HD Elastic modulus mapping
The Elastic Modulus Mapping of Immiscible Polymer Blends
Study of the relationship between morphology of multicomponent materials and their performance is an essential issue of modern material characterization. In the last two decades the compositional mapping of heterogeneous polymer materials with AFM was performed with the phase imaging. The latter reveal dissimilarities of the components, which are expressed by variations of the energy dissipated by the probe interacting with these components. Yet the correlation between the phase changes and specific sample properties such as elastic modulus, adhesion, and viscoelasticity is not well established. Even twenty years after the introduction of phase imaging its interpretation remains an unsolved problem. For practical purposes, researchers have used a tabulated relationship between the phase shift and stiffness of the components derived from studies of model systems, in which the ratio of the components has been varied in a systematic way. With the broadening of HybriD mode applications, there is definite progress. We’ll demonstrate the use of elastic modulus mapping for compositional imaging of heterogeneous polymer materials in studies of several PS-containing blends.
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The analysis of the presented results obtained on the PS/PBd blend showed that the depressed domains embedded into a matrix exhibit a much lower elastic modulus in the map recorded at 6 nN force.
A profile across the domains shows that their modulus is in the range of tens of MPa that is much smaller than the modulus of the matrix (2.5 GPa). These values are close to the macroscopic moduli of PS and PBd [1]. Hence, we assign the domains to PBd and the matrix - to PS.
[1] J. Wen “Some mechanical properties of typical polymer-based composites”” in “Physical Properties of Polymers”, ed. J. Mark (2007) p. 487.