bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic analysis of the radiation polymerization of methyl methacrylate–kaolin clay composites
Authors: Beeson J. J. , Mayhan K. G. 
Published: April 2003

AbstractIn the first of a two‐part series, a kinetic study has been made on the effects of gamma rays (60Co) in air and inert gas on the polymerization of a 50:50 weight‐mixture methyl methacrylate (MMA)–kaolin clay system. The effect of dose rate (7.35–24.9 rads/sec), temperature (25° to 75°C), and total dose on the percentage conversion of monomer to polymer was studied. The rate of formation of polymer at 25°C in the composite system was found to be faster when compared to a bulk MMA system at the same dose rate. This acceleration showed that the clay had a catalytic effect on the formation of polymer. The effect decreased as temperature increased. Two types of poly(methyl methacrylate) (PMMA) were formed in the composite. One type was called homopolymer and could be removed from the composite by extraction with organic solvents. The other type was called inserted polymer and could only be removed by dissolving the clay matrix with hydrofluoric acid. The total polymer conversion was the summation of these two types of polymer formed. The kinetic analysis examined the orders of reaction and activation energies of the homopolymer, inserted polymer, and total polymer. The initial reaction orders of the homopolymer and total polymer based on dose were −0.46 and −0.49, respectively. These indicate a definite free‐radical reaction. The reaction order of the inserted polymer was temperature dependent.The activation energies for the homopolymer and total polymer in both atmospheres were approximately 1 kcal/mole less than the bulk activation energy at the same conditions. The inserted polymer had an activation energy which was dose rate dependent.
Characterization of poly(methyl methacrylate) from radiation‐induced polymerization in the presence of a kaolin clay substrate
Authors: Beeson J. J. , Mayhan K. G. 
Published: April 2003

AbstractTwo types of polymer are formed in the radiation‐initiated polymerization of methyl methacrylate (MMA)–kaolin clay complexes. Homopolymer can be extracted from the complex by the use of organic solvents. Inserted polymer must be removed by dissolution of the polymer–clay complex with hydrofluoric acid. The polymers formed show no differences in structure (as determined by infrared analysis), had high molecular weights (1–5 × 106), and had similar molecular weight distributions (as determined by GPC). The molecular weights of the homopolymer increased as temperature increased (25°–75°C), and dose rate decreased (24.9–7.35 rads/sec). The isotacticity of the polymers when compared to irradiated bulk polymer decreased as follows: inserted > homo > bulk. The compressive properties of the irradiated composite compared well with those of commercial bulk polymers. Degradation temperatures were 20° to 30°C higher for the composite than for the commercial chemically initiated bulk polymer.
Solution properties and molecular structures of EPM and EPDM
Authors: Morimoto M. , Okamoto Y. 
Published: April 2003

AbstractThe solution properties of EPDM were investigated based on EPM as a model compound of linear molecules. The glass transition temperature and the propylene content in EPDM were measured as a function of the molecular weight. Good agreement between the solution behaviors of EPM and EPDM was observed. This was correlated to change not only in the propylene composition but also in the monomer sequence distribution.
Chemorheological treatment of crosslinked EPDM. II
Authors: Tamura Saburo , Murakami Kenkichi 
Published: April 2003

AbstractStress relaxation mechanisms were investigated on three kinds of ethylene–propylene terpolymers (EPDM), differing only in the structure of the crosslinkage, in both nitrogen and air at 160°C. The crosslinking site in these polymers consists of a carbon–carbon bond, a polysulfide linkage, and a carbon–carbon bond and a polysulfide linkage, respectively. Stress relaxation in air for peroxide‐cured EPDM was based on the oxidative scission of the main chain. Analysis of the stress relaxation data of sulfur‐cured EPDM in nitrogen indicated the presence of stable mono‐ and disulfide linkages and that the main relaxation process resulted from an interchange reaction between polysulfide linkages. In air, in addition to the interchange reaction, oxidative cleavage of mono and disulfide linkages occurred. Further, the stress relaxation for peroxide–sulfurcured EPDM polymers containing various amount of sulfur was observed in air and nitrogen and was discussed in the connection with highly crosslinked polymers.
Gel permeation and thin‐layer chromatographic characterization and solution properties of butadiene and styrene homopolymers and copolymers
Authors: White James L. , Salladay David G. , Quisenberry David O. , MacLean Donald L. 
Published: April 2003

