Abstract
This paper analyses the influence of the grind percentage on some mechanical properties of various injection-molded items in the automotive industry, which are made of acrylonitrile butadiene styrene (ABS), polyamide 6.6 (PA 6.6) and polyoxymethylene (POM). The specimens had the following compositions: new material 100%, new material 80% + grind 20%, new material 60% + grind 40%, new material 40% + grind 60%, new material 20% + grind 80% and grind 100%. The mechanical properties were measured using tensile tests, the Izod impact test and the Shore Durometer hardness test. It was observed that the hardness of the three tested polymers is not significantly influenced by the increase in grind percentage. The shock resistance of ABS and PA 6.6 decreases when the grind percentage is increased, while for POM the increase in grind percentage leads to an increase in shock resistance. The tensile strength at break decreases when the grind percentage is increased from 0% to 40% for ABS and POM. The further increase in grind leads to a slight increase in the tensile strength at break. In the case of PA 6.6 the tensile strength at break increases along with the increase in grind percentage. Keywords: acrylonitrile butadiene styrene (ABS), polyamide 6.6 (PA 6.6), polyoxymethylene (POM), tensile tests, the Izod impact test, the Shore Durometer hardness test