Molecular simulation and experimental analysis on thermal and mechanical properties of carbon nanotube/epoxy resin composites with different curing agents at high-low temperature

The performance variation and its associated factors of a polymer composites over a wide temperature range need to be particularly concerned in engineering application. In this article, on the basis of molecular dynamics simulation analysis and experimental verification of glass transition temperature (T-g) of neat epoxy resins and single-walled carbon nanotube (SWCNT)/epoxy composites with two structures of aromatic diamines curing agents, the elastic modulus of systems were studied from cryogenic temperature (100 K) until near the T-g in depth. Both simulation and experimental results showed that the thermal and mechanical performance of amine-epoxy systems were enhanced obviously after incorporating SWCNTs of 1 wt% and stiffer amine curing agent molecules, and the elastic modulus was declining as the temperature rising. Further, some microstructure parameters of resin molecules influencing the elastic modulus of amine-epoxy systems were analyzed, including the cohesive energy density (CED), free volume fraction (FFV), and mean square displacement. Among them, both CED and FFV can be significantly affected by addition of SWCNTs and different amine curing agent, and were closely related to the temperature, which can act as novel criteria to predict and optimize some thermal and mechanical performances of crosslinked resin systems and their composites for serving under different temperature. POLYM. COMPOS., 39:E945-E954, 2018. (c) 2017 Society of Plastics Engineers