THERMAL PROPERTIES:
o Melt flow index (MFI)
o Heat deflection temperature (HDT)
o Vicat softening temperature (VSP) Vicat softening temperature (VSP)
o Flammability
o Thermal conductivity
o Low temperature Brittleness
o Oxygen Index
Melt Flow Index (MFI)
Test Method: ASTM D 1238, ISO-1133, JIS-K 7210, BS-2782 Method 105 C
Sample size: Minimum 50 gm of granules
Definition: The quality of material extruded through a standard orifice under specified temperature and load, measured for 10 minutes.
Where, M
MFI = ------ x 600
t
M = Mass of the extrudate (gm)
t = Cut off time (sec.)
Significance:
1. To measure the uniformity of the flow rate of the material To measure the uniformity of the flow rate of the material.
2. This values help to distinguish between the different grades of a polymer.
3. MFI is indirectly proportional to Molecular Weight.
Factors Affecting MFI
Preheat time Preheat time Non uniformity in temperature along the wall of the cylinder if it
is not preheated for a specific length of time. This cause the flow rate to very considerably
Moosue Moosue isture in the material causes bubbles too appear appea in thee extrudate. The weight of the extrudate is influenced by the voids..
Packing Improper packing of material causes variation in the test results.
Volume of sample Any change in volume of the sample in the cylinder may cause for variation in the test result.
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