Common methods to identify ABS and PS involve assessing appearance, physical properties, and combustion behavior. ABS typically has a bright surface, feels hard and tough (especially compared to HIPS), and produces a white mark when folded. When burned, the flame is yellow, it does not tend to drip, and the charred surface shows small, dense pores, emitting a distinctive smell.
Polystyrene (PS) includes GPPS (clear and brittle), HIPS (opaque, improved impact), and EPS (for foams). HIPS has average gloss, lower toughness than ABS, and burns with an orange-yellow, flashing flame, producing dense black smoke and a sooty, aromatic smell; it continues burning when removed from the flame, softening and bubbling, leaving a shiny residue. A whitish cut surface is characteristic of HIPS, not GPPS. In products like TV housings, ABS is identified by higher surface brightness and greater hardness (requiring more force to break). A definitive test for pure grades involves an ethyl acetate wipe: HIPS will turn stringy or silky, while ABS will not.
