Effects of size and structure of silica nanoparticles on morphology and tensile behavior of flexible nanocomposite foams based on polyurethane

In this research, the effect of size and type of silica nanoparticle structure on the morphology and tensile behavior of flexible polyurethane foams were investigated. For this purpose, silica nanoparticles were prepared with two structures rigid and hollow with average particle size of 40 and 100 nm respectively, and reinforcement phases were dispersed in the matrix of flexible polyurethane foam with weight percentages of 0.1, 0.2 and 0.3. Then, comparison and investigation of nanocomposite and pure samples were studied by scanning electron microscopy (SEM) and the effect of structure on the tensile behavior examined. The results of the SEM shown that among all of the samples, polyurethane/rigid silica nanocomposites have more than the size and number of cells. Also, the results of the tensile test shown that by increasing weight percentage of the reinforcement phase in the matrix, the tensile strength were increased and elongation at break were decreased. The addition, there was direct relationship with tensile properties and size and number of cells. So that, the nanocomposite reinforced with rigid and hollow silica nanoparticles at 0.3% wt, increased tensile strength by 78% and 34%, and decrease the elongation at break by 44% and 30%, respectively, relative to the pure sample.