Phase 2: Methods Evaluation
STATE OF THE SCIENCE
Expert Task Groups are formed for Phase 2 to develop white papers on the state of the science related to three aspects of the Project: (1) Methods; (2) Materials Characterization; and (3) Release Scenarios. The focus of Task Group 1 will be determined by selection of most likely scenarios by Task Group 3, and the key properties of the selected nanomaterial-product as determined by Task Group 2.
MWCNTs in Polymer
The current methods focus on multi-walled carbon nanotubes (MWCNTs) embedded in polymer matrices. One goal of Phase 2 was to identify existing methods and/or improve or develop new methods to detect and characterize MWCNTs released from widely-used consumer articles such as tennis rackets and fabrics throughout the articles’ lifecycles. These methods will be evaluated in Phase 3 of the Project through inter-laboratory testing to refine the measurement procedures and thus ensure reproducible data. Applicability of the methods to other MWCNT-product formulations used in other consumer articles will be evaluated. Further, the methods may be useful to guide design, development, and testing of other nanomaterial products and articles, and thus assess the potential for release, exposure, and subsequent risks. Ideally, the methods would be the basis of consensus documentary standards from standards development organizations such as ASTM and ISO.
There are two stages of test methods for the detection and characterization MWCNTs released from products and articles by various means such as abrasion and incineration. The first stage, Tier 1, involves the use of “master batches” of products designed to have varying release potentials of MWCNTs from low to high that represent a range of products used in consumer articles. The second stage, Tier 2, involves the detection and characterization of released. As shown in Phase 3, a detailed graphic describing the Tier 1 and Tier 2 testing process is available below.
A state of the science team was also assembled and charged with writing an overall evaluation of the progress to date
In mid 2013 the Steering Group came to the conclusion that further detailed review of research into methods for measuring release of MWCNT from polymers.