Thermodynamics of perfect polymer fibers in tension: failure work, strength, modulus, volume, entropy, enthalpy, and melting: Comp. Theor. Polymer Sci., 1997, 7, 139

Abstract

Summary For three decades a repeated claim that stretched crystalline polymer fibers fail because intramolecular covalent bonds rupture under sufficient stress still remains an unproven assertion. From the outset this idea has been counter to scientific intuition. Consider that the energy of carbon-carbon bonds is ca. 80 times larger than the fusional heat of methylene units in polyethylene molecules. Should a completely crystalline, perfect polyethlene fiber be reversibly stretched isothermally, could not one reasonably expect the fiber to fail by melting (i.e., molecular slippage) before tensile work gains sufficient heights to induce bond scissions? Then how can the stretched fiber avoid prior failure via stress-induced fusion if it must conform to a bond scission mechanism of much higher work content? This is the essence of the problem investigated theoretically in the title paper. It concludes that melting is almost certainly the mechanism of failure, possibly excepting highly infusible materials.