Brabender measurements

Since this was the case, all data from Brabender measurements were measured as quickly as possible. When a constant reading could not be achieved, the slowly changing torque was extrapolated to zero time. The correction was normally less than 10%. The data for Solprene 414C are shown in a double logarithmic plot of shear stress against shear rate on Figure 3. 

While some ceramists swore by measured data obtained with the aid of the Pfefferkorn method, others preferred the capillary rheometric approach, and still others, including H.W. Hennicke at the University of Clausthal-Zellerfeld and researchers at the Brick and Tile Institute in Essen, devised their own techniques. In pertinent U.S. literature, studies based on the Brabender measuring kneader [11] were encountered most frequently. 

Various measured quantities such as pressure, torque Brabender measuring extruder, Haake ESM Average to high, subject to instrument High Simulation of the extmsion process... 

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 plasticity readings obtained from the Brabender measuring kneader expressed in the form of torque figixres are not identical with the plasticity figures relevant to extrusion. This also holds true for those measured values determined by the penetrometer or other measuring methods. Yet the Brabender measuring kneader is ideally suited for the development or optimisation of bodies which need to be plastified prior to extrusion by means of continuous or intermittent kneading. 

Fig. 10 Disassanbled Brabender measuring kneader (photo Brabender)...

These tests were performed using a universal Zwick tester, model 1435, coimected to a computer with appropriate software. Particle size was measured in paraffin oil using Zetasizemano S90 (Malvern Instmments) analyzer. Zeta potential of filler dispersion in water was studied by the means of Zetasizer 2000 (Malvern Instruments) apparams. Rheological properties of filler suspensions in paraffin oil were determined by viscometer RM500 (Rheometric Scientific). Dibutylphtalate (DBP) absorption was measured by means of an Absorptometer C (Brabender). The modification process was carried out in Brabender Measuring Mixer N50 at following parameters temperature 125°C rotor speed 40 RPM duration 0,5 h. 

One of the ways to prepare a blend of incompatible polymer pair in which the dispersed phase forms in-situ reinforced fibres is an utilisation of extrasion line equipped with converging die. The whole extrasion line used in this study consisted of a Brabender measuring single-screw extrader with 30/25 D, a Zenith PEP II gear pump with 1.2 cm /rev and a flat extrasion die with 2x20 mm outlet cross-section. The polymer melt passing through die was firstly... 

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). 

In preliminary tests, melt mixed blends of PP and LCP were processed at six different temperatures (Tcyi 230, 240, 250, 260, 270, and 280°C) with a Brabender Plasti-Corder PLE 651 laboratory single-screw extruder. The measured melt temperatures were about 10°C higher than the cylinder temperatures (Tcyi). The objective was to study the influence of temperature on the size and shape of the dispersed LCP phase. Two different polypropylenes were used to ascertain the effect of the viscosity of the matrix on the final morphology. Different draw ratios were obtained by varying the speed of the take-up machine. 

The changes that occur in a starch when it is heated in water can be studied in several ways. One way is to follow the changes under a microscope, another is to measure the viscosity of the paste. A Brabender amylograph is normally used to monitor the paste viscosity. 

Brabender make a whole range of instruments for testing flour. These instruments are the standard ones in use in the UK, Germany and North America. The company has recently produced new versions of these instruments that use electronic measuring systems rather than the mechanical systems previously employed. The new models use the same name but with the suffix E. Thus, the new model Extensograph is the Extensograph-E. 

Functional property tests were conducted in duplicate. AACC (21) methods were used for the determination of water hydration capacity (Method 88-04) and nitrogen solubility index (NSI) (Method 46-23). Oil absorption capacity was measured by the procedures of Lin et al. (22) and oil emulsification by a modification (22) of the Inklaar and Fortuin (23) method. Pasting characteristics of 12.0% (w/v, db) slurries of the flours and processed products were determined on a Brabender Visco/Amylograph (Method 22-10). The slurries were heated from 30 to 95°C before cooling to 50°C to obtain the cold paste viscosity value. Gelation experiments were conducted by heating 15% (w/v db) slurries in sealed stainless steel containers to 90°C for 45 min in a water bath C3). 

If the torque as measured in a Brabender is plotted in an Arrhenius plot against 1/T characteristic linear dependencies are observed (Fig. A). While powder flow is observed up to the softening point of PVC a distinct linear relationship between shear rate and reciprocal temperature exists between 150 - 180°C indicating one mechanism of flow. The deviation above ca. 180°C indicates a change in flow mechanism. 

Figure 4. Arrhenius plot of PVC melt viscosity as measured in a Brabender.

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. 

Figure 7. Variation of consistency as a function of time measured by a Brabender plastograph for a crude PVC/EPR and a PVC homopolymer...

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. 

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. 

Figure 16.12 Pasting profiles of (a) small and (b) large granules ofwaxy, normal and high-amylose barley starches measured by Brabender Amylography. (Adapted from reference 42 with permission)...

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). 

---