| Abstract: | Conclusions 1. With an increase in the stretching temperature up to a definite limit (170°C) the tensile strength of PETP and other fibres from crystalline polymers increases. However, at higher temperatures (230°C) the strength diminishes. This is evidently due to a reduction in the density of the intercrystallite regions of the fibrils, in which there is greater probability of polymer failure originating. Such behaviour of fibre made from PETP at elevated stretching temperatures is evidently associated both with the polymer structure and with its low molecular weight.2. For the preparation of a PETP fibre with high mechanical strength high orientation is a necessary but not sufficient condition; the fibre must be strengthened at these temperatures in order to form dense intercrystallite regions in the fibre fibrils together with a high degree of orientation.May we express our gratitude to Yu. A. Zubov and V. I. Selkhova (L. Ya. Karpov Physico-Chemical Scientific Research Institute) for the x-ray determination of the structure of the fibres investigated and also for the interest shown in discussions on the present.All-Union Synthetic Fibre Research Institute. Translated from Khimicheskie Volokna, No. 3, pp. 43–45, May–June, 1969. |
