Haake rheometer

Figure 20.2 Torque value as a function of PHB content for PHB/PEN/PET ternary blends measured at 285 °C and a constant rpm of 60 using a Haake rheometer molar ratio of PEN to PET of 1 1...

Rocha et al. [112] demonstrated that the parent polymer of the series, po-ly(glycolic acid) n=l, is immiscible with PCL. They blended poly(glycolic acid) with PCL-767 and PCL-787 (Table 1) by freeze drying mixed solutions under vacuum, mixing the polymers in a Haake rheometer at 235 °C and then compression moulding. Two TgS were observed by DMA, unshifted from those of the homopolymers drastic phase separation was reported for 50 50 blends. 

Instruments AB, TA Instruments, and ThermoFisher Scientific (Haake Rheometers). 

CVD MWCNT Iljin Nanotech Co., Compounded 0.1=2 dried, as-received w/HAAKE rheometer... 

All materials were dried at 120 °C in vacuo for at least 24 h before use, to minimize the effects of moisture. The PEN/CNT nanocomposites were prepared by a melt blending process in a Haake rheometer (Haake Technik GmbH, Germany) equipped with a twin-screw (nonintermeshing co-rotating type). The temperature of the heating zone, from the hopper to the die was set to 280, 290, 295, and 285 °C, and the screw speed was fixed at 20 rpm. For the fabrication of PEN/CNT nanocomposites, PEN was melt blended with the addition of various CNT content, specified as 0.1, 0.5,1.0, and 2.0 wt% in the polymer matrix, respectively. 

Waste butyl rubber has been both devulcanised and re-revulcanised by workers in the East China University of Technology [21] under conditions of high shear and high temperature in a Haake Rheometer. They investigated the effect of the process temperature on the degree of devulcanisation and also compared the damping and physical properties of the waste rubber, DR and re-cured materials. 

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... 

Chocolate does not behave as a tme Hquid owing to the presence of cocoa particles and the viscosity control of chocolate is quite compHcated. This non-Newtonian behavior has been described (28). When the square root of the rate of shear is plotted against the square root of shear stress for chocolate, a straight line is produced. With this Casson relationship method (29) two values are obtained, Casson viscosity and Casson yield value, which describe the flow of chocolate. The chocolate industry was slow in adopting the Casson relationship but this method now prevails over the simpler MacMichael viscometer. Instmments such as the Carri-Med Rheometer and the Brookfield and Haake Viscometers are now replacing the MacMichael. 

Figure 6.5 Illustration of a Searle-type rheometer with a concentric cylinder sensor to the right a cone and plate sensor. Courtesy G. Schramm [349], Copyright 1981, Gebruder Haake GmbH.

Wu et al. (73) studied the viscoelastic properties, viz. storage modulus (GO and complex viscosity (r 0 with respect to frequency (co) of PLA-carboxylic-acid-functionalized MWCNTs nanocomposites using a rheometer (HAAKE RS600, Thermo Electron Co., USA). The dynamic frequency sweep measurements were carried out at the pre-strain level of 1%. They observed that the addition of carboxylic-acid-functionalized MWCNTs weakened the dependence of G on go, especially at higher loading levels (Figure 9.12). This indicates... 

Similar to Wu and Liao (75), Wu et al. (74) used a DMA (Model -242C, NETZSCH Co.) and a rheometer (HAAKE RS600, Thermo Electron Co.) to evaluate the viscoelastic behavior of the carboxylic-acid-functionalized MWCNTs reinforced PCL/PLA blend. Using DMA, it was observed that, with the increase of MWCNT loading, the Tg of the blend system shifted to higher temperatures. This agrees with the results obtained from the other studies discussed above and indicates the MWCNTs are compatible with the blend. The viscoelastic properties observed via rheometer were similar to those by Wu et al. (73), discussed above. 

Influence of addition of free polymer on the rheology of the suspensions Fig. 3 shows the effect of addition of PEO (Mjj=20,000, 35,000 and 90,000 respectively) on the extrapolated yield value obtained from the shear stress-shear rate curves using the Haake Rotovisko. On the other hand. Figure 4 shows the results obtained using the Deer rheometer in which Tg was directly obtained. Although the trend obtained is the same, the yield values obtained using the Deer rheometer are significantly... 

