Synthesis and characterization of poly-urethane foam doped with different nano-fillers

A detailed experimental study is performed to study the deformation behaviour and thermal stability of TiO2 and ZnO reinforced PU foams. Uniform dispersion of nano-fillers in PU foams is ensured by introducing water based slurry of nano-particles in polyol. The bulk density of the foam samples observed to be in the range of 0.02-0.05 g/cc with neat PU foam sample having maximum density. The SEM analysis revealed that pores size is about 570 mu m for neat PU foams and decreases after addition of nanofiller in PU foam. SEM micrographs reveal that nanoparticles accumulate at cell walls and thus having adverse effect on the mechanical properties of foams. Moreover, the spherical morphology TiO2 nanoparticle found to substantially enhance the densification modulus but shows a marginal increase with the addition of rod like ZnO nanoparticles. On the other hand, the value of elastic modulus and plateau modulus decreases with the addition of either of the nanoparticles. The quasistatic cyclic compression tests reveal that the energy loss coefficient (ELC) increases after addition of both types of fillers but ELC found to be maximum with ZnO addition due to the frictional losses between ZnO nanoparticles. The specific energy absorbed by nanoparticles infused PU foam during compression is (similar to 7MJ/m(3)/g cc(-1)) which is higher than expanded polystyrene foam (similar to 4MJ/m(3)/g cc(-1)), which are used as inner lining of helmets. The thermogravimetric analysis of neat and modified PU foams samples shows that even though thermal stability of neat PU foam is substantially increased by adding ZnO as nanofiller, it tends to decrease for TiO2 reinforced PU foams. (C) 2019 Elsevier Ltd. All rights reserved.