Assessing shear, tensile and fracture properties of macroporous nanocomposites using the Arcan test

Abstract

Macroporous polymers and nanocomposites remain popular materials due to their low densities and unique interconnected pore structures. The determination of mechanical properties in relevant loading conditions, such as shear, remains largely underexplored due to the comparative complexity of such analysis compared to simple compression tests. We investigated the use of the Arcan test to induce uniform biaxial stress in such materials and provide insight into the effect of porosity and silica particle reinforcement on shear properties and fracture toughness of high/medium internal phase emulsion templated macroporous polymer nanocomposites, called polyHIPE/MIPEs. Increasing foam densities were associated with greatly improved tensile and shear properties. Improvements in shear strength and modulus were also noted in polyMIPEs reinforced with as little as 5 wt.% silica nanoparticles, although any increase in tensile properties was lacking. Fracture toughness was investigated using an assumed Poisson's ratio. Decreasing the porosity of macroporous polymers and increasing particle loading resulted in considerable improvements in fracture toughness. These results illustrated the potential of the Arcan test as a simple and effective method for investigating otherwise rarely reported loading conditions in macroporous polymers and nanocomposites.