Comparison of ethylene-styrene interpolymers and ethylene-octene copolymers

Comparisons between ethylene-styrene (ES) and ethylene-octene (EO) polymers were made by elucidating melting behaviour and by measuring dynamic mechanical behavior and tensile properties. At comonomer contents of 5 to 10 mole%, ES and EO polymers were found to have lamellar and micellar crystals. With 10 to 20 mole%, only micellar crystals were present. For low comonomer containing ES and EO polymers, the mechanical relaxation spectra contained alpha- (interfacial mode) and beta- (glass transition) dispersion peaks. As the comonomer content increased, the alpha- transition disappeared. Tensile properties indicated that low comonomer polymers exhibited mechanical behavior typical of ductile crystalline thermoplastics. At high comonomer contents, EO and ES were elastomeric. Structure-property relationships of elastomeric EO and ES polymers were analyzed with classical rubber and slip-link theories.