Extrusion 610 INDEX

RCM. See Ring-closing metathesis (RCM) Reaction by-products, removing, 83 Reaction extrusion, 204 Reaction index, 237 Reaction injection molding (RIM), 205 Reaction-in-mold (RIM) nylon, 149 Reaction kinetics, 76, 77 Reaction mechanisms, polyesterification, 66-69... 

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. 

Polyethylene is used in extrusion and injection molding processes. When used to manufacture blown films a standard polyethylene will have a melt index of approximately 1 g/10 min, while that used for injection molding typically has a melt index of 5 to 20 g/10 min. Why are the polymers used for these two processes so different ... 

Controlled expansion alloys, 13 520-522 Controlled flavor release systems, 11 528, 543-553, 554-555 characteristics of, ll 544t demand for, 11 555 developments in, 11 558 elements of, 11 555-557 extrusion encapsulation for, 11 550 key aspects of, 11 556t morphologies of, 11 545 Controlled free-radical polymerization, block copolymers, 7 646 Controlled humidity drying, ceramics processing, 5 655-656 Controlled indexing, 18 241 Controlled initiation, 14 268-269 Controlled laboratory studies, in... 

Effects of Nitrogen Solubility Index. Nitrogen solubility indexes of soy flour (initial NSI 65%) were modified by heating in an oven (135 C) for 2, 4 and 12 hr prior to extrusion. These treatments resulted soy flours with NSI values of 51, 46 and 14%, respectively. The NSI-14 flour was found unusable for extrusion. The original flour (NSI 65%) produced extrudates having low... 

Film. The blown film process is most commonly used in the production of PB film from resins with melt indexes from 0.3 io 10 g/10 min at a melt temperature of200-215DC using conventional equipment. Mechanical properties of blown PB film depend on the degree of orientation and other processing parameters. PB film can be sealed ai 100 220 (1. Another technique for the PB film production consists of film casting from the melt on polished chilled rolls and co-extrusion or lamination with other films. 

POLYETHYLENE, A thermoplastic molding and extrusion material available in a wide range of flow rates (commonly referred to as melt index) and densities. Polyethylene offers useful properties, such as toughness at temperatures ranging from —76 to +93°C. stiffness, ranging from flexible to rigid, and excellent chemical resistance. The plastic can be fabricated by all thermoplastic processes. 

Rotation of the core at Q = 70 min-1 shifted flow rate/pressure characteristics of extrusion curves upwards and to the left, the result of which was a notable drop of (AP)70 compared to (AP)0 (indexes used here correspond to the speed of core s rotation). Increase in (AP)70 up to values of (AP)0 due to higher speed of the screw allowed as increase is the extruder s capacity by 40-80 % (depending on the nature and content of the filler). Results very much similar to that were obtained later in experiments with filled PVC-based compositions 36). Pressure in the head can be reduced by not less than 20-30 % at a constant extrusion rate, experiments with filled PVC-based compositions 36). Pressure in the head can be reduced by not less than 20-30% at a constant extrusion rate. 

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. 

Modification of BPA-PC for adaptation to the conditions of production of CD and CD-ROM disks, and of substrate disks for WORM and EOD was necessary. BPA-PC standard qualities for extrusion and injection molding have, depending on molecular weight, melt flow indexes (MFI), (according to ISO 1130/ASTM 1238 in g/10 min at 300°C/1.2 kg, between less than 3 g/10 min (viscous types) up to 17 g/10 min. For CDs and optical data storage disks, however, MFI values exceeding 30 g/10 min, and for exceptionally short cycle times (5—7 s) even >60 g/lOmin are demanded at an injection mass temperature of 300°C (see Table 5). 

The igneous rocks of the Tuscany Province consist of an association of mafic to silicic rocks (Fig. 2.2a) exhibiting contrasting compositions and genesis. Silicic rocks (here defined as those with SiCL > 65 wt %) consist of a large number of intrusive and extrusive bodies having a peraluminous character (Alumina Saturation Index, ASI >1), and moderate variations of major and trace elements at a given silica level. 

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. 

Polypropylene - Melt flow rate after the first, third and fifth extrusion, at 500°F to determine the degree of chain scission (5). Y. I, index is also determined (6.),... 

High Density Polyethylene - [Both regular and high molecular weight (HMW)]. The time to increase in torque at 220°C. by the Brabender Plasticorder was determined as a measure of crosslinking. Yellowness Index after the Brabender test at 220°C. and after the first extrusion at 260°C. were also performed. 

On the basis of melt flow rate measurements after 1, 3 and 5 extrusions, compounds 1, 2 and 2 when used alone at 0.1 in the polypropylene base resin provide superior stabilization to BHT, 7 and 8. Under these conditions compound J2 provides the lowest Yellowness Index (Y.I.) color over other compounds evaluated. 

Melt Flow Index (MFI) — The amount in grams of a thermoplastic resin flowing through a standard orifice at a specified temperature in 10 minutes. The higher the value, the easier the resin flows in extrusion or injection molding. 

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