The flow index, or melt flow index, is a measure of the resistance (viscosity) of a polymer melt to flow at a certain temperature under a certain force for a predetermined time. In fact, melt flow index (MFI), melt flow rate or melt index are the same tests performed under different test conditions and are used to measure melt viscosity under a constant load and low shear rates. A higher melt flow index is associated with a lower viscosity resin. As the resin viscosity decreases, the flow per unit time increases.
In other words, the melt flow index is a simple measurement of the amount of polymer pushed out of a certain size die at a certain temperature in 10 minutes. This index is often used to compare grades of the same polymer because it gives an indication of the molecular weight present in that batch. The polymer with a low index value has a higher molecular weight than the same polymer with a high index value. In general, extrusion is carried out with polymers with lower melt flow indices than injection molding.
Plastic fluidity index (melt flow index, MFI) tests are based on the following two international standards:
The ISO 1133-1 standard defines two test methods for determining the melt mass flow rate and melt volume flow rate of thermoplastic materials under certain temperature and load conditions. Procedure A is a mass measurement method. Procedure B is a displacement measurement method.
ASTM D1238-10 standard defines two test methods for determining the extrusion rate of molten thermoplastic resins . After a specified preheating time, the resin is extruded through a die of a specific length and hole diameter under specified temperature, load, and piston position conditions. This standard includes four separate test methods.
Our organization, among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, also provides testing services to determine the fluency index with its trained and expert staff and advanced technological equipment.
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