The value in using melt flow rate or MFR testing is very important in different industries and in testing and providing quality control for the production of different polymers. Completing melt flow analysis on top quality equipment will provide highly accurate readings that provide the specific viscosity of the polymer at a specific and precise shear rate.
How It Works
In both theory and practice, melt flow analysis is actually very simple and not at all complicated or difficult. However, every component of the testing equipment has to be correctly calibrated and produced to ensure accuracy in the results.
As a very basic description of the process, a known about of the sample is loaded into the testing chamber. This is then heated to a molten state and moved through the system at a single flow rate and shear rate. This results in a report of the material through that one shear and flow rate, not with varying rates.
The molten material under the specific force and temperature is then measured as it moves through the capillary die. The material produced in a specific amount of time is then collected, cooled and weighed to give the Melt Flow Index or MFI for the specific sample.
Options to Consider
It is possible to use different melt flow indexers that can measure different forms of samples. Some systems are designed just to test the resin pellets of pure products. Others can be used to test an existing thermoplastic material that may have several components to the final product.
This is particularly important in the development of injectable polymers. For these types of applications, a higher melt flow rate with a lower molecular weight polymer is typically the most desired combination. Through melt flow analysis, it is possible to determine this information and choose the best polymer for the specific injection mold requirements.
