bluuebunny/crossref_metadata_2025_split huggingface dataset:
The modulus and yield stress of glassy poly(methyl methacrylate) at strain rates up to 103 inch/inch/second
Authors: Holt David L. 
Published: April 2003

AbstractSpecimens of poly(methyl methacrylate) (PMMA) were compressed at nominally constant strain rates ranging from 10−5 to 103 in./in./sec. at 0, 22, 50, and 115°C. A plot of stress at a small fixed strain (2%) and constant temperature versus logarithm of strain rate is sigmoidal in shape and, furthermore, time‐temperature superposition could be used to construct a master curve of stress versus temperature‐compensated strain rate. It is suggested that the sigmoidal curve is a manifestation of the β transition in PMMA, and this is supported by the measured value of activation energy and the strain rate value at the point of inflection on the curve. By contrast, yield stress varies linearly with log \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm \varepsilon }\limits^{\rm.} $\end{document}. Time‐temperature superposition could not be applied. Rationalizing on the basis of the high stress form of the Eyring equation, yielding is by a yet unspecified molecular mechanism in which activation volume has the order of magnitude of a monomer unit but increases with increasing temperature.
An investigation of the polymerization of furfuryl alcohol with gel permeation chromatography
Authors: Wewerka E. M. 
Published: April 2003

AbstractSeveral series of furfuryl alcohol resins, made by the polymerization of furfuryl alcoho with a variety of catalysts and having viscosities as high as 7 × 106 cpoise, were characterized by gel permeation chromatography (GPC). A series‐by‐series comparison of the GPC curves of the resins was made, to determine the effects of catalyst type and concentration on resin molecular structure as elucidated by GPC. Furfuryl alcohol resins were produced not only by thermal polymerization but also by catalysis with Imaleic anhydride, 86% phosphoric acid, γ alumina, and anhydrous magnesium sulfate. The gel permeation chromatograms of the resins made by catalysis with maleic anhydride were found to be nearly identical with those catalyzed with 86% phosphoric acid. Moreover, catalyst concentration did not affect the GPC curves of the resins catalyzed by maleic anhydride. These observations are consistant with an initial reaction mechanism, of which the rate‐controlling step is a function of pH. The chromatograms of the resins made by catalysis with γ alumina showed a shift of the peak maximums of the lower molecular weight species to lower elution volumes, indicating that esterification of the free hydroxyl groups with levulinic acid and other related acids may have taken place. The resins polymerized by thermal catalysis and by catalysis with anhydrous magnesium sulfate exhibited GPC curves that fell between those of the resins catalyzed by acids and those of the resins made by catalysis with γ alumina.
The determination of reactive‐group functionality from gel point measurements
Authors: Strecker Ruediger A. H. , French David M. 
Published: April 2003

AbstractThe usual method of calculating functionality is to divide the molecular weight by the equivalent weight. Because of the uncertainty of molecular weight determinations in the range 1000–20,000 a more precise method is needed. Several authors have published work concerning the determination of the extent of reaction at the gel point through the functionalities of the reactants. It occurred to us that this method could be reversed. We chose Stockmayer's treatment, with some changes, to calculate the average functionality of carboxyl‐terminated polybutadiene (CTPB): (PAPB)gel = (fE − 1)−1 (gE − 1)− where fE and gE are the weighted average functionalities of all molecules bearing the reactive groups A and B, and PA and PB are the fractions of initially present groups that have reacted. Two systems with an epoxide and glycerol as curing agents were investigated. The influence of dilution was investigated. Nonfunctional polybutadiene did not interfere with the accuracy of the determination of carboxyl functionality. By changing the ratio of epoxide to COOH groups from 0.6 to 1.4 it was shown that the calculated functionality remained constant. Weight‐average molecular weights for three CTPB samples were calculated from the functionality and the equivalent weight. They were compared with those obtained from intrinsic‐viscosity measurements. The precision of the functionality numbers is believed to be ±1%.
Polymerization of aromatic nuclei. XIII. X‐ray analysis and properties of poly(p‐phenylene) pellets
Authors: Kovacic Peter , Feldman Michael B. , Kovacic Jan P. , Lando Jerome B. 
Published: April 2003

