bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photopolymerization of hydroxypropyl acrylate and tetraethylene glycol dimethacrylate initiated by uranyl ion
Authors: Higgins Cecil E. , Baldwin Willis H. 
Published: April 2003

AbstractUranyl nitrate, acetate, sulfate, and dibutyl phosphate were used in solution for the photoinitiation of homopolymerization and copolymerization of hydroxypropyl acrylate and tetraethylene glycol dimethacrylate. Solvents used included water, water‐ethylene glycol mixtures, and dimethylformamide. Polymer yields in excess of 90% can readily be obtained by exposing solutions containing 0.014M UO22+ to light from a tungsten bulb for 1 hr. The rigidity of the polymers varied directly, the affinity for water in‐versely, with the concentration of tetraethylene glycol dimethacrylate in the monomer mixture. Poly(hydroxypropy1 acrylate) contained 52% water and poly(tetraethy1ene glycol dimethacrylate) 34% water, a t equilibrium.
Cleavage behavior of bonds made with adherends capable of plastic yield
Authors: Duke A. J. , Stanbridge R. P. 
Published: April 2003

AbstractThe failure behavior of adhesive joints under cleavage stresses depends upon the thickness of the adherend. With thick, rigid adherends failure occurs by rapidly propagated adhesive rupture. Thinner adherends can exhibit plastic flexural yield, the subsequent adhesive failure then being progressive and strain‐limited, and occurring only in the region of bond directly adjacent to the yielding adherend. A fairly sharp discontinuity between these two types of behavior occurs over a small range of adherend thicknessT. Work to rupture can differ by more than an order of magnitude, for otherwise identical joints havingTabove or below the transitional range (aroundTc). ForT>Tcthe applied loadPcausing rupture is proportional toT1.5while the moment arm remains constant, as predicted by Yurenka. ForT < Tcthe turning moment during failure is proportional toT2and is substantially independent of the nature of the adhesive. Empirically, the radius of the yielded adherend after failure is proportional toT. The manner of interaction of various adhesive mechanical properties in definingPin the two ranges and, thereby,Tc, are related to this and other empirical correlations. The initial free moment arm in the joint,L, determines the stability of peel at initiation of adhesive rupture. ReducingLleads ultimately to instability. The change of controlling factors asL→ 0 is discussed.
Epoxy polymers. IV. Impact‐induced voltage generation
Authors: Cuthrell R. E. 
Published: April 2003

AbstractMechanical‐stress‐induced voltage or current in epoxy polymers appears to be a function of the state of order of dipoles in the surface layer. The sign and magnitude of the voltage is correlated with the surface layer characteristics. The time required for the impact voltage to decay to its original value appears to correlate with dipole orientation relaxation times obtained by dielectric constant and loss measurements.
Characterization of branched polyethylene fractions from the elution column
Authors: Schneider N. S. , Traskos R. T. , Hoffman A. S. 
Published: April 2003

AbstractFractions from several elution column runs on samples of up to 6 g. of a well‐characterized high‐pressure polyethylene were analyzed by absolute molecular weight methods and several other techniques. The Mn and Mw integral distribution curves are free from any reversal, as was the viscosity distribution curve. Fractions with Mw as high as 8 × 106 were recovered, more than 20 times higher than the original sample's Mw. The polydispersity of the fractions increases from Mw/Mn = 1.5 or less in the low molecular weight fractions to a nearly constant value of 4.5–5.0 in fractions above 60% cumulative sample weight. Nonetheless, refractionation on the elution column shows that the fractions are narrowly distributed in terms of solubility, while GPC analysis reveals that the fractions have an extremely narrow size distribution. It is concluded from the combined results that long‐chain branching plays an important role in determining the equilibrium solubility and, further, that long‐chain branching increases the polymer solubility. Sample calculations are provided, which illustrate the effect of fraction polydispersity on calculated original sample molecular weights and the fit of the fractionation results to several model distribution functions.
The solubility parameter of polypropylene
Authors: Michaels Alan S. , Vieth Wolf R. , Alcalay Haim H. 
Published: April 2003

AbstractSolubility parameter values for polypropylene as reported in the literature cover a rather broad span, ranging from 7.9 to 9.4 (cal./cm.3)1/2. This communication suggests the approximate value 8.2. This value is based on the swelling and dissolution characteristics of polypropylene films in various organic liquids. A calculated value of 8.1, obtained by Small's method, compares well with the experimentally determined value.
Studies of the fractionation of polyoxymethylene
Authors: Kobyashi Eiichi , Okamura Seizo , Signer Rudolf 
Published: April 2003

