Investigation into crosslinking kinetics, physical properties, and thermal conductivity of humic acid epoxy composite

Natural and renewable materials, such as humic acid, for high value products has become part of the research of increasing importance due to the phenomenon of global warming there has been a lot of interest in the development of composites based on renewable resources for a variety of applications. This paper seeks by a series of FT-IR spectroscopy, gravimetric measurements, and DSC analysis to determine the curing behavior, thermo-physical properties (glass transition temperature (Tg)), thermal conductivity (TC), and moisture absorption (MA) of composites made of commercial epoxy resin (E) with humic acid (HA). It is observed that in almost all cases, the prepared composites (HAE) have similar curing behavior to that of (E) with higher activation energy, Tg, and MA. In addition, TC decreases for 5 and 10 wt.% HAE, while it increases for 20 wt.% HAE. Conversely, by increasing the amount of humic acid, the Tg and MA ability of the composites increased. Concerning TC, the presence of HA at 5 and 10 wt.% results a slight decrease in the TC of the composites. A bio-based and valuable composite have been produced from epoxy and humic acid by commonly simple mixing process which might be easily transferable to commercial production process.