Glass transition temperature of amino groups grafted carbon nanotubes reinforced epoxy resin composites: Role of strong interphase

In order to verify roles of interphase played in glass transition temperatures ( T g s) of carbon nanotubes reinforced epoxy resin (CNT/epoxy) composites, three types of interphase were produced between the CNTs and the cured epoxy. It was achieved by selection of pristine CNTs (p‐CNTs), amino groups grafted CNTs (NH 2 ‐CNTs) and hydroxyl groups grafted CNTs (OH‐CNTs) as the reinforcement, respectively. Both dynamic mechanical analysis (DMA) and molecular dynamics (MDs) simulation were conducted to study T g of the CNT/epoxy composites. The DMA tests showed that T g of NH 2 ‐CNT/epoxy composites increased, while T g of OH‐CNT/epoxy composites decreased, compared with p‐CNT/epoxy composites. The MD simulation of the CNT/epoxy composites models explained effects of interphases on T g s of the CNT/epoxy composites. T g of the NH 2 ‐CNT/epoxy composites increased with the formation of covalent bonds between the NH 2 ‐CNTs and the cured epoxy. Although T g of the OH‐CNT/epoxy composites decreased due to the weak interphase, where no such covalent bonds were formed. It can be inferred that the covalent bonds between the CNTs and the polymer matrix is beneficial to increase T g of the CNT/polymer composites. POLYM. COMPOS., 39:E1129–E1138, 2018. © 2017 Society of Plastics Engineers