The test is performed at a given temperature depending on the plastic. Not only are these shear rates different they dont represent the shear rates experienced by polymers under most melt processes.
A small sample of about 5 grams is heated above its melting or softening point and forced to flow through a capillary using a piston actuated by a specified weight usually 216 kg or 5 kg.
How to calculate melt flow index. So a 4-melt material is tested at a shear rate of about 88 sec-1 while the 20-melt material is tested at 44 sec-1. Melt Flow Index MFI is a measure of how many grams of a polymer flow through the die in ten minutes. The weight of melt in grams flowing through the capillary in 10 minutes is the melt flow index.
The formula for calculation of MFI. In order to convert the unit of MFR to g10 min the value 600 is used. The mass melt flow rate from Method A is calculated using the mass of the extrudate s as shown in the equation below.
Volumetric displacement measurement of MVR using a Dynisco LMI5500. A melt flow index of 10 corresponds to a melt viscosity of about 15 10 4 N sm 2 15 10 5 poises. Melt Flow Index is calculated by measuring the flow of melted thermoplastic polymers.
The value obtained through the melt flow index test is a single data point. Value of Melt Volume Rate While the MFR is given as a mass per unit time such as grams10 minutes MVR is reported as a volume per unit time such as cm 3 10 minutes or regrettably inches 3 10 minutes. The Plastic soften stream list is figured by playing out a manualprogrammed test system on a testing instrument with the end goal to check the Melt volume rate of the stream of plastic granules which is estimated in grams in an exact time of ten minutes.
At least 14 grams of material. The melt flow index MFI is a measure of the mass of polymer that is extruded through a capillary die at a certain temperature and force. The melt flow index MFI is the measure of how many grams of polymer pass through a standardized capillary under a standard load over 10 minutes.
The Melt Flow Index is expressed in grams of the melted polymers in ten minutes. Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. For a detailed numerical simulation of the melt flow index see or.
Flow rate 600t x weight of extrudate t time of extrudate in seconds. Where g is the mass in grams of material collected over time sec. The melt flow rate is used to determine the mechanical strength and molecular structure of the plastics to produce high-quality of plastic products.
Instead of or together with the MFR a new line item is present known as the melt volume rate MVR. MFI Weight of test in grams10 min. Melt Flow Index Formula.
Weigh the melted example utilizing an advanced equilibrium. This weight will be utilized for computing the Melt Flow Index of the example. Multiplying the MFR by approximately 22 will give the shear rate at which the test was performed.
It is also known as the mass of plastics in grams per ten minutes which is flow out from a capillary tube having specific length and diameter which comes out when heated at a particular temperature and the pressure is applied to the plastic with the help of different weight. Melt Flow rate can be calculated efficiently with the help of Melt Flow Index Tester. Melt Flow Index Formula Melt Flow Index In Grams Weight of Melted Specimen in Ten Minutes.
This testing is normally performed per ASTM D1238 or ISO 1133 using a plastometer. The Melt flow rate of most common products polyethylene is tested at a temperature of 190 Celsius and polypropylene at a temperature of 230 Celsius. The sample can be in the form of virgin resin pellets or ground material from a finished thermoplastic product.
Melt flow rate g10 min. This is an important property because it is a different number than the solid-state density that is typically provided on the data sheets. The ratio of the two valuesthe MFR divided by the MVRis a measure of the melt density of the material in gcm³.
Correlating Melt Flow Index to Molecular Weight The certificate of analysis for polymer resins often includes a melt flow index MFI or melt flow rate MFR reported as grams of material10 min under a specified temperature and load. Melt Flow Index Tester is structured only for the ideal estimation of Melt stream rate of liquid plastics or granules. Formerly MFI currently MFR Weight gram of Melted samples in 10 minutes References.
Gravity then takes over and forces the plastic through a die. Calculation of Melt Flow Rate 600tsec x mass of extrudate in grams t time of extrudate in seconds Payment Terms are paid in full before test results are released. The force used to push the plastic through the system is supplied by a weight which sits on top of a ram.
The melt flow index only tests the material at one shear stress and temperature.