Poly(p-phenyleneterephthalamide) yarn of improved fatigue resistance

Poly(p-phenyleneterephthalamide) yarn having an apparent crystallite size in the range of 40 to 50 A, an orientation angle in the range of 20.degree. to 30.degree., an elongation in the range of 4.5 to 5.6%, a tenacity of at least 18 grams per denier and a modulus of at least 200 grams per denier, but less than 450 grams per denier.