Brabender torque rheometer

Techniques for evaluating processing stabiHty and mechanochemical effects include using a Brabender torque rheometer (29,30), injection mol ding (26,28), capillary rheometry (26,28), and measuring melt index as a function of residence time (26). 

The use of Brabender torque rheometer enabled us to evaluate the behavior of melt viscosity vs. time at low shear stresses the usual operating conditions were adopted—i.e., granules (28 grams) were introduced in the bowl, the temperature was fixed at 187 °C, and each run was started after 5 minutes of conditioning. 

The apparatus used for the first tests included a 3/4-inch diameter, 20 1 L/D laboratory extruder. The second series of evaluations was run on a Brabender torque rheometer equipped with mixing head. The third tests utilized large scale processing equipment including a two-roll,... 

Figure 10.21. Variation of torque with temperature of plasticized PVC in a Brabender torque rheometer. [Adapted, by permission, from Ramos-de Valle L, Gilbert M,J. Vmyl Technol, 12, 4, 1990, p.222-5.]...

Figure 12-3. Brabender torque rheometer. (Courtesy of C. W. Brabender Instruments, Inc.)...

ASTM D3795 - Thermal Flow and Cure Properties by Brabender Torque Rheometer - This test give a simulation of what will happen during injeetion or transfer molding. 

The rigid PVC formulation was prepared using a high intensity mixer. Hyperdispersants were added to the calcium carbonate filled and un-filled dry blends. The dry blends were then analyzed using a Brabender torque rheometer and a 16 mm twin screw extfuder. The torque rheometer studies were performed at 188°C, 10 min, 65 grams and 75 rpm. The 16 mm twin screw exu-uder was set at temperatures 160, 165, 170, 180°C and the output was measured at 30,40 and 50 rpm. 

Treatment of PVC, suspended in chlorobenzene, with Et2AlCl followed by the addition of methanol greatly improved the thermal stability (6). This will be the subject of a separate publication. However, the nature of the improvement was different—i.e., film pressed in air at 200°C was yellow not colorless, but processing stability as determined by the torque rheometer test in the Brabender Plasticorder at 195°C was far superior and was measured in hours rather than minutes. The removal of labile chlorine atoms by Et2AlCl undoubtedly contributed to heat resistance. However, in the absence of a further reaction, such dehalo-genation probably became dehydrohalogenation, contributing to color development. 

Torque Rheometer. The Brabender plastograph was also used to study the relative processing stabilities of the polymers. The conditions were those recommended by P. G. O Leary (24). The melt viscosity-time curves are shown in Figure 10. Resins D, I, and E are the least stable, and A, H, G, and B are the most stable. 

Utilizing A Torque Rheometer (Brabender Plasti-corder) At Constant Mixer Temperature, The Society of The Plastics Industry, Vinyl Dispersions Division, New York, 1968. 

Commercial instruments are available the Brabender Plastograph, and Plasticorder, this latter allowing use of an extruder head the RAPRA variable torque rheometer [5]. The advantages of these instruments are based on the similarity of their action to full-scale extrusion equipment and on the fact that they can be operated at shear rates appropriate for factory equipment. But because of the difficulty of matching exactly the range of shear rates which exist in full-scale plant, successful scaling-up is difficult. Elongation flow measurements have been reported by several workers, in which a sample is stretched in uniaxial tension at a constant strain rate [6]. 

The Brabender measuring kneader or torque rheometer was originally designed for the caoutchouc industry, yet this is widely used, especially in the USA, to determine the plasticity of ceramic bodies. [15,16]... 

The Brabender plasti-corder flow test is used with screw injection molding of TS resins to graphically and accurately measure the flow as it relates to IM. Concern about whether a compound would have a sufficient flow life during its residence time in the barrel led to the use of this test. It is basically a torque rheometer designed to measure and record torque (in meter-grams) vs. the mixing time. It produces a flow curve that is a measure of the compound s processability. 

Plasli-Corder, Computerized torque rheometer system, Brabender, C. W., Instruments, Inc. 

Batches, each weighing 70.00 g, were mixed in an electrically heated Brander mixer-measuring head (with a capacity of 60 to 85 ml, a rotor speed ratio drive-to-driven of 3 2, air cooled, with stock temperature thermocouple, fitted with cam-type rotors) at 40 rpm, with the temperature set points adjusted to 100°C. The mixer-measuring head was coupled to a Brabender electronic torque rheometer. 

Swelltest die heads also allow contactless estimation of die-swell to be obtained. A Planetarimixing head also allows the study of powdery materials (again useful in PVC processing). Temperatures up to 300°C can be studied. Current equipment of this type is produced by Brabender ( Plasticorder ), Haake ( Rheocord ) and Hampden Instruments (variable torque rheometer). 

Allen, E. O. and WiUium, R. F, Prediction of Polymer Processing Characteristics Using C. W. Brabender Plasticorder Torque Rheometer, SPE ANTEC (1971), p. 587. 

Melt flow in extrusion can be determined using a torque rheometer, such as supplied by Brabender and Haake, equipped with a laboratory extmder in place of the customary mixing head. Various screw designs are available, corresponding... 

Checks on raw material sometimes are made by using a small single-screw extruder as a rheometer, or a test machine designed for the purpose—such as a Brabender Plastograph (a device for measuring torque, which may be attached for the purpose to a small extruder). 

Onufer RJ (1968) Characterization of clay plasticity with a torque measuring rheometer. In Rutgers University, Rutgers School of Ceramics, New Brunswick, New Jersey, October 5, 1968 - Brabender OHG Literaturver-zeichnis Nr. 352... 

The most common approach to characterize the PVC fusion process employs the Brabender Plasticorder or Haake Rheometer, which consists of a mixing head with two rolls. Figure 14-1 shows the PVC fusion process as reflected in the curve of fusion torque vs. time. The melt temperature in each stage can also be recorded. Point A is referred as the compaction peak and corresponds to compression and densification of the powder. Point B refers to the beginning of melting, followed by the appearance of the fusion peak. Point C occurs as PVC fuses into melt. The difference in time between A and C is called fusion time . The torque observed at... 

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