Time-crosslink density reduction investigated by photochemical scission

Abstract

Abstract The applicability of a time-crosslink density reduction principle to the terminal region creep behavior of plasticized polyurethane samples was investigated. Such reduction is similar to the well known time-temperature reduction principle, except that variation in a crosslink density, rather than temperature, is responsible for differences observed in material response. The sets of experiments which were analyzed were each carried out on single samples changes in crosslink density were caused by the photo-induced scission of disulfide bonds incorporated in the network. In this way, a high degree of experimental precision was realized. Our results indicate that time-crosslink density reduction is appropriate for this system, but the time scale shift observed here is much less sensitive to changes in crosslink density than previously reported for other systems. Changes in network topology which are not accurately reflected in the crosslink density may be responsible for this difference. Furthermore...