Temperature Influence on Fatigue Fracture of Nylon 6 Clay Hybrid Composite Materials

Abstract

Nylon 6 clay hybrid (NCH) composite consists of nano-sized Montmorillonite and nylon 6 matrix. Tensile tests at near glass transition temperature (35°C, 50°C) were conducted at a strain rate of 10^-2s^-1. Fatigue tests were performed with a stress ratio of 0.1 and frequency of 0.1Hz. Although the tensile strength and fatigue strength of 2 mass percent clay reinforced composite (NCH-2) were the highest at room temperature, the tensile strength and fatigue strength of 5 mass percent clay reinforced composite (NCH-5) became the highest at 35°C. Fatigue fracture surfaces showed that fatigue fracture of NCH-2 wais brittle at room temperature, but ductile at 35°C, while fatigue fracture of NCH-5 was brittle at both room temperature and 35°C. A parameter based on elliptical zone area was proposed to express fracture toughness of the composites, which was not dependent on number of cycles to failure.