AbstractThe precipitation of polyoxymethylene in p‐chlorophenol solution and the molecular weight fractionation of the polymer by mechanical agitation were investigated. The agitation of the solution was carried out in a glass vessel with a stirrer, usually at 60°C. After agitation for several minutes a fibrous polymer precipitated. High molecular weight polymer precipitated around the stirrer in an early stage, and therefore the method might be applied to the fractionation of polyoxymethylene. The method was applied to the fractionation of polyoxymethylene prepared in a solid‐state and in a solution polymerization of trioxane, catalyzed by BF3.OEt2. It was found that the polymer from the solid state contained a small amount of extremely high molecular weight fraction, and that obtained from the solution had a relatively narrow distribution of molecular weight.
The polymerization and copolymerization of nitroalkyl acrylates and nitroalkyl methacrylates
Authors: Takahashi Kunihiro , Abe Satsuki , Namba Keiho 
Published: April 2003

AbstractNitroalkyl acrylates and methacrylates involving some new compounds were prepared. The homopolymerization of these monomers in toluene and their copolymerization with styrene in acetone were carried out with azobisisobutyronitrile as initiator. The rate of polymerization of the nitroalkyl acrylates showed a correlation with the number of nitro groups situated on the ester side chain. The apparent activation energies of the polymerization were found to be 22.0–27.5 kcal./mole for the nitroalkyl acrylates and about 11.5–13.0 kcal./mole for the nitroalkyl methacrylates. From the reactivity ratios and Q‐e values of the copolymerization the following information was obtained. The copolymerization behavior of nitroalkyl acrylates and methacrylates showed an alternating tendency, and these monomers belong to the conjugative monomer groups. On the reactivities of these monomers, the polarity of vinyl group was affected a little by nitro group of ester bond side, and the resonance affected little. These monomers were crosslinked with 2‐methyl‐2‐nitro‐1,3‐propylene diacrylate. Some of the polymers showed marked improvement in the physical properties of elastomers.
Chlorination of polyesters
Authors: Jackson W. J. , Caldwell J. R. , Perry K. P. 
Published: April 2003

AbstractBy photochemical chlorination chlorine was substituted on the gem‐dimethyl groups of the polyterephthalate and polycarbonate of 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol, the polyterephthalate of 2,2‐dimethyl‐1,3‐propanediol, and the polycarbonate of 4,4′‐isopropylidenediphenol (bisphenol A). The factors affecting polyester degradation, the efficiency of chlorination, and the degree of chlorination were investigated, and the effects of chlorine content on the solubility, flammability, density, hydrolytic stability, thermal stability, tensile properties, electrical properties, and heat‐distortion temperatures of cast films were determined. The chlorinated polyesters of particular interest, because of their properties, are the polycarbonates of 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol and bisphenol A.
Thermal stability of modified poly(vinyl chloride) by TGA
Authors: Matlack J. D. , Metzger A. P. 
Published: April 2003

AbstractThe stability of poly(vinyl chloride), as measured by thermogravimetric analysis, is significantly different from that of other thermoplastics. It is shown that the onset of weight loss can be correlated with the development of color in a processed resin. It is further shown that the ingredients within a rigid polyvinyl chloride compound drastically alter its thermal behavior. The effect of lubricant and stabilizer on the degradation of poly(vinyl chloride) is stressed.
Poly(norbornene): Tensile and dynamic‐mechanical properties
Authors: Galperin I. , Carter J. H. , Hein P. R. 
Published: April 2003

AbstractThe tensile and dynamic mechanical properties of poly(norbornene), prepared through ring‐opening polymerization, were studied. Tensile strength and extensibility increased, while Young's modulus decreased with increasing molecular weight and with increasing content of trans relative to cis unsaturation. The damping factor Delta; was dependent on molecular weight only for the lower molecular weight samples. The out‐of‐phase modulus E″ and the damping factor decreased as the trans/cis ratio increased.
Some effects of ionizing radiation on a polyhydroxyether
Authors: Golden J. H. , Hammant B. L. , Hazell E. A. 
Published: April 2003

