bluuebunny/crossref_metadata_2025_split huggingface dataset:
Location of some typical vinyl polymers within radiation‐grafted cotton fibers: An electron microscopical survey
Authors: Rollins M. L. , Cannizzaro A. M. , Blouin F. A. , Arthur J. C. 
Published: April 2003

AbstractElectron microscopical observations of radiation‐induced rayon–styrene graft copolymers were published by Kaeppner and Huang in 1965. The present paper reports electron microscopical investigations on the relationship of the structure of vinyl–cotton graft polymers to the original morphology of the cotton fiber and into the distribution of the grafted vinyl polymer in the cotton fiber structure. The grafted vinyl monomers investigated in this study were acrylonitrile, styrene, methyl methacrylate, and vinyl acetate. Two radiation‐induced procedures were used: simultaneous irradiation grafting and post‐irradiation grafting. Ceric ion grafting of acrylonitrile to cotton was included for purposes of comparison. Distribution of the vinyl polymer within the cotton fiber is illustrated by a series of electron micrographs, selected as typical of the particular grafted species under consideration. Results indicate that the diffusion rate of monomer into the cellulose fiber plays an important role in the final distribution of polyacrylonitrile grafts within the fiber. Uniform distribution of polyacrylonitrile in the fiber was achieved by simultaneous irradiation grafting of acrylonitrile on a highly substituted cyanoethylated cotton. In samples of low degree of cyanoethylation the distribution of graft polymer was non‐uniform. In grafting initiated by ceric ion the acrylonitrile graft polymer was evenly distributed. Polystyrene–cotton copolymers from grafts, made by simultaneous irradiation of cotton in methanol solutions of the styrene monomer, were uniform throughout the fiber but showed opening of structure associated with the amount of graft formed. Grafting of methyl methacrylate occurred only in the peripheral regions of the fiber; by contrast, grafting of vinyl acetate was uniform throughout the fiber wall. Important factors governing the successful irradiation grafting in cotton fibers are choice of solvent, ratio of monomer to cellulose, nature of prior chemical modification of the cellulose, and total irradiation dosage.
Some thiol‐terminated polyethers
Authors: Arnold H. B. , Floyd D. E. 
Published: April 2003

AbstractThiol‐terminated polyethers were prepared by two different routes, the starting materials being commercially available polyether polyols and epoxy resins. The products were pale colored liquids and were found to be very stable on storage at room temperature. Thiol‐terminated polyethers of functionality from 2 to 4 were prepared. They are interesting building blocks for polymers through oxidation of the terminal SH groups or through coreaction with epoxy resins.
Microscopic determination of degree of nitration of nitrocellulose with dispersion staining
Authors: Kohlbeck J. A. , Bolleter W. T. 
Published: April 2003

AbstractA microscopical method with dispersion staining has been developed for determining the degree of nitration of nitrocellulose (NC). In the method the per cent nitrogen in unknown samples is obtained by matching the colors of dispersed refracted light between an oil of known refractive index and films of the unknown and an NC standard. Agreement with standard Du Pont Nitrometer results were excellent. Color differences were detected as the nitrogen content of the NC ranged between 12.55 and 13.5% with central screening and the polarizer. The sensitivity was found to be increased by crossing the analyzer with the polarizer and observing the phase differences resolved in the analyzer.
Effect of acid acceptor concentration on the interfacial polycondensation of nylon 610
Authors: Kispert Robert C. , Foote Seward R. , Griskey Richard G. 
Published: April 2003

AbstractThe effect of acid acceptor level (sodium hydroxide) in the interfacial polycondensation of nylon 610 has been studied. It was found that increased acceptor levels shifted the curves of intrinsic viscosity versus sebacoyl chloride concentration to the right. It was also found that peak intrinsic viscosity values first decreased and then increased with increasing acid acceptor levels. The experimental results were shown to relate to balance of reactants and character of polycondensation zone.
Imidazole catalysis in the curing of epoxy resins
Authors: Farkas Adalbert , Strohm Paul F. 
Published: April 2003

