The American Society for Testing and Materials (ASTM) defines and sets standards to assure the quality of products. Over 11,999 ASTM standards work on an international level, including tests specific to plastics. It provides support to the customers to have confidence that the products they purchase will perform as per expectation.
One of the ASTM test procedure for plastic is a test for Melt Flow Index or Melt Flow Rate (MFR). Melt flow rate evaluates the rate of extrusion of thermoplastics through an aperture at a defined load and temperature. The test provides a means of measuring the flow of melted material. The test result can be used to differentiate between grades of the same polymer to determine the extent of degradation of the plastic as a result of heat. MFR is an indirect measure of molecular weight, with a high MFR related to molecular weight and the reverse.
There has been increasing pressure on the plastic manufacturers to create quality products. So, most of them have started using a testing instrument to measure the quality of raw material and the finished product. The machine helps to measure the properties like shear rate, viscosity, shear stress, and the molecular structure. The main property is to measure with melt flow test is its flow resistance and the viscosity of the polymers at specific load and temperature.