摘要:

AbstractA study of the curing reactions of a cycloaliphatic epoxy resin/anhydride system by torsional braid analysis showed the existence of two critical isothermal temperatures. These areTg∞(the maximum glass transition temperature of the thermoset system) andTgg(the glass transition temperature of the material at its gel point). Two rheologically active kinetic transitions occur during isothermal cure which correspond to gelation and vitrification. Three types of isothermal behavior occur: ifTcure>Tg∞, only gelation is observed; ifTg∞>Tcure>Tgg, both gelation and vitrification are observed; ifTcure

ISSN:0021-8995    

DOI:10.1002/app.1974.070180401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractIn the presence of maleic anhydride‐grafted polypropylene, marked dispersibility of the polymer blend of isotactic polypropylene and nylon 6 was obtained. This appeared to be caused by the formation of a certain graft polymer between maleic anhydride in polypropylene and terminal amino groups of nylon 6. The same phenomenon was observed when polystyrene and nylon 6 were blended with styrene–methacrylic acid copolymer as the interpolymer. The existence of such a graft polymer was confirmed by solvent extraction, estimation of the amino group of nylon 6, and identification by differential scanning calorimetry. The physical properties, especially mechanical properties of nylon 6–polypropylene polymer blends, were remarkably improved with increase of maleic anhydride added to the polymer blend. On the other hand, the physical properties those of nylon 6–polystyrene polymer blends were very little improved even in the presence of good dispers

ISSN:0021-8995    

DOI:10.1002/app.1974.070180402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractDer Vernetzungsverlauf eines Epoxidharz–DMAPA‐Systems wird mittels UR‐Spektroskopie, Kalorimetrie, Zugfestigkeits‐, Mikro‐ und Makrohärte‐, Gleichstromwiderstands‐ und Schubmodulmessungen untersucht. Die Bestimmung des zeitlichen Verlaufes der Glastemperatur während der Vernetzung führte zur physikalischen Aufklärung von Eigenschaftsanomalien bei höheren Vernetzungstemperaturen. Eine Erklärung für den eigenartigen Verlauf der Glastemperatur konnte dagegen

ISSN:0021-8995    

DOI:10.1002/app.1974.070180403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractLe greffage de films de 6 microns d'épaisseur en poly(téréphtalate d'éthylène glycol) (PTEG), de marque Terphane, avec l'acide acrylique, conduit à des membranes exploitables en électrodialyse mais inutilisables en osmose inverse. La technique radiochimique permet de réaliser le greffage dans des conditions très satisfaisantes. Les observations portant sur la cinétique du greffage, sur le gonflement des films greffés, sur leur resistance électrique, sur leur cristallinité et enfin sur leur structure révélée par microscopie électronique permettent de mieux comprendre le mécanisme du greffage et mettent en évidence des corrélations étroites entre la structure des films greffés, les conditions du greffage et les propriétés des membranes résultantes. Le rǒle joué par les zones amorphes dans le système considéré revět une importance primordiale: les zones amorphes sont seules susceptibles de recevoir l'acide acrylique et de permettre la formation en leur sein de poly(acide acrylique). Ce dernier s'accumule dans les zones amorphes où sa concentration tend vers une limite déterminée concurremment par deux facteurs. D'une part la barrière physique des zones cristallines s'oppose à l'extension du greffage. D'autre part les conditions měmes de la réaction, dans la mesure où l'état d'enchevětrement ou de réticulation qui peut s'établir entre les chaǐnes de poly(acide acrylique) finit par s'opposer à l'arrivée du monomère, peuvent créer éventuellement une seconde limite au développement de la réaction. Le diphényle utilisé comme agent gonflant paraǐt favoriser l'extension des zones amorphes par l'attaque des zones cristallines. Il est possible que sa présence conduise en outre à un poly(acide acrylique) de poids moléculaire plus faible donc de structure moins enchevětrée et plus ouverte à la diffusion de l'eau, ce qui expliquerait qu'une perméabilité à l'eau ait seulement pu ětre obtenue par greffage en présence de diphényle. L'acide formique utilisé également comme agent gonflant semble avoir eu un résultat opposé en donnant lieu à des taux de gonflement plus faibles. Il est possible que ce composé favorise la formation de poly(acide acrylique) de haut poids moléculaire aboutissant à un pseudo‐gel par enchevětrement moins facilement gonflable. En conclusion, ce travail montre que dans les conditions utilisées, le greffage du PTEG par l'acide acrylique tend vers un taux limite déterminé principalement par le degré de cristallinité. L'armature cristalline du PTEG n'est pratiquement pas altérée. Les propriétés du PTEG sont très diversement affectées par le traitement. La perméabilité à l'eau et la résistance mécanique sont

