High temperature X-ray analysis applied to investigate thermoplastics

Phenomena taking place during heating of specimens made of Tarnamid T-27 (Polyamide 6) and Tarnoform 300 (Polyoxymethylene) in the raw state (after injection moulding) and after annealing were considered. Specimens were annealed in turbine oil at the temperature of maximum recrystallization (Tarnamid T-27 - 170 deg C and Tarnoform 300 - 140 deg C). During heating a change of phase composition and gradual decrease of crystalline phases to zero at melting temperature take place while in Tarnamid T-27 the transformation of crystalline α phase to γ phase also occurs. From X-ray investigations the percentage content of the various phases and the course of changes of crystalline degree as a function of heating temperature were determined. The characteristic parameters of the elementary cells of the crystalline phase in Tarnamid T-27 and Tarnamid 300 were estimated. It was ascertained that the heating increases the content of crystalline phase in the tested plastics on an average by 20%. 6 figs., 4 tabs., 18 refs. (author)