Properties and applications of plastics and resins. The afrt automatically allows the flow rate to be measured and is suitable for flow rates between 0. Polymer blends have received a lot of attention in recent years due to the possibility of getting compounds with novel andor different properties through proper marriage of the properties of the respective monocomponents. This presentation is designed to be an informative introduction and guide to melt flow test, and to assist with troubleshooting inconsistencies in results. We buy materials, set conditions and sell our products all based on this number, which has been around for over 50 years. Decrease in mfi melt flow index in this case, indicates the deterioration of pe over multiple cycles of heating. No further improvement is seen when working at 30% water table 3 melt flow data effect of water peo mw water melt flow 100,000 2. Polymer processors usually correlate the value of mfi with the. Both offer a manual means procedure a or method a and automatic timedflow measurement procedure b or method b. Measuring mass flow rate mfr and other polymer properties. It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.
Investigation of melt flow index and impact strength of. The viscosity in this region is known as the zero shear, or newtonian, viscosity ho. The reported melt index values helps to distinguish between the different grades of polymers. Mfr and the melt volume flow rate mvr of thermoplastics3 3. Typical reactions for chain assembling are polyaddition continuous or step wise and condensation polymerization polycondensation 1 figure 1. Influence of polymer melting point and melt flow index on the performance of ethylenevinylacetate modified bitumen for reducedtemperature application a. Note 2 melt density is the density of the material in it molten state. The test, while often disparaged, gauges the relative average molecular weight mw of the polymer. Because the viscosity of a polymer varies with flow rate, or shear rate, a complete characterization of viscosity must allow for measurements at multiple shear. More than just a quality control rheological parameter.
Information in this document is subject to change without notice. Thermophysical properties of linear amorphous polymers. The influence of moisture content in polyamides plastix. First of all, melt index or mi, or melt flow index, or mfi is a measure of melt viscosity, but its the inverse of real viscosity that is, a resin with. The polymer melt viscosity is an important variable in the process and others because it effectively controls not just the way the process works but the strength of the final product.
It includes possible correlations of melt flow index with various parameters involved in polymer manufacture, product fabrication and property evaluation. Us4766200a process for improving the melt flow index of. Melt flow index is an assessment of average molecular mass and is an inverse measure of the melt viscosity. The melt flow index value allows for direct comparison of materials to each other and is a valuable tool for quality assurance. Different standardised conditions of extrusion temperatures and pressures are used for different types of polymer but, for. The objective of suchpaper is to evaluate suitable hot melt adhesive for polyamidetitanium mixedsubstrate joining including characterization, wetting and adhesion behavior of these polymers. The result of this analysis is used for quality control and as a guideline for the process in which the plastic will be destined, with polymers with low melt flow being used in extrusion processes, while the medium and high are. Note 1 polymers having melt flow rates less than 0. Us4766200a us06945,784 us94578486a us4766200a us 4766200 a us4766200 a us 4766200a us 94578486 a us94578486 a us 94578486a us 4766200 a us4766200 a us 4766200a authority us united states prior art keywords melt flow mastication process polymer flow index prior art date 19840601 legal status the legal status is an assumption and is not a legal conclusion. Melt flow rates of thermoplastics by extrusion plastometer1. Latest breaking news and headlines in the rubber and plastic industry.
Determination of the melt massflow rate mfr and melt volumeflow rate mvr of thermoplastics. However, because of the nature of nonnewtonian polymer melt flow the dimensionless numbers used to describe flow and heat transfer. Us4632977a method of plasticizing thermoplastic polymers. Different plastics for different applications need different mfis to make them easy to mould. Determination of the melt massflow rate mfr and the melt. Understanding melt flow testing and its importance instron. Melt flow rate depends on molecular weight, additives, and other ingredients. In the present paper a method proposed earlier to estimate the rheograms of polymer melts through the use of the melt flow index has been extended to polyblends. Fundamentals of melt flow testing linkedin slideshare.
Melt flow index mfimfr a plastic recyclers guide impact. From melt flow index to rheogram welcome to ias fellows. Pla, ldpe, polymer blends, melt viscosity, flow activation energy. Melt flow index of polymers weight of melted samples in grams. Astm d1238 standard test method for melt flow rates of. Melt flow index is a measure of how runny the plastic is how it flows through an extruder. The viscosity is also directly dependent on molecular mass and so inversely related to melt flow index. Melt rheology of polymer blends from melt flow index. Pdf despite the fact that mfi is an empirically defined parameter with certain limitations as described above, it is. Mfr100 manual basic melt flow system united testing systems.
