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The melt flow index (MFI) of seven commercial poly(lactic acid) (PLA) grades is investigated in view of 3D printing quality. A threshold value of 10 g (10 min)−1 (2.16 kg; ISO 1133) is put forward for a successful printing (190–220°C), enabling a fast and practical screening of PLA materials.The melt flow index (MFI) of seven commercial poly(lactic acid) (PLA) grades is investigated in view of 3D printing quality. A threshold value of 10 g (10 min)−1 (2.16 kg; ISO 1133) is put forward for a successful printing (190–220°C), enabling a fast and practical screening of PLA materials.
What is the purpose of melt flow index?
1 Melt flow index. MFI is a simple measurement of the quantity of polymer pushed through a die of specified dimensions at a set temperature within 10 min. It is frequently used to compare grades of the same polymer, as it gives an indication of the molecular weight present in that batch or grade.
What does a higher melt flow index mean?
Melt Flow Indexer 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 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 .
How do you increase melt flow index?
Mixing with (high MFI) virgin polymers will reduce the risk of mechanical qualities. However in this case you have to add more amounts than in case of lubricant to get high enough MFI, so in general the material cost will increase. You can add very high MFI PP , or else you can add peroxide to boost the melt flow.
What is the difference between melt flow index and melt flow rate?
The Melt Flow Index (MFI) is a measure of the ease of flow of the melt of a thermoplastic polymer. Melt flow rate is inversely proportional to viscosity of the melt at the conditions of the test, though it should be borne in mind that the viscosity for any such material depends on the applied force.
How do you measure melt flow index?
To perform the MFR test a small portion of the material–usually in pellet or powder form–is placed into a heated barrel, where it melts into a viscous fluid. A portion of the sample is extruded through a capillary die by a deadweight piston over the course of a set time frame.
What is the melt flow index of pet?
The value of the intrinsic viscosity for the PET resin is very important and analogous to the Melt Flow Index (MFI). In general, bottles made from PET have an intrinsic viscosity value IV of about 0.8 dl / g. Otherwise, food trays have a measurement of about 0.6 dl / g.
What is the MFI of LDPE?
1. LDPE has an MFI of 0.3 ± 0.05 g/10 min; however, PLA has an MFI of 5.9 ± 0.08 g/10 min which are very close to values found for non-extruded pellets. This measurement was undertaken to check any degradation of polymers when being extruded.
What is melt volume flow rate?
The Melt Flow Rate is a measure of the ease of flow of melted plastic and represents a typical index for Quality Control of thermoplastics. An alternative quantity is the volume flow expressed (SI units) in cm3/10min, called Melt Volume-Flow Rate or MVR.
What is the melt flow rate of polypropylene?
2.1 Materials The polypropylene used in this research is grade EH-102 of the company “PETKIM.” The most important reason for choosing this material is that its melt flow index (9.0–13.0 g/10 min) is high and it is possible to use this material in combination with relatively high filler contents.
What material property significantly affects the melt flow rate?
Flow rate in a polymer is related inversely to viscosity. High-viscosity materials flow with greater resistance and therefore more slowly under any particular set of conditions than low-viscosity materials do. Therefore, higher-MW polymers have lower MFR values and lower-MW polymers have higher MFR.
What is the MFI of HDPE?
Several grades of high-density polyethylene have an MFI ranging from 0.2-3 gm/10min.
How does a melt flow tester work?
The melt flow test itself is simple and straightforward. A small amount of a thermoplastic sample (usually in granule or flake form) is heated in a barrel at a specified temperature, melted to a viscous fluid, and is forced out of a capillary die by a piston loaded with dead weights.
What is the relationship between melt index and molecular weight?
The higher the melt index of the material the lower the average molecular weight of the polymer. If you ask a processor what type of PE they are running, a typical response will be, “I’m running a 7-melt, 953 material.” Translation: a material with a nominal melt index of 7 g/10 min. and a density of 0.953 grams/cm3.
What is the MFI of PVC?
The measured MFR value was found equal to 7.27 g/10 min and related MVR 5.99 cm3/10 min, with a measured melt density of 1.2 g/cm3.
How do you find melt density?
Dividing the mass from the MFR test by the volume from the MVR test gives you the melt density. Alternately, you can use an MFR tester to measure the melt density of a material.
What is melt volume?
Therefore, for the viscosity commonly the MVR (melt volume-flow rate) is used. This value describes how much mass of a polymer is flowing during 10 minutes at a specific temperature and pressure (mostly 2,16 kg or 5 kg) through a given capillary.
What is the difference between MFR and MVR?
While the MFR is given as a mass per unit time, such as grams/10 minutes, MVR is reported as a volume per unit time, such as cm3/10 minutes or, regrettably, inches3/10 minutes.
What is melt viscosity?
Melt Viscosity measures the rate of extrusion of thermoplastics through an orifice at a prescribed temperature and load. It provides a means of measuring flow of a melted material which can be used to evaluate the consistency of materials, or determine the extent of degradation of the plastic as a result of molding.
