End-of-life thermal decomposition of nano-enabled polymers: effect of nanofiller loading and polymer matrix on by-products

Abstract

Increased penetration of nanotechnology into consumer products has caused concern over potential exposure to engineered nanomaterials (ENMs) across the product life cycle. A nano-enabled product (NEP) at its end of life may undergo thermal degradation in an incineration facility. Even though efforts have been made to understand the thermal decomposition behavior of various industrially relevant nano-enabled thermoplastics and associated life cycle released particulate matter (LCPM), critical questions such as the effect of nanofiller loading and impact of the host polymer matrix on environmental health and safety (EHS) implications are still open. Here, we employed the recently developed Harvard Integrated Exposure Generation System (INEXS) to study the effect of nanofiller loading and polymer matrix on by-products of this highly important end-of-life process using industrially relevant polymers. Increased nanofiller loading affects the particle number concentration, size, and released nanofiller amounts in both released LCPM (aerosol) and residual ash. On the other hand, changing the polymer matrix in the presence of the same nanofiller conditions influences not only the particle concentration, size and morphology but also the chemical composition and morphology of the residual ash. The overall chemistry of the released LCPM appears to be governed by the host polymer matrix. These findings are critical for understanding the mechanisms behind the release of ENMs incorporated in NEPs and associated EHS implications and can be used for safer-by-design formulations. Further toxicological studies are warranted in order to assess possible EHS implications during the thermal decomposition of NEPs.