Since molecular weight mw is the force that drives the performance of polymers, it turns out to be a highly beneficial number. Although pom fg40u01 cf2001 is a melt blown grade copolymer, it has a very low melt flow rate of 40g10 min at 230oc according to astm d1238, which indicates that the resin has a high average molecular. It provides a means of measuring flow of a melted material which can be used to differentiate grades as with polyethylene, or determine the extent of degradation. Melt flow index on high molecular weight polyethylene. Data on the variation of melt viscosity over a wide range of shear rates and temperatures are necessary in the processing of cellulosic polymers. Thus, the polymer with the greater melt index value will flow more rapidly at the same stress level and therefore, will have a lower viscosity.
The thermoplastics materials industry uses the melt flow index mfi as a basic tool for quality control and acceptance of incoming products. Melt flow indexer is used to measure the flow rate of different polymers. You can see on this page more information about how melt flow index or melt flow rate is performed and calculated. 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. Both measure the same property, but slight procedural and equipment differences can yield different results. Viscous properties dominate during the earlier stages of processing but elastic effects are also important. Pdf melt rheology of polymer blends from melt flow index.
Using the time interval to extrude the polymer its flow rate over 10 minutes can easily be determined, thus giving the melt flow index mfi or melt mass flow rate mfr in g10 min. Estimation of melt elasticity of degraded polymer from melt. Note for convenience, the term melt flow index or mfi defined the melt flow of polymer extrudate in g10 min when subjected to a load of 2. In plastics manufacturing, the melt flow index mfi is used as a routine indicator of rheological behavior when more expensive and laborious determinations of. Influence of polymer melting point and melt flow index on. This means that there is no single constant that applies here. If you want to buy prestos melt flow index tester to test the quality and viscosity of polymers, contact presto.
Two or more existing polymers may be blended for various reasons. Note 2melt density is the density of the material in it molten state. The melt flow index thereby characterizes the complex polymer. Since mw is the driving force behind performance in polymers, it turns out to be a very useful number. Standard test method for melt flow rates of thermoplastics by. It, therefore, can be molded or processed over a comparatively wide.
Some instruments can also calculate the shear rate, shear stress, and viscosity in. A method for obtaining the melt flow index of the polymer blends at various compositions from the melt flow index of the individual components and the blend ratio has been suggested based on the. Application of melt flow index for rheological characterization of branched and linear polymers z. The measure of the flow properties is contained on the identity card, and is used as a check to verify if the plastics grade is within the required fluidity range. The melt flow index measurement in some polymers is remarkably influenced by both moisture content and additives. Melt viscosity is a constant at low shear rates or frequencies. Zwickroell plastometers for the determination of melt flow indexes mfr and mvr mareike arnold testxpo 2018. Use of melt flow rate test in reliability study of. The text offers a stepbystep procedure for developing a speadsheet computer program to obtain accurate thermoplastic rheograms at any tempertature without using sophisticated rheometres.
The sample can be in the form of virgin resin pellets or ground material from a finished thermoplastic product. Melt flow tester mfi melt flow indexer rayran manufactures an extensive range of advanced plastics and rubber testing equipment such as 6mba advanced melt flow indexer which is a highly precise melt testing instrument for the measurement of melt flow rate mfr or melt volume rate mvr in quality control and. Rheograms for engineering thermoplastics from melt flow index. An effective method, proposed earlier by the authors, has been extended to generate normal stress difference versus shear rate curves from the melt flow index of polymer waste. It is not to be confused with the standard density value of the material. The melt flow index mfi is a measure of the ease of flow of the melt of a thermoplastic polymer. Standards volume information, refer to the standards document summary page on. Hence the need to quantify such influence, and consequently to adopt a reliable analytical method authors. For a polymer with a molecular weight of 600,000 amu, the melt flow increases up to 25% water. The melt flow index only tests the material at one shear stress, and temperature. Melt flow index, melt flow rate, astm d1238, iso 13. Polymer degradation and stability 11 1985 297307 estimation of melt elasticity of degraded polymer from melt flow indext a. Melt flow rate mfr when 20 kg weight used then mfr test is hlmi or high load melt index melt flow index mfi flow rate of pe obtained under 190 c and 2. Typical reactions for chain assembling are polyaddition continuous or step wise and condensation polymer ization polycondensation 1 figure 1.
Results of the experiments carried out with of polymer selected types materials proved a minimal influence of surface roughness of the runners on the polymer melt flow. There are correlation charts if anyone wants to get viscosity in mpa or centipoises from a melt index number, but hardly anyone use s them in industry. To avoid this, many producers add short chain molecules, which are acting as. However, only this index is not sufficient to characterize the flow properties of any commercial material, and in particular of commercial highdensity polyethylene hdpe.
The melt flow index mfi or melt flow rate mfr is a measure for the ease of flow of melted plastics. Is it possible to change the mfi increase or decrease of. The melt flow index in practice the melt flow index mfi is verified in a device called plastometer, common in petrochemical laboratories and plastics recyclers. Mfr and the melt volumeflow rate mvr of thermoplastics3 3. Dobkowski 1 rheologica acta volume 25, pages 195 198 1986 cite this article. Saini polymer science and engineering group, chemical engineering division, national chemical laboratory, pune 411008, india received.
