FLEXIBLE HYBRID AEROGELS PREPARED UNDER SUBCRITICAL CONDITIONS AND THEIR PREPARATION PROCESS

摘要

The present invention regards flexible aerogels, characterized by being hybrid organic-inorganic-fiber nanocomposites (1), designed to work as thermal insulators in transportation, building, textile or other industries. Their preparation procedure consists in coating textile fibers or mixtures of textile fibers, either organic or inorganic, with a hybrid aerogel of silica and polymer nanoparticles of low glass transition temperature, chemically bonded to the inorganic matrix. The coating is performed by the sol-gel process, immersing the fibers in a precursor mixture of the hybrid gel. By hydrolysis and condensation reactions wet flexible gels are formed, which are aged, washed and dried under subcritical conditions. The flexible aerogels, hereafter referred to as aerogel blankets, contain between 20 and 80 wt% of fiber, between 13 and 79 wt% of silica, between 0.2 and 40 wt% of polymer nanoparticles, have thicknesses between 1 and 80 mm, present thermal conductivities between 0.03 and 0.08 W.K^-1.m^-1, apparent densities between 100 and 165 kg.m^-3, surface densities between 2 and 4.5 kg.m^-2, are stable at atmospheric moisture and are hydrophobic.