Limiting oxygen index reduction in bitumen modified with nanoclays

摘要

Organo-modified nanoclays may improve the fire resistance of polymers and bitumen. However, in some cases the nanoclay determines a reduction in the limiting oxygen index (LOI). In polymers, this effect is attributed to an increase of viscosity that limits the dripping of the molten samples during combustion. However, in the case of bitumen this explanation is not sufficient because the reduction is not always associated to high viscosities. In contrast, the mass losses recorded by thermogravimetry in well-defined temperature regions seems to correlate with LOI. Both viscosity and decomposition kinetic of the binders suggest that the nanoclays establish a high degree of interaction with the bitumen, thus determining a significant re-arrangement of its colloidal structure.