Viscosità Mooney: cosa significa realmente il numero

Mooney viscosity is the most quoted and most misinterpreted number in rubber purchasing. It is a processability indicator, not a quality grade.

Reading the notation

ML(1+4) at 100 °C means: Mooney, large rotor, 1 minute preheat, 4 minutes running, at 100 °C. Both the time and the temperature matter. A value quoted without them is incomplete.

What it does and does not tell you

Mooney viscosity indicates how the compound flows during mixing, extrusion and calendering. It does not predict cured hardness, strength or abrasion resistance. Two compounds with identical Mooney values can have completely different cured properties.

Why readings differ between labs

• •Rotor condition and calibration state.
• •Sample preparation and conditioning time.
• •Small differences in test temperature, which have a large effect on the reading.
• •Die closure and instrument compliance.

How to specify

Always state the test conditions in the purchase specification: rotor type, preheat and run times, and temperature. Agree a tolerance — a ±5 Mooney unit band is common for production compounds — and ask the supplier to quote the same conditions you will test at. For incoming inspection, compare against your own machine's historical values rather than against the supplier's number alone. ## Need the documents or today's price? Send us the grade, quantity and destination port — we return a quotation with COA and MSDS attached. Email manager@fipolymer.com or use the inquiry form on this site.