Influence of impurities on mechanical properties of recycled glass fiber reinforced polyamide 66

This work investigates the influences of impurities on the durability and the reliability of the mechanical properties of recycled glass fiber reinforced polyamide 66. A critical size-concentration zone could be determined based on changes in tensile properties of samples containing untreated glass beads of different size and concentrations, which were used as simulated impurities in in-plant reprocessed material. Characterization of samples based on recyclate from post-use radiator end-caps, which contained residues of EPDM rubber, showed that the tensile strength was almost unaffected by rubber particles up to an equivalent diameter, d, of ～700 μm. However, a significant strength reduction commenced for rubber particles larger than 1200–1300 μm, and the strength showed a correlation with d^?1/2. Furthermore, large simulated impurities (425–590 μm) in in-plant material and rubber residues in post-use recyclate showed a negative effect on the mechanical reliability.