AbstractX‐ray diffraction experiments with poly(p‐phenylene) pellets demonstrated an increase in crystallinity with increase in molding temperature or annealing temperature. The increase in crystallinity may be attributed to annealing effects and loss of chlorine under severe conditions. Lattice constants for the crystalline polymer are presented, and the crystallographic data are compared with those of the lower oligomers. Poly(p‐phenylene) was investigated also in relation to oxidative thermal stability, chemical and solvent resistance, and the effect of temperature and variation in molding conditions on fracture strength. The decrease in strength at elevated temperatures appears to be related to the increase in crystallinity.
Elastic behavior of concentrated solutions of acrylonitrile copolymers. II. The shear‐stress dependence of the shear modulus of a pseudo network in concentrated solutions
Authors: Hayahaila Takuro , Takao Seiji 
Published: April 2003

AbstractThe shear‐stress dependence of the shear modulus in concentrated solutions of acrylonitrile copolymer was investigated by the capillary end‐correction method. The shear modulus decreases with an increase of shear stress above a critical polymer concentration at ti higher shear rate than that at which the decrease of the viscosity begins to occur. The non‐Hookian behavior of the concentrated solutions may be considered to arise from the breakdown of the tangled network structure, namely elastically deformable pseudo network.
The effect of surfactant and copolymer polarity on the film‐formation temperatures of some vinylidene chloride copolymers
Authors: Powell E. , Clay M. J. , Sauntson B. J. 
Published: April 2003

AbstractThe minimum temperature required for a copolymer emulsion to form a continuous film Tmf, and the glass transition temperature Tg of the copolymer were studied for vinylidene chloride‐acrylate copolymers and vinylidene chloride‐acrylonitrile copolymers. The Tmf and Tg were studied as a function of the nature of the surfactant used in the preparation of the emulsion. The Tmf was found to deviate markedly from the Tg for most compositions and the Tmf‐composition curves were found to be similar in shape to the Tg‐composition curves, exhibiting a maximum in the case of the acrylate copolymers. The quantity Tmf—Tg changes from negative to positive with decreasing polar character of the methyl and ethyl acrylate copolymers. This is especially obvious in the ethyl acrylate copolymer. The high Tmf values for copolymers containing acrylonitrile is attributed to strong interchain forces, which orientate the neighboring segments in a latex particle unfavorably for interpenetration with other particles. The nature of the surfactant used in the preparation of the emulsion was found to affect the Tmf. Emulsions of nonpolar, hydrophobic copolymers containing a blend of anionic and nonionic surfactants have a higher Tmf than those containing only anionic surfactant; however, with an increase in the amount of hydrophilic units in the copolymer the converse is true, except in the case of the highly polar copolymers of vinylidene chloride‐methyl acrylate, in which the Tmf's for both surfactant systems are similar.
Turbidimetric determinations of theta compositions
Authors: Suh K. W. , Clarke D. H. 
Published: April 2003

AbstractThe turbidimetric titration method of determining theta conditions developed by Elias and modified by Cornet and van Ballegooijen has been extended and generalized for different types of polymer–solvent–nonsolvent systems. The modified procedures for the determination of theta compositions have been verified with the following systems: polystyrene–cyclohexane–n‐hexane, polystyrene–cyclohexane–n‐butanol, and polystyrene–toluene–nonsolvent.
Radiation chemical studies of protein reactions: Effect of protectors against radiation
Authors: Nisizawa Mizuho 
Published: April 2003

AbstractSodium glutamate and sodium benzoate were found to protect protein reactions from radiation damage. The behavior of the viscosity changes was determined. The experimental equation for the protective effect is given by ηred(∞) = a(log X)2 + b(log X) + c, where ηred(∞) is the reduced viscosity of the solution at infinite time X is the concentration of the radiation protectors, and a, b, and c are adjustable constants.
Pyrolysis of phenolic resins. IV.
Authors: Learmonth G. S. , Osborn P. 
Published: April 2003

