Effect of temperature on the structure of prepolymers of diallyl benzenedicarboxylates

The effect of bulk polymerization temperature on the structure of prepolymers of diallyl phthalate (DAP), diallylisophthalate (DAI) and diallylterephthalate (DAT) was investigated in the temperature range of 80°C–285°C. The degree of unsaturation of the prepolymers of each of the monomers unexpectedly increased with temperature in the range above 160°C. The average length of linear CC chain in the prepolymers decreased with temperature. The branching ratio for prepolymers increased with conversion of the monomer at each of the temperatures. The degree of cyclization of monomer units ( P c P ) was always arranged in the order: poly(DAP)>poly(DAI)>poly(DAT). But, contrary to expectations, at temperatures above 160°C the P c P values diminished progressively, which was attributed mainly to the diminished probability of cyclization occurring by chain transfer.