Amorphous polyolefins: A relationship between molecular structure, submolecular motion, and mechanical behavior

摘要

AbstractThe thermomechanical spectra of two series of amorphous polyolefins represented by$rlap{--} [{rm CH}_2 )_m {rm - C}left( {{rm CH}_3 } right)_2 rlap{--} ]_n$and$rlap{--} [left( {{rm CH}_2 } right)_m bond {rm C}left( {{rm CH}_3 } right)left( {{rm C}_2 {rm H}_5 } right)rlap{--} ]_n$, wherem= 1, 2, and 3, are presented from −180°C to above the glass transition temperatures. The polymers were obtained by cationic polymerization of α‐olefins. The mechanical spectra show a maximum in glass transition temperature and secondary transition temperature for the second member of each series. This maximum is interpreted in terms of a proposed geometrical intermolecular interlocking which is considered to be at a maximum for the second member of the series and serves to restrict the submolecular motions associated with the transitions. The proposal is discussed in terms of its consequences upon free volume, density, cohesive energy density, and chain flexib