AbstractThermoset resins were made from benzene, naphthalene, phenanthrene, anthracene, or pyrene by condensation with p‐xylylene dichloride in presence of stannic chloride. The extent of reaction, consequently the crosslink density, was controlled by measurement of the HCl evolved. The absence of oxidation was confirmed by infrared spectroscopy. On pyrolysis at 500, 1000, and 1200°C. in vacuo (after Madorsky) it was found that the yield of char was directly related to the number fraction of carbon atoms in the aromatic nucleus used. Benzene was anomalous, and all resins gave lower char yields than standard phenol formaldehyde resins.
Mechanism of photostabilization of polypropylene by nickel oxime chelates
Authors: Briggs P. J. , McKellar J. F. 
Published: April 2003

AbstractRecent work has shown that certain nickel oxime chelates act as effective light stabilizers for polypropylene. The mechanism of their protective action was examined by spectrophosphorimetry and flash photolysis. Examination of the phosphorescence from the commercial polymer shows that it is due to aldehydic carbonyl groups. From flash photolysis observations of the triplet quenching action of a range of nickel chelates it is suggested that stabilization by the oxime chelates is achieved by a mechanism of efficient energy transfer from the photoreactive carbonyl group to the chelate, where the energy is harmlessly dissipated. The efficiency of this quenching action is primarily dependent on the spatial configuration of the ligand around the central metal atom in the chelate.
Radical bulk polymerization of N‐vinylcaprolactam
Authors: Solomon O. F. , Corciovei M. , Boghin˘ C. 
Published: April 2003

AbstractBulk radical polymerization of N‐vinylcaprolactam was studied at temperatures between 60 and 120°C. with different initiators. Satisfactory results were obtained with azobisisobutyronitrile, tert‐butyl perbenzoate, and tert‐butyl peroxide as initiators. The polymerization reaction of N‐vinylcaprolactam with these initiators is first order with respect to the monomer and 0.5 order with respect to the initiator. A linearity of the kinetic curves up to high conversions was observed. The cause of this behavior is a feeble gel effect, which also induces an increase of the molecular weight during polymerization.
Environmental stability of ethylene–acrylic acid adhesive copolymers bonded to metal substrates
Authors: Wargotz B. 
Published: April 2003

AbstractA study was conducted on the influence of high humidity and temperature on aluminum and copper sheet coated with ethylene–acrylic acid or ethylene–methacrylic acid copolymers. Infrared spectrometric and differential thermal analysis data indicate that a contributing cause to failure of the bond between the acrylic acid copolymers and copper is the solubilization of an underlying weak oxide layer under conditions of the test. No significant weakening of the bond of aluminum–adhesive copolymer was observed under high humidity. From oxygen uptake studies, thermogravimetric analysis in air, and infrared spectra of polymer bonded to metals, a general understanding of the thermal‐oxidative stability of the ethylene–acrylic and ethylene–methacrylic copolymers has emerged. The acrylic acid copolymers are less stable in an oxidative environment than ethylene homopolymers and the ethylene–alkyl acrylate copolymers.
Effects of thermal history on isotactic polypropylene
Authors: Pae K. D. , Sauer J. A. 
Published: April 2003

AbstractThe effect of past thermal history on the melting behavior of isotactic polypropylene is investigated in some detail. It is shown that a series of stepwise annealing treatments at steadily increasing temperatures will raise the final melting point and will result in a double endothermic peak if the final anneal temperature is at or close to 160°C. It is also shown that a series of stepwise annealing treatments at steadily decreasing temperature will lead to multiple DSC peaks. The number of such separate peaks is equal to or greater than the number of annealing steps. Even low‐temperature anneals (100–130°C) affect the melting endotherm, while high‐temperature anneals have a marked effect on both the degree of crystallinity of the sample and the final melting temperature. For a 3‐min anneal, the highest degree of crystallinity is produced by an anneal temperature of 155°C. The highest melting temperature (∼182°C) is produced by a 30‐min, or longer, anneal at about 160°C. The implications of these results in terms of crystal thickening and perfection are discussed.
Effects of thermal history on polypropylene fractions
Authors: Sauer J. A. , Pae K. D. 
Published: April 2003

