Studies on thermo-oxidative degradation of synthetic rubbers 1-4 and 1-2 polybutadienes

Abstract

The production of natural latex is limited, and the related demand for terrestrial transportation has increased. The synthesis of rubber has become necessary and the resulting synthetics’ properties must be known. Thermooxidative degradation of synthetic rubbers 1,4- and 1,2-polybutadienes caused by heating the compounds at 100°C in the air, was monitored. The volatile compounds released during the degradation were identified using coupled modern physical methods, including NMR, TGA, MS, FTIR, etc.. Thermal gravimetric analysis showed that oxidation occurred for both 1,4 and 1,2-PB. Below 400°C, major functional groups were formed, including peroxides, ketone, aldehyde, ester, etc.. Oxidation was found to start on the methylene (CH₂) carbon of 1,4-PB and on the methylene (CH₂) and methine (CH) carbons of 1,2-PB. The polycyclohexane-like structures were identified resulting from the oxidation of 1,2-PB. Above 400°C, the main resulting compounds were carbon dioxide, carbon monoxide, water, and some hydrocarbons and aromatics. Radical mechanisms for thermo-oxidative degradation of 1,4 and 1,2-PBs were proposed.