Abstract
A “crystalline” and flexible film with high transparency was developed by uniaxially drawing of fluorinated copolymer. For the practical use of “crystalline” film-type optical waveguide in the near future, an accurate control of the solid-state structure is indispensable because of the necessity of reducing light refraction at the crystalline/amorphous interface. In the present study, changes in the lamella arrangement and molecular mobility in the amorphous region upon fixed annealing and free shrinkage after drawing poly[tetrafluoroethylene-co-(perfluoroethylvinylether)] (abbrev. PFA) transparent crystalline films were investigated by using small-angle X-ray scattering (SAXS) method and dynamic viscoelastic measurement. The PFA was crystallized as a lamella crystal in the films and formed a thicker lamella. Upon the drawing of the PFA films, four-point SAXS diagrams developed in the photograph at through direction to the film, which implied that a particular type of layer structure, an alternately tilted lamella arrangement known as the herringbone, was formed. From the result of SAXS measurements, it is found that changes in lamella arrangement with shrinkage. From the result of dynamic viscoelastic measurement, it is found that fixed annealing film was formed rigid amorphous fraction. In contrast, free shrinkage film disorganized the rigid amorphous fraction.
