Melt flow index

According to ASTM D-1238

The calculation of Melt Flow Index (MFI) is a variation of the capillary viscometer method with a standard diameter and length of capillary.

The heating procedure is well defined and determined by the polymer under investigation. After equilibration for a specified time the polymer is forced by a piston of a specified weight through the capillary.

The MFI is obtained by cutting off lengths of extrudate which are forced out of the orifice in a standard time period.The MFI is measured in grams per 10 minutes at a defined temperature.