Abstract: Microindentation and nanoindentation measurements of model pressure-sensitive adhesives have been used along with scanning probe imaging to follow changes in properties with aging. One blend that is initially miscible stiffens markedly with time for tackifier loadings above a certain value. Lateral phase segregation at the surface is seen for some of the blends along with strong increases in stiffness. Changes with time are less pronounced in the miscible blend with a tackifier stabilized by hydrogenation. While microindentation provides quantitative measurement of changes in overall stiffness and adhesive performance, nanoindentation provides lateral resolution of the changes near the surface. Of the techniques used here, phase detection mode scanning probe imaging provides the most highly surface selective means of noting changes in properties with aging.

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