New Considerations on the Determination of the Apparent Shear Viscosity of Polymer Melt with Micro Capillary Dies

Capillary rheometers have been widely used for the rheological measurement of polymer melts. However, when micro capillary dies are used, the results are usually neither accurate nor consistent, even under the same measurement conditions. In this work, theoretical modeling and experimental studies were conducted for a more profound understanding of the mechanism by which the initial and boundary conditions influence the inaccuracy in the apparent shear viscosity determination with micro capillary dies (diameters: 500 μm, 200 μm, 100 μm). The results indicate that the amount of polymer initially in the barrel, the pre-compaction pressure and the capillary die diameter have a significant influence on the development of the micro scale inlet pressure, which directly determines the accuracy of the measurement at low and medium shear rates. The varying melt compressibility was confirmed to be the main factor directly related to the inaccuracy in the micro scale apparent shear viscosity determination. It is suggested that measures such as reducing the amount of polymer initially in the barrel and increasing the pre-compaction pressure could be used to reduce the measurement inaccuracy.

Extraction and Characterization of Galactan from Seaweed Gracilaria verrucosa of Vietnam

In this study, we extracted galactan from the seaweed Gracilaria verrucosa of Vietnam and investigated its structure and properties. The seaweed was immersed in water in the different temperatures to obtain the solution of galactan. Thereafter, the solution was coagulated and purified to obtain galactan as a powder. Kjeldahl method, infrared spectroscopy, viscosity determination and differential scanning calorimetry (DSC) were used to characterize structure and properties of the resulting material. It was found that the obtained galactan had agar structure without sulfate as substitute group. The proteins content, the intrinsic viscosity and the thermal resistance of the galactan extracted in water at 40 oC were higher than those of the galactan extracted in water at 100 oC.

Mooney Viscosity Determination Of Rubber With A Charm Filler

Research on the Determination of Viscosity Mooney From Rubber by Fillers Charcoal has been done. Each latex was added into the coconut shell charcoal ( particle size 80 mesh ) were 36 , 38 , 40 , 42, and 44 gram. Then the latex is coagulated with formic acid in pH 4.7. Formic acid is used as a control for the rubber crumple without the addition of coconut shell. Research carried out by measuring the quality of rubber Money Viscosity. From the results of research it turns out that the value of the viscosity of the money obtained by the addition of charcoal to the rubber in the latex is 72.5 ; 74 ; 75.5 ; 77 ; and 75. It can be seen that the value of the best rubber Mooney viscosity of 75 , so the rubber with medium Mooney viscosity value able to provide a meeting point between the energy efficient with superior physical properties .

A facile oxygen-17 NMR method to determine effective viscosity in dilute, molecularly crowded and confined aqueous media

This NMR probe of water dynamics enables viscosity determination in concentrated and crowded solutions and allows quantifying internal fluidity within biological condensates.