Difficulty with in situ reduction of graphene oxide in epoxy composite: A potential solution

Graphene Oxide (GO) was prepared and dispersed in DER 332 epoxy. Preliminary work using Broadband Dielectric Spectroscopy (BDS) has shown that the epoxy and its composite could start to degrade at temperature as low as 120°C. Thermogravimetric analysis measurement indicated a slight mass loss difference at 150°C between samples with and without GO. Both samples as produced were initially post-treated at 100°C for 24 h. Then, the thus-prepared samples were submitted to consecutive thermal steps (T_max = 150°C and step duration at T_max ~ 15 min), and monitored using BDS. A limit on the number of thermal steps that could be applied, was established before degradation/deformation of the samples occurred. When the AC conductivity at 20°C was compared before and after the complete thermal treatment, it was found that 1 wt% of GO may bring an increase in the conductivity by a factor of about 50. In addition, there is a cumulative effect of the thermal steps translating into a linear continuous increase of the electrical conductivity of the epoxy/GO, reaching as much as 20%.