Brookfield YR-1 Rheometer - Manual (Page 42)

Brookfield Engineering Labs., Inc. Page 42 Manual No. M02-215-B0412
IV.4 Torque vs. Time for Various Products
Figure IV-5 shows graphs of Torque (%) vs. Time (seconds) and Stress (Pa) vs. Strain for sev-
eral different materials: body wash, skin care cream, ketchup and a pudding. Experimentally
determining an appropriate combination of torque range, spindle and speed for testing each
material ensures that the torque readings are within the recommended 10-100% on the torque
scale. If a sample has a relatively low torque reading for the yield (<10%), then try using a
faster speed or larger spindle to get a larger torque reading. Alternatively, a YR-1 Rheometer
with a more sensitive spring could be used as well; e.g., RVYR-1, or 1/4RVYR-1 for weak gels,
instead of HBYR-1.
You will need different spring torques in order to test a wide range of products that have vastly
different yield characteristics. The spring torque of the HB is eight times greater than that of
the RV, which is four times greater than the 1/4RV.
Even firmer materials maybe tested with EZ-Yield TM . The 5xHB range is available, but only
on the Brookfield 5xHB DV-III Ultra Rheometer; the Brookfield DV-III Ultra Rheometer is the
only additional instrument capable of running the EZ-Yield test. Creamy Peanut Butter is one
material successfully tested with this range.
An advantage of the EZ-Yield TM software is that multiple samples can be compared graphically
on the same set of axes for easy and rapid evaluation of yield behavior.
Figure IV-5: Torque vs. Time Graphs for Various Products