MFR / MFI Explained — Melt Flow Rate
MFR (also called MFI) measures how easily a molten polymer flows under a set temperature and load. It is the quickest indicator of processability and batch consistency.
What it measures
Melt Flow Rate (MFR) — also called Melt Flow Index (MFI) — is the mass of molten polymer that flows through a standard die in ten minutes under a defined temperature and weight. It is reported as, for example, 3–4 g/10 min at 190 °C / 2.16 kg. A higher number means the melt flows more easily.
Why it matters
MFR is the fastest, most common indicator of a polymer’s processability and of batch-to-batch consistency. A grade with the right MFR drops into your moulding or extrusion process without re-tuning. Always compare MFR at the same temperature and load, because the conditions differ by polymer (for example PE is tested at 190 °C, PP at 230 °C, PC at 300 °C).
On Sinox products
Where relevant, each catalog product lists its MFR with the test conditions. For polyester recyclate such as PET, molecular weight is instead expressed as intrinsic viscosity.
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