CYCLOPENTADIENYLATION OF PVC - CHARACTERIZATION AND THERMAL AND THERMOOXIDATIVE DEGRADATION STUDIES

In the reported experiments, PVC has been cyclopentadienylated by two conventional basic, LiCp and NaCp, and a new acidic, Me//2CpAl, cyclopentadienylating agent. PVCs treated with basic cyclopentadienylating agents undergo severe random dehydrochlorination and exhibit a significant decrease in thermal and thermooxidative stability. In contrast, according to ozonization and degradation experiments, Me//2CpAl does not cause dehydrochlorination during cyclopentadienylation. The thermal stability of PVC treated with relatively high concentrations of Me//2CpAl and Me//3Al at 25 degree C markedly increases due to substitution of labile chlorines in PVC with methyl groups. Acceleration of thermal dehydrochlorination disappears and the length of polyene sequences is reduced on Me//2CpAl and Me//3Al treatment. These observations are attributed to differences in rates of protonation-deprotonation; that is, rates of reinitiation of zipping of treated and untreated PVCs during thermal degradation.