THERMOREVERSIBLE GELATION AND PLASTICIZATION OF POLYACRYLONITRILE

The behaviour of highly concentrated polyacrylonitrile propylene carbonate (PAN PC) solutions with up to 70% polymer is reported. The PAN powder obtained from the slurry polymerization method was very porous and hence it was able to hold a large volume of liquid PC at room temperature, while remaining a free-flowing powder. On compression moulding the PC-blended powder, the PAN 'melted' like a thermoplastic and a moulded sheet was formed on cooling. X-ray diffraction showed that the plasticized sheets contained crystallites of PAN. There was a change in the crystallite structure in the PAN-PC moulded sheets compared with the reactor powder, and it is postulated that PC is incorporated in the crystallite lattice of the former. This would be an interesting case of polymer crystallization.