Elastic moduli of highly stretched tie molecules in solid polyethylene

Abstract

The elastic properties of interlamellar bridges in semicrystalline polyethylene (PE) were estimated from the molecular-mechanics calculations on the assumption that the energy loading of a chain backbone represents the principal deformation mechanism. The calculations result in the force–length functions featuring abrupt discontinuities due to sequential annihilation of the defects by the conformational transitions. The correlation of the chain elastic moduli E with the concentration of defects in the chain and with the chain extension ratio x were established. The distribution functions ζ(E) of Young's moduli of interlamellar bridges in semicrystalline PE were calculated by using the literature data on the chain length distributions of tie molecules. The impact of the distribution function of moduli ζ(E) on the overall elastic response of solid PE materials was examined, particularly in cases of the stacked lamellae morphology involving so-called hard elastic PE.