AbstractThe behavior of the polyhydroxyether derived from bisphenol A and epichlorohydrin on exposure to electron irradiation (0–500 Mrads) in vacuum has been investigated. The polymer underwent chain scission, G = 0.20 (scission per 100 e. v.), with no evidence of crosslinking. Degradation was accompanied by the loss of H2 together with smaller quantities of CO, CO2, and CH4. Spectroscopic studies are reported, and a mechanism of degradation is proposed. The tensile yield stress and fracture energy of molded specimens were also examined, and changes in these properties as functions of radiation dose and molecular weight are discussed.
Properties of solutions of poly‐N‐vinylcaprolactam
Authors: Solomon O. F. , Corciovei M. , Ciută I. , Boghină C. 
Published: April 2003

AbstractThe properties of poly‐N‐vinylcaprolactam organic and aqueous solutions were studied. Toluene solutions present an increasing [η] from 10 to 40°C. Aqueous solutions present a very accentuated diminishing of [η] from 10 to 30°C. Above 30°C. The polymer precipitates from its aqueous solutions. The precipitation temperature does not depend on the concentration but on the molecular weight of the polymer. Some acid and basic agents have a marked influence on [η] and the precipitation temperature of the aqueous solutions.
Chain reaction mechanism of cellulose pyrolysis
Authors: Chatterjee Pronoy K. 
Published: April 2003

AbstractChatterjee and Conrad1 studied the kinetics of pyrolysis of cotton cellulose in the temperature range 270–310°C and proposed a chain reaction mechanism. Lipska and Parker8 studied the pyrolysis of the α‐cellulose in the temperature range 250–300°C and interpreted the kinetic data differently. Both articles were published almost simultaneously. In this paper Lipska and Parker's complete data have been again analyzed and reinterpreted in light of the chain reaction mechanism. The energies of activation for initiation and propagation steps of the cellulose decomposition reaction are discussed.
Determination of degree of nitration of nitrocellulose by refractometry
Authors: Kohlbeck J. A. , Bolleter W. T. 
Published: April 2003

AbstractNitrocellulose (NC) films, when dried on a rigid substrate, tend to be biaxial and thus exhibit two refractive indices. The absolute difference between these indices has been found to provide an accurate measure of the degree of nitration of NC. A film of NC is cast from a 1% solution in butyl acetate to provide a film about 0.5 mil thick. The dry film, when placed in an Abbé‐3L refractometer, gives two white lines which go to extinction alternately upon rotation of a cap analyzer through the east–west (EW) and north–south (NS) directions. Refractive index measurements are made using the line visible in each direction of the analyzer. The absolute difference between the two indices is related to the degree of nitration through standard curves for various grades of NC. The standard deviation for the proposed method was found to be ±0.01% N.
Some properties of low molecular weight polybutadiene and polytetrahydrofuran
Authors: Huglin M. B. , Whitehurst D. H. 
Published: April 2003

AbstractThe proposition, that low molecular weight polymer fractions in good solvents behave as if they were under ⊖ conditions, has been examined experimentally. Series of monodisperse hydroxy‐terminated polytetrahydrofuran (PTHF), 82% 1,4‐polybutadiene (PBD), and 30% 1,4‐PBD were prepared, and values of M̄n obtained by vapor‐pressure osmometry and endgroup analysis. The Mark–Houwink viscosity parameters K and ν were determined in a number of solvents. The general conclusion is that the proposition is invalid for these systems notwithstanding the fact that ν = 0.50 for one of them [82% 1,4‐PBD in methyl ethyl ketone (MEK) at 25°C]. For this particular case, the following evidence suggests that these are actually ⊖ conditions so that the apparent fulfilment of the proposition is fortuitous. (1) Cloud‐point precipitation yields ⊖ = 26 ± 3°C in MEK. (2) The value of K is close to that of K⊖ found elsewhere for PBD in a different solvent at a similar temperature. (3) Application of the Kurata‐Stockmayer iterative procedure for estimating K⊖ from data in good and bad solvents yields a reasonably small discrepancy (10%) between the K⊖ values from data in toluene and MEK at 25°C for this polymer and only a 3% difference in the unperturbed dimensions (〈r02〉/M)1/2 derived from them. Measured melting points Tm of PTHF (M̄n = 1000–13000), plotted as a function of chain length Z, viz., 1/Tm = 1/Tm0 + 2R/ZΔHf, yield 43 ± 3°C and 1.6 kcal/submole, respectively, for the limiting melting point Tm0 and the heat of fusion ΔHf. The former is in good agreement with the value obtained dilatometrically for high molecular weight polymer, while the latter indicates a degree of crystallinity of ca. 54%.
Molding of polyacrylonitrile
Authors: Griffith R. K. 
Published: April 2003

