Abstract
Fine structure of polyester fibers prepared by the necking drawing of various undrawn fibers was investigated.
The results obtained are as follows;
1. The birefringence of the necking region and the necking draw ratio of polyester fibers are strongly influenced by preorientation of undrawn fibers. For an isotropic undrawn polyester fibers, the maximum value of birefringence of the necking region and necking region and necking draw ratio were about 0.200 and 6 times, respectively.
2. The birefringence of the necking region (Δnneck) vs necking draw ratio curves at low necking draw ratio for various undrawn fibers can be interpreted by Kuhn and Grun's theory for rubber photo-elasticity, and at high necking draw ratios, it agrees with Kratky's ‘first borderline case’.
3. The experimental coefficients of Kuhn and Grun's theory, and K2=NkT increase with increasing pre-orientation of undrawn fibers.
4. The crystallization induced by necking is dependent only on the necking draw ratio of the samples.
5. The highest density obtained by means of necking drawing method was 1.369g/cm3 and the crystal structure of this sample is smectic at high orientation.
