Rheological Verification of Recycled High Density Polyethylene in Multicavity Tooling
Verifying recycled HDPE in multicavity tools requires capillary rheometry beyond standard melt index to map shear thinning and prevent cavity filling imbalance.
ISO 1133-2
Meaning
International testing standards define the precise methodologies for measuring the flow rates of molten plastics under controlled thermodynamic conditions. The standard ISO 1133-2 governs the determination of the melt mass-flow rate and melt volume-flow rate for materials that are highly sensitive to temperature and moisture history. It specifies more rigorous temperature controls and preheating routines than general testing standards.
Testing Standard
Some polymers degrade quickly when exposed to moisture at high temperatures. Testing moisture-sensitive materials under this method prevents thermal degradation from skewing viscosity results. It enforces strict sample drying to ensure repeatable measurements.
Quality Assurance
Resin suppliers use the method to certify the high consistency required for precision blow moulding or thin-wall injection moulding. If the measured flow rate drifts outside the specified bounds, it indicates polymer degradation or a shift in molecular weight. Moulders use these certificates to verify that the resin will run consistently without causing part failures.
Equipment Specification
The testing machinery must feature tighter temperature tolerances along the cylinder wall compared to standard testers. Accurate temperature control ensures that local viscosity variations do not introduce errors into the test results. A displacement transducer monitors the piston movement to calculate the volume flow rate with high precision.
This hardware configuration reduces measurement uncertainty, allowing laboratories to reliably compare batches of highly sensitive engineering plastics.