| Abstract: | Polypropylene powder has been moulded by the application of ultrasonic vibrations and attempts have been made to optimize the strength of the mouldings. The most important variables are the duration of the ultrasonic vibrations and the subsequent dwell time during which the pressure is maintained. It was also found that the smaller the particle size of the powder the greater was the tensile strength of the mouldings. The compaction pressure did not have any significant effect on strength.Under the best conditions a tensile strength of 20 MPa was recorded, which is about 85% of the value achieved by injection moulding. However, the ductility of the mouldings was always considerable less than that which would normally be expected from polypropylene. |
