Effects of loading rate and temperature on tensile yielding and deformation mechanisms of nylon 6-based nanocomposites

Tensile tests were conducted on nylon 6/organoclay nanocomposites, with and without POE-g-MA rubber particles, over a range of temperatures and strain rates 10^-4-10^-1 s^-1. It was shown that the 0.2% offset yield strength varied with both temperature and strain rate which could be described by the Eyring equation thus providing results on the activation energy and activation volume for the physical processes involved. In addition, their tensile deformation mechanisms were characterized using the tensile dilatometry technique to differentiate the dilatational processes (e.g., voiding/debonding caused by the organoclay and rubber particles or matrix) and shear yielding (e.g., matrix with zero volume change). Dilatometric responses indicated that the presence of POE-g-MA rubber particles did not alter the shear deformation mode of neat nylon 6. In contrast, the presence of organoclay layers changed the tensile yield deformation behavior of nylon 6 matrix from dominant shear yielding to combined shear yield plus dilatation associated with delaminations of nanoclay platelets. In nylon 6/organoclay/POE-g-MA ternary nanocomposite, the volume strain response indicated that the POE-g-MA rubber particles promoted shear deformation and suppressed delamination of the organoclay layers. Supports for the deformation mechanisms deduced from the tensile dilatometry tests were corroborated by optical microscopy and transmission electron microscopy micrographs of the studied materials.