STRESS-RELAXATION BEHAVIOR OF LOW EPOXIDIZED POLY(STYRENE-B-BUTADIENE-B-STYRENE) TRIBLOCK COPOLYMERS

The stress relaxation properties of low epoxidized poly(styrene-b-buta diene-b-styrene) (ESBS) triblock copolymers were investigated in this study via the stress-relaxation technique. The relaxation of the ESBS copolymers depend on the temperature and oxirane content. ESBS copolym ers at low oxirane contents do not completely obey the common rule tha t the relaxation rate decreases with increasing epoxidization. ESBS wi th 1.9% oxirane has the largest relaxation rate constant. The relaxati on activation energies of the ESBS copolymers with 0-2.4% oxirane were calculated to be about 85 kJ mol-1. ESBS with 1.9% oxirane has the lo west number of chains in stress for relaxation.