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What is Large Amplitude Oscillatory Shear (LAOS)

And Why Do You Need It?

Male Engineer near Alpha Technology instrument

Michele Scacchi

Applications Engineer, Europe

In this five part series, our applications engineer, Michele Scacchi, outlines why you need Large Amplitude Oscillatory Shear (LAOS) for rubber quality control, how it helps you measure your quality of mix, how to evaluate natural and synthetic rubber, fillers and reinforcement and how to analyze the results. 

Part 1: Optimizing your Mixing Process Using FT-Rheology via Large Amplitude Oscillatory Shear (LAOS)

FT-Rheology via Large Amplitude Oscillatory Shear (LAOS) reveals more information about the filler-filler / filler-polymer interactions and provides a check at the end of the mixing process to determine if the full dispersion of the filler in the rubber matrix has been achieved. 

Part2: Tracking the Progress of Filler Dispersion – Examples of LAOS Experiments

To validate the approach presented by Leblanc, we performed tests using several filled rubber compounds – including not only carbon black compounds but also silica rubber compounds. Experiments were run on Alpha Technologies’ Premier RPAs using FT-Rheology via LAOS. 

Part 3: Using LAOS to Quantify Long Chain Branching and to Predict Processability

The presence of long chain branching (LCB) in a polymer has a large impact on his viscoelastic properties and can affect significantly the processability of filled rubber compound: black incorporation time, die swell, extrusion behaviour. For instance, the incorporation of long chain branches has been used in EPDM and polyethylene (PE) to enhance shear thinning/flow behaviour and, in the case of PEs, to delay the onset of melt fracture toward higher shear rates.

Part 4: Case Studies: Determination of Long Chain Branching in Polymer and Prediction of the Processability in Their Applications

The LAOS technique is very sensitive to detect the long chain branching (LCB) in polymers and can be used for quality control in the thermoplastic and synthetic rubber production to check the polymer architecture and to predict the processability in their applications. Learn more in part four about case studies we have completed.

Putting Theory into Action: case studies  

To validate the approach presented in this blog and in several paper published by Alpha, we show  several case studies in which we investigated several raw polymers, elastomer and thermoplastic materials such as Li-BR, EPDM, NBR, PE. Experiments were run on Alpha Technologies’ Premier™ RPAs using the LAOS test method. 

Coming Soon! Part 5: How to Analyze LAOS Results on a Premier RPA with Enterprise Software

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