HDPE HDPE for greater strength and stiffness than LDPE. High Impact Polystyrene High Impact Polystyrene is a low st, tough plastic, easy to thermoform and fabricate. KYDEX Thermoplastic Sheet KYDEX Thermoplastic Sheet, outstanding toughness, appearance and formability. HENAN Okay HENAN Okay; stiff, strong plastic, outstanding bearing and wear properties.