ISSN:0021-8995    

DOI:10.1002/app.1974.070180404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractAn experimental study of the influence of carbon black loading, particle size, and structure on the extrusion characteristics of polybutadiene and butadiene–styrene copolymer synthetic rubber is described. The development of extrudate distortion and its mechanisms are considered. The viscosity and die swell have been related to black loading, particle size, and structure. Generally, it is found that black surface area and structure acts to increase viscosity and decrease elastic memory. This situation is analyzed in terms of the theory of nonlinear viscoelasticity. Two mechanistic theories are described which may explain this behavior. One theory is based on the continuum mechanics analysis of suspensions of particles in viscoelastic media. The rheological behavior of the black compounds is explained in terms of the increased severity of deformation in the polymer matrix surrounding the particle agglomerates. The second theory is based on the view of an entanglement network containing black particles. Polymer chains may be adsorbed onto the surface giving rise to increased entanglement densitie

ISSN:0021-8995    

DOI:10.1002/app.1974.070180405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

Abstract“Replica gel” polymers, characterized by their extremely high specific surface area, have not previously been prepared in “redox” form. Some illustrative syntheses are described, and the capability of these materials to oxidize acetic acid and to epoxidize oleic acid and cyclohexene is demon

ISSN:0021-8995    

DOI:10.1002/app.1974.070180406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractEpoxy resin was cured with diethylaminopropylamine (DEAPA) in amounts ranging from 10% to 50% of stoichiometric amount. The yield strength of resulting thermosets formed by heat curing at 75°C is found to increase with decreasing amount of hardener. This is attributed to a more densely crosslinked structure resulting from increased tertiary amine‐initiated epoxide–epoxide chain reaction and decreased primary and secondary amine–epoxide reaction. Infrared analysis and swelling data are also presented. Styrene oxide diluent is found to have a moderate effect on mechanical properties in the range from 10 to 25 parts per hundred

ISSN:0021-8995    

DOI:10.1002/app.1974.070180407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractApparatus has been developed for studying the development of crystallinity and orientation during the melt spinning of synthetic fibers. Tension in the fiber and temperature, diameter, and x‐ray diffraction patterns are measured as a function of distance from the spinneret for a running monofilament. Measurements are presented for linear polyethylene over a range of spinning variables together with other investigations carried out on the final as‐spun fibers. These data indicate that the development of crystallinity in polyethylene is controlled by a balance between increased crystallization kinetics caused by the stress in the fiber and a tendency for increased supercooling with change in any spinning variable that increases cooling rates in the fiber. The type of crystalline orientation observed, its development during the spinning process, and the changes observed with changes in spinning conditions suggest a model for the as‐spun fiber structure in which varying amounts of row nucleation and twisting of lamellar, folded‐chain crystal overgrowths occur depending on the spinning conditions. As‐spun fiber birefringence was shown to depend primarily on the crystalline orientation. Mechanical properties correlated well withc‐axis crystalline orientation function and spin

ISSN:0021-8995    

DOI:10.1002/app.1974.070180408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe crosslink density of small microtomed samples of rubber vulcanizates has been determined using a gas‐chromatographic method for estimating the amount of solvent in the swollen rubber. The method may be used for determining the variation in crosslink density through thick rubber articles, for determining the change in crosslink density after aging service, or, for the investigation of rubber bonds and interface

ISSN:0021-8995    

DOI:10.1002/app.1974.070180409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractAn empirical model is proposed for viscosity of elastomers containing one or more fillers and/or one or more plasticizers. Only one coefficient for each filler and plasticizer is required, and the coefficients themselves are viewed as basic filler and plasticizer characteristics. The model has found wide applicability to many elastomer systems.

ISSN:0021-8995    

DOI:10.1002/app.1974.070180410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY