Sodium silicate based aerogels were successfully synthesized from using ion exchanged waterglass. The gelation process was investigated and we found rapid gelation for silicic acid (ion exchanged waterglass) and considerably slower gelation with commercial low-sodium silica sols did. Optimal gelation pH is between 4.5 and 5.5 with gelation times ranging from 40 to a few minutes at room temperature. After aging, the water inside the gels is replaced by removed by solvent exchange. Efforts directed at finding a simple and cost competitive hydrohpobization process were very successful. At this point we are able to carry out drying of the gels under ambient pressure and obtain aerogels with quite intriguing properties. These new aerogels show comparable optical and mechanical properties to alkoxide (TEOS) based aerogels. Experiments to improve the mechanical strength by microfibrillated cellulose (MFC) modification were tried but only showed moderate success. In the coming year of 2013, improved ion exchange processing, gelation and aging conditions will be identified, supported by means of analytical methods, and polymer as well as fiber-reinforced aerogel composites will be systematically screened and characterized.
