Effect of initiator end groups and trichlorethylene units on the dehydrochlorination of solution polymerized poly(vinyl chloride)

High proportions of initiator end groups are incorporated into poly(vinyl chloride) when the monomer is polymerized in solution. The rate of thermal dehydrochlorination of these polymers increases linearly with the number of initiator end groups and varies with the type of initiator. The effectiveness of the end groups for causing dehydrochlorination is in the ratio, lauroyl peroxide: isopropyl peroxydicarbonate: benzoyl peroxide: azoisobutyronitrile: 9.7:5.8:4.4:1.6. It is suggested that the low stability of the benzoyl peroxide polymer could be due to the incorporation of phenyl groups while primary radical transfer might decrease the stability in the lauroyl peroxide and isopropyl peroxydicarbonate initiated polymers. High conversion polymers have greater stability than low conversion ones. Transfer polymers produced in the presence of trichloroethylene have much lower stability and this is attributed to both copolymerized CHClCCl2 groups and unsaturated end groups.