We offer an array of rheological tests that may help answer the questions, to drive the project, to meet the business need ranging from basic comparative screening to comprehensive characterization using a state of the art Malvern Kinexus Pro rheometer. We perform a broad range of analyses on solutions, suspensions, mixtures, oils, and semisolids covering food, cosmetic, pharmaceutical, and other industries to quickly and quantitatively model real life applications under highly defined and controlled conditions. Outputs from these tests may provide better insight into product manufacturing, handling, performance, efficacy, and sensory attributes.
More detailed information can be found at www.rheologytestingservices.com
Below are summaries of the core tests offered. We can certainly perform other analyses to meet your needs. More detailed descriptions for each core test are found in other sections in this website. More detailed information can be found at www.rheologytestingservices.com.
•Yield Stress and Yield Viscosity (flow curves) measure the breaking point of the macro structure across a range of stress to model properties like spreadability and pumpability. It can be a useful tool to screen formulation properties.
•Thixotropy, a 3 step test, models product rebuild after shear thinning that often occurs during manufacturing, dispensing and application. For example, toothpaste is rheologically designed to remain in an open tube until sufficient stress is applied (flow), after which it quickly rebuilds to remain intact on the toothbrush. Paint and ketchup are also classic examples of thixotropic materials.
•Amplitude Sweep determines the LVER (Linear ViscoElastic Region) that tends to correlate with physical stability and is also a critical input parameter for other oscillation tests.
•Frequency Sweep generates a "rheological fingerprint” and also determines viscoelastic properties such as stiffness (complex modulus) and complex viscosity across a frequency range (1/time). Silly Putty rolled into a ball is an excellent example of the effect of frequency on material properties. At rest (slow event=very low frequency), it slowly flows as a viscoelastic liquid (G">G'), yet when dropped on a surface (fast event=high frequency) it bounces as a viscoelastic solid (G'>G").
•Temperature Sweep models properties over a temperature range. Is your product reversibly or irreversibly rheologically changed after storage in a hot or cold car? Is your product sensitive to temperature changes during manufacturing that affect product efficacy and quality?
VERTICAL PULL-AWAY TEST
•Pull-Away test quantitates the stickiness of a product, an important sensory consideration for consumer satisfaction and compliance.
It should be noted that several studies can be coupled in many interesting and informative ways. For example, a follow-up frequency sweep could be performed after LVER is determined, following a yield stress, thixotropy study, or temperature sweep to compare the changes in viscous (G'), elastic (G"), and complex (G*) modulii, along with complex viscosity and phase angle due to exposure to various controlled shear rates and/or temperatures.
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I have known the owner - Mark Patrick - for many years and I recommend Rheology Testing Services very highly. He has an impressive expert understanding of the science of rheology. I worked with Mark for many years during our time with GlaxoSmithKline and saw first-hand the exceptional quality of his work. He conducts his work with great rigor and professionalism.