Conversion of work of deformation to heat in polymers

The time dependence of the conversion of mechanical work of deformation to heat in polymers is investigated using viscoelastic models. The deformation chosen is a constant strain rate, $\text{?}\text{?}{}_0$, in tension for t?t₀ and a constant strain $\text{?}{}_0\text{=}\text{?}\text{?}{}_0\text{t}{}_0$ for t?t₀. For a simple Maxwell model with only one relaxation time, τ, the ratio of heat produced to work done (‘conversion fraction’) is calculated as a function of time for different values of $\text{t}{}_0\text{τ}$. At t=t₀ the conversion fraction is high only when τ?₀. For a continuous Maxwell model with a distribution of relaxation times H(τ) we obtain the result that the conversion fraction is near 100% at t=t₀ if H(τ) is not peaked strongly in the region τ>0·1t₀ but extends with reasonable values into the region τ < 0·1t₀. A formula is given which allows the calculation of the conversion fraction at t=t₀ from the distribution of relaxation times H(τ).