AbstractThe effects of thermal history on the melting behavior of several polypropylene fractions have been studied. The specific fractions investigated include one that has crystallized in the triclinic modification, one that has crystallized in the monoclinic modification, and a third that contained a combination of the two types of crystals. Thermal histories given to these specimens included a series of stepwise annealings at steadily decreasing temperatures, a series of annealings for various times at a given elevated temperature, and a series of stepwise annealings at a set of steadily increasing temperatures. The melting behavior was investigated by means of a differential scanning calorimeter and various DSC peaks are presented. The nature of multiple peaks produced by the different treatments is discussed, and the results are compared with similar data obtained on whole polymer.
Crosslinking efficiency of gelatin hardeners
Authors: Tabor B. E. 
Published: April 2003

AbstractBy using the criteria of melting point and sol fraction, a study has been made of the stoichiometric efficiencies of hardeners for gelatin, as distinct from their rates of reaction. The factors which affect these measurements were investigated. Both melting point and sol fraction distinguish gelatins in respect of molecular weight and origin. Sol fraction measurements give evidence of molecular weight distribution. Various hardeners have a wide range of molecular efficiencies, and these do not correlate with rates of reaction as judged from solution viscosity rise methods. Sol fraction measurements can separate hardeners which would have been considered similar from melting point behavior.
Molecular weight changes during polyolefin autoxidation
Authors: Reich Leo , Stivala S. S. 
Published: April 2003

AbstractExpressions were derived relating changes of intrinsic viscosity to reaction time, based on a scheme previously presented for the uncatalyzed, uninhibited thermal oxidation of polyolefins. A value of the kinetic parameter A may be obtained from these expressions by using an iterative type of procedure and employing data presented by other workers for the oxidation of atactic polybutene‐1. This value of A was compared with the corresponding value obtained by the authors from rate of carbonyl formation studies in oxidation of atactic polybutene‐1 by means of infrared absorption spectroscopy methods. The good agreement between the values of A obtained from the two different experimental techniques employed lends further support to the validity of the scheme used and the expressions derived therefrom.
Analysis of bisphenol A sulfonate–carboxylate polymer
Authors: Forrette John E. , Burroughs James E. , Booker Christine C. 
Published: April 2003

AbstractThe method of analysis for a polycondensation polymer containing the carboxylate and sulfonate functional groups has been devised. A combination of infrared spectroscopy and combustion analysis provides a simple and accurate determination of the monomeric units and their molar distribution in the polymer.
Studies on polymer blends. III. Butadiene–acrylonitrile copolymer and polybutadiene–polyacrylonitrile blend
Authors: Shundo Minoru , Komuro Keiji , Goto Kunio , Imoto Minoru , Minoura Yuji 
Published: April 2003

AbstractThe properties of butadiene–acrylonitrile copolymers were compared with those of polybutadiene–polyacrylonitrile blends. Also, the properties of copolymers having an acrylonitrile unit content of about 30% were compared with those of polymer blends having the same acrylonitrile unit content, i.e., NBR–NBR, polybutadiene–NBR, and polyacrylonitrile–NBR, having different acrylonitrile unit contents. These blends were prepared by roll blending and the vulcanizates were prepared by sulfur cure. The properties of the copolymers were markedly different from those of the blends, that is, in the blends the properties showed a linear relationship with their blending ratios, while in the copolymers the properties showed a curvilinear relationship. In the cases of the polymer blends having a constant acrylonitrile unit content, those blends which were prepared by blending two polymers having similar acrylonitrile unit contents showed better properties than the ones having very different acrylonitrile unit contents.
Permeation of ethane–butane mixtures through polyethylene
Authors: Robeson Lloyd M. , Smith Theodore G. 
Published: April 2003

AbstractPermeation of ethane–butane mixtures a t atmospheric pressure through polyethylene was investigated in the temperature interval of 30–60°C. The integral permeation constant P̄ and the integral diffusion coefficient D̄ of both ethane and butane were satisfactorily correlated by using an exponential and also a linear function of butane concentration. This was attributed to the plasticizing of the film by butane, whose solubility constant is approximately ten times that of ethane in the temperature interval investigated. The separation factor Gi, j defined as the ratio of the permeation constant of butane to the permeation constant of ethane over the range of mixture compositions and temperatures investigated, remained nearly constant at values in the range of 2.8–3.2. The insignificant change in Gi, j is due to the proximity of the activation energies of permeation of ethane and butane (10.95 and 10.75 kcal/mol, respectively) and the similar magnitude of change in the permeation constants with increasing butane concentration. Experiments were run in which the film was initially in equilibrium with the same partial pressure of butane as in the mixture to be studied. It can be shown that the diffusion coefficient of ethane in this case is related to the following function of film position: D = D(o)(β0 + β1x)δ. The time lag of diffusion of ethane in these experiments decreased with inrreasing butane concentration.
Detection of polymer transition temperatures by infrared absorption spectrometry
Authors: Anton Anthony 
Published: April 2003

