EFFECT OF PROCESSING ON THE RECYCLABILITY OF NYLON-66 POLY(2,6 DIMETHYL-1,4 PHENYLENE OXIDE) (PPO) ALLOYS

The recyclability of two commercial nylon 66/PPO [poly(phenylene oxide )] alloys has been investigated by examining the effects of multiple a nd abusive melt processes upon the impact strength. The loss of perfor mance associated with these exposures has been correlated, in one inst ance, with the thermal degradation of polybutadiene-based impact modif ier. The degradation of the rubber has been quantified using an indire ct measurement of rubber mobility obtained from the NMR free induction decay of mobile and rigid protons in the material. Substitution of th e unsaturated rubber modifier with a saturated hydrocarbon resulted in improved recyclability. Both formulations provide evidence of changes In morphology related to instability of the dispersed PPO phase. The coalescence of PPO particles, evident in later stages of prolonged the rmal exposure, appears to cause further loss of impact strength. Curre ntly the chemical and/or physical changes responsible for the increase in average PPO particle size are not known. It is probable that the t hermal stability of the compatibilizer, formed during the reactive ext rusion manufacturing process, may be insufficient to provide a durable morphology for repeated recycling of these alloys.