How do you calculate melt flow index?
A weight specified for the material is applied to a plunger and the molten material is forced through the die. A timed extrudate is collected and weighed. Melt flow rate values are calculated in g/10 min. melt flow rate = g/10 min.
How does melt flow index work?
Melt Flow Index (MFI) is a measure of how many grams of a polymer flow through the die in ten minutes. The test is performed at a given temperature depending on the plastic. The force used to push the plastic through the system is supplied by a weight which sits on top of a ram.
What is the MFI of masterbatch?
The melt flow index or (MFI) is a measure of the ease of flow of the melt of a polymer. Melt Flow Rate measures the rate of extrusion of polymer at a prescribed temperature and load. It is one of the main test that provides the extent of degradation of the plastic as a result of molding and processability.
What is MFI value?
The MFI value quoted on many datasheets refers to the amount of polymer that is extruded through a known given orifice (die) and expressed as quantity in g/10 mins or for Melt Volume Rate in cm3 /10mins .
What is unit of MFI?
MFI is expressed in grams of polymer per 10 minutes of duration of the test.
What factors affect melt flow index?
Factors that Affect Test Accuracy The melt indexer needs to be in good working order. The machine must have been calibrated by a certified metrologist, checking temperature, physical dimensions, and distance and time measurement accuracy. The machine cleanliness needs to be maintained.
What is letdown ratio?
The terms let down rate (LDR) and dosing rate (DR) mean the same thing, this is the percentage ratio of masterbatch that has to be added to the finished product (e.g. 3% LDR, this can be calculated as 3grams of masterbatch to every 100grams of base polymer, or 3kg of masterbatch for every 100kg of base polymer.)
How do you increase PP MFI?
You can increase MFI by mixing with some lubricant. However it may reduce mechanical properties. So it would be better to conduct a small scale experiment in advance to know the optimum amount of lubricant you should add.
What is a high melt index?
Melt flow indices are often listed on data sheets of thermoplastic materials. In general, a higher MFI indicates a lower material viscosity, and when comparing polymers of the same class, a lower melt flow rate corresponds to a higher molecular weight and/or less branching.
What is LDR in plastic?
What is LDR? LDR is “let down ratio” it is the dosage or concentration level at which a masterbatch is incorporated into the base polymer. Hence an LDR of 2 (%) is 98 % polymer, 2% masterbatch.
How are masterbatches prepared?
Masterbatch is a concentrated mixture of pigments and/or additives encapsulated during a heat process into a carrier resin which is then cooled and cut into a granular shape. Masterbatch allows the processor to color raw polymer economically during the plastics process.
What is the melt flow index of HDPE?
The range of grades available for MDPE and HDPE can cover densities from 0.940 to 0.965 g/cm3 and melt flow indices from 0.06 to 10 g/10 min.