In a controlled-shear rate viscometer such as the Haake Rotovisco, T is determined as a function of Q, while in constant stress rheometers, such as the Carri-Med, is determined as a function of T. In order to determine surface slip in a co-axial cylinder viscometer, one must vary the ratio ri/r2 as well as T and (Mooney, 1931). Specifically, one can determine S2 at constant T using three combinations of cups and bobs of radii, r3/r2, and rj/r]. The coefficient of slip is given by ... 

For smaller particles, smaller stresses are exerted. Thus, in order to predict sedimentation it is necessary to measure the viscosity at very low stresses (or shear rates). These measurements can be carried out using a constant stress rheometer (Carrimed, Bohlin, Rheometrics, Haake or Physica). Usually, a good correlation is obtained between the rate of creaming or sedimentation, v, and the residual viscosity rj 0), as will be described in Chapter 21. Above a certain value of ri(0), v becomes equal to 0. Clearly, in order to minimize sedimentation it is necessary to increase rj 0) an acceptable level for the high shear viscosity must be achieved, depending on the application. In some cases, a high rj[0) may be accompanied by a high rj (which may not be acceptable for apphcation, for example if spontaneous dispersion on dilution is required). If this is the case, the formulation chemist should seek an alternative thickener. 

Thus, to predict creaming or sedimentation, it is necessary to measure the viscosity at very low stresses (or shear rates), and these measurements can be carried out using a constant stress rheometer (e.g., Carrimed, Bohlin, Rheometrics, Haake or Physica). 

A commercial instrument for extensional viscosity measurements is currently offered by the Thermo Electron Corporation [40], The device uses capillary breakup techniques and is called the Haake CaBER . Vilastic Scientific, Inc. also offers an orifice attachment to their oscillatory rheometer for extensional viscosity determinations [41,42], The principle of operation of the rheometer is oscillatory tube flow [43,44], Dynamic mechanical properties can be determined... 

The next example is of a Pre-Startup Review or a Process Hazards Audit held on a piece of purchased processing equipment, a Haake Rheocord Torque Rheometer and Laboratory Twin-screw Extruder. The organization responsible for this extruder has a standard checklist of eleven pages of items to be considered by the technical person or persons in charge of the equipment or process, before the review is held. Copies of the completed checklist are then sent to each committee member before the meeting for review. Generally, in a review of this type, the group will convene at the location of the equipment rather than in a conference room to go over the material provided. In this case, the committee consisted of ... 

Several researchers reported viscoelastic behavior of yeast suspensions. Labuza et al. [9] reported shear-thinning behavior of baker s yeast (S. cerevisiae) in the range of 1 to 100 reciprocal seconds at yeast concentrations above 10.5% (w/w). The power law model was successfully applied. More recently, Mancini and Moresi [10] also measured the rheological properties of baker s yeast using different rheometers in the concentration range of 25 to 200 g dm. While the Haake rotational viscometer confirmed Labuza s results on the pseudoplastic character of yeast suspension, the dynamic stress rheometer revealed definitive Newtonian behavior. This discrepancy was attributed to the lower sensitivity of Haake viscometer in the range of viscosity tested (1.5 to 12 mPa s). Speers et al. [11] used a controlled shear-rate rheometer with a cone-and-plate system to measure viscosity of... 

Figure 6.1 Cut-away illustration of fluid in a concentric cyiinder rheometer. (Courtesy G. Schramm [1]. Copyright (1981), Gebruder Haake GmbH.)...

For example, the Haake Rheo Stress Rheometer from Thermo Electron (Karlsruhe) GmbH. 

PET/HDPE/EBA-g-GMA Haake torque rheometer/capillary rheometry/SEM morphology/ effect of EBA-g-GMA level on blend properties Li and Lu 2008 Li et al. 2009d... 

Rheological Measurements Polymer solutions with various concentrations were prepared in a small sample bottle by moderately heating for several days, and then used for rheological measurements. The study was carried out using a cone-and-plate rheometer (Haake CV-20N) with a shear rate range of 0 300 s at 30 C. 

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