Structural studies of polyesters. I. Crystal structure of polyglycolide

Abstract

Abstract In the course of structural study of aliphatic polyesters, the crystal structure of polyglycolide, the simplest polyester of the type [(CH 2 ) z COO] n was determined by interpretation of the X‐ray diffraction patterns of the fibers. The crystallographic data are: a = 5.22 Å, b = 6.19 Å, c (fiber axis) = 7.02 Å, the orthorhombic spacegroup, Pcmn‐D . Two molecular chains pass through the unit cell. The crystal structure was determined by the help of two dimensional and three dimensional FOURIER syntheses. The planar zig‐zag chain molecules form a sheet structure parallel to the ac plane and have not the polyethylene type arrangement. High density of the crystallite, 1.69 g/cm 3 , namely the tight molecular packing and the close approach of the ester groups might stabilize the crystal lattice and contribute to the high melting point of this polymer.