The Melt Flow Indexer is an instrument used to test the melting properties of plastic materials. It evaluates the processability and physical properties of a material by measuring its ability to melt flow under certain conditions.
In the melt indexer, the commonly used test methods are the volume method and the mass method, and their differences are as follows:
The testing principles are different:
Volume method: Put a certain weight of plastic sample into the test cylinder, heat it to melt, then apply a certain pressure at a certain temperature, and determine the melt index by calculating the volume of the melt that flows out of the test cylinder within a specified time.
Mass method: Put a certain weight of plastic sample into the test cylinder, heat it to melt it, then apply a certain pressure at a certain temperature, calculate the volume of the molten material flowing out of the test cylinder within a specified time, and then determine the melt index according to the amount of molten material and the outflow time.
The test results are presented in different forms:
Volumetric method: The test results are presented in the form of melt volume, usually in cm³/10min.
Mass method: The test result is presented in the form of the amount of molten material, and the unit is usually g/10min.
The precision is different:
Volume method: Due to the expansion and contraction of the melt during the flow process, the test results of the volume method are slightly less accurate than the mass method.
Mass method: Since the volume change of the fluid object is not involved in the test, the test result of the mass method is relatively accurate.
The test method parameters are different:
Volume method: In the volume method test, the temperature is usually set between 190°C and 275°C, and the pressure is usually between 0.325MPa and 1.2MPa.
Quality method: In the quality method test, the temperature is usually set between 190°C and 330°C, and the pressure is usually between 0.325MPa and 1.2MPa.
The scope of application is different:
Volume method: The volume method is mainly suitable for plastics with low melting point and good fluidity, such as polyethylene, polypropylene, polyvinyl alcohol, polystyrene, etc.
Quality method: The quality method is suitable for all kinds of plastics, especially materials with high melting point and poor fluidity, such as polyamide, polyphenylene sulfide, polycarbonate, etc.
Both the volumetric method and the mass method are commonly used test methods for melt indexers. To select a suitable test method, factors such as the nature of the sample, test accuracy requirements, and test standards should be considered.
