Improving the mechanical properties of polymer nanocomposites

As the stiffness of the nanocomposite increases, so, in general, does its strength and this is accompanied by a reduction in its strain to failure. The strain to failure for a nanocomposite material is often higher than when the reinforcement is micrometre-sized (Petrovic et al 2000). However, there are exceptions to this and, as with strength, it critically depends on the bonding between the reinforcement and the matrix - if this is poor then both the strength and strain to failure are reduced (Chan et al., 2002). 

For clay-reinforced nanocomposites, increases in modulus compared with the unfilled polymer matrix have been observed in many systems with the effect increasing with filler content as expected but the properties are highly sensitive to microstructure (Luo and Daniel, 2003). In general, to maximise stiffness (and thermal properties) it is necessary to achieve fiiU exfoliation and dispersion which is not readily achieved (Vu etal., 2001, Zhang etal., 2004). 

The increase in tensile strength or Young s modulus for nanocomposites compared with microcomposites can partly be explained by the details of the interaction between the filler and the matrix. Good adhesion between matrix 

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