AbstractGel permeation chromatographic (GPC) and thin‐layer chromatographic (TLC) studies of polystyrene, polybutadienes (BR), and their copolymers (SBR) have been carried out. GPC primarily separates them on the basis of molecular size, and TLC, on the basis of composition. Methods of obtaining absolute molecular weight distributions for BR and SBR based upon variations of the Strasbourg Universal Calibration procedure are described. In particular, [η]–M relationships in both the GPC solvent (THF) and in a second solvent (toluene) were used; in addition, results of statistical mechanical calculations for \documentclass{article}\pagestyle{empty}\begin{document}$\overline {s^2 }$\end{document} (based on the assumption of negligible steric hindrance and freely rotating bonds) were applied. An experimental comparison of these methods was carried out, and use of the [η]–M relationships for both solvents was found to give satisfactory results. The predictions of the statistical theory were too low. A detailed study of polymer–solvent–gel interaction in the GPC unit was made through investigation of ternary phase equilibrium in the (polystyrene)–THF–(polymer) system. The polymers studied included BR and SBR with varying styrene contents. Experimental techniques for TLC separations of BR, SBR, and polystyrene according to the composition are described.
A thermoanalytical study of chemical reactions of durable press and acrylic soil release textile finishing agents
Authors: Warburton C. E. 
Published: April 2003

AbstractChemical reactions in systems with durable press reagents and acrylic soil release polymers are analyzed using differential scanning calorimetry. Self‐condensation of N‐methylol compound is the preponderant chemical reaction when a film with 70% methacrylic acid/30% ethyl acrylate copolymer and dimethylolethylene urea (DMEU) or dimethyloldihydroxyethylene urea (DMDHEU) is heated. This reaction proceeds through formation of transitory methylene ether bridges with methylene bridges as the thermodynamically favored product. An exotherm is observed under certain circumstances in DSC thermograms of films containing DMEU or DMDHEU and is attributed to a rapid shift of methylene either to methylene bridges. Appreciable anhydride formation occurs in the polymer only above about 160–170°C. Esterification of polymer by methylol reagent probably also occurs to a limited extent, especially above about 160–170°C. Soil release of fabrics treated in a one‐bath process is often unsatisfactory because polymer is embedded in a matrix of condensed N‐methylol compound which restricts swelling of polymer and, therefore, its utility as a soil release agent. The limited extent of reaction between polymer and methylol compound is of minor importance compared with this adverse morphology. However, in some cases, ester formation may be responsible for significantly inferior soil release of fabrics cured at higher temperatures, for example 210°C/30 sec rather than 160°C/3 min. In such cases, polymer may be trapped chemically as well as physically in the resin matrix.
Thermal regeneration of the tensile properties of hydrolytically degraded polyimide film
Authors: Deiasi R. 
Published: April 2003

AbstractHeat treatment at temperatures of 224° to 310°C of hydrolytically degraded polyimide film has been shown to regenerate the ultimate tensile strength from 15.1 ksi to 24.3 ksi after 80 hr at 224°C and to 25.8 ksi after 2 hr at 310°C, whereas the elongation to failure is simultaneously increased from 6.3% to 38.3% at 224°C and to 50.7% at 310°C. Prior to degradation, the film had an ultimate tensile strength of 26.6 ksi and an elongation to failure of 62.0%. The kinetics of this regeneration indicate that the reaction corresponds to the two‐step recombination of the hydrolytically attacked amide linkages that were initially present in the “as received” polyimide film. The regenerated polyimide exhibits a much improved hydrolytic stability over the untreated material and specimens heat treated directly without prior aqueous degradation.
Crosslinked polyesters from “bisacid A2.” The mechanical properties of glass fiber‐reinforced laminates
Authors: Lenk R. S. 
Published: April 2003

