Microphase Separation in Strain-Crystallizing Rubber

Based on a microscopic
numerical model, we describe strain-induced
crystallization in rubbers as a cooperative phenomenon governed by
the formation of crystal superstructures. The main paradigm is that
crystallization is faster than the relaxation of the matrix and can
be modeled as a local process. During mechanical cycling, a microphase
separation is observed, which is driven by more efficient strain regulation
of parallely arranged crystals and even emerges without local interaction
between crystals. By introducing direct crystal–crystal interaction,
we are able to reproduce critical experiments performed on natural
rubber. Our study suggests that strain crystallization, specifically
its reinforcing and crack propagation inhibiting effects, cannot be
fully understood on the level of a single crystal alone.