PMID 28776036. ^ The majority of polyurethanes are thermosets, nevertheless some thermoplastics are also made, For example spandex ^ PP&A stand for polyester, polyamide and acrylate polymers; all of which can be used to make synthetic fibers. Treatment really should be taken never to confuse it with polyphthalamide (PPA) ^The Screw-In Series of Go