MFI - Melt Flow Indexing of Thermoplasts

Melt flow indexing (MFI) is a technique used to measure the viscosity or ability of a polymer to flow under pressure through a certain fixed sized orifice in the molten state.  The exact dimensions of the orifice, set temperature and load mass (pressure) are specified by a standard method such as ISO 1133. The measured value is expressed as the mass of polymer that flowed through the orifice in 10 minutes. The MFI test is used widely among the various segments of the plastics industry.