acrylic glass acrylonitrile butadiene styrene alkyl amide amino acid aramid carboxylic acid condensation reaction hydrogen chloride monomer nylon peptide bond plastic polybutylene polybutylene terephthalate polycarbonate polyester polyethylene polyethylene terephthalate polyimide polylactic acid polymer polypropylene polystyrene polysulfone polytetrafluoroethylene polyurethane polyvinyl chloride polyvinylidene chloride protein silk water wool