Nanofillereffect on the glass transition of a polyurethane

The effect of silicananofiller on the glass transition of a polyurethane was studied by DSC. Thepristine polymer exhibits a single glass transition at about –10°C.Uniform SiO2 spheres with different average sizes and narrow size distributionswere synthesized in solution by the Stöber method [1]. Both the effectsof silica content within the polymer and particle size were investigated,as well as two different surface treatments. Scanning electron microscopy(SEM) clearly confirms the presence of the particles within the polymer matrix,showing uniform distribution and no agglomeration. While shifting of the glasstransition has been reported by many authors, we have not seen any noticeableshift in this polymer. Surprisingly, we found no relevant effects when eitherincreasing the filler content or changing the particle size. Different amountsof particles with average diameters of 175, 395 and 730 nm did not affectthe glass transition temperature of the pristine polymer.