Mechanical properties of carbon nanotubes/epoxy nanocomposites: Pre-curing, curing temperature, and cooling rate

Abstract

The effects of composite fabrication, such as pre-curing, curing temperature, and cooling rate, were studied. In this work, the pre-curing was defined as heat treatment of Multi-Walled Carbon Nanotubes (MWNCTs) with Diglycidyl Ether of Bisphenol A (DGEBA) epoxy resin. Acid purified MWCNTs were characterized by Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The pre-curing facilitated bonding between MWCNTs and epoxy via the oxirane ring of DGEBA, which accelerated the curing process of epoxy and increased mechanical properties. The elevated curing temperature on the pre-cured sample further improved the composite’s mechanical properties by increasing interfacial bonding due to cross-linking. The rapid cooling using liquid nitrogen during pre-curing treatment prevented re-agglomeration of MWCNTs, showing smaller agglomerates and improving the mechanical properties. Agglomeration was characterized by scanning electron microscopy, while the bonding between MWCNTs and epoxy was examined by the length of fibre pull-out on the fracture surface. Tensile testing was deployed for mechanical properties characterization. The degree of cure was determined by FTIR and Differential Thermal Analysis (DTA).