AbstractThe high catalytic activity of imidazoles and particularly of 2‐ethyl‐4‐methylimidazole (EMI) for the curing of epoxy resins and the properties of the resulting resins prompted this study concerned with the nature of the curing reaction. Epon 828 epoxy resin and the model compound phenyl glycidyl ether were used as starting materials with EMI, 2‐methylimidazole, and dimethylbenzylamine as catalysts. During the curing of the resin at 50°C., the decrease in the infrared absorption of the epoxy band with time is accompanied by a decrease in the intensity of the imine band of the imidazole moiety, indicating its reaction with the epoxy group and its incorporation into the resin. The measurement of the residual epoxy content after curing for 24 hr. at 50 and 140°C. showed that the imidazoles were not more efficient in completing the epoxy reaction than dimethylbenzylamine. In the experiments with phenyl glycidyl ether the rate of reaction of the epoxy group with EMI was faster than the rate of polymerization, proving that the imidazole becomes permanently attached to the polymer chain. These results also suggest that the true catalytic species is not EMI but some addition product thereof. In comparative rate measurements the compound formed from equimolar quantities of EMI and phenyl glycidyl ether was found to be an excellent catalyst. The NMR analysis of the 1:1 and 1:2 adducts of EMI and phenyl glycidyl ether has shown that the second mole of phenyl glycidyl ether reacts with the ring nitrogen in the 3 position and not with the hydroxyl group of the mono adduct. By forming the bis adduct in this way the imidazole molecule acts as a crosslinking agent and at the same time introduces an alkoxide ion which can initiate further polymerization. It is very likely that this crosslinking is the process that leads to the superior physical and chemical properties (high heat deflection temperature, resistance to chemicals and oxidation) of the resins prepared with imidazoles as catalysts.
N‐methylaniline formaldehyde: Its synthesis and use as an epoxy curing agent
Authors: Bilow Norman 
Published: April 2003

AbstractA series of poly‐secondary aromatic amines was prepared by the acid‐catalyzed condensation of N‐methylaniline with formaldehyde. These condensation products were evaluated as curing agents for a standard epoxy prepolymer, namely bis(2,3‐epoxypropoxyphenyl)propane. Various molar ratios of N‐methylaniline to formaldehyde were used to produce polyamine condensation products with varying degrees of polymerization. These molar ratios ranged from 1.60 to 1.30. Dielectric properties of the cured epoxy resins at temperatures above 100°C. were highly dependent upon these ratios. Lower‐ratio condensation products produced resins with optimum dielectric properties at the higher temperature and also with good physical properties.
Calendering thermoplastic materials
Authors: Chong J. S. 
Published: April 2003

AbstractA general equation for the true shear rate encountered in calendering non‐Newtonian fluids is derived. Based on several constitutive equations (for a power‐law, a three‐constant Oldroyd, and a modified second‐order Rivlin‐Ericksen fluid), calendering is analyzed from the hydrodynamic point of view. The significance of dimensionless groups (the Deborah number, the Weisenberg numbers, and the viscoelastic ratio number), consisting of rheological and kinematic parameters, is discussed for scaling from prototype to production calendering. Correlation of experimental data obtained by using laboratory and production calenders is presented, and the scaling criteria obtained from the theory are examined. The onset of unstable flow, which causes non‐uniform internal strain patterns (nerve) in calendered sheeting, is discussed in terms of the Weisenberg number. Good and poor calendering regions for a polymer are discussed qualitatively by using a dynamic response diagram, and the importance of the overall calendering conditions on the final sheeting quality is discussed.
Anomalous freezing point depression of swollen gels
Authors: Boonstra B. B. , Heckman F. A. , Taylor G. L. 
Published: April 2003

AbstractThe anomalous freezing point depression, ΔT, of benzene‐swollen vulcanizates has previously been attributed to the limitation of (benzene) crystallite size by the polymer network. This study was initiated to determine the benzene crystallite size in a number of rubber and benzene systems. A special low‐temperature specimen holder was designed and constructed in the Cambridge Laboratories for running diffraction patterns at temperatures near −30°C. X‐ray line broadening techniques were used to study a series of filled and unfilled vulcanizates of varying crosslink density. The results indicate that crystallite size is not depressed to the degree predicted by freezing‐point measurements. Benzene crystallite sizes were similar in all rubber benzene systems, regardless of degree of crosslinking or benzene fraction, although carbon black loading appears to increase crystallite size. This effect may be attributed to lesser depth of penetration of the x‐rays due to greater density as carbon black loading increases. Additional studies measuring the ΔT for solutions and similar vulcanizates of NR and SBR over a wide range of rubber concentrations showed that at the same rubber in benzene fraction, crosslinking increases ΔT but the addition of carbon black reduces ΔT. An explanation for the observed phenomena is advanced.
Studies of the water‐soluble polymers. XVI. Azo dyes of poly‐N‐vinylimidazole
Authors: Machida Seishi , Araki Mikio , Matsuo Keizo 
Published: April 2003

