Analysis of Molecular Weight Changes and Gel Data of Some Irradiated Vinyl Polymers

Abstract

The theoretical equations of Inokuti of the preceding paper are applied to the interpretation of data obtained during the irradiation of isotactic and atactic polypropylene, and poly‐(1‐pentene) and poly‐(1‐hexene). Inokuti's modified Charlesby—Pinner function calculated for initial values of the Mw /Mn ratio greater than 2 can be made to agree with observation within experimental uncertainties in the case of polypropylene, but in the case of the other two vinyl polymers, the observed discrepancies are probably too great to be explained by experimental error. A G(S) value decreasing at high doses would account for the observed gel data. It is shown that in the pregelation dose range irrespective of the initial molecular‐weight distribution and scission to crosslinking ratio, both Pw,0/Pw and Pn,0/Pn change very nearly linearly with the dimensionless parameter y/yg where yg is the number of crosslinks per initial number‐average molecule at the gel point.