Melting Index, MI
is an easy parameter to evaluate molten plastic’s melting speed under a specific condition.
Generally, a common MI value is around 1 to 25.
The higher the MI, the smaller the molecular mass which means the molten plastic is under a good fluidity, while the lower the MI, the larger the molecular mass which means the worse the fluidity.
MI Testing Method
|
MFR |
MVR |
|
|---|---|---|
|
Method |
Set a fixed period to heat the plastic resin up to particular temperature. Then extrude the molten plastic though out a standard hole with a fixed pressure to measure the molten plastic’s weight. |
Measure the volume of the molten plastic extruded at the fixed period. The volume value multiplies by the molten plastic’s density is the mass measurement value. |
|
Unit |
g/min |
㎤/10min |
|
Applicable to high fluidity material. Suggest to use this method when MI value is above 30. |
Application of MI Test
Quality Inspection & Controlling
By testing the melt index, it helps to find problems such as bubbles, defects or poor mechanical properties in plastic resins, which can improve the quality and reliability of plastic products.
Inspect if there is regrind material
Manufacturers can confirm that the melt index of materials made from recycled plastic is compared with the original material. If there is a significant difference in the melt index between the two, it may lead to inconsistent fluidity of the molten plastic during the manufacturing process, thus affecting product quality.
Reference for Modified Plastic
With the continuous development of industry and limited resources, many companies have begun to search for and utilize renewable energy. Therefore, whether the physical properties of recycled materials can meet the needs can also be based on MI test results as a reference.
Incoming Resin Inspection
TSC enterprise has purchased a manual melting index inspection instrument. We will test every batch of plastic resin when receiving the material to ensure there’s no impurities in it, or if there’s any characteristic difference to the official data.