AbstractThis paper reports the flexural and tensile test results on glass fiber laminates prepared from solutions in styrene of polyesters containing bisacid A2 and from standard commercial liquid polyester resins. The results are compared with each other. Suggestions are made for differences in strength, modulus, and strain. The results are presented in tables which give a statistical evaluation of numerous tests in terms of mean, range, and standard deviation.
Characterization of homopolymers and copolymers by the coupling of gel permeation chromatography and automatic viscometry
Authors: Grubisic‐Gallot Z. , Picot M. , Gramain Ph. , Benoit H. 
Published: April 2003

AbstractAn improvement in gel permeation chromatography for polymer characterization has been effected by combining it with an automatic viscometric technique. This allows not only determination of the molecular weight distribution but also the intrinsic viscosity for any kind of homopolymer. Moreover, it permits determination of the viscosity–molecular weight relationship for linear polymers and the degree of branching for branched polymers. The use of this technique, coupled with UV or IR spectrometric measurements, provides information with respect to composition and molecular weight distribution in the case of copolymers. It is thus possible to characterize copolymers from the double point of view of composition and molecular weight polydispersity.
An improved numerical interconversion for creep compliance and relaxation modulus
Authors: Knoff Warren F. , Hopkins Irving L. 
Published: April 2003

AbstractAn imporved method for the numerical evaluation of the convolution integral in the relationship between creep compliance and relaxation modulus is discussed. The better approximation is obtained by the assumption that both functions can be assumed to be linear within a series of increasing time intervals which do not change as the calculation progresses. The calculation is carried out on both hypothetical and real examples which substantiates its applicability and accuracy.
The color of absorbing scattering substrates. I. The color of fabrics
Authors: Allen E. Hope , Goldfinger G. 
Published: April 2003

AbstractA treatment of the color of textile materials is proposed which is an extension of G. G. Stokes' “pile of plates” problem. Unlike the conventional treatment of this subject, e.g., that by Kubelka and Munk, this approach permits independent determination of all variables: coefficient of absorption of the dye, refractive indexes of the fibers, the effect on color of the geometry of the fabric and yarn, and the distribution of the dye within the fiber. Here, cylindrical, optically homogeneous fibers in a parallel array are assumed. Experimental data show that this treatment predicts far more satisfactorily the color of fabrics at high dye concentrations and low reflectance values than does the Kubelka‐Munk approach.
Study of the pyrolysis of saturated chlorinated polyethylene fibers
Authors: Saglio N. , Berticat Ph. , Vallet G. 
Published: April 2003

AbstractThe thermal degradation of saturated chlorinated polyethylene in powder and fiber form has been studied. Direct observations of fiber length variations have enabled us to prove the reactional mechanisms proposed. In the temperature range of 200°–300°C, the material exhibits some fluidity. Its degradation is explained by intrachain and interchain dehydrochlorination reactions, followed by an arrangement of conjugated double bonds obtained in the shape of polyacenic cycles. Between 300°C and 800°C, the polyacenic cycles react with each other to give a pregraphitic structure which is responsible for the increase in rigidity of the material. The fibers of saturated chlorinated polyethylene can be used as a precursor of carbon fiber.
Optimum method for osmotic pressure measurements with membrane‐permeating solutes
Authors: Hayduk W. , Laudie H. 
Published: April 2003

AbstractOsmotic pressure experiments were conducted with PVC samples of different molecular weights dissolved in THF, using both a block osmometer and a Hewlett‐Packard automatic osmometer equipped alternately with Schleicher and Schuell 07 and 08 membranes to optimize the procedure for accurate osmotic pressure measurements. It was found that, provided a flow of solvent could be maintained through the membrane and into the solution, an osmotic pressure of good accuracy was obtained even though the membrane was nominally much too coarse for the polymer analyzed.
Terpolymers. I. The mechanical properties and transition temperatures of terpolymers of n‐octadecyl acrylate, ethyl acrylate, and acrylonitrile
Authors: Jordan Edmund F. , Riser George R. , Salber Charles , Wrigley A. N. 
Published: April 2003