AbstractHomopolymer of 2‐methyl‐N‐vinylimidazole and copolymer of the monomer with acrylamide were coupled with some aromatic diazonium compounds to give polymeric azo dyes. The dyestuff prepared from the homopolymer was soluble in water only when it was coupled with diazonium component containing sulfonic acid group, but the dyestuffs prepared from the copolymer were soluble. The reactivity, chemical structure, color, and dyeability of the polymeric dyes are discussed by comparing them with those of the corresponding monomeric dyes. The color fastness of the polymeric dyes was found to be in a high class; the rubbing and dry‐cleaning fastness were especially excellent.
Fine structure of cellophane–acrylamide graft copolymer by the ceric ion method
Authors: Hori Yasuhiko , Takahashi Toru , Nagata Masanori , Sato Ichiro , Okamura Seizo 
Published: April 2003

AbstractThe relationship between the grafting yield and the structure of graft copolymer is studied by measuring the branched chain lengths, the number of branches, the crystallinities, and the diffraction intensities of the (101) and (101) + (002) planes determined by x‐ray diffraction, and the distribution of branched polymers, observed by interferometry. Over a relatively wide range of grafting yield the number of initiating sites is almost constant and about 1–2 per 2 moles of cellulose chain. Therefore, the increase of grafting yield seems to be due mainly to the propagation of branched polymers. Branched polymers are assumed to be formed in cellulose crystallites both on the normal (101) planes and in the amorphous regions of cellulose. It is found that branched polymers grow from the outer layer into the inner part of the film as the grafting yield increases. At more than 250% of grafting yield, however, branched polymers are uniformly formed throughout the layer of film in which the crystalline regions of cellulose are gradually destroyed. This result agrees with the dimensional change of gel film during the reaction. The temperature dependence of tensile strength and elongation and the wet strength of graft copolymer are also investigated. At higher grafting yields, such as 250%, the crystalline structure of cellulose is disturbed by the formation of branched polymer, and no improvement in waterproofness can be expected from grafting; the secondary bonding between branched polymers may be presumed to be same as those among cellulose. In addition, the fine cracking of the film in the burst state is found to appear more easily as the grafting yield increases, in which the aggregating state of cellulose is recognized to be changed by the formation of branched polymer.
Correlation of capillary entrance pressure drops with normal stress data
Authors: La Nieve H. L. , Bogue D. C. 
Published: April 2003

AbstractThe pressure loss at the entrance of a capillary tube was studied as a means of characterizing viscoelastic fluids. Measurements of four polymer solutions were made and correlated with an equation of the form

where D is the shear rate and where Hch and λch are a characteristic stress and a characteristic time, respectively, determined independently from viscosity and normal stress measurements. Various theoretical analyses of capillary entrance flow are also compared.
Diffusion during the coagulation step of wet‐spinning
Authors: Paul D. R. 
Published: April 2003

AbstractThe coagulation of viscous polymer solutions by diffusional interchange with a liquid bath is the key step to fiber formation by wet‐spinning. Model experiments were performed on gelled solutions of an acrylic polymer in dimethylacetamide, to determine the mass‐transfer rates of solvent and nonsolvent (water) during coagulation, the rate of movement of a boundary associated with coagulation, and the final equilibrium between the coagulated phase and the bath. Each is given as a function of bath composition and temperature. The data are analyzed by means of various diffusion models, one of them giving quite good agreement. The data and the models are used in conjunction with each other for the elucidation of the mechanism of the processes involved in coagulation.
Cure of polyester resins. I
Authors: Learmonth G. S. , Tomlinson F. M. , Czerski J. 
Published: April 2003

