ISO 1133 covers test methods for determining the melt flow index (MFI) of thermoplastic polymers.
According to ISO 1133 and ASTM D1238, the MFI is the weight of polymer melt that flows from a standard die (2.095 x 8 mm) at a given temperature when a standardweight is applied to the piston.
The ISO 1133 MFI is used to verify that a grade of plastic material is within the required flow range. This is typically used for polyolefins (polyethylene HDPE, LDPE, LLDPE
and polypropylene PP).
Melt flow rate test
ISO 1133 specifies two test methods:
Procedure A is a manual mass measurement method where a timed period of the extrudate is weighed on a balance after the test to determine the melt mass flow rate (MFR) of the plastic.
Procedure B is a displacement measurement method based on measuring the piston displacement using an encoder.
This is expressed in g/10 min. The result is the melt volume flow (MVR) rate.
Expressed in cm3/10 min, it is the average of the data from the different encoder acquisition points.
The melt density is also measured and used to calculate the associated MFR.
We recommend using the MVR measurement when comparing filled and unfilled thermoplastics and when comparing materials with different filler contents.
Plastic Melt Flow Index Tester: Main Recommendations
The lixian is ideal for measuring the melt flow properties of polypropylene according to ISO 1133 Procedure B. The melt flow tester is equipped with an encoder, a motorized weight lifter for automatic weight
application after a selected time, and automatic cutting of the extrudate for easy measurement of the melt density.
Due to the high flowability of this type of material, we recommend plugging the die outlet with a die plug accessory before starting the measurement to prevent dripping of the molten sample.
In addition, we recommend using encoder acquisition with 40 measurement points to obtain high-precision results. This way, customers can obtain reliable measurement results even with high sample flowability, with MFR values equal to 102.55 g/10 min.
At the end of the test, we recommend to thoroughly clean the instrument using our automatic barrel cleaning device to reduce the test time and optimize the quality control process.
For chemically aggressive materials such as PVC or fluoropolymers, we have developed a special corrosion-resistant kit (barrel, mold, piston) that is available with all our instruments.
