Spiral flow measurement

The brominated phosphate is an efficient flame retardant for polycarbonate resin. UL-94 ratings of V-0 with oxygen index values of greater than 40 are obtained. Polycarbonate resin containing brominated phosphate processes with greater ease than resin containing brominated polycarbonate as measured by injection molding spiral flow measurements. The heat distortion temperature is reduced... 

The three flame retardants are compared in Table VI. Brominated phosphate disperses readily in the resin presumably due to its high solubility in aromatics. Resin containing brominated polycarbonate is relatively difficult to process as measured by injection molding spiral flow measurements. 

In the present study, we discuss the development of new high flow filled flame retardant polyester compositions using extrusion process and similar flow additives. The correlation between standard viscosity measurements and spiral flow measurements is discussed along with mechanical and flame retardant properties. 

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. 

Spacings are from 6.35 to 31.75 mm (in 6.35 mm increments) with 9.5 mm the most common. Stud densities are 60 x 60 to 110 x 110 mm, the former the most common. The width (measured to the spiral flow passage), is from 150 to 2500 mm (in 150 mm increments). By varying the spacing and the width, separately for each fluid, velocities can be maintained at optimum rates to reduce fouling tendencies or utilize the allowable pressure drop most effectively. Diameters can reach 1500 mm. The total surface areas exceed 465 sqm. Materials that work harder are not suitable for spirals since hot-forming is not possible and heat treatment after forming is impractical. 

Spiral flow ASTM D3123-83 Measure length of flow along spiral die at end of test Set pressure and temperature from transfer press... 

The blends were prepared in a twin-screw extruder. The spiral flow was determined at a melt temperature of 288°C (550°F) for the PC and 266°C (510°F) for the transparent DB. The mold release energy was determined by measuring the force required to eject a disc measuring 76 mm in diameter and 3.2 mm thick with 6.4 mm high ribs. The chemical resistance was determined by measuring the maximum allowable outer fiber strain on 2.0 mm tensile bars, which did not reduce tensile elongation. 

A mechanical resistance is introduced into the flow and the resulting pressure drop is measured. Thus, flow measurement is transformed into the measurement of pressure difference. An orifice guage or standard orifice plate is generally used (Figure 2.8-5). Other types of throttle are the standard jet, the standard Venturi jet, and the spiral tube, which have the advantage over the standard orifice plate of a lower permanent pressure drop. This measurement principle is applicable over a wide measuring range, requires... 

Flow properties of thermosets can also be measured using transfer molding into a spiral flow tool as described in ASTM D3I23 [66]. Material injected under specified transfer conditions flows spirally outwards along a groove with numbered distance marks until cured to an extent that flow ceases. Molding is carried out at 150 C. Length of spiral is measured to the nearest 25.4 mm (1 inch). The standard states that the test is suitable for... 

Figure 11 Diagrams of multistage dryer with spiral flow plates. 1—spiral flow bed 2—spiral flow panel 3—first-stage cyclone 4—measure tank 5 storage tank 6—butterfly value 7—electric heater 8—flowmeter 9—second-stage cyclone 10—inlet.

The resin viscosity shown on the left-hand axis in Fig. 5.5 is an arbitrary measure of viscosity and may be taken to represent the predominant resinous component or it can be the net viscosity of the combined resin system. In either case, as the viscosity increases the spiral flow decreases. This effectively means that the viscosity range of the resins that may be employed is limited, to a large extent, by the... 

Testing of lubricants is based on the determination of the flow behavior of plastic melts (capillary viscosi-metry, spiral flow test, demolding force, by plasto-graph, extrusiometer, melt strength, roll-mill tests, etc.) or by finished part testing (gloss and smoothness, slip measurements, determination of static friction, etc.). 

Flow tests are run in an actual injection molding machine. Results are usually direct, tangible, and easy to interpret. Typically the flow length mold forms a part in the form of a graduated spirals. The flow length is measured and can be related to flow conditions in an actual production mold. Spiral Flow Length (SFL) data is used especially for comparing various resins for ease of fill [13]. 

ASTM D3123 Spiral Flow - This test measures how a filled molding compound will behave when injection or transfer molded. It enables the molder to set the optimum mold temperature. The compound is forced into a heated spiral mold under controlled conditions. Once cure is complete the part is removed and the flow length is measured directly from the specimen. 

Another common way to characterize higher melt index resin is to measure the spiral flow number. The Equistar spiral flow number (SFN) is the number of centimeters of flow produced when molten resin at 227° C is injected into a long, spiral-channel insert (half-round 0.635x0.157 X 127 cm) at a constant pressure of 6.9 MPa. Estimated shear rate is approximately 10,000 reciprocal seconds. The equivalent ASTM Method for SFN is D3123. The following equation was defined. 

Spiral flow was measured in an injection molding machine with a spiral mold. The flow length (in cm) in the mold was measured under the given test conditions. Melt temperatures, mold temperature, gauges of spiral flow, and boost pressure were 250 °C, 270 °C, 80 °C, 0.75 mm. 

Figure 5 shows spiral flow data at wall thickness of 0.75 and 0.3 mm measured at 270 °C for flame retardant 30% glass filled PBT-13K with and without flow... 

Figure 4. Spiral flow data at 0.75 mm wall thickness of 30% GF PBT with and without flow promoter measured at 240,250 and 270 °C.

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