AbstractInfrared bands in the 900–1100 cm−1 region are sensitive to thermal energy. These bands can result from intermolecular coupling, producing the crystal lattice, or from intramolecular coupling of the various atomic groups in a regular helix or coiled chain. In either case an increase in temperature will disrupt the coupling mode, resulting in a form of structural relaxation and a reduction in the integrated absorbance. It is proposed that the temperature at which the peak areas begin to decrease be assigned as the Tg. This is measured by continuously scanning a selected peak in the infrared spectrum of a polymer film while it is heated at a rate of about 1°C/min. Using this technique polyamides (nos. 6,66, and 610) exhibited transitions in the 30–50°C range, and by studying the increase in the free NH region (3440 cm−1) of nylon 66 two other transitions were detected at 80 and 137°C; the latter represents a change in the nylon 66 crystal state. An amorphous film of poly(ethylene terephthalate) displayed a transition at 58–68°C (Tg) and at 85°C, which is the crystallization temperature. Films of poly(vinyl acetate) and polystyrene exhibited transitions at 25–37°C and at 70°C, respectively.
Effects of monomer impurities on the emulsion polymerization of chloroprene and properties of polychloroprene. I. Effect of methyl vinyl ketone
Authors: Sufčák Miloslav 
Published: April 2003

AbstractThe influences of small amounts (up to 2%) of methyl vinyl ketone in chloroprene on properties of polychloroprene and kinetics of the emulsion polymerization of chloroprene with mercaptans as regulators has been studied. Methyl vinyl ketone causes a substantial increase in molecular weight of polymer, which results in increased viscosity, gel formation, lowered plasticity of polymer, deterioration of processability, decreased tensile strength, and high modulus of vulcanizates. Methyl vinyl ketone interferes with the regulation of molecular weight by both primary and tertiary dodecylmercaptan; some differences are due to lower reactivity of tertiary dodecylmercaptan. In the presence of diisopropyl xanthogene disulfide as a molecular weight regulator the polychloroprene properties are not affected by methyl vinyl ketone. All changes in polymer properties have been proved to be caused by the addition reaction of dodecylmercaptan on methyl vinyl ketone, yielding 1‐dodecylthiobutan‐3‐one. This compound itself has no influence on the polymerization of chloroprene. Methyl vinyl ketone has a marked promoting effect on polymerization rates, which accounts for its high reactivity and solubility in the water phase. A fast polymerization of methyl vinyl ketone takes place in the water phase of emulsion polymerization system simultaneously with the reaction of methyl vinyl ketone with dodecylmercaptan.
Radiation chemical studies of protein reactions: Effect of irradiation atmosphere on viscosity
Authors: Nisizawa Mizuho 
Published: April 2003

AbstractWhen protein is irradiated by γ‐rays from a 60Co source in various atmospheres such as N2, CO2, H2, O2, and NH3, the effect of the radiation varies with the gases composing the irradiation atmosphere. An empirical equation for the viscosity change was obtained.
Infrared and nuclear magnetic resonance of maleic anhydride copolymers and their half esters
Authors: Saier Eleanor L. , Petrakis L. , Cousins L. R. , Heilman W. J. , Itzel J. F. 
Published: April 2003

AbstractInfrared and NMR group‐type methods for the analysis of the anhydride content of maleic anhydride copolymers such as poly(maleic anhydride‐co‐α‐olefin) and the half ester content of their reaction products with alcohols are described. The infrared analyses are based on the integrated absorptivities of the anhydride carbonyl and the combination of the acid and ester carbonyl. The NMR method is based on the intensities of the various chemically shifted groups in the copolymer. The use of dimethyl sulfoxide as an auxiliary solvent has made the infrared analysis possible.