Characterization of polymers in large deformation by repeated chemical stress relaxation of vulcanized rubbers

Summary

In this investigation, the repeated chemical stress relaxation measurements were carried out to observe the relaxation behaviors at large deformation.

It was found that the repeated chemical stress relaxation curves were affected by both temperature measured and extension ratio of rubber. It was suggested from the results obtained that temperature and mechanical stimulus have a similar effect on the stress relaxation curves. Thus we propose the followingArrhenius type eq. [1] for high extension ratios.${{f(t)} \mathord{\left/ {\vphantom {{f(t)} {f(0)}}} \right. \kern-\nulldelimiterspace} {f(0)}} = \exp (A \cdot e^{\frac{{E_f }}{\alpha }} \cdot t).[1]$

Where,α is the extension ratio, andA, andE _f are the constants determined experimentally. On the other hand, from eq. [1] and usualArrhenius equation, the universal eq. [2] for the extension ratio and the temperature in large deformation was derived as follows,$\begin{gathered} \ln \{ (\ln f(0)/f(t))/t\} - E/R(1/T_0 - 1/T) \hfill \\ = \ln A - E_f /\alpha [2] \hfill \\ \end{gathered}$ where,T ₀ is adequate temperature. The curves obtained for different temperatures and extensions were very well consistent with those by eq. [2] in large deformation.