AbstractThe application of physical test methods to studying the crosslinking of unsaturated polyesters is reviewed. Experimental work on changes of hardness and electrical resistivity is described and it is shown that these are not mutually related, due to continual mobility of ionic conditions after the resin network is immobilized by gelation.
Studies on the stretching of polypropylene film. II. Polyaxial stretching
Authors: Okajima Saburo , Homma Keisuke 
Published: April 2003

AbstractPolypropylene film was stretched polyaxially at 100–160°C., and the orientation behavior was studied by means of optical and x‐ray method. The molecular chains oriented progressively to the film surface with an increase in stretching area vA in the range 1–16, and the (040) selective uniplanar orientation developed at the extreme stretching. The plot of orientation versus vA was less steep when the stretching was carried out at higher temperature, but the final degree of orientation was independent of the temperature, because the final vA increased with temperature. At 160°C. premelting occured to such a degree that the high stretching and, consequently, the high orientation could not be obtained. The orientation of the amorphous chains was always behind that of the crystalline region. In the initial stage the polyaxial stretching was not as effective in attaining high biaxial orientation as the two‐step biaxial stretching, but the final orientation was the same in both types of stretching because vA reached a value of 16 in the polyaxial stretching while it was only 2 in biaxial stretching.
Cohesive energy density of polytetrahydrofuran
Authors: Huglin M. B. , Pass D. J. 
Published: April 2003

AbstractMeasurements have been conducted on radiation‐crosslinked polytetrahydrofuran (PTHF) of stress‐strain and of swelling coefficients in simple esters. For the linear polymer, measurements have been made of density and intrinsic viscosities in the esters. [η] was also determined under the θ conditions of 33.5°C. in diethyl malonate. The results have been incorporated into several (sometimes interdependent) approaches towards the evaluation of the solubility parameter δp of PTHF. The mean of the nine values obtained is 8.55 (cal./cc.)1/2, whence the cohesive energy density is 5.17 kcal./mole. Seventeen experimental values of the Flory interaction parameter χ are also reported.
Elution column fractionation of branched polyethylene
Authors: Traskos R. T. , Schneider N. S. , Hoffman A. S. 
Published: April 2003

AbstractIn a systematic study of the elution column fractionation of a well characterized branched polyethylene sample it was found that one of the most important factors contributing to the efficiency was the composition selected for the p‐xylene‐butyl cellosolve eluting mixture. With a mixture representing the critical solvent composition at 126°C., as determined by cloud point measurements, and deposition to an amorphous phase on a fine sand support, viscosity–distribution curves were obtained which were highly reproducible and completely free of any reversal. No further improvement was gained by using an elution temperature other than 126°C. or by the substitution of tetralin or mesitylene for p‐xylene. Precipitation down a temperature gradient to produce a physical separation of species provided enhanced fractionation but is of doubtful practical interest. Fractionation was readily scaled up from 2g. to 4 or 6g., merely by increasing the mixing vessel size from 500 cc. to 1000 cc. There was no loss of efficiency, and fractions with M̄w = 8 × 106, more than twentyfold higher than the sample value, were obtained despite eluted polymer concentrations exceeding 0.2%. There is evidence that many of the expected differences in the fractionation behavior of linear and branched polyethylene are erased when a solvent mixture is used which has been adjusted to the appropriate critical composition.
Effects of molecular weight and strain rate on the flexural properties of polycarbonate
Authors: Golden J. H. , Hammant B. L. , Hazell E. A. 
Published: April 2003

