Exploring the Limits of Viscoelastic Phenomena with AFM-Based Nanomechanics
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AFM-nDMA makes possible dynamic modulus determination (storage modulus, loss modulus, and loss tangent) with a wide-frequency range that is directly comparable to bulk DMA, but with the nanometer level resolution of AFM.
Prof. Nakajima shares the pioneering work that he and his team have done to investigate the viscoelastic properties of heterogeneous rubber materials. Due to its frequency and temperature control capabilities, they used AFM-nDMA to validate time-temperature superposition (TTS) principle within microstructured domains. A rubber vulcanizate and a filler-reinforced rubber were studied as model samples. An interesting nanoscale heterogeneity in the rubber matrix was observed, which may imply the breakdown of the time-temperature superposition principle due to the heterogeneous nature of the glass transition.
Bede Pittenger, Ph.D., discusses the work done at Bruker to optimize and validate the AFM-nDMA method. The technique is covered in detail along with examples to show its capabilities in both mapping at a single frequency and collecting spectra at user-specified points that are co-located with other mechanical property maps.
Dr. Bede Pittenger is a Senior Staff Development Scientist in the AFM Unit of Bruker's Nano Surfaces Business. He received his PhD in Physics from the University of Washington (Seattle, WA) in 2000, but has worked with scanning probe microscopes for 25 years, building systems, developing techniques, and studying properties of materials at the nanoscale. His work includes more than thirty publications and three patents on various techniques and applications of scanning probe microscopy. Dr. Pittenger's interests span topics from interfacial melting of ice, to mechanobiology of cells and tissues, to the nanomechanics of polymers and composites.