Rheology melt flow index

High density (HDPE), 52 Irregularities, 52 Linear low density (LLDPE), 52 Low density (LDPE), 52 Molecular weight, 52 Melt flow index, 53 Melting temperature, 51 Moisture absorption, 51 Polymeric forms, 52 Resistance to chemicals, 52 Resistance to oxidation, 52 Shrinkage, 54 Unsaturations, 54 a-transition, 51 P-transition, 51 y-transition, 51 Polyisocyanate, 79 Polylactic acid, 79, 91 Polymer alloys, 48 Polymer processing additives, 646 Polymer rheology, 619 Polymeric forms, 52 Polyphase PlOO, 451 polypropylene (PP), 2, 11 Polypropylene homopolymer, 70... 

More details about the viscosity are described in Chapter 4, which deals with rheology of polymers. The industry prefers to measure melt fluidity (inverse viscosity), by using a standard rheometer, named Melt Flow Indexer. The measured property (mass of polymer that flows through a standard capillary under determined load and temperature, for 10 minutes) is also known as MH (Melt Flow Index). Because MFI is inversely related to melt viscosity, it is important to remember that low values of MFI are obtained by high MW polymers. 

Flow properties See melt-flow index, viscosity, pseudo-plastic fluid, and rheology. 

Keywords peroxide, molar weight distribution (MWD), rheology, crystallization, extrusion, melt flow index (MFI), controlled rheology (CR), peroxide-degradation, residence time distribution (RTD), halflifetime of peroxides, melt elasticity, die swell, viscosity curve, shear rate, elongational viscosity, melt fracture, heterophasic PR... 

There has been little or no published work on the melt rheology of PHB, presumably because of problems associated with its melt instability. However, some information on melt viscosity can be derived from melt flow index data such as that given in Fig. 9, using the empirical relationship ... 

Rheological properties Intrinsic viscosity. Pa s Melt-flow index, g/10 min D1238 1133... 

Some type of melt viscosity is included in the specification for almost every polymeric or plastic product. This is because viscosity is related to the molecular weight and to the performance of a polymer. Equipment used for rheological measurements range from the simple and ubiquitous melt flow indexer to the precise and quantitative capillary and cone-and-plate rheometers. 

The most apparent correlation is between the rheology and the GPC measurements. The samples had a broad range of melt flow index values, the amount of material that will flow through a standard oriface in 10 min under a fixed combination of temperature and pressure. Higher melt flow index values indicate a greater tendency to flow. The most frequently... 

The rheological behaviour of NR and polystyrene (PS) blends had been carried out in the presence and absence of the NR-g-PS compatibilizer using a capillary rheometer and a melt flow indexer. ... 

Shenoy, A.V. and Saini, D.R. (1986) Melt flow index more than just a quality control rheological parameter. Advances Polymer Technol, 6, (Part I) 1-58, (Part II) 125-45. 

For appropriate calculations of the flow in spinning machines one thus needs a rheological curve over about four decades of shear rate, such as Figure 17.14. A zero-shear viscosity tj ) or a melt flow index (MFI) gives insufficient insight. 

Shenoy, A. V, Saini, D. R., and Nadkami, V. M., Melt rheology of polymer blends from melt flow index, Int. J. Polym. Mater., 10, 213-235 (1984). 

In most monographs and texts on polymer rheology, the Melt Flow Indexer has been treated briefly because it has generally been considered an instrument meant only for quality control. However, it has been shown in the recent past [66] that the Melt Flow Indexer provides more than just a quality control rheological parameter. As the main accent of the present book is to show the multiple uses of the data from the Melt Flow Indexer, this particular instrument will be treated in the utmost detail. However, the discussion will not be done in this subsection but will be carried forward to the next chapter where thorough justice will be done. 

Shenoy, A. V. and Saini, D. R., Upgrading the melt flow index to rheogram approach in the low shear rate region, J. Appl Pofym. ScL, 29, 1581-1593 (1984). Minoshima, W., White, J. L., and Spniiell, J. B., Experimental investigation of the influence of molecular weight distribution on the rheological properties of polypropylene melts, Fofym. Eng. ScL, 20,1166-1176 (1980). 

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