Melt Flow Index test

The Melt Flow Rate (MFR) is a widely measured parameter in the ambit of material’s rheology quality control. It evaluates the ability of a melted material to flow.

For this purpose, a plastometer is used. Its basic principle is as follows: a sample in pre-heated until it reaches the melting point. At this stage, the mass or volume of material flowing through a die of a particular diameter within ten minutes is measured, keeping constant pressure and temperature. Thus, the main parameters involved in the measurement of the polymer’s fluidity are the test pressure and the temperature.

The importance of MFR is indisputable upon many manufacturing processes involving thermoplastic materials, such as injection moulding, extrusion or rotational moulding.

Examples of standards in force related with this test are ASTM-D1238 and ISO 1133.