Achieve Material Characterization Using Viscosity Measurements

Material characterization plays an important part when it comes to conducting quality testing of products. Owing to the increasing complexity of materials and devices, techniques used to study and perform characterization have become progressively more sophisticated.

What is material characterization and why is it important?

Material characterization is the process of measuring and determining the physical, chemical, mechanical, and microstructural properties of materials. It is also an essential part of materials engineering analysis that helps to identify the right material for specific applications.

Advanced material characterization techniques are used to analyze many properties in products, such as mechanical strength, thermal stability, electrical conductivity, flowability, hardness, corrosion resistance etc. These techniques help manufacturers optimize their designs / structures to improve performance and reliability by understanding the material characteristics of different components to help make better decisions about how to create safe and efficient products, as well as analyze potential new materials that behave in a specific way.

Steps to material characterization

To characterize your material using viscosity measurements for your products, it is advisable to have a clear strategy. In this blog, we will discuss the various steps that will help you execute your strategy and achieve your goals. These steps are repeatable and can be used and applied for many applications - like food products, polymers, inks, oils, and more!

Step 1. Defining your goals

The first step towards any process is to have clarity of what you wish to achieve through that process. In other words, what are your goals? Knowing your goals will make it easier to determine how to put the viscosity data to the best use and to choose the best instrument for your application.

These goals can range from predicting specific performance properties for conducting R&D, performing quality control checks, quick screening, or just sample characterization and exploration. Usually, performing material characterization for specific performance properties as a part of R&D is the most common measurement goal.

Step 2. Testing and experimenting based on your goals

Once you have determined your goals, the next step will be to design your tests and experiment. It would be helpful to identify what testing and formulation parameters are relevant to your experiment. Testing parameters can range from a quick screen to a thorough sample characterization.

If your goals are centered around quick quality screening, limited test parameters are adequate to establish a single-point type measurement. When choosing your shear rate and temperature, it is important to select parameters that are relevant to your material and process.

If your goals are related to performance prediction, you need to estimate the most practical or realistic shear rates that can be determined from your measurements. It is also important to note that temperature conditions will play an important role in the results. Consider all storage and application temperatures relevant to your sample and the common conditions you are trying to simulate in your testing, including processing conditions and temperatures as well.

In cases when your goals include thorough sample characterization, a broad range of parameters, including shear rates and temperatures should be considered. Once you have identified your testing parameters you can create testing plans designed around these specific parameters.

Step 3. Designing your measurement protocols

The next step to a successful experimental strategy is choosing the right tools, understanding sample volume requirements, and creating your measurement protocols.

When determining the right instrument for your testing it's important to be clear about what solutions you require, and what kind of materials you are dealing with.

Based on the kind of samples that you are measuring, it is advisable to consider the following parameters to achieve accurate and high-quality data.

• Viscosity range – While you may not know the exact viscosity of your product, it is necessary to at least estimate the viscosity range of the material being tested. For instance, water and oil have different viscosities and with that information, it will be easier to select the right instrument and measuring range.
• Fluid behaviour (Newtonian or non-Newtonian) - Depending on the viscosity behavior as a function of shear rate, stress, and deformation history, fluids are characterized as Newtonian (the fluid viscosity remains constant, no matter the amount of shear applied for a constant temperature) or non-Newtonian. Fluid flow is directly proportional to the viscosity of fluids. It is vital to determine if a fluid is Newtonian or non-Newtonian, and what range of shear rates needs to be considered for a specific application to properly characterize your fluid
• Yield stress / thixotropy – Unlike Newtonian fluids, non-Newtonian fluids display either a non-linear relation between shear stress and shear rate, have yield stress, and/or viscosity that is dependent on time or deformation history. It is important to know the thixotropic behavior of your sample. The fluid’s flow characteristics may change as shear stress/rate vary.
• Sample stability - Another important parameter to consider is your sample stability. Does shearing impact your sample? Do your samples age or degrade over time without any external forces?
• Sample volume (volume of the sample you have available for testing) - When determining the best instrument for your measurements, you want to have a firm understanding of the volume of the sample you have available for testing.

  AMETEK Brookfield’s range of Viscometers and Rheometers have the capability of testing very small sample sizes. Learn more about our advanced and innovative series of Instruments.

• Fluid Structure - When considering your sample, it is also important to understand and account for the composition of your fluid.

1. 1. Particles, aggregates, droplet size and rigidity - it's important to consider particle size in the case of an emulsion or slurry.
   2. Potential phase separation or inhomogeneity
   3. Some samples may cure or harden during testing. It is essential to understand the best methods and solvents to flush or clean the instrument to maintain repeatable results.

In this step, it is also important to consider throughput, automation, portability, and sample retrieval and recovery options. Once you have selected the right instrument for your experimental testing, you can create your measurement protocols.

Step 4. Data Analysis

This step is vital for research, development, and formulation - correctly processing, analyzing, and interpreting the viscosity data.

Processing your data begins with data organization, consolidation, and analysis. This data can then be processed through math models and graphs to help model and understand the flow characteristics of your fluid.

RheocalcT Software and Rheo3000 from AMETEK Brookfield have been designed to make sample measurement and testing of products, simple and easy. The software analyzes data, generates multiple plot overlays, prints tabular data, runs math models and performs other time-saving routines.

Key Takeaways

In four steps you can achieve advanced material characterization using viscosity measurements.

• Define Goals – Material characterization for specific performance properties
• Test & Experiment – Could be quick quality screening, performance prediction taking a broad range of parameters into consideration, and more
• Design Measurement Protocols – Using the right tools, understanding the sample volume, considering a variety of parameters if they pertain and creating the measurement protocols
• Data Analysis – Vital step easily processed through easy-to-use software

If you would like guidance on applying material characterization techniques, AMETEK Brookfield is here to help! We are happy to discuss your application, the tools, and the software that would be most appropriate to support quality testing to easily achieve optimal results.

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