Examples of condensation type polymers include polyesters such as polyethylene terephthalate, polybutylene sebacate and unsaturated polyesters derived from phthalic anhydride, maleic anhydride and ethylene glycol or other difunctional alcohol; polyamides, including poly(hexamethylene adipamide), poly(hexamethylene terephthalamide) and polycaprolactam, the acetal resins and polysulfides.