X-ray diffraction and TGA studies on annealed PPT Twaron fibers and powder

Twaron fiber is spun from the polymer poly(paraphenylene terephthalamide), PPT, and has a crystallinity of 82%. Wide-angle X-ray diffraction, combined with the multipeak resolution procedure, was applied to study the changes in the structure after annealing the fiber in the temperature range of 100-675 degrees C. The structural parameters included crystallinity (crystalline order), microparacrystal (mPC) size, and netplane spacing. A thermogravimetric analysis (TGA) was made to determine the loss in mass of the fiber in the temperature range in which the annealing study was carried out. Crystallographically-disordered (amorphous) powder of the PPT polymer was prepared by grinding crystalline Twaron fibers, which had a crystallinity of 87%, in a vibratory ball mill for a period of 64 h. A study was then made to determine the extent to which the original crystallinity or mPC size is restored after annealing the powder in the temperature range of 100-425 degrees C.