Effect of crystallinity on the properties of nylons

Increasing the degree of crystallization of unoriented 66 or 610 nylon increases the stiffness, yield point, tensile strength, and hardness, but reduces the impact strength, particularly in the high crystallinity range. The impact strength was increased by increasing the molecular weight, but the other properties were substantially unchanged. The effect of varying water content was independent of the effect of varying crystallinity and generally acts in the opposite direction.