The melt flow index (MFI) is a measure of the ease of flow of the melt of a thermoplastic polymer. 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.Polymer processors usually correlate the value of MFI with the polymer grade that they have to choose for different processes, and most often this value is not accompanied by the units, because it is taken for granted to be g/10min. Similarly, the test load conditions of MFI measurement is normally expressed in kilograms rather than any other units. The method is described in the similar standards ASTM D1238 and …show more content…
At the same time, melt flow rate is a measure of the ability of the material's melt to flow under pressure. 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. Ratios between two melt flow rate values for one material at different gravimetric weights are often used as a measure for the broadness of the molecular weight distribution.
Melt flow rate is very commonly used for polyolefins, polyethylene being measured at 190 °C and polypropylene at 230 °C. The plastics engineer should choose a material with a melt index high enough that the molten polymer can be easily formed into the article intended, but low enough that the mechanical strength of the final article will be sufficient for its use.
2.9.1: Measurement
ISO standard 1133-1 governs the procedure for measurement of the melt flow rate.The procedure for determining MFI is as
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MFI is expressed in grams of polymer per 10 minutes of duration of the test.
Synonyms of Melt Flow Index are Melt Flow Rate and Melt Index. More commonly used are their abbreviations: MFI, MFR and MI.
Confusingly, MFR may also indicate "melt flow ratio", the ratio between two melt flow rates at different gravimetric weights. More accurately, this should be reported as FRR (flow rate ratio), or simply flow ratio. FRR is commonly used as an indication of the way in which rheological behavior is influenced by the molecular mass distribution of the material.
The flow parameter that is readily accessible to most processors is the MFI. MFI is often used to determine how a polymer will process. However MFI takes no account of the shear, shear rate or shear history and as such is not a good measure of the processing window of a polymer. It is a single-point viscosity measurement at a relatively low shear rate and temperature. Earlier, it was often said that MFI give a ‘dot’ when actually what is needed is a ‘plot’ for the polymer processors. However, this is not true now because of a unique approach developed for estimating the rheogram merely from the knowledge of the
Have you ever wondered why the plastic bag that you left on the porch during winter cracks or breaks more easily than when you left it during summer time but a piece of wood which was left just like the plastic bag has no effect whatsoever? This is because of a phenomenon, which only happens to polymers, known as the glass transition. For each polymer, there is a certain temperature at which the amorphous polymers undergo a second order phase transition from a rubbery and viscous amorphous solid to a brittle and glassy amorphous solid called the glass transition temperature, Tg.1 When the polymer, or in this case, the plastic bag, is cooled below their glass transition temperature, it becomes hard and brittle like a glass but when it is used above their glass transition temperatures, it might have a different effect than when used at room temperature or below the glass transition temperature as normally, different types of polymers like clothes, food packaging, insulations for wires, etc. are either used above their glass transition temperatures or
The thermometer, containers, and iron ball were secured of any possible contaminants. The stopwatch was calibrated and checked to be correctly measuring the time in seconds and milliseconds, by comparison with other stopwatches. The thermometer was checked to be accurately measuring the temperature of lukewarm water, and was al...
A group of polymer chains can be organised together in a fiber. How the polymer chains are put together is important, as it improves the properties of the material. The flexibility, strength and stiffness of Kevlar fiber, is dependent on the orientation of the polymer chains. Kevlar fiber is an arrangement of molecules, orientated parallel to each other. This orderly, untangled arrangement of molecules is described as a “Crystalline Structure”. A manufacturing process known as ‘Spinning’ is needed to achieve this Crystallinity structure. Spinning is a process that involves forcing the liquefied polymer solution through a ‘die’ (small holes).
on how long it takes to heat up. If we heat a large volume of water it
Plan 1. Collect 4 different sized beakers 2. Boil some water in the kettle 3. Pour 50ml into each beaker 4. After 1 minute check temperature 5.
low current to melt. Below is a graph of the results I expect to get.
Once the machine was preheated the two samples of pure urea was placed inside of the machine. Once placed in the machine, the sample was watched to observe the melting point. The melting point was noted as soon as the first drop of liquid appeared until the crystal completely
PVC is classified as a thermoplastic, which can be re-shaped in the presence of heat. Situations where temperatures reach up to 160 degrees Celsius (melting point) would cause deformation to the PVC; this would be considered a
- Temperature was measured after and exact time i.e. 1 minute, 2 minutes, 3 minutes.
Have you ever wonder what some personality test consist of, are they good to rely on, and are they structured well? Well the Minnesota Multiphasic Personality Inventory as known as MMPI test is one of the longest test conducted. It is based on a true and false answer test, so there is no right or wrong way of doing it. This test consists of its validity, clinical, and content scales. I will be emphasizing on the last five clinical scales, which are paranoia, psychasthenia, schizophrenia, hypomania, and social introversion.
The other metallurgical feature that is directly affected by the heat input rate is grain size in the heat affected zone (HAZ) and in the weld metal. In steel welding, it is necessary to seek a heat input rate that gives the optimum combination of grain size and cooling rate [11]. Before the actual welding is done, all the earlier steps such as layout, plate edge preparation, fit up and alignment should be well planned with regard to achieving desired product quality. Sikandar Singh Assistant Engineer, Department of Welding Engg. Cheema Boilers Limited, Kurali, India.
By exposing the chocolate and the cookies before the light and heat of the 60-watt light bulb, the students will be able to progressively observe the process of the material melting and make records at every stage of the experiment. Using the 15 seconds step, the students can identify the melt temperature and time of the chocolate under the lab conditions as well as make and analyze their records in the final part of the experiment. The experiment is expected to establish, which of the chocolates and cookies melt faster, and make conclusions about the influence of the consumables ingredients on their physical properties. This corresponds with the TEK 112.11 (5B) procedure, which allows students to “observe, record, and discuss how materials can be changed by heating or
Although it is to administer and has documented validity scoring is time consuming. A number is obtained by measuring in millimeters up to the point the patient has
This essay focuses on the Behaviour of base metals during partial melting in the upper mantle and fractional crystallization in the crustal magma. A base metal is a metal that easily oxidise and reacts with a diluted hydrochloric acid (HCL) to form hydrogen. The examples of base metals include iron, nickel, copper, zinc and lead. The Behaviour of these metals in terms of partial melting and fractional crystallization is discussed by using their partition coefficients. Partition coefficient is the ratio of concentration of an element in a mixture of a phase relative to another phase. In addition, the partition coefficient depends on pressure, the composition of the solid, the composition of the melt and the temperature (Hall, 1987). Furthermore, the Behaviour of these metals during fractional crystallization is discussed based on the results that were obtained from the study of Okataina Volcanic Center on how metals (Zn, Pb, Cu, Mo) Behaviour during crystallization and degassing of rhyolites. Then their Behaviour during partial melting is discussed based on the results that were obtained from the experiments which were done at 1.5-2.0GPa and 1300-1500ᵒC for divalent metals (Zn, Fe, Mn, Co, and Ni).