Investigation of structural changes of polyacrylonitrile on swelling. Wide-angle X-ray scattering study

Polyacrylonitrile samples swollen in a system of polymer plus low-molecular-weight substance have been investigated by means of wide-angle X-ray scattering. Nitromethane, pyridine and nitrobenzene have been used as swelling agents. Equilibrium degrees of swelling for these substances have been estimated. Influence of swelling temperature and of kind of swelling liquid on structural changes in polyacrylonitrile has been determined. An explanation of the improvement of order within paracrystalline regions on swelling has been given.