Model Effect of Temperature Cycling for R&D, Stability and Processing
Temperature sweep probes rheological changes across a temperature ramp or over one or more heat-cool cycles. Does your product reversibly or irreversibly change after storage in a hot or cold car? Is your product sensitive to temperature changes during manufacturing that impact product efficacy and quality? A temperature ramp or up/down cycle is well designed to efficiently probe this important property. This assay can be performed under constant shear rate (1/sec) or shear stress (Pa) in the rotation mode or under a constant strain, stress or frequency in the oscillatory mode.
Figure 1 demonstrates how temperature sweep quantifies the difference in spreadability of 2 butter products under constant frequency. The less stiff, more spreadable butter (red line) has a lower G' (elastic modulus = solid nature) between refrigerator and room temperatures.
Figure 2 shows the benefit of multiple heating and cooling cycles resulting in an irreversible rheological change. A more rheologically stable form of the material is identified and confirmed with subsequent heating and cooling cycles.