BEHAVIOR OF ETHYLENE-PROPYLENE ELASTOMERS IN SALT-SOLUTIONS .2. HEAT-CAPACITY

An investigation of changes in heat capacity for irradiated ethylene-p ropylene elastomers between 335 and 430 K is presented. DSC measuremen ts were carried out in an argon atmosphere. The O'Neill method was use d for c(p) calculation. The degradation process influenced the thermal behaviour of the tested elastomers EPR (thickness of 1.0 mm) and EPDM (thicknesses of 0.5 and 1.0 mm) by forming oxygenated products and by material crosslinking during gamma irradiation. The main feature of t he changes in heat capacity dependence on irradiation dose is the chem ical involvement of the irradiation environment (air, distilled water, 0.1 and 10% NaCl solutions). Some mechanistic aspects concerning radi olysis of ethylene-propylene elastomers in the presence of oxygen, wat er and chloride ions are discussed. The relationships between c, and t esting temperature are presented for all experiments. (C) 1997 Elsevie r Science Limited.