Calcium carbonate filled polyethylene: correlation of hardness and yield stress

Abstract The validity of the correlation between hardness and yield stress of particulate composite materials was investigated. Vickers hardness and monotonic tensile and compression tests have been carried out on calcium carbonate–polyethylene composites at various testing speeds ranging from 0.2 to 50 mm min−1. It was found that Tabor's relation was conceivable when the yield stress was determined from compression test, but not from tensile test. This is associated with the difference in the role and degree of crack formation between two testing modes. The correlation was also found to be rate dependent and Tabor's relation was valid when the deformation rate in hardness and yield determination tests were comparable.