BRABENDER RHEOMETER

The results are reported of a study of the effects of different rotor speeds and circulating oil temperatures on the rheological properties of HAF black filled SBR powder carried out using a Brabender rheometer and the results obtained compared with those for HAF black filled bale SBR. 5 refs. 

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). 

To evaluate extensively the processability of PVC/EPR and to compare it with that of PVC having roughly the same molecular weight, we carried out a set of measurements by a capillary extrusion rheometer and Brabender plastograph. Other runs were carried out by an industrial size extruder. 

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. 

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. 

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). 

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,... 

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. 

Materials. Two types of standard tire cord obtained from Gen Corporation were used in this investigation polyester, 1300/3, and nylon 66, 1260/3. The rubber composition to which the adhesively dipped cords were bonded had the following composition in parts by weight styrene-butadiene rubber (SBR) 1502, 100 N330 carbon black, 50 zinc oxide, 5 stearic acid, 0.5 sulfur, 1.7 2-morpholinothio-benzothiazole, 2. Master batches were mixed 7 min in a 350-ml Brabender Plasticorder, and curatives were added on a cool two-roll mill. Cure characteristics at 155 °C were determined with an oscillating disc rheometer (ASTM D 2084). The time to reach 90% of the final cure state was 23 min, and the Shore A hardness of the final vulcanizate was approximately 60. 

Rheometrv. The following rheometers were used in this study An Instron capillary rheometer, a Rheometries mechanical spectrometer, used in both cone and plate mode as well as in the biconical mode, and a Brabender Plastograph (4). 

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]. 

Brabender plasticorder flow See test, Brabender plasticorder rheometer melt-flow, brackish water See water, brackish, braiding See fiber braided reinforced-plastic pul-trusion, braided. 

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]... 

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 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. 

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.]...

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). 

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