Morphology and crystal structure in single crystals of poly(p-phenylene terephthalamide) prepared by melt polymerization

Abstract

Using the confined thin film melt polymerization technique lamellar single crystals, of two morphologies, have been grown for poly(p-phenylene terephthalamide). Electron diffraction (e.d.) patterns from these crystals and from fibre-like samples polymerized from sheared monomer, are in best agreement with a modified phase I cell. The lattice parameters (a = 7.88, b = 5.22, c = 12.9 Å; α, β, γ = 90°) are similar to those in previously proposed cells, but the Pla1 space group rather than Pn or P21/n space groups more closely fits the e.d. data. In particular, 210, 120, 320 and 410 reflections are present with moderate intensity, which are forbidden for the latter structures and do not result from double diffraction.