Structure-microhardness correlation in blends of nylon 6/nylon 66 monofilaments

The microstructure (crystallinity, long spacing) and the micromechanical pr operties (microhardness H) of two series of nylon 6 and nylon 66 monofilame nts and their blends were investigated as a function of annealing temperatu re T-A and uniaxial deformation in a wide composition range. In case of the homopolymers, the gradual rise of microhardness with T-A is interpreted in the light of the increasing values of the crystallinity alpha and the hard ness of the crystals H-c. The depression of the hardness values of the blen ds from the additive behavior of the hardness of individual components is d iscussed in the basis of the crystallinity depression of one component by t he second one and viceversa. Finally, the influence of drawing and pressing the blends at 130 degrees C which leads to a hardness increase is also exp lained in the light of an increase in the H-c value of nylon 66 due to orie ntation. (C) 2000 John Wiley & Sons, Inc.