Radiation Synthesis of Silica Aerogel Reinforcement by Polymers as Thermal Insulator Material"

Abstract

In the present research, the first synthesis of aerogels through cross-linked polyacrylamide (PAAm) hydrogel was reported through the use of gamma irradiation technique. Hydrogel obtained from gamma irradiation of acrylamide monomer dissolved in a solution of sodium silicate as a silicon precursor. Various irradiation doses (10 up to 60 KGy) and various acrylamide (AAm) contents (6.25, 9.37, 12.5, and 30%) were utilized in the polymerization process. The polyacrylamide (PAAm) hydrogel loaded with sodium silicate inside is soaked in a solution of CaCl2 and then heated at a temperature of 250 oC for 2 hr to provide Ca-silicate aerogels , another form sodium silicate soaked in solution of AlCl3 and then heated at a temperature of 250 oC for 2 hr to provide Al-silicate aerogels with density around 0.16–0.06 gm/cm3 and porosity of 84–94.8%. Almost all samples of the obtained (Ca-Si) and (Al-Si) aerogels have porosity greater than 80% and low thermal conductivity (thermal conductivity value around 0.114 and 0.073 W/m.K) at ambient condition. In particular, the cross-linked polyacrylamide has higher modulus as reinforced silica aerogels of low density. The reinforced Ca-silicate aerogels can be an outstanding thermal insulating material used for different industrial and space exploration, with their very porous texture.