Plateau modulus of epoxidized polybutadiene

Dynamic mechanical spectra in the terminal and plateau regions were measured for 1,4-polybutadiene (PBD) epoxidized to different degrees. The chemical modification results in a chain of increased flexibility and larger cross-sectional area. Although small, both structural changes are anticipated from current theories to contribute to reduced topological interaction among chains. Notwithstanding, the plateau modulus was observed to systematically increase with epoxidation level. The results are similar to those found previously for epoxidized polyisoprene, ' in which the effect of chemical structure on chain entanglements was also contrary to expectations. This qualitative failure of available predictions suggests that the relationship between chemical structure and entanglement interactions remains an open question.