Crystal Structures of Polyamides X 18 Made from Long Alkyl Dicarboxylic Acid

Abstract

Morphologies and crystal structures of a series of even−even polyamides X 18 have been investigated using transmission electron microscopy (TEM) and wide-angle X-ray diffraction (WAXD), where X varies from 2 to 12. It is shown that solution-grown crystals of these polyamides are lath-like lamellae, which consist of chain-folded hydrogen-bonded sheet. Selected-area electron diffraction reveals that both αp phase and βp phase present in these samples except for polyamide 2 18, while the latter only shows αp crystal structure. Moreover, the unit cell parameters of all polyamides under consideration are obtained based on electron diffraction and WAXD results.