AbstractA method has been devised whereby clear, chemically resistant, compression‐molded articles of polyacrylonitrile are prepared within minutes. The molding powder consists of preformed polyacrylonitrile, acrylonitrile, and initiator. The effects of process variables on the physical properties are discussed.
Polymer–solvent interaction parameters and efficiency of crosslinking of ethylene–propylene copolymers
Authors: Flisi U. , Crespi G. 
Published: April 2003

AbstractA study has been carried out of the vulcanization of ethylene–propylene copolymers having different propylene contents, by use of an organic peroxide. The polymersolvent interaction parameter μ, calculated by the Flory‐Rehner equation from values of νe and vr, was found to be a linear function of vr with benzene as the swelling agent. Values of μ and their dependence upon vr were independent of copolymer composition, at least within the limits of experimental error, for samples having a propylene content of 30–60 mole‐%. The crosslinking efficiency of the peroxide used was found to depend considerably on copolymer composition, in agreement with the results found for dicumyl peroxide. Finally, sulfur as a crosslinking coagent was found to exert a large effect on the value of νe, calculated from the equilibrium retractive force of benzene‐swollen specimens.
Torsional braid as a kinetic tool for the study of the polymerization of viscous materials. II. Catalytic effects in the polymerization of carboxylic acid‐terminated polybutadiene prepolymers with tris[1‐(2‐methyl)aziridinyl]phosphine oxide
Authors: Adicoff Arnold , Yukelson Arnold A. 
Published: April 2003

AbstractThe torsional braid technique for studying the polymerization of viscous substances has been extended to a study of the homogenous catalytic behavior of a number of acidic and basic catalysts int he polymerization of carboxy‐terminated polybutadiene with tris(methyl aziridinyl)phosphine oxide. No general catalytic behavior was observed. Specific catalysis was observed in the case of lithium oleate, where the gel time was decreased, and in the case of bis(tri‐n‐butyltin) oxide, where the gel time was increased. The average energy of activation for all of these polymerizations was 13.9 ± 0.5 kcal./mole. This energy of activation and the reaction environment, when compared with the data in the literature, strongly suggest that the explanation that a change in the rate‐determining step occurs as a function of the polarity of the reaction medium fails to account for all of the results.
Steric effects in the basic hydrolysis of poly(ethylene terephthalate)
Authors: Namboori C. G. G. , Haith Malcolm S. 
Published: April 2003

AbstractA comparative study of the reactivity of hydroxide and various alkoxide anions was made by determining percentage weight loss of poly(ethylene terephthalate) fiber. Regardless of the basicity of the anions, the order of reactivity was found to be hydroxide < tert‐butoxide < sec‐propoxide < methoxide < ethoxide. This observed order follows the nucleophilicity of the bases, and the relatively lower reactivity of sec‐propoxide and tert‐butoxide is assumed to be due to steric retardation during the equilibrium reactions.
Study of radiation‐induced graft polymerization of vinyl monomers to cellulose by infrared spectroscopy. II. Cellulose–polystyrene copolymers
Authors: Imrišováa D. , Maryška S. 
Published: April 2003

AbstractInfrared spectral analysis has been applied for the study of cotton‐polystyrene copolymers prepared by using the preirradiation method. The degree of grafting was determined from the absorption at 700 cm−1, which is characteristic of the polystyrene spectrum, with an accuracy of ± 1.5%.
Viscoelastic changes of epoxy resin–acid anhydride system during curing
Authors: Shimazaki Akio 
Published: April 2003

