Mechanical anisotropy in rolled nylon 66

Abstract

AbstractThe nine independent stiffness constants Cpq for rolled nylon 66 at thickness reduction ratios λt = 2.4, 4.9, 7.6 have been measured from −40 to 50°C by an ultrasonic method at 10 MHz. Analysis of x‐ray pole figures indicates that at high λt the material has a uniplanar‐axial texture, with hydrogen‐bonded (010) planes parallel to the roll plane and the molecular chains along the roll direction. The mechanical behavior is determined not only by the alignment of molecular chains and hydrogen bonds but also by the microfibrillar morphology. On the basis of this idea the magnitudes of the tensile moduli along the three principal axes can be understood in terms of the Takayanagi model. The effects of water absorption have also been investigated.