Creep and Dynamic Mechanical Behavior of Natural Fiber/Functionalized Carbon Nanotubes Modified Epoxy Composites

The creep and dynamic mechanical behavior of natural fiber/epoxy composites using functionalized multiwalled carbon nanotubes (MWCNTs) modified matrix were investigated. 0.4 wt% of MWCNTs functionalized with carboxylic acid groups (MWCNTs-COOH) were dispersed in epoxy and three-phase multiscale hybrid composites were processed by hot press. Natural fiber/epoxy two-phase composites without MWCNTs were also processed by the same method for comparison. The morphologies of the two kinds of natural fiber reinforced composites were observed with the aid of Scanning Electron Microscopy (SEM). Two hours creep tests at 35C with a constant stress level of 2 MPa and temperature scan from 55C to 180C at a frequency of 1 Hz were performed by a Dynamic Mechanical Analysis (DMA) instrument. The results showed that the creep resistance of natural fiber reinforced composites was greatly improved by the addition of MWCNTs. Both the dynamic mechanical analysis and morphology observations indicated the incorporation of MWCNTs restricted the movement of molecular chain of the epoxy resin and also set up bridging between natural fiber and polymer matrix, which all contributed to the improvement of the creep resistance of the composites.