摘要:

AbstractPolystyrene, in common with a number of other long chain polymers, can be crosslinked by exposure to high energy radiation, the degree of crosslinking being directly proportional to the radiation dose. Measurements were made of the solublity in benzene and toluene, as a function of degree of crosslinking. A theoretical derivation is given for the sol fractions of a long chain polymer as a function of the crosslinking index γ, assuming that the initial molecular size follows a Poisson (random probability) distribution. The relationship betweensand γ is shown to be:\documentclass{article}\pagestyle{empty}\begin{document}$$ s(1 + \gamma - \gamma s)^2 = 1 $$\end{document}According to this formula a gel forms if γ>0.5. An extension to deal with the possibility of chain fracture is described. A comparison of the observed solubility curve with this formula, and with that given by Flory for a uniform initial molecular size shows that only the former agrees with the experimental data. Little or no chain fracture occurs due to adiati

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110601

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

AbstractPolystyrene has been crosslinked by atomic pile radiation, the degree of crosslinking being proportional to the radiation dose. The swelling properties of the crosslinked polymer have been studied as a function of degree of crosslinking γ. There is found a relationship of the form required by theory:V5/3∝︁ 1/γ,Vbeing the volume swelling ratio. This formula fails at low degrees of crosslinking. A fuller investigation shows that a number of corrections must be applied, taking into account gel fraction, distribution of molecular weight, and crosslinking index in the gel, etc. On the assumption that the initial molecular weight follows a Poisson distribution, good agreement is obtained between the fuller theory and observed data. The number‐average molecular weight is between 1.53 × 105and 2.14 × 105. The relationship between γ and radiation doseRis also obtained, and is identical with that deduced previously by entirely different means from solubility data. Pile radiation provides a means of producing polymers with accurately known crosslinking index. The energy required to produce a crosslink in polystyrene by high energy radiation is much greater than in many other linea

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110602

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

AbstractThe polymerization of certain vinyl monomers in the presence of some vinyl polymers leads to the formation of a chemical bond between the resulting two polymers. A study of the efficiency of this graft copolymerization process under various conditions in emulsion has been made and the following conclusions drawn. An increase in the catalyst concentration and temperature of polymerization increases the efficiency, while the addition of dodecyl mercaptan decreases it. The list of the monomers used in the order of decreasing activity toward graft copolymerization is vinyl chloride, vinyl acetate,and styrene. A list of polymers in order of decreasing susceptibility to graft copolymerization is polyvinyl chloride, polyacrylonitrile, polyvinyl a cetate, and polystyrene.

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110603

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

AbstractLiquid polymers of ethyl,n‐butyl, and 2‐ethylhexyl acrylates were prepared using an anionic initiating system. Liquid polyethyl acrylate was tested as a plasticizer in a stabilized and unstabilized polyvinyl chloride plastisol composition. In the unstabilized composition, fused samples were obtained which were comparable in color to a di‐2‐ethylhexyl phthalate (DOP) plasticized polyvinyl chloride sample prepared under the same conditions. Stress–strain tests on stabilized films indicated that with liquid polyethyl acrylate as the plasticizer a film was obtained showing higher tensile strength, yet equivalent ultimate elongation as compared to a similarly prepared DOP plasticized co

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110604

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

AbstractAn approximate solution is obtained for the nonlinear diffusion equation in which the coefficient of diffusion is a linear function of the concentration. Methods are developed for deducing the relevant parameters from experimental data and of constructing theoretical curves from these parameters. The results are illustrated by a worked example.

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110605

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110607

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

AbstractIt is obvious that the starred carbon atoms in vinyl polymers of the type exist in two distinct steric configurations which are denoted here by symbols + and −. It is shown that the existence of these configurations leads to the formation of different types of polymers; however, no simple relation correlates the optical activity of such polymers with the relative distribution of + and − configurations along the polymeric chain. The various possible structures are discussed in some detail. The kinetics of such polymerizations initiated by an optically active catalyst are treated by statistical meth

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110608

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

AbstractA new approach to orientation processes is proposed in terms of the morphology of crystalline polymers. Our present knowledge of the morphology of unoriented crystalline polymers is summarized, and the process of orientation is visualized as an alignment and pulling out of the submicroscopic and microscopic structural units. The various stages of this process are discussed and it is found that in this way several anomalous and hitherto unexplained orientation effects frequently described in the literature can be accounted for. The phenomenon of preferential tilt of the chains with respect to the fiber axis can now be explained in general terms. Peculiarities in the drawing‐relaxation process, and the special case of perpendicular orientation, also substantiated by recent experiments, follow naturally from the new mode

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110609

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

摘要:

Abstractβ‐Vinylnaphthalene, 6‐chloro‐2‐vinylnaphthalene, 4‐chloro‐1‐vinylphenanthrene, and 2‐ and 3‐vinylphenanthrenes have been copolymerized with styrene, methyl methacrylate and methyl acrylate. All copolymerize well to give products generally softening at higher temperatures than polystyrene of its copolymers. Analysis of the relative reactivities in copolymerization indicates that, with the exception of the single α‐vinylnaphthalene derivative, these monomers are more reactive in copolymerization than styrene. This is in agreement with expectations based on the greater possibilities for resonance stabilization of an adjacent free radical by the naphthalene an

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110610

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1953.120110611

出版商:Interscience Publishers, Inc.    

年代:1953

数据来源: WILEY