Nanoparticles are increasingly used in polymer coatings (i.e., nanocoatings) to improve multiple properties of traditional coatings such as mechanical, electrical, gas barrier, and UV resistance. These high performance nanocoatings are often used in outdoor environments. However, because polymers are susceptible to degradation by weathering elements, nanoparticles in a nanocoating may be released into the environments during its life cycle, which potentially poses an environmental health and safety concern and may hinder application of these advanced coatings. This study presents protocols and experimental technique to quantify the release of nanosilica from epoxy nanocoating as a function of UV exposure. Specimens of an epoxy coating containing 5 % untreated nanosilica in specially-designed holders were exposed to 295 nm 400 nm UV radiation in a well-controlled high-intensity UV chamber. Exposed specimens were removed at specified UV dose intervals for measurements of coating chemical degradation, mass loss, nanosilica accumulation on specimen surface, and nanosilica release as a function of UV dose. Measurement of nanosilica release was accomplished by a) periodically spraying UV-exposed specimens with water, b) collecting runoff water/released particles, and c) analyzing collected solutions by inductively coupled plasma-optical emission spectrometry (ICP-OES) using a NIST-developed protocol. Results showed that the amount of nanosilica release was substantial and increased rapidly with UV dose. Mass loss, chemical degradation, and silica accumulation on specimen surface also increased with UV dose.
Proceedings Title: Proceeding of American Coatings CONFERENCE
Conference Dates: April 7-9, 2014
Conference Location: Atlanta, GA
Conference Title: American Coatings CONFERENCE: April 7-9, 2014
Pub Type: Conferences
AFM, ATR-FTIR, ICP-OES, nanocoatings, nanoparticle release, Surface morphology, UV degradation, XPS