiocarbamate to produce a modified PVC containing N‐methyl dithiocarbamate of varying degrees of substitution. The resulting adducts were markedly more stable when subjected to γ‐radiation than the unmodified PVC. The transport parameters (permeability, solubility, and diffusivity) of fixed gases were determined in modified and unmodified films. Although the radiation stability was dramatically improved by this novel substitution, the barrier properties of the PVC were only slightly changed by the controlled substitution of N‐methyl dithiocarbamate.
Radiation‐induced sulfoxidation and sulfochlorination of powdery polyethylene produced by radiation process
Authors: Konishi Kunio , Yamaguchi Kouichi , Takehisa Masaaki 
Published: April 2003

AbstractGamma radiation‐induced sulfoxidation and sulfochlorination of the high specific surface area powdery polyethylene which was produced by radiation‐induced polymerization of ethylene at room temperature were studied and were compared with sulfonation by fuming sulfuric acid. In these reactions the effect of surface area on the chemical reactivity was observed to a certain degree. In gamma radiation‐induced sulfochlorination, it was elucidated that as the reaction proceeds, the ratio of SO2Cl to Cl introduced into the polymer decreases, which can be explained by the difference between the diffusibilities of SO2 and Cl2 molecules through sulfochlorinated and/or chlorinated polyethylene. Crystallinity, melting temperature, and density of the sulfochlorinated polymers were measured and are discussed.
Factors in rubber compounds affecting the adhesion of polyester tire cords
Authors: Iyengar Y. 
Published: April 2003

AbstractSeveral factors in rubber stocks were demonstrated to be important in the adhesion of polyester tire cords to rubber compounds. The retained adhesion of polyester tire cords, determined after heat‐aging laboratory cord–rubber samples at elevated temperatures, was improved by (a) eliminating the sources of amines in the elastomers and compounding ingredients, (b) reducing the moisture content of the stocks, (c) increasing the overall water vapor permeability (WVP) of the cord–rubber composite, and (d) lowering the modulus of the stock. Sulfenamide cure accelerators and water were found to be synergistic in reducing the retained adhesion of polyester cord after in‐rubber aging at high temperatures. The harmful effects of amines released from sulfenamides during curing and heat aging were eliminated by compounding the stocks with accelerators that do not form amines. Aliphatic diamines present as nonrubber components in natural rubber (NR) were shown to be detrimental to adhesion. Since synthetic polyisoprene rubber (IR) does not contain any nonrubber components, IR stocks containing the nonamine accelerator benzothiazyl disulfide (MBTS) showed excellent retained adhesion to polyester cords. A recently developed nonamine‐type accelerator gave adhesion essentially equal to MBTS but showed excellent scorch safety and high stock modulus typical of sulfenamides. The retained adhesion in IR stocks after heat aging was less dependent on moisture level and stock modulus than in NR stocks. Finally, examples of practical rubber compounds giving improved retained adhesion to polyester tire yarns are given.
The relation between melt flow properties and molecular weight of polyethylene
Authors: Saeda Shigeru , Yotsuyanagi Junji , Yamaguchi Kinya 
Published: April 2003

AbstractThe non‐Newtonian behavior of commercial linear polyethylene samples and their fractions were studied at 190°C. The viscosity η versus shear rate \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} curves of whole polymers could be superimposed onto a single master curve despite the variations of their molecular weights and molecular weight distributions. For fractions, however, the same master curve was inapplicable, and the sensitivity of the viscosity to shear rate was found to be greater than those of the whole polymers. The zero‐shear viscosities η0 of fractions were related to the 3.42 power of the weight‐average molecular weight Mu as follows:

For whole polymers, the zero‐shear viscosities were found to be considerably higher at the same Mw and markedly lower at the same z‐average molecular weight Mz than those of the fractions. Thus, it was concluded that η0 corresponds to an average of molecular weight between Mw and Mz. It was found that the molecular relaxation time τ is proportional to Mz5.3 for whole polymers and to η0Mw for fractions. Using these relations it was possible to relate the flow ratio, the ratio of flow rates at two different shear stresses, with the molecular weight distribution.
A new apparatus for measuring various properties of plastics using C specimens
Authors: Ohishi F. 
Published: April 2003

AbstractA new apparatus for measuring various properties of plastics is proposed. Using a split circular ring‐type specimen (C specimen), displacement L, tension P, and fringe order N are measured by means of a differential transformer, a load cell, and a polarizeranalyzer. The Young's modulus and photoelastic sensitivity of samples can be estimated from L, P, and N. Experiments are carried out in the environments of air, water, oils, and chemical reagents under‐temperature controlled conditions. Typical data are, presented showing the applications of this apparatus to the determination of the heat distortion temperature and the effect of temperature on the rigidity and photoelastic properties, to the simultaneous measurement of stress relaxation and birefringence and of creep and birefringence, and to the continuous measurement of resistance to chemical reagents and ultraviolet rays.
Cellulose graft copolymers. III. Effects of oxygen on graft copolymerization of ethyl acrylate with γ‐irradiated cellulose
Authors: Nakamura Yoshio , Hinojosa Oscar , Arthur Jett C. 
Published: April 2003

