The drawing and heat-treatment in dimethylformamide or dimethylacetamide aqueous solution were performed for poly (metaphenyleneisophthalamide) films, and the most suitable conditions on the concentration, temperature of swelling solution and the time of treatment were decided. Under the suitable condition, the films were drawn to 6 or 7-fold of the initial length. The initial modulus and tensile stress at break of the high-drawn specimens increased to as much as 5 or 6-fold of those of un-drawn one, and the change of elongation at break with draw ratio showed a maximum value. When the drawn specimens were heat-treated, the initial moduli increased much more.
Above method for the drawing and heat-treatment can be made more easily than Du Pont's method, in which high-pressure steam is used. Also, changes in fine structure of the films by drawing or heat-treatment were investigated by optical and X-ray methods. From the results, it was clarified that the degree of orientation by optical method increased rapidly at the early stage of drawing, and changed gradually after the draw ratio 3. When the drawn specimens were heat-treated, the degree of crystallinity and orientation increased remarkably.