Structural studies on polymer whiskers by transmission electron microscopy: I. Morphological and high-resolution observations

The structures of poly(p-hydroxybenzoic acid) (PHBA) whisker crystals and c rystalline fine fibrils of copolymer prepared from p-hydroxybenzoic acid (H BA) and 2-hydroxy-6-naphthoic acid (HNA), namely poly(HBA/HNA) (monomer mol ar ratio: 97/3), were investigated by transmission electron microscopy (TEM ). Rs fbr a PHBA whisker, microfibril-like bright regions were recognized i n the 210 dark-field image. In the high-resolution TEM image of another PHB A whisker, however, lattice fringes were continuous through the whisker, sh owing that the whisker is highly crystalline and almost perfect. On the oth er hand, in the high-resolution images of poly(HBA/HNA) fine fibrils, granu lar crystallites (20- 40 nm in lateral dimension) were observed. The lattic e fringes in the crystallites were not successfully indexed with the orthor hombic unit cells of the homopolymer crystal, suggesting the coexistence of another different structure as a minor component. (C) 1999 Wiley-Liss, Inc .