What does MFR refer to ? Is it the bigger, the better the performance will be ?

What is MFR ？

Melt flow rate (short for MFR) is a parameter to describe the melt flow of plastics under certain temperature and pressure. At the same time, it also indirectly describes the average molecular weight of plastic weight. The melt index is commonly expressed by MI and is now internationally known as melt flow rate and is expressed by MFR. It is usually used as a parameter of thermoplastic resin quality control and thermoplastic molding process conditions. It is the weight value in grams per 10 minutes of thermoplastic resins and plastics that melt through standard capillaries over a specified period of time at a specified temperature and constant load. The melting index is used to distinguish the fluidity of various thermoplastic materials in the melting state.

How to measure MFR ?

FIG. 1 is a test machine, and FIG.2 is a schematic diagram of melt flow rate test.

The material sheet is wrapped with a heater. At the bottom of the barrel, there is an orifice die. The center of the orifice die is the capillary tube that the melt extrusion flows out.

A piston rod is inserted into the barrel and a weight is pressed on the top of the rod.

During the test, the cylinder is heated first, and after reaching the expected test temperature, the piston rod is pulled out and the sample plastic particles or powder are poured into the central hole of the cylinder.) After the tool is compressed, the piston rod is put into the cylinder, and the sample is melted, and a weight is pressed on the top of the piston rod. The molten sample material is extruded through the orifice mold capillary.

FIG. 1 FIG. 2

What’s the meaning of MFR ?

The melt flow rate characterizes the melt flow performance of the thermoplastic polymer. By measuring the melt flow rate, we can understand the polymer’s molecular weight and its distribution, degree of cross-linking, machining performance, etc.

For the same resin, the melt index can be used to compare the molecular weight of the resin for production quality control.Generally speaking, the chemical structure of a certain resin, its melting index is smaller, the greater the molecular weight, then its fracture strength, hardness, toughness, aging resistance stability and other properties have been improved. And melt index is big, molecular weight is small, the fluidity when molding is corresponding some better.

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