Tensile properties at different temperature and observation of micro deformation of carbon nanotubes–poly(ether ether ketone) composites

In this study, poly(ether ether ketone)/carbon nanotubes (CNTs) composites were fabricated by using multi-walled carbon nanotubes (MWNTs) as fillers. Tensile properties of nanocomposites at below and above the glass transition temperature of pure poly(ether ether ketone) (around 145 °C) were studied. At room temperature, the addition of 15 wt% MWNTs increased the tensile modulus (at 0.1–0.3% strain) by 89% and the yield stress by 19%. Above the glass transition temperature, they increased by 163% and 42%, respectively. The experimental results showed that the reinforcement of MWNTs is effective for poly(ether ether ketone), and is more effective at high temperature than at room temperature. Dynamic mechanical thermal analyzer results showed an increase in storage modulus with increasing MWNTs loading fraction at both below and above the glass transition temperature. Scanning electron microscope and transmission electron microscope images showed that the MWNTs were well dispersed in the polymer matrix. The information regarding composite deformation mechanisms was provided by in situ transmission electron microscopy studies, and also interfacial bonding between the carbon nanotubes and polymer matrix was qualitatively studied.