Importance of Melt Flow Index in Understanding the Rheological Behaviour of the Polymers

FARIDABAD, India - April 4, 2015 - PRLog -- In today’s world, quality matters a lot and there is no room for defects and imperfections. Same applies to the polymer industry as well. In a polymer industry, many types of polymers are used for various purposes. It is inevitable determine the best practices to ensure highest quality of eth end product produced. There are many physical, chemical and mechanical properties that need to be determined related to a polymer to assess its quality standard and melt flow index is one of them.

Melt flow index

The Melt Flow Index or MFI can be considered as a means of measuring the ease of flow that polymer has in its molten state. It is expressed in terms of grams flowing per ten minutes through a capillary tube with a specific diameter and length, under specific shear stress and at a given temperature. MFI is also an indirect indicator of the molecular weight of the polymer and is inversely proportional to it. The ratio of the MFI of a polymer at two given temperatures is called as FRR or Flow Rate Ratio. It helps in understanding the rheological behaviour of a certain polymer under different working conditions. It should be understood that polymers that have a simple geometry with short chain links may flow faster that those having longer chains with complex geometry.

Melt flow index tester

Melt flow index tester is a specially designed lab testing apparatus containing a sample enclosure, a load for applying pressure on the sample, pressure sensor, temperature control unit, output port and a monitoring system. The sample is place in the tester and the temperature is set. Now the sample is allowed to flow through the capillary tube and when the testing is carried out, a specimen is cut from the sample after ten minutes and is weighed to determine the weight of the polymer which represents the MFI of that particular polymer at that temperature.

Importance of measuring melt flow index

Measuring melt flow index is very important and crucial for the polymer industry as determining MFI helps finding out any defect in the polymers, even on the molecular levels. Any change in the MFI indicates that there has been change in the molecular structure of the polymer during processing or storage. In this way the polymer industries can improve their quality product in a great way. A material with a higher MFI might tend to be processed in an easier way but the other desired qualities that are directly proportional to the molecular weight, might be low. For more information you can visit here- http://www.testing-instruments.com/melt-flow-index-tester/