A study on the thermal degradation of rubber in dilute solutions

The kinetics of low‐temperature (60–100°C.) thermal degradation of deproteinized and deresinified petroleum ether soluble fraction of natural rubber in two chemically inert solvents, cyclohexane and trans ‐decalin, have been studied. The changes in M w , A 2 , and ( r 2 ) 1/2 at various stages of degradation have been obtained from the lightscattering data. The rate constants and the energy of activation for chain scission have been calculated from the observed variation in M u . The scission has been found to be random and the average energy of activation is 25.8 kcal./mole. This low‐energy requirement suggests the presence of weak links in the rubber molecule which get ruptured at low temperature.