Thermo-oxidative processes polyamides

During the first 100 h of oxidation there were no significant differences between the samples, i.e. they all seemed unaffected by thermo-oxidation and no influence of repeated processing was found [65]. However, after 500 h of thermo-oxidation, all recycled samples showed a marked deterioration in tensile strength whereas the virgin material remained unaffected. The magnitude of the decrease in tensile strength corresponded well to the number of times the material was extruded. After 1200 h of thermo-oxidation the deterioration in mechanical properties was even more pronounced and at this point the polyamide 6.6 recycled three times retained only 20% of its... 

The comparison of the results obtained in this study for the LCP degradation imder processing temperatures with the peculiarities of some thermally stable polyheteroaiylenes degradation [14] brings to light some common features carbonization of the structure, H2 evolution, improvement in thermo-oxidative stability with transition metal compoimds. That is why we took into accoimt the stabilization of polysulfones, aiyl-aliphatic polyimides, polyamides etc. The approach to such stabilization is based on the following proposals on the mechanisms of the above said polymer degradation ... 

---