Nanoindentation, viscoelastic

Preliminary nanoindentation results on other teeth (premolars, incisors and canines) indicate variations in mechanical properties as large as those discussed for molars [unpubl. data]. In each case the exact distribution of mechanical properties within the enamel appears to correlate with the extent of mechanical loading experienced by the tooth during mastication. However, there appears to be an increase in the viscoelasticity (loss modulus) for the enamel of anterior teeth when compared to posterior teeth, again this may be related to their function. 

Pellicle and tea-immersed pellicle were analyzed using nanoDMA (dynamic mechanical analysis) to see if the tannins had an effect on the viscoelasticity of the pellicle. NanoDMA is a technique used to study and characterize mechanical properties in viscoelastic materials. The method is an extension of nanoindentation testing [58, 59], An analysis of the nanoindentation load-depth curve gives the hardness (H) and reduced elastic modulus (E ), provided the area of contact, A, between the indenter tip and the sample is known [ 13]. By... 

Odegard GM, Bandorwalla T, Herring HM, Gates TS Characterization of viscoelastic properties of polymeric materials through nanoindentation. SEM Ann Conf Exp App Mech, Charlotte, NC, 2003. 

Van Landigham et al. reviewed nanoindentation of polymers, [40, 41] including a summary of the most common analyses of load-indentation data. Chief among these methods is an analysis of indentation load-penetration curves according to the Oliver-Pharr method. [42] This method is based on relationships developed by Sneddon for the penetration of a flat elastic half space by different probes with particular axisymmetric shapes (e.g., aflat-ended cylindrical punch, a paraboloid of revolution, or a cone) [43], More recently, Withers and Aston discussed indentation in the context of plasticity and viscoelasticity [44]. 

For viscoelastic materials such as polymers and many biomaterials, recently developed nanoindentation dynamic mechanical analysis (DMA) techniques enable the study of dynamic response as a function of load amplitude and frequency. The DMA stiffness mapping technique offers the unique capability of mapping storage and loss moduli of the sample... 

Bembey, A., Oyen, M., Bushby, A., Boyde, A., 2006. Viscoelastic properties of bone as a function of hydration state determined by nanoindentation. Philos. Mag. 86, 5691—5703. 

Probing of local mechanical viscoelastic and adhesive properties, incl. nanoindentation... 

Figure 5.7 Schematic of nanoindentation load-unload versus displacement for a viscoelastic-plastic material. Adapted from Ref [154].

Lehaf, A.M., Hariri, H.H., Schlenoff, J.B. Homogeneity, modulus, and viscoelasticity of polyelectrolyte mirltilayers by nanoindentation refining the buildup mechanism. Langmuir... 

---