Meaning
Analytical thermogravimetric and muffle furnace test methods determine the non-combustible inorganic mass fraction remaining after complete polymer matrix pyrolysis. In mineral-filled polyolefins, calcium carbonate ash content represents the weight percentage of inorganic filler left after burning off the polypropylene or polyethylene substrate at elevated temperatures. The test establishes raw material compliance against resin supplier datasheets and verifies compounding consistency before injection moulding.
Beyond confirming filler loading, the value marks the boundary where tensile strength degrades and mould shrinkage drops.
Mineral Loading
Quantifying solid residue provides verification of raw material stoichiometry. Higher concentrations of filler increase flexural modulus while lowering impact toughness. Polyolefin compounding facilities rely on calcium carbonate ash content to maintain density specifications.
Thermal Stability
Matrix combustion requires controlled heating schedules to prevent premature decomposition of inorganic constituents. Standard ISO 3451 procedures maintain burn temperatures around six hundred degrees Celsius to volatilize organic polymers without driving off carbon dioxide from the mineral filler. If temperatures exceed seven hundred degrees, calcium carbonate ash content determinations become inaccurate due to calcination into calcium oxide.
Moulders use proper furnace calibration to isolate resin degradation from filler degradation.
Processing Impact
Part weight tolerances and cycle times respond directly to changes in inorganic filler levels across moulding runs. Variances in calcium carbonate ash content alter thermal conductivity inside the mould cavity, shifting cooling rates and part warpage. A higher mineral fraction accelerates heat removal, which reduces cooling time but increases melt viscosity.
Moulders adjust injection pressure profiles to compensate for these viscosity changes during continuous processing. Variations across lots can lead to sink marks or short shots if barrel temperature settings remain static.
