Azide Poly (Acryiic Acid) Grafted Carbon Nanotubes And Its Application In Composite Materials

Modification of carbon nanotubes are usually adopts acid pretreatment, lead to the decrease of length, weakened the modified carbon nanotubes in the application of polymer matrix composite materials. This paper adopts the method of covalent functionalization of carbon nanotubes, azide poly (acrylic acid)(APAA) was grafted to the surface of multi-walled carbon nanotubes (MWNTs), obtained the APAA coated carbon nanotubes. Applied to styrene-acrylonitrile copolymer (SAN) resin modified, significantly improve the mechanical properties, electric properties and foaming properties of SAN resin.1. Using the thermal decomposition of azide group, produce nitrogen and reaction with the sidewall of carbon nanotubes, grafted the APAA to the surface of MWNTs. Using Fourier infrared spectrum (FT IR), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), High-resolution transmission electron microscopy (HTEM), Thermo-gravimetric analysis (TGA) characterized the structure of product. The results show that the APAA successfully grafted onto the surface of the carbon nanotubes, and obtained uniform coating, the highest amount of grafting rate was77%, the increase of APAA azide degree and degree of polymerization was beneficial to the improvement of the grafting rate.2. Azide poly (acrylic acid)/styrene-acrylonitrile copolymer (APAA g-MWNTs/SAN) composite materials, was prepared by in situ polymerization and solution method, respectively. Electrical performance showed that compared with the in situ polymerization, solution blending method had better antistatic properties of composite materials. Composite materials prepared by solution blending, the volume resistivity of the conductivity percolation threshold appeared when the loading of APAA-g-MWNTs was1.5wt%. The addition of APAA-g-MWNTs obviously improved the mechanical properties of composite materials, tensile modulus increased by50%when the loading was3wt%.3. Using supercritical CO2as foaming agent, studied the foaming performance of APAA-g-MWNTs/SAN composite material. Characterized and analyzed the foam expansion ratio, the bubble hole diameter, and the hole density. The results showed that composite materials has the best of hole diameter and hole density when the loading of APAA-g-MWNTs was2wt%, the ratio of expansion was22.7. The addition of carbon nanotubes mainly effect as nucleating agent, it is enhanced the foam behavior of composites materials, and the foaming performance is better than the composite materials of MWNTs loading.