1 This International Standard specifies a method for the determination of the melt flow rate of molten thermoplastic materials under specified conditions of temperature and pressure. When the test conditions are specified in a material specification, this method may be used to characterize the melt flow rate of the material.
NOTE — Test conditions commonly used are listed in the annex.
1 The melt flow rate of high polymers is dependent on the rate of shear. The rates of shear in this test are much smaller than those used under normal conditions of fabrication, and therefore data obtained by this method for various thermoplastics may not always correlate with their behaviour in actual use.
The method is useful in quality control.
1 When the method is used with certain materials, consideration should be given to the factors leading to the loss of reproducibility. Such factors include
a) thermal degradation or crosslinking of the material, causing the melt flow rate to change during preheating or the period of test; powdered materials requiring long preheating times are sensitive to this effect. In certain cases the inclusion of stabilizers is necessary to reduce the variability;
b) filled or reinforced materials, where the distribution or orientation of the filler may affect the melt flow rate.