Polymer Melt Flow Testing for Industry and Education

Melt flow testing is simply a measure of the flow of a polymer when melted. The result of a melt flow test, called the melt mass-flow rate (MFR) or melt volume-flow rate (MVR), is defined as the amount of mass or volume of a polymer that flows through a small die at a specified temperature and pressure.

The melt flow test itself is simple and straightforward. The Common International Testing Standard are ASTM D1238 and ISO 113, where a small amount of a thermoplastic sample (usually in granule, resin or = flake form) is heated in a barrel at a specified temperature, melted to a viscous fluid, and is forced out of a capillary die by a piston loaded with dead weights. Once enough sample has exited the die, it is removed and weighed, or the volume of the sample is measured by the machine.

Importance of Melt Flow Index 

• A typical index value for verifying in-house material
• Quality check of entrance materials
• Comparison of new materials in a product development setting
• Evaluation tool for new material suppliers
• Quick comparisons of batches of material
• Estimation of flow properties for simple extrusion processes
• Predictions of how a polymer will behave in a number of processing techniques

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