How to install a hydraulic hose crimp joint
Plastics are ubiquitous in daily life and industrial production, ranging from high-grade materials (with higher costs) to general-purpose plastics (more affordable). Unfortunately, some suppliers may cut costs by substituting premium materials with cheaper alternatives, compromising product quality and reducing service life. To avoid such issues, here are four practical methods to distinguish plastic types effectively.
1. Density Test
By submerging plastic samples in water, you can observe whether they float or sink:
Floating plastics (density<1 g/cm³) are likely PE (polyethylene) or PP (polypropylene).
Sinking plastics (density >1 g/cm³) may include PVC (polyvinyl chloride).
Example: A plastic pipe floating on water is unlikely to be PVC since PVC has a higher density than water.
2. Burn Test (Combustion Method)
When exposed to flame, different plastics exhibit distinct burning characteristics:
Plastic Type Flame Color Odor & Smoke Dripping Behavior
PE / PP Blue or yellow Mild paraffin-like Melts and drips
PVC Greenish-yellow Sharp, chlorine-like Self-extinguishing, no dripping
ABS / PS Yellow, sooty Pungent (styrene) May drip and continue burning
Key Observations:
Black smoke and strong odors suggest halogenated plastics (e.g., PVC).
Self-extinguishing behavior indicates flame-retardant additives.
3. Transparency Check (Optical Method)
Plastics vary in clarity:
Transparent: PS (polystyrene), PC (polycarbonate), PMMA (acrylic), AS (SAN).
Translucent: PE, PP, soft PVC, some ABS.
Opaque: Most engineering plastics (e.g., nylon, POM).
4. Color Observation
Unmodified plastics with double bonds (e.g., ABS) often appear slightly yellow due to molecular structure. Additives or stabilizers can alter this, but natural discoloration can hint at material composition.
Advanced Testing (Lab Methods)
For precise identification, specialized equipment is used:
FTIR Spectroscopy (chemical fingerprinting)
Related posts
