Rheology
What is Rheology?
Rheology is the study and measurement of how materials flow and deform under applied stress, strain, and time. Rheology testing characterizes key properties such as viscosity, viscoelasticity, yield stress, thixotropy, and curing behavior—critical for predicting how a material will perform during mixing, pumping, coating/printing, dispensing, molding, and end-use.
Rheology is widely used for polymers, adhesives, inks, coatings, slurries, gels, pastes, and suspensions, helping optimize both processability and product performance.
What Rheology Can Help You Solve
Processability issues: pumping, filling, mixing, leveling, sagging, dripping, stringing
Dispensing & printing performance: jetting/screen printing, bead stability, edge definition
Stability & sedimentation control: thixotropy tuning, particle network strength
Batch consistency & QC: lot-to-lot comparison and specification setting
Cure/gelation monitoring: crosslinking kinetics, working time, gel point, post-cure behavior
Formulation optimization: thickener selection, solvent ratio, filler loading, additive effects
Typical Applications
Coatings & paints: leveling vs sag control, shear-thinning behavior, application feel
Adhesives & sealants: yield stress, open time, curing profile, squeeze-out control
Inks & pastes: screen/gravure/inkjet suitability, recovery, print definition
Battery slurries: dispersion quality, coating uniformity, sedimentation resistance
Polymers & melts: viscoelastic behavior, temperature dependence, molecular structure insights
Food, cosmetics, and gels: texture, stability, spreadability, consumer feel
Test Capabilities & What You Receive
Common Test Modes
Flow curve (viscosity vs shear rate): shear-thinning/thickening, Newtonian behavior
Yield stress: flow onset and sag/slump resistance
Thixotropy & recovery: structure breakdown and rebuild after shear (3-interval tests, hysteresis loops)
Oscillatory tests (SAOS): storage/loss modulus (G′/G″), viscoelastic fingerprint
Frequency & amplitude sweeps: linear viscoelastic region (LVR), network strength
Temperature ramps: thermal sensitivity, transition behavior, process window
Time sweep / curing test: gelation and cure kinetics (gel point indicators, modulus build)
Deliverables
Plots and key parameters (e.g., viscosity, yield stress, G′/G″, tan δ, recovery %)
Clear interpretation tied to your process (dispense/coat/print/mix)
Comparative conclusions (sample A vs B, batch trend, before/after aging)
Optional: recommended test conditions for routine QC
Sample Requirements
Sample types: liquids, slurries, gels, pastes, melts (project-dependent)
Typical amount: usually 10–50 mL (varies by geometry and test plan)
Condition: homogeneous; note any settling, bubbles, or skin formation
Information to provide: target application/process, temperature range, expected shear rates, pot life/cure behavior, and any handling constraints
Packaging: sealed container to prevent solvent loss; label clearly
Workflow
Requirement review (application + key questions + acceptance criteria)
Test design (geometry selection, shear/temperature/time profile, pre-conditioning)
Sample conditioning (mixing/degassing/rest time as needed)
Measurement (flow, oscillation, thixotropy, temperature/time sweeps)
Data analysis & reporting (parameters + plots + practical recommendations)
FAQs
What’s the difference between viscosity and rheology?
Viscosity is one part of rheology. Rheology also covers elastic behavior, yield stress, time dependence (thixotropy), and curing, which often drive real-world performance.
Why do different labs get different viscosity values?
Rheology results depend on temperature, shear rate, geometry, and sample history. Defining a consistent method is essential for meaningful comparisons and QC.
Can you simulate my process conditions (dispensing, coating, printing)?
Yes—by selecting appropriate shear-rate ranges, time profiles, and temperature conditions, we can design a test that better represents your process window.
Can rheology help predict sedimentation or stability?
Often yes. Yield stress, low-shear viscosity, and recovery behavior can correlate with particle suspension stability, though real-time shelf studies may still be needed.
Can you measure curing or gel time?
Yes. Time sweep and temperature-controlled tests can track modulus build and provide gelation/cure indicators relevant to working time and handling.
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