The structure and working principle of the melt index instrument

- Apr 23, 2020-

The melt flow rate measuring instrument is to use a high temperature heating furnace to make the measured object reach a molten state under a specified temperature condition. The test object in this molten state is subjected to an extrusion test through a small hole of a certain diameter under a predetermined weight load gravity. In the research of plastic production and scientific research units of industrial enterprises, "melt (mass) flow rate" is often used to express the physical properties of polymer materials such as fluidity and viscosity in the molten state. Melt flow rate refers to the average mass of each sample of the extrudate converted into 10 minutes of extrusion. The melt (mass) flow rate is expressed in MFR and the unit is: grams / 10 minutes (ie g / min)

The expression in the formula: MFR (θ, mnom) = tref × m / t = 600 × m / t (g / 10min)

In the formula: θ——Test temperature

mnom——nominal load Kg

m-average mass cut off g

tref-reference time (10min): 600

t——The unit of time interval for cutting off: second.

Example: A group of plastic samples, cut a section every 30 seconds, the results of the quality of each section are: 0.081 grams, 0.086 grams, 0.081 grams, 0.089 grams, 0.082 grams.

The average mass cut off m = (0.081 + 0.086 + 0.081 + 0.089 + 0.082) ÷ 5 = 0.0838≈0.084 (g)

Substitute formula: MFR = 600 × 0.084 / 30 = 1.680 (g / 10min)