"Examples of such structural polymers include polyolefins such as polybutylene, polypropylene (either homopolymers or copolymers with ethylene), polyethylene homopolymer or co- or terpolymers of ethylene with other monomers such as vinyl acetate, carboxylic acids, such as acrylic acid, or methacrylic acid (with or without neutralization to form ionomers), polyethylene terephthalate or its copolymer" . . . .