Abstract
This paper presents the influence of subsequent pressure of high-density polyethylene (HDPE), polymethyl methacrylate (PMMA), polycarbonate and acrylonitrile butadiene styrene blend (PC+ABS) on some mechanical properties when obtained through the injection of items from various industries. The HDPE samples were obtained at the following subsequent pressure: 800 bar, 900 bar, 1000 bar, 1100 bar, and 1200 bar. The PMMA samples were obtained at the following subsequent pressure: 450 bar, 550 bar, 650 bar, 750 bar, and 850 bar, and PC+ABS samples were obtained at the following subsequent pressure: 500 bar, 600 bar, 700 bar, 800 bar, and 900 bar. Determining the mechanical properties was made using determining methods of tensile properties, of Izod impact test, and Shore Durometer hardness test. It was observed in the case of the three analyzed polymers that increasing the subsequent pressure when injecting HDPE leads to a slight increase of hardness, and in the case of PMMA and PC+ABS blend, an increase in the subsequent pressure leads to a decrease in hardness. The Izod shock resistance for HDPE and PMMA decreases along with the increase of the subsequent pressure. In the case of PC+ABS, an increase of the subsequent pressure from 500 bar to 700 bar leads to a decrease in the shock resistance from 68.675 kJ/m² to 51.475 kJ/m². A further increase in the subsequent pressure to 900 bar leads to an increase in the shock resistance up to 63.900 kJ/m². The tensile strength at break is influenced by the subsequent pressure. An increase in the subsequent pressure in case of HDPE and PC+ABS blend leads to an increase in the resistance of the tensile strength at break, whereas in the case of PMMA, an increase in the subsequent pressure leads to a decrease in the resistance of the tensile strength at break. Keywords: high density polyethylene (HDPE), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene polycarbonate blend (PC+ABS), tensile tests, Izod impact test, Shore Durometer hardness test