MI Melt index

MI = Melt index (ASTM D 1238, condition E) HLMI = Flow rate (ASTM D 1238, FR = Flow ratio ratio of melt index HLMI to melt index MI... 

MI melt index from an ASTM method used as an indicator of MW of PE... 

The MI (melt indexer) is easy to operate and relatively low cost thus, it is widely used for quality control and for distinguishing between members of a single family of polymers. Specifically, this MI makes a single-point test that provides information on... 

The weight average molecular weight of acetal copolymers may be estimated from their melt index (MI, expressed in g/10 min) according to the relation... 

Polyethylene and polypropylene are semitransparent plastics made by polymerization. They are produced from ethylene and propylene in a variety of grades. Their mechanical properties are determined mainly by density (degree of crystallinity) and molecular weight, characterized by the Melt Index (MI). 

Increase in Density (crystallinity) Decrease in Melt Index Basic Properties Unaffected by Density and MI... 

The melt index (MI) or melt flow index (MFT) is an inverse measure of viscosity. High MI implies low viscosity and low MI means high viscosity. Plastics are shear thinning, which means that their resistance to flow decreases as the shear rate increases. This is due to molecular alignments in the direction of flow and disentanglements. 

Figure 10. Pelletizer pressure drop. Effect of polymer melt index (MI).

Io Intensity of incident light MFT, MI Melt flow index... 

Fig. 12. The porosity of the catalyst determines not only its activity but also the chain length. Here melt index (MI) varies with catalyst pore volume in a series in which a common hydrogel was dried by extraction with different organic solvents to achieve variations in porosity.

This explains the melt index behavior of coprecipitated silica-titania catalysts which is shown in Fig. 16. With each catalyst, the MI rises with increasing calcining temperature until sintering begins, then it drops. The... 

The optimum reoxidation temperature, shown in Fig. 20, is about 600°C. This depends to some extent on the type of support. Highly titanated samples produce peak melt indexes at only 300°C. Probably the temperature is needed to bind the chromium to the dehydroxylated support. Above 600°C the activity remains high, but the promotional effect of low temperature attachment is lost, and the MI drops. 

Evaluating the Melt Index (MI) from the Flow Curve Develop a methodology and computer program logic to evaluate the Melt Index (ASTM Standard D) of a material from its flow curve (non-Newtonian viscosity as a function of shear rate). 

First, the rate of shear, which is not linear with the shearing stress due to the non-Newtonian behaviour, varies with the different types of polymer. The processability of different polymers with an equal value of the MI may therefore differ widely. An illustration of this behaviour is given in Fig. 15.14. Furthermore the standard temperature (190 °C) was chosen for polyethylenes for other thermoplastics it is often less suitable. Finally, the deformation of the polymer melt under the given stress is also dependent on time, and in the measurements of the melt index no corrections are allowed for entrance and exit abnormalities in the flow behaviour. The corrections would be expected to vary for polymers of different flow characteristics. The length-diameter ratio of the melt indexer is too small to obtain a uniform flow pattern. 

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