Size dependent hardness of polyamide/imide

Abstract

Indentation experiments with indentation depths in the nano- and micrometer ranges in the literature have shown that that an indentation size effect similar to metals is present in polymers. In this paper we present indentation experiments of a polyamide/imide polymer of indentation depths in the range of 1 to 30 microns. An increase in hardness of about 70% was observed at small indentation depths compared to hardness at large indentation depths. The indentation results are discussed with respect to an indentation hardness rule based on Frank elasticity suggested in a previous paper by the authors. It is found that the hardness model agrees well with the experiments. © Tatiraju et al.