Abstract:
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 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 (7MJ/m ̴ 3
/g cc-1) which is higher than expanded polystyrene
foam (̴4MJ/m3
/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.
