Different materials of automotive exterior plastics can be quickly identified through methods such as appearance, flammability, density, and hardness. Combining these with tactile feedback and simple tests can effectively determine common material types.
Appearance and Tactile Characteristics
PP (Polypropylene): Semi-transparent or milky white surface, soft and elastic to the touch, commonly found in bumpers, mudguards, etc., retains its toughness even at low temperatures.
ABS: Mostly opaque ivory or yellowish-brown color, high surface gloss, hard texture, commonly used in grilles, door handles, and other decorative parts, can be electroplated to achieve a metallic finish.
PC (Polycarbonate): Highly transparent, similar to glass, but lightweight and impact-resistant, mainly used in headlight covers and transparent trim panels.
ASA: Similar in appearance to ABS, but less prone to yellowing after prolonged exposure to sunlight, mostly used in high-weather-resistant areas such as rearview mirror housings and side skirts.
TPO: Slightly rubbery on the surface, good elasticity, commonly found in bumper panels, and has good scratch resistance.
Density and Floating Test
PP: Density approximately 0.9 g/cm³, floats on water, one of the few engineering plastics that can float.
ABS, PC, ASA, TPO: Density greater than 1, sinks in water, and can be quickly distinguished from PP using this method.
Hardness and Tapping Sound
PC > ABS > PP: When lightly scratched with a hard object, PC is the most difficult to scratch, while PP is the easiest to leave marks.
When tapped, ABS produces a crisp, loud sound, PP produces a dull sound, and PC falls somewhere in between.
