Polyphthalamide is a thermoplastic synthetic resin of the polyamide (nylon) family that is used to replace metals in high temperature automotive applications, as the housing for high temperature electrical connectors and multiple other uses. It has found a degree of favor for use in cutlery.
As a member of the nylon family, it is a semi-crystalline material composed from a diacid and a diamine. However, the diacid portion contains at least 55% terephthalic acid (TPA) or isophthalic acid (IPA). TPA or IPA are aromatic components which serve to raise the melting point, glass transition temperature and generally improve chemical resistance vs. standard aliphatic nylon polymers.