Waste Cessation Criteria for Secondary Polyolefin Resin Compounding
Secondary polyolefin waste cessation requires verified feedstock sorting limits, vacuum devolatilization, REACH threshold compliance, and audited FPC dossiers.
Charpy Impact ISO 179
Meaning
Standardized mechanical testing assesses the resistance of plastic materials to sudden fracture under high strain rates. The charpy impact ISO 179 test protocol provides a repeatable metric for evaluating the toughness of rigid thermoplastic resins. This test uses a swinging pendulum to strike a supported specimen, measuring the energy absorbed during the break.
The resulting values indicate the brittleness of a polymer under rapid loading conditions.
Standard Protocol
The specimen rests horizontally and receives an impact from the pendulum at the center of the bar. This charpy impact ISO 179 measurement helps engineers choose resins for parts that must survive drops or impacts in daily use. Adjustments in specimen thickness or the introduction of a notch alter the stress distribution, changing how the polymer fractures.
Testing occurs at different temperatures to locate the transition point where the polymer becomes brittle.
Material Resistance
Virgin polymers usually exhibit higher impact strength than recycled or highly filled polymers because of longer molecular chains. The test helps molders determine if regrind addition has degraded the mechanical performance of the final moulded part. If recycled material dominates the blend, toughness can decline.
Process Influence
Moulding conditions such as melt temperature and injection speed directly affect the impact resistance of the finished part. Fast cooling can freeze in molecular stresses, which lowers the impact strength measured on the actual part compared to the datasheet value. Parts break early when process parameters drift.