AbstractThe changed viscoelastic properties of the epoxy resin‐acid anhydride system, Epikote 834‐HHPA, are followed to the gel point at 130, 140, and 150°C with a dynamic viscoelastometer. The viscosity increases with curing time through two inflections designated A and B. The point A is interpreted (from the reference to the chemical changes reported in the previous paper) as the termination of the initial stage of this curring reaction, and point B coincides with the gel point determined by the torsion method. The resonance frequency remains constant value up to the point B, followed by a rapid increase. The extents of reaction for epoxide, anhydride, and initial OH are 15, 45.8, and 100% at the point A; 27.8, 63.7, and 100% at the point B, respectively. The apparent activation energies for viscosity are 7.5 kcal/mole for the resin mixture before curing, 10.5 kcal/mole for point A, 48.8 kcal/mole for point B (gel point). The overall apparent activation energies of this curing reaction are obtained from the Arrhenius plots for the curing time required for the resin mixture to reach the state of the points A and B; these values were 8.9 kcal/mole for point A and 16.2 kcal/mole for point B.
Gel–water relationships in hydrophilic polymers: Thermodynamics of sorption of water vapor
Authors: Masuzawa Mitsunobu , Sterling Clarence 
Published: April 2003

AbstractA thermodynamic study was conducted of water vapor adsorption on four hydrophilic polymers (agar, carboxymethyl cellulose, gelatin, and maize starch) at 12 and 25°C. Monolayer coverage amounted, after correction for crystallinity, respectively, to 0.93, 1.46, 0.51, and 0.77 mol water/mol monomer. Evidence is adduced from the Bradley equation and thermodynamic data to indicate that at least during coverage with the second layer of water, the energy of adsorption is greater than that due to condensation alone. Differences in the amount of sorption and in the trend of values of ΔS̄° and ΔH̄° with the amount of sorbed water are related with differences in the strength of intermolecular association as affected by steric hindrances.
Chlorination of polystyrene
Authors: Jenkins Robert K. , Byrd Norman R. , Lister James L. 
Published: April 2003

AbstractChlorination of a low molecular weight polystyrene in the α position was studied by following changes in the infrared spectrum, glass transition temperature, and molecular weights of the polymer. The logarithm of the absorbance ratio at 2920 and 1500 cm−1 as a function of mole per cent chlorination was linear. The glass transition temperatures, determined by use of a differential scanning calorimeter (DSC), were found to obey an equation developed by Dyvik for copolymers. The molecular weight of the chlorinated polystyrene decreased as a function of chlorination.
Characterization of nylon 66 structure from x‐ray diffraction
Authors: Dumbleton J. H. , Buchanan D. R. , Bowles B. B. 
Published: April 2003

AbstractA description of methods available for the determination of structural parameters in nylon 66 is given for both wide‐ and small‐angle x‐ray diffraction. The methods are applied to a series of drawn nylon 66 fibers, and the results indicate that the drawing process is one of crystal slip. It is concluded that the methods of characterization give a great deal of information about the structure along the fiber axis but that methods for examining the structure perpendicular to the fiber axis give less quantitative information and new methods are desirable.
Physical properties of some vinyl tetrahydroabietate and vinyl maleopimarate acid anhydride copolymers
Authors: Magne F. C. 
Published: April 2003

AbstractThe stress–strain and torsional characteristics of some experimental copolymers of vinyl tetrahydroabietate and vinyl maleopimarate acid anhydride with vinyl chloride and vinyl acetate have been determined. Similar studies were also undertaken on peroxide‐cured compositions of a vinyl chloride‐vinyl tetrahydroabietate copolymer. Elastie moduli for the uncured copolymers range from 80,200 to 338,000 psi. Cured compositions of vinyl chloride–vinyl tetrahydroabietate copolymer exhibited both lower and higher moduli than that of the uncured copolymer. Some of the cured compositions appear to have an improved impact resistance over that of the uncured polymers.
Crosslinking poly(ethylene oxide) in dilute solutions by gamma rays
Authors: Van Brederode R. A. , Rodriguez F. , Cocks G. G. 
Published: April 2003

AbstractA high molecular weight poly(ethylene oxide) is gelled by radiation from a 60Co source. At concentrations of 0.25 to 1 wt‐%, doses of 4.5 to 7.5 × 104 rad cause gelation. The storage modulus of the gel formed increases linearly with additional dose to a plateau value and then remains constant during further irradiation. The does needed to reach the plateau, Dp in rads, and the plateau modulus Gp in dynes per square centimeter, are related to the concentration c, in weight per cent: Dp = 1.05 × 106c and Gp = 1.75 × 104c2.5. The energy absorbed by the polymer per crosslink formed is about 80 ± 10 kcal/mol. The crosslink density produced by radiation is calculated from the measured modulus by using the theory of rubber elasticity. Both modulus and loss are measured in a special air‐bearing, recording torsion pendulum with a coneplate geometry.