Plastometer melt-flow

Flowability MFI melt flow index, ASTM D 1238 Procedure A Extrusion plastometer... 

Figure 5.5 shows a schematic diagram of a melt indexer (which is also sometimes referred to as an extrusion plastometer). To determine the melt flow rate of a polymer resin, we place a suitable mass of it into the barrel, which is pre-heated to a standard temperature appropriate to the polymer. We then place a weighted piston on top of the sample. After allowing the polymer to reach the temperature of the barrel we allow it to extrude from the capillary orifice. The melt flow rate is the mass of polymer in grams that extrudes in ten minutes. 

ASTM D1238-04c Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer, Book of Standards Vol. 08.011, ASTM International (formerly known as American Society for Testing and Materials), West Conshohocken, PA, USA. 

In 83) the authors studied the flow of polypropylene and polyethylene with the help of a constant-velocity viscosimeter developed on the basis of a standard extrusion plastometer for measurement of the melt flow index (MFI) to the stem of which acoustic vibration was applied. 

Figure 2.45 Schematic diagram of an extrusion plastometer used to measure the melt flow index.

The melt flow indexer. The melt flow indexer is often used in industry to characterize a polymer melt and as a simple and quick means of quality control. It takes a single point measurement using standard testing conditions specific to each polymer class on a ram type extruder or extrusion plastometer as shown in Fig. 2.45. 

Some of the test methods being used to measure the processing stability of polypropylene include melt flow drift measurements at elevated temperatures using an extrusion plastometer (melt indexer), melt viscosity retention measurements using a torque rheometer, retention of melt flow after repeated extrusions, and injection molded spiral test measured by the flow in inches at various temperatures and the retention of melt flow of the injected spirals. The nine commercial resins were evaluated by these methods. 

ASTM D 1238-04, Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer ... 

The nanocomposite viscosity was characterized by the melt flow index (MFI). The measurements of MFI were performed on an extrusion-type plastometer with a capillary diameter of 2.095 0.005 mm, at a temperature of 240°C and a load of 2.16 kg. This sample was maintained at the indicated temperature for 4.5 0.5 minutes. 

The amount in grams of a thermoplastic resin forced through a 2.10 mm (0.0825 in. orifice when subjected to the prescribed force, e.g., 2.16 kg force during 10 min at the prescribed temperature (°C) using an extrusion plastometer (ASTM D1238). It is customary to refer to the flow rate of polyethylene as melt index. However, for all other materials, the term melt flow rate should be used. 

Extrusion plastometer (melt-indexer) ru A simple viscometer consisting of a heated vertical cylinder with two bores, a central one that contains a close-fitting piston and a recess for an orifice block, the other, nearby, for a thermoswitch. The orifice is 2.1 nun in diameter and 8 mm long. Plastic particles are loaded into the bore, allowed to heat for 6-8 min, then the weighted piston is released, and the extrudate is collected for a measured time internal. The melt-flow index (MFI) is stated as the rate of extrusion in grams/10 min. The instrument and its use are described in ASTM D 1238. Originally developed in 1953 for low-density polyethylene, the melt-indexer is now used with many other polymers with specific temperatures and piston weights. It... 

D1238, flow rate (melt index) by extrusion plastometer D569, flow properties D1525, Vicat softening point D746, brittleness temperature Analytical tests... 

D1238 Melt flow rates by extrusion plastometer... 

The melt flow index test method is used to monitor the quality of plastie materials. The quality of the material is indicated in this test by melt flow rate through a specified die under preseribed conditions of temperature, load, and piston position in the barrel as timed measurement is being made. The melt flow rate through a specified capillary die is inversely proportional to the melt viscosity of the material if the melt flow rate is measured under constant load and temperature. The melt viseosity of the material or MFR is related to the moleeular weight of the material if the molecular structures are the same. The extrusion plastometer as specified in... 

ASTM D1238-04C, Standard test method for melt flow rates of thermoplastics by extrn-sion plastometer, 2004. 

Melt flow measurements were performed according to ASTM D-1238-86 with an extrusion plastometer Davenport model 3. 

Melt flow rate (MFR) was measured following the ISO 1133 standard using a Ceast 6932 extrusion plastometer at 230°C/2.16 kg. 

ASTM D1238 Flow Rate of Thermoplasties by Extmsion Plastometer (Melt Index) - Compound melted at a predetermined temperature is extruded by a piston loaded with a specified weight under conditions that are determined by the composition. The weight in grams of compound extmded in 10 minutes is the Melt Flow Index. A higher value means a lower melt viscosity. 

Another value is also measured on the plastometer at 190 °C, but under a load of 21.6 kg (ASTM D 1238-04C Condition 190/21.6). This is called the high load melt index (HLMI) and is also reported in g/10 min or dg/min. HLMI is often used for polyethylenes that have very high molecular weights. Because it may be difficult to measure the small amount of extrudate from the standard conditions for what are called "fractional" MI products (typically resins that have Mis <1), HLMI may be a more accurate measure of molten flow. 

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