Geometrical and mechanical characterisation of hollow thermoplastic microspheres for syntactic foam applications

Recently, hollow thermoplastic microspheres, have emerged as an innovative filler material for use in polymer-matrix composites. The resulting all-polymer syntactic foam takes on excellent damage tolerance properties, strong recoverability under large strains, and favourable energy dissipation characteristics. Aside from foams, microspheres are finding increasing usage a variety of applications industries. Despite this, there is absence statistical geometrical mechanical data certain classes microspheres. In this work we characterise two microsphere using X-ray computed tomography, focused ion beam electron microscopy. We observe the spatial distribution these within polyurethane-matrix show that volume-weighted polydisperse shell diameters follow normal distribution. Interestingly, polydispersity wall thickness not observed furthermore correlated to diameter. utilise information obtained analytical micromechanical techniques small strain regime determine, first time, estimates Young's modulus Poisson's ratio itself. Our results contribute potential future improvements design fabrication materials employ including foams.