INHIBITION OF DEGRADATION IN STYRENE-BASED THERMOPLASTIC ELASTOMERS BY HYDROGEN-DONATING HYDROCARBONS

The effects of hydrogen-donating hydrocarbon additives derived from pe troleum (HHAPs) on styrene-based thermoplastic elastomers, styrenebuta diene-styrene (SBS) and styrene-isoprene-styrene (SIS), during mixing at 180 degrees C in air were investigated and the following results we re obtained: (1) Changes in torque, temperature, gel fraction, mechani cal properties and molecular weight distribution were investigated for SBS (crosslinking is the main cause of degradation), and mechanical p roperties and molecular weight distribution were studied for SIS (scis sions are the main cause of degradation). (2) The obvious effects agai nst these types of degradation can be attributed to the high radical s cavenging abilities of the additives. Thus, the inhibiting effects cor respond precisely to the reaction rates with DPPH (2,2-diphenyl-1-picr ylhydrazyl). HHAPs are new conceptual inhibitors because of their pure hydrocarbon constituents without functional groups containing heteroa toms, and they are interesting enough to be investigated further.