Compression behavior of micro-scale truss structures formed from self-propagating polymer waveguides

The structure–property relationships in newly developed polymer micro-truss structures were investigated, correlating compressive behavior with structural features, including density, cell size and truss angle. These open-cellular polymer micro-truss structures were formed from an interpenetrating array of self-propagating polymer waveguides. Compression experiments verified that the effective modulus scaled linearly with the measured relative density of the micro-trusses and was reliably predicted from a simple analytical model. However, the measured peak strength at initial truss member buckling was well below the values predicted from inelastic buckling theory, which was attributed to imperfections in the structure and the nonlinear compressive behavior of the solid polymer. In addition, a micro-truss structure was post cured at a higher temperature in an oxidizing environment which suppressed the tendency for truss members to prematurely buckle. The polymer modulus increased by approximately 40% and the peak strength of the micro-truss structure nearly doubled to 5.9 MPa.