Performance Consistency and Recyclability of Injection Molded Thermoplastic Bumpers

A study was conducted to evaluate the effects of using post-processor polymer regrind on the impact performance of an injection molded thermoplastic bumper. An unfilled, impact-modified polycarbonate/polybutylene terephthalate (PC/PBT) alloy was evaluated because this material is widely used in the automotive industry in bumper applications - making regrind material readily accessible - and because it displays excellent impact resistance at both room and low temperatures. Samples of 100% regrind and 100% virgin polymer were injection molded separately in a prototype bumper tool.

The molded parts (designated as virgin or regrind) were then tested according to Federal Motor Vehicle Safety Standard (FMVSS) 581. Only barrier impact tests were conducted. Impacts were conducted at speeds of approximately 8 km/h (5 mi/h). Half of the virgin and regrind bumpers were tested at room temperature (22C/77F), and the balance were tested at approximately -30C (-22F). Test results were then collected and examined for differences in deflection, impact load, and performance consistency. Preliminary results from this study are discussed here.