US Patent 11505649 Polymerization process

The present invention relates to a process comprising the step of melt-mixing a semi-aromatic polyamide (A) having a melting point on second heating of 295° C. or less comprising terephthalamide repeat units and a polyamide oligomer (B) comprising terephthalamide repeat units and having an amine end group concentration of less than 2000 me q/Kg and an inherent viscosity of at least 0.10, at a temperature which is greater than the melting point on first heating of both semi-aromatic polyamide (A) and polyamide oligomer (B) for a time period sufficient to produce semi-aromatic polyamide (C) having a melting point on second heating which is greater than or equal to 300° C.