Preparation And Properties Of Poly (aryl Ether Nitrile) / Carbon Nanotube Composites

Poly(arylene ether nitriles)(PEN) as special engineering polymer have been widely used in high-temperature environments and many other related fields for its excellent thermal and mechanical properties. This thesis focuses on the preparation and characterization of Poly(arylene ether nitriles)(PEN)/multi-walled nanotubes (MWNT) composites.4-aminophenoxyphthalonitrile was grafted onto multi-walled carbon nanotubes (MWNT) via acid-thionyl chloride route. These functionalized MWNT were characterized by Fourier transform spectrum (FTIR), Transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). These results indicate that the dispersion of MWNT was greatly improved by using the acid-thionyl chloride treatment. Three processing methods were used to prepare PEN/MWNT composites, and the dependence of processing methods on the properties of the composites was studied in this thesis.These obtained results showed that the PEN/grafted-MWNT composites have the best properties comparing with composites made by directly solution process. In solution process, the PEN/grafted-MWNT composites using Sodium dodecyl sulfate (SDS) as disperation agent have better properties than direct-mixing without treatment. Because the best dispersion of MWNT in PEN matrix, the PEN/MWNT composites made by grafted process have more significant increase in properties. It was found that there a critical MWNT concentration around 1wt% where a fine network of MWNT was formed, which provides the PEN/MWNT composites much improved mechanical properties. The tensile strength of PEN/MWNT composites was increased from 85MPa to 133Mpa, improve 56%, the grass transition temperature reached 174oC, increased 13oC, the maximum thermal degradation temperature reached to 475oC, increased 25oC, the residues increased 10% at 700oC in nitrogen, the surface resistance decrease to 109?·cm .The cross-link reaction of PEN were studied with the aid of stress rheometer, the cross-link reaction were proved be happened during the heating process. The degree of the crosslinked reaction is dependent of the temperature and time of heating process. Thermal analysis was further carried to investigate the thermal decomposition kinetics of PEN and PEN/MWNT composites using TG techniques with constant heating rate in nitrogen. The activity energy of thermal decomposition of PEN and PEN/MWNT composites in nitrogen was obtained using Ozawa-Flynn-Wall (OFW) method and Firedman method free analysis without involving any decomposition mechanism of solid state. The activity energy of thermal decomposition of PEN, PEN/MWNT (MWNT 1wt%,SDS trement) and PEN/MWNT(MWNT 1wt% grafted trement) are 103KJ/mol, 92KJ/mol and 78KJ/mol in nitrogen, the decomposition mechanism were both accommodated nuclei roduction and nuclei growth model, The activity energy of thermal decomposition of the crosslingked PEN is 160KJ/mol, the decomposition mechanism was two-dimensional phase boundary.