Temperature effects fracture energy affected

The increase of temperature has a fourfold effect on the number of free radicals observed at the point of macroscopic fracture. Firstly as seen previously the bond strength is decreased and thus chain scission at a given molecular stress is facilitated. Secondly the decrease in intermolecular attraction and the increase in molecular mobility lead to more rapid relaxation of molecular stresses. For the same reason — thirdly — the density of stored elastic energy at a given strain level is decreased which will in turn affect crack stability and propagation. Fourthly, the increased reactivity of the free radicals may lead to an increased discrepancy between the concentrations of radicals formed and of radicals observed at the point of failure. 

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