Textures in thin films of polyvinyl chloride

Conclusions

The electron-diffraction study of thin films of two types of low-molecular PVC obtained by evaporating the solvent from a dilute solution of the polymer on a water surface has revealed the existence of a preferred orientation of the crystallites, namely, an axial texture, the axis of which is perpendicular to the surface of the film.

The texture axis in the case of unheated films is one of the crystallographic axes (in the present case the c^* axis, along which the axes of the molecular chains extend). On heat-treating the electron-diffraction specimens (polymer I) an [0kl] direction of the reciprocal lattice (in our case the [013] and [015]) may be revealed on the texture axis; if we form the film on an anisotropic base, for example, on the cleavage of an NaCl single crystal, yet another axis of the lattice, a^*, takes a preferred orientation (or more precisely the a^* axis has two preferred directions of orientation perpendicular to each other).

Analysis of the electron-diffraction photographs of these textures has led to the conclusion that the crystal structures of both types of PVC studied are the same as that proposed by Natta et al. for another type of low-molecular PVC [1] (possible obtained by using metallo-organic catalysts [1, 14]).