Oxidation of Two Isomeric Elastomers: Poly(Propylene Oxide) and Poly(Vinyl Methyl Ether)

Rates of oxygen absorption and chain scission have been measured for benzoyl peroxide initiated oxidation of the two isomeric hydrocarbons, poly(propylene oxide) and poly (vinyl methyl ether) in the temperature range 80–100° C and in the solid phase. Oxygen absorption data show that poly(propylene oxide) forms hydroperoxides 3.5 times as fast as poly (vinyl methyl ether). This may be attributed to steric hindrance in the propagation reaction. Chain scission, measured by stress relaxation of crosslinked samples, demonstrates that each initiating radical produces one scission in the poly(propylene oxide). The process appears to be less efficient in the poly(vinyl methyl ether). Two possible reactions are proposed to explain this observation.