ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
An attempt is made in this paper to calculate G values for simultaneous crosslinking and degradation during irradiation of polymers with side chains. Equations are given for the change in the weight-average to number-average molecular weight ratio as a function of dose for the case of degradation only. It is shown that the change in the logarithm of this ratio with the square root of the dose goes through a broad maximum over a certain dose range. This result coupled with estimates of Katsuura of the effect of branching on the intrinsic viscosity is used to explain the relationship discovered by Keyser, Clegg, and Dole between the logarithm of the intrinsic viscosity and the square root of the dose. It is concluded that the G value for degradation must change with dose; in the case of poly-1-hexene, for example, it is believed that G(S) falls from an initial value of about 0.15 to about 0.04 at high doses. Similar conclusions result from an application of the equations to polypropylene, but with higher values of G(S), about 1.1 initially and dropping about tenfold at doses above the gel point.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1963.100011103
