Ash Content, Carbon Black Content & Dispersion Testing of Plastics

Three thermal-analysis tests answer the question 'what is actually inside this plastic?': ash content reveals total inorganic filler, carbon black content (ASTM D 1603) verifies the 2–2.5 % carbon black that protects PE pipes and cables from UV, and carbon black dispersion (ISO 18553) checks that the black is spread evenly rather than clumped into failure-initiating agglomerates.

The equipment is classic and dependable: a Muffle Furnace, a Digital Hot Air Oven, a Carbon Black Content Apparatus and a Carbon Black Dispersion setup with microscope.

Ash Content: Total Filler by Fire

A weighed specimen is burned and then held in a muffle furnace — typically at 600 °C or as the material standard directs — until only inorganic residue remains. Residue weight ÷ original weight = ash percentage. It verifies calcium carbonate, talc or glass loading in compounds, exposes excessive mineral filler in bought-in recycled granules, and confirms masterbatch dosing.

Carbon Black Content: ASTM D 1603

Carbon black would burn away in open air, so the specimen is pyrolysed in a stream of inert nitrogen inside a tube furnace: the polymer volatilises, the carbon black stays. Weighing before and after gives carbon black percentage. PE pressure pipe and cable-sheathing standards require this value inside a tight band — enough black for decades of UV protection, not so much that mechanical properties suffer.

Carbon Black Dispersion: ISO 18553

Content alone is not enough — poorly dispersed black forms agglomerates that act as stress concentrators. Thin microtomed sections are examined under a microscope and agglomerate sizes are rated against the standard's grading scale; pipe standards set a maximum grade for acceptance.

Frequently Asked Questions