AbstractEarlier work revealed that the internal plasticization of polyacrylonitrile by the higher n‐alkyl acrylates or N‐n‐alkylacrylamides yielded only brittle copolymers. This difficulty was circumvented in the present work by starting with copolymers of acrylonitrile and ethyl acrylate, over the range of compositions, and further modifying these by incrementally displacing the ethyl acrylate in each recipe by n‐octadecyl acrylate through terpolymerization. In this way, the stepwise small reduction in Tg for the base ethyl acrylate–acrylonitrile copolymers was greatly increased for each of the terpolymers. Compositions were obtained ranging from glassy, brittle terpolymers, with glass transitions above room temperature, to soft plasticized polymers having sufficient polar networks retained from the nitrile to confer useful properties. The decline in the glass temperature was shown to be dependent on the free volume conferred by the side‐chain methylene groups of each acrylate ester. In contrast, the decline in tensile and flexural strengths and moduli for the terpolymers having glass transitions above room temperature was produced entirely by the presence of the methylene groups of the 18‐carbon ester. The glass transition region corresponded to room temperature when the acrylonitrile content of the base copolymer had been reduced to 50 mole‐%. Terpolymers of this nitrile content and lower had the low moduli and large elongations of plasticized compositions. An equation was developed which correlated empirically the glass transitions and the mechanical properties with the weight fraction of the acrylate esters for the glassy terpolymers.
Drag reduction in dilute polymer solutions
Authors: Kelkar J. V. , Mashelkar R. A. 
Published: April 2003

AbstractThe problem of drag reduction in a helically coiled tube is examined experimentally. The general problems involved in the correlation of drag reduction data are analyzed critically, and some important recommendations are made based on the findings of this work. A phenomenological approach is suggested for correlating the drag reduction data. An examination of the straight‐tube data from the literature and the coiledtube data obtained in this work shows that for a variety of aqueous polymer solutions the data could be uniquely correlated by the following equation:

where β = reduced friction factor and De′ = modified Deborah number.
Thermomechanical behavior of poly(carborane–siloxane)s containing CB5H5C cages
Authors: Roller M. B. , Gillham J. K. 
Published: April 2003

AbstractThe thermomechanical spectra of two new carborane–siloxane polymers containing five‐boron carborane cages in the backbones are reported and discussed. The polymers are the homopolymer, HO[Si(CH3)2CB5H5CSi(CH3)2O]nH, and the random copolymer with 20 mole‐% of the ten‐boron meta‐carborane analogue, [Si(CH3)2CB10H10CSi(CH3)2O]. The mechanical spectra (∼1 cps) were determined from −180° → +625° → −180°C (ΔT/Δl = 3.6°C/min for T > 25°C and 2°C/min for T < 25°C) using the semimicro thermomechanical technique, torsional braid analysis. In nitrogen, both polymers displayed secondary transitions at −140°C. The glass transition (Tg) for the homopolymer was −60°C and for the copolymer was −52°C. The homopolymer had a melting point of +70°C. The copolymer was amorphous. The high‐temperature stability in nitrogen of both polymers appeared to be identical; thermal stiffening commenced at 400°C, continued to 625°C, and resulted in materials that were typical of highly crosslinked resins. In air, the homopolymer began to stiffen catastrophically near 270°C, while the copolymer began to stiffen similarly nearly 50°C higher. The intrinsic elastomeric nature together with the thermomechanical results prompted further study of the copolymer. Thermomechanical cycling studies in nitrogen and air are reported for the copolymer. Some correlating TGA and DTA are also discussed.
Interaction of Biebrich Scarlet with keratoses from performic acid‐oxidized wool
Authors: Rao L. Seshagiri , Rattee I. D. 
Published: April 2003

AbstractThe interaction of the acid dye Biebrich Scarlet (C.I. Acid Red 66) with α‐, β‐, and γ‐keratoses obtained from wool fiber by performic acid oxidation was studied. The extrapolated saturation values of dye bound to protein and the association constants for the interactions were obtained. Maximum dye uptake was found for α‐keratose, followed by γ‐ and β‐keratoses, in that order. Incorporation of varying amounts of m‐cresol in the dye solutions showed no significant effect. There was no indication of an interaction between m‐cresol and the keratoses from direct studies.
Thermal stability of “living” polymer–lithium systems
Authors: Kern W. J. , Anderson J. N. , Adams H. E. , Bouton T. C. , Bethea T. W. 
Published: April 2003

