PMID 28776036. ^ The majority of polyurethanes are thermosets, even so some thermoplastics may also be made, for instance spandex ^ PP&A stand for polyester, polyamide and acrylate polymers; all of that are used to make artificial fibers. Care ought to be taken not to confuse it with polyphthalamide (PPA) https://protectivevents26702.total-blog.com/protective-vents-fundamentals-explained-61745290