Preparation, Characterization And Properties Of Graphene Filled Epoxy Nanocomposites Produced Using Colloidal Polymerization Method
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Date
2018-04-01
Authors
Abdul Kudus, Muhammad Helmi
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Common issues during fabrication of graphene filled epoxy mostly are
dispersion of graphene, re-agglomeration problem and reduction of crosslink density.
A different sequence of epoxy composite preparation was performed by mixing
oxidized graphene platelets (oGNP) with a curing agent prior to mixing it with epoxy
resin. When oGNP was mixed with trimethylhexamethylene diamine (TMD), the
condensation reaction between the hydroxyl and amine groups resulted in the
formation of a TMD/oGNP colloid. The TMD/oGNP colloid was used to cure epoxy
resin. The colloidization eventually improved the dispersion and prevented reagglomeration of graphene in the epoxy resin and resulted in higher crosslink density.
A thermogravimetric analysis (TGA) showed that the thermal stability of the
epoxy/oGNP system had improved, while the presence of the oGNP gave more
stability to the solvent in terms of an increase in the crosslink density. These results
showed that the TMD/oGNP colloid mixing sequence was able to enhance the
properties of the epoxy composite compared to the conventional method of obtaining
graphene filled epoxy nanocomposites. Conventional method refers to fabrication of
epoxy/graphene nanocomposites by mixing the graphene into the epoxy resin prior to
adding into the curing agent. Epoxy/oGNPcolloidized showed higher crosslink density
than Epoxy/oGNPconventional nanocomposite. Epoxy/oGNPcolloidized nanocomposites
showed a higher thermal conductivity than an epoxy/oGNPconventional nanocomposite
with the same concentration of filler, which is parallel to the crosslink density result.
From the observation, in Epoxy/oGNPconventional, where amide network between
carboxylic and amine groups were relatively formed, a high crosslink density enhanced
the thermal conductivity via phonon transport. Through the analysis, the dielectric
properties of epoxy nanocomposites also showed direct relationship with crosslink
density as Epoxy/oGNPcolloidized obtained higher dielectric constant value than
Epoxy/oGNPconventional. The summary of the study concludes that fabrication of
graphene filled epoxy nanocomposites via colloidal polymerization method, enhance
the thermal properties, tensile properties and dielectric properties due to the increasing
amount of crosslink density and better dispersion of graphene. Further thermal
degradation analysis via non-isothermal kinetic study shows an F1 mechanism occurs
for epoxy thermal degradation and the Epoxy/oGNPcolloidized achieved the highest
lifetime for thermal degradation.