What is a Melt Flow Index Test?
The Melt Flow Index (MFI) test measures the quantity of polymer that is extruded through a die of specified dimensions at a set temperature within a 10-minute period. This test is commonly used to compare different grades of the same polymer, as it provides an indication of the molecular weight present in a particular batch or grade.
How to Use a Melt Flow Index Tester?Conducting a Melt Flow Index Test involves the following steps:
Sample Loading: Load the polymer sample into the melt flow index tester at a temperature above its melting point.
Heating: The tester consists of an electrically heated outer zone and an inner die. The sample is placed in the inner die.
Melting: Allow the sample to melt completely for a few minutes.
Testing: Once melted, the polymer is extruded through the die, and the flow rate is measured.
What is the Formula for MFI Test?The Melt Flow Index is calculated using the following formula:
MFI=Weight of sample in grams10 minutes
MFI=
10 minutes
Weight of sample in grams
This formula determines the amount of polymer extruded per 10 minutes, providing a standard measure of the material’s flow characteristics.
What is a Melt Flow Indexer Used For?Melt Flow Index testers, also known as extrusion plastometer or Melt Flow Indexers, are used by plastic processors to determine the melt mass flow rate (MFR) and melt volume flow rate (MVR) of a plastic melted mass. These measurements help in assessing the material's viscosity and flow properties, which are critical for processing and quality control.
What is the Unit of MFI?The MFI value, as quoted on many datasheets, refers to the amount of polymer extruded through a given orifice (die) and is expressed in grams per 10 minutes (g/10 min) or, for Melt Volume Rate, in cubic centimeters per 10 minutes (cm³/10 min).
ConclusionMelt Flow Index testing is a fundamental process in the plastic industry, providing essential data on the flow properties and molecular weight of polymers. By using a Melt Flow Index tester, manufacturers can ensure the quality and consistency of their plastic materials, making it a critical tool for production and quality assurance.
