Abstract
Changes in fine structure with drawing of poly[tetrafluoroethylene-co-(perfluoroethylvinylether)] (abbrev. PFA) transparent thin films and fibers were investigated by wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) methods. The PFA is random copolymer containing comonomer units of fluorinated ether derivatives as the side-chain in the repeating tetrafluoroethylene backbone. This polymer is crystallized as lamella crystal in their thin films and fibers although polytetrafluoroethylene itself usually forms extended-chain crystals because of their inflexible and rigid nature of 13/6 helices. PFA are exhibited thicker lamella thickness at least 30 nm by the SAXS measurement than general hydrogenated crystalline polymer. In these copolymers, we consider the formation of 'switchboard-type' lamellae model according to P. J. Flory's suggestion. With increase in elongation to their thin film, the four points SAXS diagrams has developed in the photograph of PF A transparent films, which means that a particular kind of layer structure is formed, alternately tilted lamella arrangements as a 'Herring-bone'.
