The occurrence of weak links in vinyl polymers undergoing thermal degradation

A survey is made of vinyl‐type polymers in which there appear to be links more susceptible to scission (during thermal degradation) than the normal links. The presence of such links is indicated by an examination of the change in molecular weight during the course of the reaction. A theoretical expression is used which assumes that both normal, and weak link scission, are random processes. Apart from the polymers already known to have weak links, polystyrene, polyethylene, polymethylene, and polypropylene, it appears that poly(methyl methacrylate) also contains such links. It is suggested that an alternative explanation may account for the apparent presence of weak links in so many polymers.