Preparation and Characterization of Carbon Nanotubes Reinforced Polyamide 66 Nanocomposites
Topic(s) : Material science
Co-authors :
Seira MORIMUNE-MORIYA (JAPAN), Hu XINDI (JAPAN)Abstract :
In the past decades, polymer nanocomposites have been widely applied to various fields such as aerospace and automotive due to their light weight and enhanced mechanical properties.
Carbon nanotubes (CNTs), which is well known for its extraordinary mechanical, electrical and thermal properties, has been expected as an ideal candidate for the reinforcing nanofiller for polymer nanocomposites. However, the strong van der Waals have often led CNTs to agglomeration in polymer matrices, resulting in serious reduction of the reinforcement effects as well as the interfacial area. Therefore, the performance of polymer nanocomposites with CNTs have often been poorer than expected. How to achieve the homogeneous dispersion of CNTs within polymer matrices and the strong interactions at the interface are the major challenges.
In this study, we developed polyamide 66 (PA66) nanocomposites reinforced with CNTs. The surface modification of CNTs was conducted by plasma-treatment. In order to achieve the strong interfacial interaction of covalent bond (urea bond) between CNTs and PA66, isocyanate groups were introduced on the surface of CNTs by the mixture gas of carbon dioxide and nitrogen during the plasma-treatment. The effect of plasma-treatment of CNTs on the structure and properties of the PA66/CNTs nanocomposites were investigated.
The PA66 nanocomposites were synthesized by in-situ polymerization. The aqueous suspension of non-treated CNTs (nCNTs) or plasma-treated CNTs (pCNTs) was added to the aqueous suspension of hexamethylenediamine and sodium hydroxide. The CNTs suspension was slowly added to the mixture of adipoyl chloride and carbon tetrachloride for the interfacial polymerization of PA66. The obtained PA66 nanocomposite was washed and purified by reprecipitation, and then dried in vacuum for 72h at 40 ˚C. The PA66/CNTs nanocomposites were prepared by melt pressing at 270 ˚C. The filler content was controlled as 0, 0.1, 0.3 and 0.5 wt%.
The optical images of the samples show that the transparency decreased by the incorporation of CNTs. The low transmittance of the nanocomposites with nCNTs indicates the agglomeration caused by the low compatibility of nCNTs and PA66. According to FTIR spectra, isocyanate groups on pCNTs were used to form urea bonds between pCNTs and PA66.
The PA66/CNTs nanocomposites exhibited significant increases in the mechanical properties and thermal resistance compared to PA66. The Young’s modulus and the tensile strength increased with increasing of CNTs content. In addition, the thermal decomposition temperatures were largely increased by the addition of pCNTs, indicating that the molecular motion of PA66 was effectively restricted by the high dispersibility as well as the strong interfacial interactions of covalent bond.
In conclusion, stiff, strong and thermally resistant PA66 nanocomposites were successfully synthesis by a simple and cost-effective method.
Carbon nanotubes (CNTs), which is well known for its extraordinary mechanical, electrical and thermal properties, has been expected as an ideal candidate for the reinforcing nanofiller for polymer nanocomposites. However, the strong van der Waals have often led CNTs to agglomeration in polymer matrices, resulting in serious reduction of the reinforcement effects as well as the interfacial area. Therefore, the performance of polymer nanocomposites with CNTs have often been poorer than expected. How to achieve the homogeneous dispersion of CNTs within polymer matrices and the strong interactions at the interface are the major challenges.
In this study, we developed polyamide 66 (PA66) nanocomposites reinforced with CNTs. The surface modification of CNTs was conducted by plasma-treatment. In order to achieve the strong interfacial interaction of covalent bond (urea bond) between CNTs and PA66, isocyanate groups were introduced on the surface of CNTs by the mixture gas of carbon dioxide and nitrogen during the plasma-treatment. The effect of plasma-treatment of CNTs on the structure and properties of the PA66/CNTs nanocomposites were investigated.
The PA66 nanocomposites were synthesized by in-situ polymerization. The aqueous suspension of non-treated CNTs (nCNTs) or plasma-treated CNTs (pCNTs) was added to the aqueous suspension of hexamethylenediamine and sodium hydroxide. The CNTs suspension was slowly added to the mixture of adipoyl chloride and carbon tetrachloride for the interfacial polymerization of PA66. The obtained PA66 nanocomposite was washed and purified by reprecipitation, and then dried in vacuum for 72h at 40 ˚C. The PA66/CNTs nanocomposites were prepared by melt pressing at 270 ˚C. The filler content was controlled as 0, 0.1, 0.3 and 0.5 wt%.
The optical images of the samples show that the transparency decreased by the incorporation of CNTs. The low transmittance of the nanocomposites with nCNTs indicates the agglomeration caused by the low compatibility of nCNTs and PA66. According to FTIR spectra, isocyanate groups on pCNTs were used to form urea bonds between pCNTs and PA66.
The PA66/CNTs nanocomposites exhibited significant increases in the mechanical properties and thermal resistance compared to PA66. The Young’s modulus and the tensile strength increased with increasing of CNTs content. In addition, the thermal decomposition temperatures were largely increased by the addition of pCNTs, indicating that the molecular motion of PA66 was effectively restricted by the high dispersibility as well as the strong interfacial interactions of covalent bond.
In conclusion, stiff, strong and thermally resistant PA66 nanocomposites were successfully synthesis by a simple and cost-effective method.