Time dependence of crack healing

We propose that crack healing in polymers occurs by the stages of surface rearrangement, surface approach, wetting, diffusion, and randomization. The stages of wetting and diffusion are responsible for the majority of the mechanical property recovery or healing, and control the intrinsic healing function Rh(t). However, the observed macroscopic recovery R is a convolution product of Rh(t) and a wetting distribution function Φ(t). Each Rh(t) function contains a wetting and diffusion component. Experiments were designed to investigate intrinsic healing functions for fracture stress, strain, and energy; the results were found to be in excellent agreement with theory.