AbstractThe effects of oxygen on graft copolymerization of ethyl acrylate from methanol–water systems with γ‐irradiated fibrous cotton cellulose were investigated by electron spin resonance spectroscopy and by the formation of cellulose–poly(ethyl acrylate) copolymer. The concentrations of free radicals in cellulose irradiated dry in an atmosphere of nitrogen at 25°C decreased during postirradiation storage in nitrogen or oxygen. The concentration of free radicals in the irradiated cellulose, moisture regain of the irradiated cellulose, and formation of cellulose–poly(ethyl acrylate) copolymer decreased with increase in temperature and time of postirradiation storage and to a greater extent when stored in oxygen rather than in nitrogen. From the decrease in moisture regain of irradiated cellulose during postirradiation storage, it was concluded that increased intermolecular bonding occurred in irradiated cellulose during storage in both nitrogen and oxygen atmospheres. When irradiated celluloses which had been stored in either oxygen or nitrogen were copolymerized with ethyl acrylate at 60°C, less formation of copolymer was observed than when the copolymerization reactions were conducted at 25°C. It was concluded that there was no evidence for the formation or decomposition of cellulose peroxides during these reactions and that formation of graft copolymer depended primarily on the concentration of free radicals in the irradiated cellulose at the time of copolymerization.
Inhibitory action of phenols and amines in the photo‐oxidation of tetralin
Authors: Goda Kiyoshi , Tanaka Makoto , Murata Niro 
Published: April 2003

AbstractThe inhibitory efficiences of antioxidants (phenols and aromatic amines) were determined under irradiation for elucidation of their behavior in photo‐oxidation. We determined the ratio of termination rate constant to propagation rate constant and compared the ratio under irradiation with that in the dark. Phenols are classified into two categories with respect to their behavior under irradiation. The first is as antioxidants that have the same ratios under both conditions; the second, as antioxidants that have smaller ratios under irradiation than in the dark. We assumed the smaller ratios to be due to the following: quinones formed via the excited state of phenols by light absorption, in addition to the original phenols, participate in radical capture. Aromatic amines were also classified into two categories relative to their behavior under irradiation.
A simplified method for correction of polydispersities from gel permeation chromatography
Authors: Baker J. R. 
Published: April 2003

AbstractA simple method is presented for correction of polydispersity obtained by gel permeation chromatography. The method proposed utilizes well‐characterized polystyrene standards for both instrument calibration and construction of a correction curve which is then used for calculation of weight‐average and number‐average molecular weights and polydispersity of samples to be characterized.
On the internal structure of pressure‐sensitive adhesives
Authors: Kamagata Kazuo , Kosaka Hideo , Hino Kinnosuke , Toyama Mitsuo 
Published: April 2003

AbstractThe internal structure of pressure‐sensitive adhesives was studied using electron microscopy and measurements of mechanical loss, tensile modulus, viscosity, stress relaxation, and critical surface tension. The adhesives were blends of natural rubber and the pentaerythritol ester of hydrogenated rosin. Compositions containing up to 40 wt‐% resin are homogeneous mixtures. The temperature dispersion of mechanical loss shows a single peak, and the peak value remains almost constant. When the resin concentration exceeds 40 wt‐%, phase separation occurs. The disperse phase is resin containing a small amount of rubber. Two peaks, or a peak and a shoulder, appear in the temperature–loss peak curves. It is postulated that one of the peaks corresponds to the phase in which resin is uniformly dispersed in the rubber and the other peak corresponds to the resin phase which contains a small amount of rubber. Evidence for homogeneity in compositions containing 40 wt‐% or less resin and of heterogeneity at higher concentrations of resin was also obtained from the electron microscope observations. The relationships between the internal structure of pressure‐sensitive adhesives and viscosity, Young's modulus, the relaxation spectrum, tack, and critical surface tension are discussed.
Photoreactive polymers. IV. The synthesis and characterization of photocrosslinkable polysulfonates
Authors: Arcesi J. A. , Rauner F. J. , Williams J. L. R. 
Published: April 2003

AbstractA series of new light‐sensitive polysulfonate copolymers have been prepared by the interfacial polycondensation of mixed bisphenols and aromatic disulfonyl chlorides. The light‐sensitivity bisphenols contain the styryl ketone group. These polymers exhibit good light sensitivity, and upon exposure to light they crosslink and harden to give alkali‐ and acid‐resistant materials which are useful in photoresist applications.
Light scattering studies on the ripening of viscose solution
Authors: Ghosh Kalyan K. 
Published: April 2003

AbstractInvestigations were made on cellulose xanthate molecular weights by light scattering during the ripening of the solutions of (a) viscose‐containing colored thio salts and (b) pure cellulose xanthate separated from viscose. Though an apparent reduction in molecular weight was recorded with time of ripening for the viscose solution, no such fall was observed with pure cellulose xanthate. The apparent fall of molecular weight in the case of viscose has been shown to be due to the increasing absorption of the incident beam and to the change in the value of dn/dc with progressive color formation. Reproducible results can be obtained for cellulose xanthate solutions freed from color. Intrinsic viscosity of the viscoses and the degree of polymerization (D.P.) of the regenerated cellulose from viscoses during ripening were also measured and found to be constant. The results indicate that no degradation of alkali cellulose molecule takes place during the ripening process, irrespective of the state of degradation of alkali cellulose from which the viscose is made.