A Quantitative Study of Nanosilica Release from Polymer Nanocomposites Exposed to UV Radiation

T. Nguyen, D. Stanley, S. Rabb, D. Banerjee, X. Gu, L.L. Yu, J.W. Chin
NIST, US

Keywords: release, nanoparticles, nanocomposite, quantitative, UV radiation

Summary:

Polymer nanocomposites are increasingly used in harsh environments. Because polymers are susceptible to degradation by weathering, nanofiller in polymer nanocomposites may be released into the environments during the composite’s life cycle. Such release potentially poses an environmental health and safety concern. Previous study showed that UV irradiation causes polymer photodegradation, leading to release of nanoparticles. This study quantifies the release of nanosilica from epoxy nanocomposites with UV radiation at four temperatures. Specimens of epoxy/nanosilica composites in specially-designed holders were irradiated with high intensity UV radiation. Irradiated specimens were measured for chemical degradation, mass loss, nanosilica surface accumulation, and nanosilica release as a function of UV dose. Nanosilica release measurement was accomplished by spraying irradiated specimens with water, collecting runoff water/released particles, and analyzing collected solutions by inductively-coupled plasma optical emission spectroscopy using a NIST-developed protocol. Mass loss, chemical degradation, and silica surface accumulation increased with UV radiation dose. Quantities of nanosilica release at four different temperatures are being analyzed. The release data will be used to validate a reaction-kinetics base model with UV dose as the independent variable. The nanosilica release model will be presented and discussed.