DEGRADATION OF POLYISOPRENE INDUCED BY CHLORANIL

The aim of this work was to study the degradation of polyisoprene and polybutadiene in the presence of chloranil (tetrachloro-1,4-benzoquino ne). The influences of polymer concentration, chloranil concentration and temperature were evaluated using a 2(3) factorial design. The effl ux times of toluene solutions containing different polymer and chloran il contents at 25. 45 and 65 degrees C were measured, using a Ubbelohd e viscometer. When high concentrations of polymer and chloranil were u sed, at 65 degrees C, the efflux time decreased to approximately 10% o f its initial value after 7 min, and, after 250 min, the efflux time r educed to approximately 50% of its initial value. The efflux time of p olybutadiene solutions containing chloranil did not decrease with the reaction time. H-1 NMR of polyisoprene and polybutadiene, dissolved in CDCl3 containing chloranil, were used to evaluate the changes in poly mer unsaturation. H-1 NMR measurements showed an exponential decrease in the area for peaks due to the hydrogen bound to the unsaturated car bon in polyisoprene solutions. These results suggest the occurrence of degradation of polyisoprene. Using the same conditions, it was observ ed that polybutadiene degradation did not occur. Thus, it was conclude d that the methyl group in polyisoprene is very important in the degra dation in the presence of chloranil. (C) 1998 Elsevier Science Limited . All rights reserved.