Abstract
The use of multi-walled carbon nanotubes (MWCNTs) as reinforcing materials for thermoplastic polymer matrices, such as poly(methyl methacrylate) (PMMA), polystyrene (PS) and polycarbonate (PC), has been studied extensively. A considerable improvement on mechanical properties of the composite can be observed when the mass fraction of MWCNTs increases. In the thesis, we investigated the evolution of hardness, the trace of creep and stress relaxation behavior in PMMA/MWCNTs composites, respectively. Hardness increases with increasing annealing temperature and contents of MWCNTs, but decreases with increasing UV doses. The hardness change is attributed to the variation of defects in microstructure. The kinetics of defects follow a first-order kinetic model. Furthermore, the rate constant satisfies the Arrhenius equation, and the corresponding activation energy increases with increasing contents of MWCNTs and decreasing UV doses. It was found for PMMA/MWCNTs composites that the creep strain increases with increasing annealing temperature and UV doses and decreases with increasing contents of MWCNTs. To understand the mechanism, the standard linear solid model is employed. The viscosity coefficient obeys the Arrhenius equation, and the corresponding activation energy increases with increasing contents of MWCNTs and decreasing UV doses.