AbstractThe effects of changes in molecular weight (7000 to 22,000) and strain rate (0.0001 to 4 min.−1) on the flexural properties of polycarbonate have been examined in detail with the use of speciments of different molecular weight prepared by high‐energy electron irradiation. The results have been plotted as surfaces which show the dependence of both stress and strain on molecular weight and strain rate, and these surfaces have been described in terms of brittle, transitional, and ductile regions. The relationships between stress or strain and molecular weight in the brittle region have been shown to be hyperbolic. A single failure locus has been found to include all the corresponding stress and strain data obtained at the various molecular weights and strain rates. In the low strength region this locus exhibits a proportionality between stress and strain, while at high strength values, strain becomes a logarithmic function of stress. Stress–molecular weight data obtained at the various rates have been superimposed to form a single composite curve, and the corresponding crossplots of stress–log rate have been treated similarly. It is concluded from these superpositions that an equivalence exists between changes in both molecular weight and strain rate such that a tenfold change in strain rate corresponds approximately to a change of 1000 in molecular weight. Strain‐strain rate data obtained at the various molecular weights have also been superimposed in a similar manner. Modulus is shown to increase slowly with decrease in molecular weight and appears to be relatively insensitive to changes in strain rate.
Examination of the temperature coefficient of polystyrene. Effect of solvent, temperature, and molecular weight
Authors: Cerny L. C. , James H. , Stasiw D. , Willcox H. 
Published: April 2003

AbstractThe temperature coefficient of polystyrene was examined in three θ solvents by several different methods. Four homogeneous samples were employed, having molecular weights of 51,000, 97,200, 160,000, and 392,000. It was found that the linear expansion factor α and the temperature coefficient were dependent upon the solvent, temperature range and molecular weight of the polymer.
Dynamic mechanical behavior of a polyimide
Authors: Bernier G. A. , Kline D. E. 
Published: April 2003

AbstractThe dynamic mechanical properties of a polyimide (poly‐4,4′‐oxydiphenylene pyromellitimide) were studied from about 4 to 800°K. at audio frequencies. A prominent relaxation associated with absorbed water content occurs near 230°K. Below 270°K., the modulus undergoes a corresponding increase in value with increasing water content. Above 550°K. the onset of a major relaxation process is observed in the modulus data, and a maximum in the internal friction is observed at about 675°K. Minor relaxation peaks are also noted throughout the temperature range. Relatively minor differences are noted in the mechanical relaxation spectra for the polyimide when treated (after drying) with dimethylformamide, dimethylacetamide, and dimethylsulfoxide, whereas the treatment with water after drying has a marked effect on the relaxation behavior. A reactor radiation dose of 3000 Mrad also causes only minor alterations in the dynamic mechanical spectra.
Cure of polyester resins. II
Authors: Learmonth G. S. , Pritchard G. , Reinhardt J. 
Published: April 2003

AbstractThe copolymerization reaction between unsaturated polyesters and styrene has been studied by a torsional pendulum. The accuracy of the dynamic‐mechanical measurements obtained is discussed briefly, and the results are compared with those of previous work on the change of hardness during cure.
Relation between nylon fiber mechanical properties and dye diffusion behavior
Authors: Bell James P. 
Published: April 2003

AbstractThe mobility of polymer chain segments is shown to play a major role in the diffusion of dyes in nylon 66. The rate of dye diffusion has been related to the time‐dependent mechanical properties, such as creep and stress relaxation, which are controlled by the mobility of the chain segments. The theoretical relations derived by Fujita et al. relating the diffusion of small molecules in amorphous polymers to other properties are shown to be applicable for the dyeing of semicrystalline nylon. Data showing the effects of surface area, temperature, and the amount of dye absorbed at saturation on the dyeing rate are presented and discussed.
The mechanism of oxidative degradation of ABS resin. Part I. The mechanism of thermooxidative degradation
Authors: Shimada Junichi , Kabuki Kimiaki 
Published: April 2003

AbstractIn this work the early stages of the thermal oxidation of ABS resin films for commercial utilization and purified samples were studied by means of infrared spectroscopy. The film samples were submitted to thermal oxidation in a Gear oven at 70–90°C. During the aging in the Gear oven the nitrile and phenyl absorbance did not change, but oxidative products containing hydroxyl or carbonyl groups were produced rapidly, and the butadiene content decreased gradually. Two parts of the oxidative reaction were easily distinguished by analysis of the degradation procedure in the differential method and in the half‐time method. An activation energy of 10 kcal./mole or less was obtained for the initiation process, involving mainly the formation of hydroperoxides induced by radical formation, which was apparent in the commercial samples, whereas a value of 10–20 kcal./mole was obtained for the subsequent process, initiated by the decomposition of the hydroperoxides, which induces chain‐carrier reactions. A reaction scheme is proposed, and kinetic expressions are developed therefrom. These expressions explain the experimental results very well.