Viscosity evolution

Viscosity evolution.—Figure 2 shows the evolution of the relative viscosity of the reaction medium during the reaction time for a reactor without membrane. Relative viscosity decreased because of the depolymerising activity of the enzyme. After 6 hours of reaction the viscosity became almost constant, which suggested that almost no molecules (polymers) were present in the reactor to contribute to the viscosity. 

Figure 7. Predictions of viscosity evolution for copolymer C at pH 7, 0.1 NAC1 at different temperatures...

Figure 2. Viscosity evolution of plasticized PVC (------) and zinc stearate...

RALLS responses show a sharp increase in insoluble aggregates between 19 and 32 days for resin UF-R2 and between 32 and 53 days for resin UF-R5. This is related to the viscosity evolution previously measured for both resins (Fig. 6) the... 

Fig. 5.13. Intrinsic viscosity evolution for different chemical structures of the polymer chain...

Figure 11.5. Viscosity evolution of three solutions as indicated, according to ASTM D 562-01. The Stormer Type Viscometer employed was able to register data only above 59 Krebs units. Data collection stopped at the gel...

Figure 4.6 Complex viscosity evolution during phase separation in 20phr PEtl- modified DGEBA-anhydride systems cured at different temperatures. Dots correspond to the...

Rheological tests of epoxy resin were performed using a TA Instruments Discovery Hybrid Rheometer with a peltier plate fixture of 25-mm disposable parallel plates. Similar to DSC tests, batches of approximately 50 g of epoxy resin, with GO contents of 0,0.05,0.1, and 0.2 wt%, and the appropriate amount of hardener were mixed. Samples of approximately 2 mL of mixed resin samples were pipetted onto the rheometer bottom plate. Rheological tests were performed with a 0.5-mm plate gap at a constant shear rate of 2.5 s Temperature sweep tests were completed for the determination of temperature-dependent viscosity evolution and were performed on all samples from 25 to 95 °C. Isothermal rheology tests were conducted at 80 °C to determine the viscosity evolution with respect to time. This temperature was selected after investigating the dynamic DSC scans in which peak temperature was approximately 82 °C. 

Hydrogel flow curves are established by means of a rotational rheometer. During the gelation viscosity evolution of the fluid is followed in the reactor by means of a torque sensor set up on the agitator shaft (laboratory reactor). 

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