熱延伸熱処理したポリエチレンテレフタレート繊維の伸長と非晶領域の挙動

抄録

Undrawn Tetron polyester filament of low crystallinity was stretched by 6.6 fold and heat-treated at 205°C in an oil bath, where the filament shrank by 25%. The filament was further stretched at 100°C to the original length, and again heat-treated at 200°C allowing shrinkage. This stretching and shrinking cycles were repeated twice. The final length was 80% of the original length. The parameters of the fine structure are expressed: X(X-ray crystallinity)=0.346, f_x (X-ray orientation degree)=0.931, f₀ (over-all orientation degree)=0.571 and f_a (amorphous orientation degree)=0.664.
This stabilized filament was stretched toward the original length at 100°C and the fine structure was investigated at each stretching stage and the following results were obtained.
(1) The crystalline region is stable (X and f_x were kept unchanged during the stretching), while f₀ and f_a increase remarkably. The f_a_??_elongation ratio curve is convex to the draw axis saturating before it reaches the original length.
(2) The stretching degree of amorphous chains, r/nl, was estimated from the filament length.
The curve f_a_??_r/nl agrees well with the one calculated by the Treloar's rubber theory, where r is the end-to-end distance of the chain between net points, the crystallites nl the value of r at the fully stretched state, and_??_^-1 the inverse Langevin function. So the behavior of the amorphous chains within the polyester filament at 100°C or above may be considered to be nearly rubberlike.