Two - step gradation of particle size in an inorganic - organic hybrid

An inorganic-organic hybrid (IOH) of silica particulates and polyethylene (PE) was investigated, where silica was employed as an analogue to lunar soil. The objective was to search for the optimum materials design strategy for “lunar cements” – infrastructural materials based on locally harvestable resources on the Moon. If the silica particulate size was uniform, the flexure strength of the IOH decreased quite linearly with the PE content. With a two-step size gradation of silica particulates, the flexure strength of the silica-PE IOH could be much improved, higher than that of Portland cements with only 4 wt% of PE. A threshold PE content around 6 wt% existed. Above the threshold, the PE content has only a secondary effect on the IOH flexure strength; below the threshold, the IOH flexure strength decreases abruptly. In order to further enhance the IOH strength and to reduce the binder content, this threshold value must be minimized.