Brookfield YR-1 Rheometer Manuel d'utilisateur télécharger pdf (Page 39)

Brookeld Engineering Labs., Inc. Page 39 Manual No. M02-215-B0412

IV. EXAMPLES

IV.1 Example Application: Body Wash Gel with Bath Beads

The test method and data shown in Figure IV-1 show an analysis of yield from a typical body

wash gel product. It is usually desirable to measure yield on products without transferring

them from their containers because doing so would “pre-shear” the material. This body wash

was a weak gel with suspended beads in it. The V-73 vane spindle was selected because it was

small enough to t in the container’s neck with the cap removed. A 1/4 RVYR-1 Rheometer

was used for the test.

The spindle was immersed to the primary immersion mark and pre-shear was turned off. Zero

was turned on and a nominal “zero” speed of 0.1 rpm was chosen. This allows the motor to reset

the torque to zero prior to running the test. Occasionally, the spindle rotates a bit while being

lowered into the sample. This moves the torque sensor away from zero. It is usually desirable

to reset it to zero before starting the measurement. Run speed was set to 2.0 rpm. Often, 1.0

rpm is selected and is a good starting point when establishing test parameters. Low and high

yield limits (for Q.C.) were ignored.

This test resulted in a good mid-range torque of 77.0% at the yield stress, which was reported

as 19.3 Pa.

Figure IV-1: Body Wash Gel Sample

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Brookfield YR-1 Rheometer Manuel d'utilisateur Page 39