How to Identify ABS and PS Plastics

  Several methods exist to distinguish between ABS and PS plastics. A relatively new technique involves an ethyl acetate wipe; pure ABS typically does not become stringy or silky upon wiping, while HIPS (a type of PS) will show this silky effect, though this method is primarily reliable for pure grades. Common identification practices rely on observing physical and combustion properties. ABS generally exhibits a higher surface gloss and superior toughness compared to PS. When burned, ABS produces a yellow flame, tends not to drip, and the burnt surface reveals densely packed small pores, accompanied by a faint sweet odor.

Polystyrene (PS) encompasses several types: GPPS (general purpose), which is brittle and transparent; HIPS (high impact), which has moderate gloss and lower toughness than ABS; and EPS, used primarily for foams. Upon combustion, HIPS burns with an orange-yellow, flashing flame, emitting dense black smoke and continuing to burn when removed from the flame, accompanied by a distinctive aromatic smell, leaving a shiny surface. In applications like TV housings, materials are often distinguished by these characteristics: higher surface brightness usually indicates ABS. ABS also demonstrates higher hardness; breaking a sample with pliers requires more force for ABS than for HIPS. The cut surface of HIPS appears whitish, unlike GPPS.