AbstractThe thermal stabilities of polybutadienyllithium, polyisoprenyllithium, and polystyryllithium solutions have been determined in hydrocarbon solvents. Kinetic analysis indicated that a complex mechanism was involved in the thermolysis of polybutadienyllithium. The thermal stability was observed to increase with increasing lithium concentration, suggesting the presence of competitive reactions in addition to the expected elimination of lithium hydride. The thermal stability of the three systems studied was consistent with their reported degrees of association: dimeric polystyryllithium was less stable than tetrameric polyisoprenyllithium or hexameric polybutadienyllithium.
Thermolytic reactions of polybutadienyllithium
Authors: Anderson J. N. , Kern W. J. , Bethea T. W. , Adams H. E. 
Published: April 2003

AbstractIn addition to the expected elimination of lithium hydride, metalation and addition reactions have been observed as competitive, thermolytic reactions of polybutadienyllithium. The importance of these reactions at temperatures frequently utilized for the polymerization of butadiene was illustrated and the effect of these reactions on the macrostructure of polybutadiene determined.
Thermal conductivity of polymers filled with particulate solids
Authors: Sundstrom Donald W. , Lee Yu‐Der 
Published: April 2003

AbstractThe thermal conductivities of polystyrene and polyethylene containing several different particulate solids were measured over a range of solid concentrations. Experimental data were compared with results predicted by theoretical models for two‐phase media. The equations of Bruggeman and Cheng‐Vachon both gave reasonable agreement with measured results. The applicability of these equations does not appear to depend upon the structure of the polymer.
On the mechanisms for drag reduction: A viscoelastic evaluation based on a bead‐spring model
Authors: Ting R. Y. 
Published: April 2003

AbstractTwo possible drag reduction mechanisms were examined by studying the viscoelastic effects of polymer solutions for the separate cases of oscillatory shear flow and elongational flow. The constitutive equation used was based on a modified dumbbell molecular model which predicts non‐Newtonian viscosity and both the primary and the secondary normal stress differences. It can be shown that when this constitutive equation is arranged in the form of the Oldroyd model, the latter becomes a special case of this more general equation. The present results show that viscoelastic effects on the mean local rate of energy dissipation of a fluid element in an oscillatory motion are negligibly small. However, such effects introduce very large increases in the elongational viscosity as the stretching rate exceeds a certain limiting value and the flow time exceeds the terminal relaxation time of the fluid. The relative merits of these findings as possible explanations of turbulent drag reduction are briefly discussed.
Thermal degradation of polymers. V. Vacuum pyrolysis of poly(p‐N,N‐dimethylaminostyrene). The products volatile at pyrolysis temperature, liquid or gaseous at room temperature
Authors: Still R. H. , Evans M. B. , Whitehead A. 
Published: April 2003

AbstractThe products obtained on degradation of poly(p‐N,N‐dimethylaminostyrene) in vacuo are described. The effects of molecular weight and pyrolysis temperature are discussed and the behavior compared with polystyrene under similar conditions. Product analysis has revealed significant differences between the products of degradation obtained from the two polymers, and mechanisms involving methyl‐group migration have been proposed and discussed to account for the anomalous behavior of poly(p‐N,N‐dimethyl‐aminostyrene). The liquid products of pyrolysis have been separated and identified by gas‐liquid chromatography using the Kovats retention index, and quantitative analysis is also described. Analysis of the gaseous fraction by mass spectrometry is described.
Thermal degradation of polymers. VI. Vacuum pyrolysis of poly(p‐N,N‐dimethylaminostyrene). The residue and the fraction volatile at pyrolysis temperature, involatile at room temperature
Authors: Still R. H. , Whitehead A. 
Published: April 2003

AbstractThe effect of the extent of degradation of poly(p‐N,N‐dimethylaminostyrene) on the quantity and composition of the residue and the effect of pyrolysis temperature on the fraction volatile at pyrolysis temperature are discussed. The behavior of poly(p‐N,N‐dimethylaminostyrene) is compared to that of polystyrene. A significant difference has been found for the behavior of the residue from poly(p‐N,N‐dimethylaminostyrene), which is ascribed to a crosslinking reaction involving the dimethylamino substitutent. Mechanisms to account for the observed products of degradation have been suggested and are discussed.