Techniques for Identifying ABS and PS Plastics

Accurately identifying ABS and PS plastics is a fundamental skill. ABS, a copolymer, is characterized by a bright surface, high strength, and good toughness. When folded, the crease turns white. When burned, it produces a yellow flame without dripping, leaves a surface with dense small holes, and has a distinctive smell. Polystyrene (PS) comes in three main types: the brittle and transparent GPPS, the tougher HIPS, and the foam EPS. HIPS has average brightness and lower toughness than ABS. It is highly flammable, burning with an orange-yellow, sparkling flame and dense black smoke, continuing to burn after the flame is removed while softening and bubbling, and releases an aromatic smell. A key identifier is that a cut surface of HIPS appears whitish, unlike GPPS. In practical scenarios, such as with TV housings, the brighter surface usually indicates ABS. Furthermore, ABS is harder; attempting to break it with pliers requires more force. The most reliable method for pure materials is the ethyl acetate test: HIPS will silk upon wiping, while ABS will not.