Dynamic Tensile Behavior and Light Transmittance of Cyclo-Olefine Polymer/Clay Composites

Abstract

To design the transparent automobile interior and exterior components under crash loading, it is necessary to understand the dynamic mechanical properties as well as the transparency. This paper characterizes the tensile behavior of a thermoplastic amorphous resin, cyclo-olefine polymer (COP) and COP/clay composites, at the dynamic strain rate. Moreover, the present research attempts to study the effect of the total amount of clay content on the mechanical properties such as the apparent elastic modulus, the yield strength, the fracture strain and the strain energy up to failure. Meanwhile, the influence of the amount of clay content on the transparency of the COP/clay composites is also investigated. The studied blend ratios are COP/clay = 100/0, 99/1, 98/2 and 95/5 vol%, respectively. Dynamic tensile tests are conducted at the nominal strain rates of 0.1 s-1, 1 s-1, 10 s-1 and 100 s-1. It is found that the total light transmittance is reduced by about 13% in the case of blending 1 vol% of clay particles, compared to that of neat COP. The apparent elastic moduli of COP and COP/clay composites show the weak sensitivities of the strain rate and the clay content. However, the absorbed strain energy up to failure has the strong dependencies of the total amount of clay content as well as the strain rate. It appears that the material ductility of COP/clay = 99/1 vol% is the largest among all the blends at the nominal strain rate of 100 s-1. It is considered that such morphology, in which the small content of clay particles is blended, can nucleate the initiation of nano voids leading to the stress concentration in the adjacent matrix and then fibrillation of the matrix polymer, which results in the ductile fracture mechanism.