The Liquid Cell
Mechanical
properties of biological and polymeric samples often vary
considerably when in a fluid environment compared to the usual
dry testing conditions. If we wish to understand their
properties and behaviour in fluid media it is highly desirable
to test under these conditions rather than to attempt to infer
from measurements on dry (or 50% relative humidity) samples.
To meet this need, the testing capability of the NanoTest has been extended by the development of a liquid cell allowing nanoindentation, nano-scratch and nano-wear testing of samples fully immersed in fluids. This development builds on the earlier success of the NanoTest humidity control chamber which allows testing under 25-90% relative humidity. The liquid cell works with the existing pendulum design and the horizontal loading has several key advantages for testing in fluid.
Due to the unique pendulum system employed by the NanoTest, we are able to immerse both the sample and indenter tip in a liquid bath.
Case Study: Effect of test environment on elastic modulus of PA6 after 24 hour immersion
The above graph shows typical dry and wet indentation curves for a low MW PA6 sample. The investigation used a Berkovich indenter loading at 0.2 mN/s to a peak load of 5 mN. Appreciable creep and creep recovery effects are observed during the hold periods in both wet and dry samples.
Further Reading
MML Fluid Cell Application Note (178kB PDF)
The influence of fluid environment on the nanoindentation creep behaviour of nylon 6, BD Beake, G Bell and D Bielinski, Journal of Applied Polymer Science, 107(2008) 577.
Multiscale creep compliance of epoxy networks at elevated temperatures, TF Juliano, MR Van Landingham, CA Tweedie and KJ Van Vliet, Experimental Mechanics 47(2007)99.
