① most plastic quality light, chemical sex stable, not rust; II resistance impact sex good; ③ has better of transparency and wear consumption sex; II insulation sex good, thermal conductivity sex low; ⑤ General forming sex, and coloring sex good, processing cost low; ⑥ most plastic heat sex poor, hot expansion rate big, easy burning; sadly size stability poor, easy deformation; ⑧ most plastic resistance low temperature sex poor, low temperature Xia variable crisp; Krispy Kreme easy aging; ⑩ some plastic easy dissolved Yu solvent. Plastics for thermosetting and thermoplastic can be distinguished two classes, the former cannot be reshaped using, which can be repeated.