High Temperature Nanoindentation of Neat Resins and Carbon Composites of PMR-15 Polyimide

This paper presents the high temperature nanoindentation experiments performed on neat resins and unidirectional carbon fiber composites of the well-studied aerospace polymer, PMR-15 polyimide. A sharp-tipped Berkovich nanoindenter equipped with hot-stage heating system was used. The creep deformation is observed to occur during nanoindentation of polymers and can affect the determinations of contact stiffness, elastic modulus and hardness. Experimental methods on minimizing the creep effect are proposed; analytical procedure for considering creep deformation is also given. The temperature dependent mechanical properties of PMR-15 are successfully measured and results indicate that the present high temperature nanoindentation technique is reliable for quantitative characterizations of local material properties at elevated temperatures. A study of the carbon composite follows, and presents previously unstudied behavior of the local material properties in the interfacial region at high temperature in-situ conditions.