Grinding Behaviors of Polystyrene and Polycarbonate by Ball Mill

Abstract

Mechanical degradation of polystyrene (PS) has been studied kinetically by a ball mill with various sizes of balls at a constant velocity of revolution (60rpm) and packing ratio (30%) at room temperature. The sizes of steel balls used were 91, 51, 31, and 26mm in diameter. The degree of degradation was determined by measuring the number-average chain length at various stages of mechanical degradation. The extent of degradation was represented by the rate constant of degradation and the final average chain length. The order of effective size of balls for the degradation of PS was 51>31>26>95mm.
The mechanical degradation of polycarbonate (PC) was also carried out at the same conditions. The order of effective size of balls for the degradation of PC is 95>51≥31≥26mm.
In order to know the interaction between PS and PC during the mechanical degradation in a ball mill, the mixtures of PS and PC with various mixing ratios were also ground with balls of 95 mm in size. The rate of degradation of PS was increased in the presence of PC, while that of PC was decreased.
These results are used to discuss the grinding behaviors of polymer in a ball mill.