Abstract
In the first part of the paper we touch on the influence of the processing temperature by injection of HDPE, of PMMA, and of PC+ABS blend on some mechanical flexural properties, while the other factors which could influence the injection remain unchanged. In the second part of the paper, we present the influence of the subsequent pressure in the injection of HDPE, PMMA, and PC+ABS blend on mechanical bending properties, while the other factors which could influence the injection remain unchanged. The HDPE samples were obtained at the following injection temperatures – 180, 190, 200, 210 and 220°C – and at the following subsequent pressures – 800, 900, 1000, 1100 and 1200 bar. The PMMA samples were obtained at the following injection temperatures – 220, 230, 240, 250 and 260°C – and at the following subsequent pressures – 450, 550, 650, 750 and 850 bar. The PC+ABS samples were obtained at the following injection temperatures – 230, 240, 250, 260 and 270°C – and at the following subsequent pressures – 500 bar, 600 bar, 700 bar, 800 bar, and 900 bar. We have used the method of determining flexural properties, such as the flexural stress, flexural deformation, and flexural modulus. It was observed that in the case of HDPE, the highest values of flexural stress were registered at its lowest temperature (180°C) – the flexural stress recorded 28,3038 MPa – and at the highest value of subsequent pressure (1200 bar) – the flexural stress recorded 29.3380 MPa. PC+ABS acts in a similar manner to HDPE. In the case of PC+ABS, 240°C recorded the highest value for the flexural stress of 89.2246 MPa, while the highest subsequent pressure of 900 bar recorded the highest value of flexural stress of 88.5375 MPa. In the case of PMMA, the highest value for flexural stress (124.2563 MPa) was recorded at the lowest processing temperature (220°C) and at the subsequent pressure of 550 bar, where the value of the flexural stress was of 110.5376 MPa. In the case of HDPE and PC+ABS, the flexural deformation is barely influenced by the processing temperature and the subsequent pressure, whereas in the case of the PMMA, the processing temperature and the subsequent pressure influence the flexural deformation. The increase in the subsequent pressure leads to a slight increase of the flexural modulus in the case of the three studied polymers. The increase in the processing temperatures of HDPE and PC+ABS leads to a slight decrease of the flexural modulus, whereas in the case of the PMMA, the increase in the processing temperatures barely influences the flexural stress.
Keywords: high density polyethylene (HDPE); polymethyl methacrylate (PMMA); acrylonitrile butadiene styrene polycarbonate blend (PC+ABS; flexural stress; flexural deformation; flexural modulus