The melt flow index mfi is a widely used rheological property of polymers and occasionally the standalone rheological information used in the industry. Thermoplastics melt rheology and processing aroon shenoy. This value is also commonly called the melt index, mi, or melt flow index, mfi. Working procedure of mfi tester to measure the viscosity.
It is often used in the plastic industry for quality control of. Melt flow testing is simply a measure of the flow of a polymer when melted. Melt flow index is a measure of the resistance to flow viscosity of the polymer melt at a given temperature under a given force for a predetermined period of time. I was wondering if this page could be editted in some way to give further mention of the mfis effect on mechanical properties. It is defined as the mass of polymer, in grams, flowing in ten minutes through. From lab to production, providing a window into the process. Melt rheology of polylactic acidlow density polyethylene. One reason is to achieve a material that has a combination of the properties of the constituents.
The automatic method procedure b requires that the melt density either be known or calculated using the calculate option in the embedded software. In the present work, a method has been proposed to estimate the rheograms of a melt at temperatures relevant to its processing conditions with the use of a master curve, knowing the melt flow index and glass transition temperature of the material. This type of plastic material does not have a sharp melting point, but softens to a melt over a broad range of temperature. Expired lifetime application number us06945,784 inventor john riazi. Extruders prefer polymers with relatively high melt indexes. Rotational moulding is one of the fastest growing polymer. Knowing the mfi of a polymer is vital to anticipating and controlling its processing. Some instruments can also calculate the shear rate, shear stress, and viscosity in centipoise. This would be a useful tool for the plastics processor to assess the. The physical properties of the polymer depend significantly on variables such as the extent and type of branching. What links here related changes upload file special pages permanent link page information. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.
Although frequently critiqued, melt flow rate mfr is an excellent measure of the polymer s relative average molecular weight. The value obtained through the melt flow index test is a single data point. Melt flow rate testing part 2 to fully appreciate the strengths and weaknesses of the melt flow rate mfr test it is important to know something about the way the test is performed. Iso 13 melt massflow rate and melt volumeflow rate.
One reason is to achieve a material that has a combination of the properties of the constituents, e. Dimensionless analysis is a powerful tool in analyzing the transient heat transfer and flow processes accompanying melt flow in an injection mold or cooling in blown film,to quote a couple of examples. The extruded polymer is cut off manually and is then weighed. Mfi melt flow index gm10 min n slope of the shear stress versus shear rate curve.
The mass of resin, in grams, that is extruded in 10 minutes equals the mfr, expressed in units of g10 min. Rheograms of cellulosic polymers from the melt flow index. Using melt flow rate as a gauge for molecular weight of a. Astm d1238 standard test method for melt flow rates. Polymer properties stressstrain, viscosity, melt index. The weight of melt in grams flowing through the capillary in 10 minutes is the melt flow index. For a given type of polymer, a lower viscosity usually means a lower molecular weight. This is due to the fact that plastic materials are seldom manufactured without incorporating additives, which affect the processing characteristics of material like stability and. 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. Basic study on the evaluation of thermoplastic polymers as. Astmd1238 standard test method for melt flow rates of. Melt indexers, or extrusion plastometers, are common lab tools used to determine the melt flow rate mfr.
Viscosity is not usually constant polymers are very nonnewtonian fluids, with dependance on the flow rate. This will be used to calculate the melt flow rate of the polymers. The value of melt flow index testing polymer solutions. Plastics determination of the melt massflow rate mfr and the melt volumeflow rate mvr of thermoplastics 1 scope this international standard specifies two procedures for the determination of the melt massflow rate mfr and the melt volumeflow rate mvr of thermoplastic materials under specified conditions of temperature and load. The root variable is molecular weight, which determines both properties.
The melt flow rate apparatus has been designed in accordance with iso. This means that the melt flow rate and the base color may be somewhat. Standard test method for melt flow rates of thermoplastics. Draw down is the extending of the polymer extrudate by its own weight as the extrudate lengthens. Both melt flow and rheology tests can be very helpful tools for qc monitoring and development of polymers. Melt flow rate measures the rate of extrusion of thermoplastics through an orifice at a prescribed temperature and load. These factors are thus of direct importance to a processor or moulder. Part i article pdf available in advances in polymer technology 61. Pdf estimation of melt elasticity of degraded polymer. However, uniformity of flow rate among various polymers as made by. An effective method has been proposed to estimate the viscosity vs. The physical properties of the polymer depend significantly on variables such as the extent and type of branching, the crystal structure and the molecular weight. A method for obtaining the melt flow index of the polymer blends at various compositions from the melt flow index of the individual components and the blend ratio has been suggested. Expired lifetime application number us06616,053 inventor john riazi.
1242 1281 664 126 1144 962 1189 122 541 788 1225 694 831 1212 1464 783 18 64 69 914 1189 128 1339 446 1392 680 1447 1440