Nanofillers are increasingly used to enhance multifunctional properties of polymers. However, recent research suggests that nanomaterials may have a negative impact on the environmental health and safety. Since polymers are susceptible to photodegradation by solar ultraviolet (UV) radiation, nanofillers that are embedded in a polymer nanocomposite will eventually be released into the environment during itslife cycls. Such release of nanofillers may have an adverse effect on the environment and present a roadblock to more widespread implementation. This study investigated the degradation and potential nanofiller release of amine-cured epoxy nanocomposites containing multi-walled carbon nanotube (MWCNTs) and nanosilica fillers exposed to UV radiation from 295 nm to 400 nm at 50 oC and 75 % RH. During the exposure period, measurements of chemical degradation, mass loss, and surface morphological changes were carried out on the samples. Amine-cured epoxy underwent rapid photodegradation, resulting in substantial mass loss and increase in MWCNTs and nanosilica concentrations at the composite surface. The rates of mass loss and chemical degradation were lower for the MWCNT-filled epoxy than those of the unfilled or nanosilica-filled materials, suggesting that MWCNTs may have enhanced the photo-stability of amine-cured epoxy. Further, while silica nanoparticles almost uniformly covered the composite surface after prolonged exposure, MWCNTs formed an aggregated network at the degraded surface. Research is in progress to provide direct evidence of any nanofiller release to the environment during the exposure.
Proceedings of the 4th European Weathering Symposium
September 15-18, 2009
Building technology, degradation, environments, nanoparticles, polymer nanocomposites, release, UV