Investigation of nano mechanical properties of microballoons by nanoindentaion test

Microballoons are gas-filled microcapsules with thermoplastic gasimpermeable shell. The mechanical properties of microballoons are important in their applications[1]. Enough mechanical strength isneeded to avoid shell rupture under load and through application. Nanoindentation is a method for determination of thenanomechanical properties of the materials. In this method, the surface is indented by a stylus indenter and it consists of two loadingand unloading steps. During loading state, the surface is indented and elastic and plastic deformation take place and in follow the load isremoved with the same rate so that plastic and elastic recovery take place[2,3]. In this study, core/shell microcapsules comprising of crosslinked PMMA shell encapsulating pentane, were synthesized by suspension polymerization (Fig1).Elastic modulus and hardness of microballoons were determined by nanoindentaion test