Diffusion of long molecules through solid polyethylene. I. Topological constraints

It is proposed that the mobility of sufficiently long molecules undergoing translational diffusion through solid polyethylene is significantly reduced by tie molecules and fixed entanglements within the interlamellar regions of the matrix. The effect on the diffusion coefficient both of diffusant molecular length and of the host matrix morphology is considered, and a semiquantitative relation between them obtained. This indicates that the mobility of long diffusants is higher in polyethylene which has been cooled slowly from the melt than it is in quenched polyethylene, in marked contrast to the behavior of gaseous and other small diffusants.