Application of in situ vapor sorption small-angle neutron scattering (SANS) to semicrystalline polymers: vapor pathway and structure evolution in semicrystalline linear polyethylene

SANS has not been successfully applied to study the structure of semicrystalline polyolefins without deuterated polymers because of the fundamental limitation of negligible contrast between the crystalline and amorphous phases in spite of the mass density difference. The proposed in situ vapor sorption SANS technique circumvents this limitation and enables structural changes to be studied quantitatively with sorption of a contrast-generating vapor. The results verify the long-standing assumption that vapor selectively diffuses into the amorphous regions of semicrystalline polyethylenes. The proposed technique makes it possible to correlate the structure, sorption isotherm and diffusion coefficient, which is not possible using conventional gravimetric methods.