Monte Carlo calculation of SANS for various models of semicrystalline polyethylene

Abstract

Small-angle neutron scattering (SANS) of semicrystalline polyethylene is computed using a Monte Carlo technique similar to that used by Yoon and Flory. Models of polymer chains with substantial amounts of chain folding (with a probability of adjacent re-entry of 0.6–0.8) are shown to give the following: (1) proper density in the crystalline and amorphous regions, (2) the experimentally obtained radius of gyration, (3) scattering close to the experimentally obtained scattering. While SANS alone cannot decisively distinguish between the Yoon and Flory “switchboard” model and models with folds, present indications are that only models with a substantial amount of folding satisfactorily meet all conditions (1)-(3). The “switchboard” model used by Yoon and Flory to explain the SANS of semicrystalline polyethylene is shown not to meet criterion (1) above.