Strong reinforcement effects of nanodiamond on mechanical and thermal properties of polyamide 66

In this study, polyamide 66 (PA66)/nanodiamond (ND) nanocomposites were prepared by in-situ polymerization and their chemical/physical structures and properties were investigated. Since ND was highly dispersed at the nanoscale in PA66, the nanocomposites with a low loading of ND (<0.3 wt%) exhibited high optical transparency similar to that of neat PA66. FTIR spectra revealed that the amide bond content of the nanocomposite was greater than that of neat PA66, indicating that the amide bond was formed at the interface between PA66 and ND in the process of in-situ polymerization. In terms of the mechanical properties, the Young's modulus and tensile strength considerably increased by the incorporation of ND. With the loading of only 0.5 wt% of ND, the Young's modulus and tensile strength increased by 140% and 39%, respectively. In addition, the nanocomposites showed excellent enhancement in the thermal stability as well as the thermal conductivity. The thermal decomposition temperature increased by 16 degrees C at an ND content of 0.5 wt%. The strong reinforcement effect of ND was assumed to be considerably greater than that of previously reported random oriented nanocarbons, related to not only the nano-dispersion and strong interfacial interaction but also the nanoconfined region at the interface.