Viscoelastic properties of UHMW‐PE fibers in simple elongation

Abstract

AbstractStress relaxation after a simple elongational step strain, creep under a constant simple elongational stress, and stress build‐up under a constant Hencky strain rate have been measured for ultrahigh‐molecular‐weight polyethylene (UHMW‐PE) fibers. The data from the various experiments are consistent with the Boltzman superposition principle in the experimental region of small strains or short times. This leads to a simple constitutive equation in which temperature can be incorporated via time‐temperature superposition. The measured power‐law relaxation of the UHMW‐PE fiber leads to analytical expressions for the dynamic quantities in simple elongation.The constitutive equation is the one‐dimensional equivalent of the gel equation derived for cross‐linking gels at the gel point. The similarity between the rheological behavior of fibers and cross‐linking gels at the transition point might lead to an enhanced understanding of the molecular processes occurring during deformation.