Synthesis, characterization and thermal properties of novel epoxy/expandable graphite composites

Epoxy resins bare widely used as coatings, adhesives and primers and in semiconductor encapsulation. A requirement that has recently gained importance is that of flame resistance, and imparting flame retardancy to epoxy resins has attracted much attention. Expandable graphite (EG) can improve flame-retardant properties of polymers. Due to poor compatibility between polymer matrix and EG, flame-retardant performance will be impaired. EG can be functionalized using a coupling agent. This gives rise to covalent bonding between organic and inorganic phases. This will improve the compatibility between filler and polymer to enhance the thermal stability of composites. X-ray photoelectron spectroscopy was used to characterize the functionalizing reaction between coupling agent and EG. Thermogravimetric analysis (TGA) and integral procedural decomposition temperature (IPDT) were used to calculate the thermal stability of composites. The results show that functionalized EG can improve the thermal stability of the composites. TGA/mass spectroscopy (MS) shows that the amount of toxic gases liberated from the composites is less than that from pure epoxy. Novel epoxy/EG composites were prepared successfully via the sol-gel method. The results of TGA, IPDT and TGA/MS showed that functionalized EG can enhance the thermal stability of composites and can suppress the production of toxic gases. The composite materials could provide a safer choice. (C) 2009 Society of Chemical Industry