Abstract
Thermoplastic polyetherimide has been prepared successfully by one step process. Acid-modified multi-walled carbon nanotube (MWCNT) was grafted with soluble polyimide and silane modified aluminum nitride were added to the polyetherimide to form AlN/MWCNT/Polyether imide composite. A series of polyetherimide-based nanocomposites containing polyimide grafted multi-walled carbon nanotubes (PI-g MWCNT) and silane modified ceramic (aluminum nitride) have been prepared. The surface of AlN modified by silane could increase the adhesion with matrix effectively, which was beneficial for AlN to reinforce the polyetherimide matrix. After polyimide was modified by grafting MWCNTs showed good dispersion and wettiability in the polyetherimide matrix and imparted excellent mechanical properties, electrical properties and thermal properties. The utilization of hybrid filler was found to be effective in increasing thermal conductivity of the composite due to the enhanced connectivity between AlN particles by high aspect ratio MWCNT filler. The use of spherical AlN filler and MWCNT filler resulted in composite materials with enhanced thermal conductivity and low CTE. Tensile strength of the MWCNT/AlN/PEI composite increased 21.9% from 6.82 MPa (Neat Polyetherimide) to 8.32 MPa(with 26.25wt% AlN and 3.75wt% MWCNT). Young’s Modulus of the MWCNT/AlN/PEI composites increased from 189.7 GPa(Neat Polyetherimide) to 628.6GPa (with 56.25wt% AlN and 3.75wt% MWCNT). Thermal decomposition temperature (Td.) of the MWCNT/AlN/PEI composite increased 44℃from 485℃(Neat Polyetherimide) to 529℃(with 75wt% AlN and 5.0wt% MWCNT). Activation energy of the MWCNT/AlN/PEI composites increased from 167 KJ/mol (Neat Poly etherimide) to 312 KJ/mol (contains 75wt% AlN and 5.0wt% MWCNT).Glass transition temperature(Tg) was elevated from 237℃(net Polyeyherimide) to 297℃(with 75wt% AlN and 5.0wt% MWCNT). Thermal conductivity increased from 0.24W/mk(Neat Polyetherimide) to 1.99 W/mk(with 75wt% AlN and 5.0wt% MWCNT). The surface electrical resistivity of the MWCNT/AlN/PEI nanocomposites decreased from 1.30×1016Ω/cm2(Neat Polyether- imide) to 1.39×108Ω/cm2 (with 75wt% AlN and 5.0wt% MWCNT). Volume electrical resistivity of the composites decreased from 6.85×1016 Ω-cm (Neat Polyetherimide) to 1.41×108 Ω-cm (75wt% AlN and 5.0wt% MWCNT). Results indicated that the hybrid filler PI-g-MWCNT and AlN incorporated into the polyetherimide matrix enhance thermal stability, thermal conductivity, electrical properties and mechanical properties of the polyetherimide matrix significantly.