ISSN:0022-3832    

DOI:10.1002/pol.1955.120168201

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractDivinylbenzene (48%)/ethylvinylbenzene copolymer was converted to a series of pyrolytic derivatives. Enough of the carbon bond network remained intact throughout thermal rearrangement and condensation to retain the original gross shape of the copolymer in the final polymer carbon. Although a carbon residue (6% by weight) was obtained by direct heating of the copolymer, yields were increased eightfold by preoxidation or prechlorination. Such an alteration of thermal degradation is obviously a complex process involving both “inhibition,” in the ordinary sense, and a considerable contribution toward an increased valence network density. As a consequence, the average molecular weight of volatile fragments evolved during carbonization is inversely proportional to the oxygen content of the original hydrocarbon polymer. Pyrolysis of divinylbenzene copolymer, containing 18% oxygen, resulted in a 50% volume shrinkage, 50% weight loss, and a 100% density gain. Unless these data are attributable to extensive microporosity, it is difficult to account for the sorption of up to 3 cc. of helium gas per gram of polymer carbon at 30°C. and 600 mm. pressure; and calculated surface areas as large as 1400 sq.m./g. Abrupt changes in the progress of polymer carbon formation occurred between 600 and 700°C. The residue became rigid; vigorous evolution of volatile products, principally hydrogen, suddenly diminished; and paramagnetic resonance absorption (unpaired electron concentration) dropped about tenfold while d.c. resistivity decreased 106ohm cm. In this region, also, x‐ray patterns were most diffuse, exhibiting no maxima characteristic of carbon scattering in either hydrocarbons or condensed rings. Finally, the x‐ray patterns of polymer carbon intermediates became less diffuse in samples prepared at 700°C. or above. Yet, scattering indicated the presence of crosslinked graphitic layers of such stability that reordering or true graphitization did not occur

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168202

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractEvidence is brought forward that the noticeable reinforcing effect by cyclized rubber, if added as a filler to natural rubber, is bound to a certain minimum particle size of the cyclized rubber. It is further shown that the reinforcing effect of some condensation polymers is enhanced if chemical bonds with the rubber are formed. The reinforcing effect by resins is connected with their hardness.

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168203

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractEssential features of the crystallization of unoriented high polymers from the molten and supercooled liquid conditions are outlined to provide a background for a proposed structure and mechanism of growth of spherulites. Homogeneous and heterogeneous nucleation mechanisms of crystallite growth are discussed. Spherulites are recognized as crudely oriented spheroidal aggregates of crystallites and their attached amorphous regions. It is proposed that a spherulite originates from a single nucleus and that growth proceeds thence in a statistically radical fashion until all crystallizable domains are utilized or until growth is arrested due to increasing viscosity of the medium. It is assumed that crystallite growth occurs by lateral accretion of suitable oriented molecular segments and that nucleation proceeds from one crystallite to another by means of fine streamers of crystalline order (protofibrils) which may grow either by longitudinal extension along fringes or by lateral aggregation of very short segments. The predominant shapes of the crystallites are believed to determine the structure and optical properties of the spherulite. A roughly conical arrangement of crystallites around a spherulite radius is preferred to a helical one.

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168204

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractLes propriétés exceptionnelles d'une nouvelle classe d'hydrocarbures macromoléculaires à structure linéaire obtenus par polymérisation d'α‐oléfines sont décrites. La haute température de fusion, la cristallinité élevée, la faible solubilité, les propriétés mécaniques spéciales de ces polymères sont attribuées à une régularité particulière de structure due à l'existence, dans chaque macromolécule, de longues successions ordonnées d'atomes de carbone asymétriques ayant la même configuration stérique. Pour ce type particuler d'ordonnement d'atomes de carbone asymétriques dans des macromolécules linéaires

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168205

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168206

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractA short review is given of the development of the theory and of the new experimental technique of x‐ray low‐angle scattering. The study of human γ‐globulin leads to a cylindrical particle of about elliptical cross section with axes of 19 and 57 A. and with a length of 230–240 A. The volume is found to be 1.98 × 105A.3, which involves a molecular weight of 1.62 × 105in satisfactory agreement with the value found by ultracentrifuge me

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168207

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe viscosity slope constantk′,i.e.,\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\lim }\limits_{c \to 0} \frac{{d\left( {{{\eta _{sp} } \mathord{\left/ {\vphantom {{\eta _{sp} } c}} \right. \kern-\nulldelimiterspace} c}} \right)}}{{dc}}\frac{1}{{[\eta ]^2 }} $\end{document}, is shown to be of increasing significance in polymer science as a molecular‐weight‐independent criterion of solvent power and as a parameter sensitive to various changes in polymer structure, such as long‐chain branching. Ideally, it is a dimensionless parameter, independent of molecular size, which arises only from the mutual hydrodynamic interaction of polymer molecules and depends, therefore, on the intrinsic flexibility of the polymer chain and on the polymer density in the coiled molecule. In real systems, however, other interactions may contribute, sometimes very significantly, tok′. For such real systems, the general expression:\documentclass{article}\pagestyle{empty}\begin{document}$ k' = k + a + \frac{K}{{[\eta ]^2 }}\left( {[\eta ]_{(2)} - [\eta ]_{(1)} } \right) $\end{document}is suggested. In ternary systems, polymer–polymer–solvent, ideal expressions for ηsp/candk′ are developed, that fork′ being:\documentclass{article}\pagestyle{empty}\begin{document}$ k' = \sum\limits_i {\sum\limits_j {\surd \bar k_i [\eta ]_i w_i {{\surd \bar k_j [\eta ]_i w_i } \mathord{\left/ {\vphantom {{\surd \bar k_j [\eta ]_i w_i } {(\sum\limits_i {[\eta ]_i w_i } )^2 }}} \right. \kern-\nulldelimiterspace} {(\sum\limits_i {[\eta ]_i w_i } )^2 }}} } $\end{document}It is proposed that deviations from ideal behavior so defined are due to nonhydrodynamic polymer‐polymer interactions and might be used to detect and measure the strength of such interactions. Some preliminary data for the system polystyrene–poly(methyl methacrylate)–m‐xylene a

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168208

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractA new method has been developed for obtaining molecular weight distribution curves from turbidimetric titration data. The latter are plotted directly in a curvilinear coordinate system where one set of axes is the solubility frequency curves for the polymer in question and which can be constructed once and for all. The method is very simple and no assumptions about the homogeneity of successive fractions are made. A formal mathematical treatment of the procedure is also given.

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168209

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe addition of carboxylic acid to Epon 834‐phthalic anhydride resins accelerates the rate of cure. The maximum thermal yield point corresponds to reaction of all the epoxide groups in the ratio of two anhydride carbonyls to one epoxide oxygen or of one acid carbonyl to one epoxide oxygen. The initial presence of some secondary alcohol groups appears to be essential for initiation of reaction as suggested by Fisch and Hofmann. Carboxylic acids react directly with epoxide groups to produce secondary alcohols which in turn react with phthalic anhydride, regenerating carboxylic acid groups. Succinic acid gives a rapid cure (although not as fast as amines) to a resin with only slightly lowered thermal yield point, while benzoic acid depresses the yield point by about 15° because it acts as a chain‐sto

ISSN:0022-3832    

DOI:10.1002/pol.1955.120168210

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY