AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Development of an Analytical Methodology for Measurement of Aerosol Debris Generated from Sanding of CNT Composite Materials
TRACI LERSCH, Kristin Bunker, Gary Casuccio, Jonathan Kang, Lorenzo Cena, RJ Lee Group, Inc.
Abstract Number: 498 Working Group: Nanoparticles and Materials Synthesis
Abstract Carbon nanotubes (CNTs) are being used in a wide range of commercial products due to their inherent properties. Bulk CNTs are incorporated in commercial products ranging from rechargeable batteries, home care products, automotive parts, and epoxy resins used in sporting goods to spacecraft. Evaluating the life cycle of products containing CNTs and potential release of CNTs from a product to the environment is of interest to the scientific community. To this end, researchers at NIOSH have been evaluating the potential for release of ‘free’ CNTs and debris containing exposed CNT protrusions in composite materials. In this study, composite materials containing 0.15-3% CNT by weight were sanded with fine and coarse sandpaper in a chamber while aerosol samples were collected using filter-based methods and a thermophoretic sampler. Bulk samples of the debris were also collected from within the chamber. Sample analysis was complicated because traditional electron microscopy preparation techniques involving dissolution of the filter resulted in liberation of the CNTs contained in the composite debris. Therefore, an analytical methodology was developed involving the analysis of the thermophoretic samples focusing on the release of ultra-fine free CNTs and the analysis of the debris collected on the as-received filters. The specific methodology consisted of using a combination of computer controlled scanning electron microscopy (CCSEM) followed by manual evaluation in a high resolution SEM/STEM. During off-line review, the CCSEM images were examined for CNT protrusions. The sample was then placed in a high resolution SEM/STEM and particles of interest were relocated and scrutinized to distinguish CNT protrusions from plastic protrusions. Preliminary results show that free CNTs were not detected and that approximately 20% of the composite particles contained exposed CNT protrusions, with an average number of CNT protrusions of 3-5 per composite particle. The length and width of the CNTs were also documented.