Finite element predictions for the thermoelastic properties of nanotube reinforced polymers

The overall effective thermoelastic properties of nanotube reinforced polymers (NRP) were estimated numerically by using a finite element based procedure. Three-dimensional multi-inclusion periodic computer models were built for three different nanotube orientation states, namely, fully aligned, two-dimensional random in-plane and three-dimensional random states. The enhancement of the Young's modulus as well as the decrease of the thermal expansion coefficient were calculated numerically, assuming technologically relevant combinations of the nanotube aspect ratio and volume fraction. Maximal changes of the thermoelastic properties can be achieved in the longitudinal direction of NRPs with fully aligned carbon nanotubes whereas two-dimensional random in-plane and three-dimensional random composite morphologies exhibit more moderate enhancements but in more than one direction. Numerical predictions for the enhancements of the thermoelastic properties confirmed that carbon nanotubes can be considerably more effective for the reinforcement of polymers than conventional glass or carbon fibres.