ABSTRACT
A comparison analysis have been undertaken to study the effect of different commercial fillers on density and mechanical properties of two different types of commercial polyether-based polyurethane (PUR) foams: low-density flexible foams and high-density rigid foams. Two types of fillers have been used: micro-fillers based on wood flour (wood waste of the furniture industry) particles of size 70–250 microns and nano-fillers based on mineral type which exists in form of clusters of average size 8 to 10 microns; the thickness of individual clay flake particle is 0.3–0.5 nanometer. The relationship between the filler size and content, density and various mechanical properties has been studied. It was found that micro- and nano-fillers provide various effects depending on flexibility/rigidity and low/high-density nature of PUR foams. For low-density flexible PUR foams, the density and mechanical properties increased for both types of fillers. However, for high-density rigid PUR foams these effects is just the opposite: the density and compression strengths decreased for both types of fillers. However, nano-fillers decrease less in compression strength when compared to micro-fillers. In general, the relative mechanical property (property/density ratio) is higher for nano-size filler than micro-size filler. The comparison of the reinforcement effects of micro- and nano-fillers has been discussed.
