Interlaboratory Study (ILS) Launched & New Material Identified as Candidate Reference Material
February 8th, 2017
Guest Post by: Sarah Ackermann of Thermal Analysis Labs(TAL)
Last week, I attended the ASTM D13.51 subcommittee
meeting in Norfolk, Virginia. One of the primary agenda items for discussion was the need to proceed with the ILS study for ASTM Standard D7984-16
, Measurement of Thermal Effusivity of Fabrics Using a Modified Transient Plane Source (MTPS) sensor. Shannon Yawney, a research analyst in product innovation at Mark’s (Canada) led the development of D7984-16. The standard which was formally published in early 2016.
Thermal effusivity, sometimes also referred to as thermal inertia, is a function of a material’s density, mass specific heat capacity, and thermal conductivity, as seen in the equation above. Measuring the thermal effusivity of textiles reveals the rate at which a fabric absorbs heat when it first comes into contact with skin. Yawney notes that a fabric with a low thermal effusivity would feel warmer to the initial touch and would be slower to transfer heat away from the body, thus keeping the wearer feeling warmer. Conversely, for summer apparel, in which someone wants to stay cool, a higher thermal effusivity is desirable, as fabric will quickly draw heat away from the skin on initial contact.
The new standard will be useful to textile mills as a benchmark test method to compare and develop new technologies for managing heat. At the same time, clothing developers will benefit from an objective quantifiable method for evaluating how fabric manages heat from the body.
The technique is commercially offered as part of the C-Therm TCi Thermal Conductivity Analyzer
. The manufacturer, C-Therm Technologies Ltd., is currently the only commercial source offering the equipment at the time of writing this.
The importance of this standard to the industry is well defined. My role at TAL Labs is to support industry partners such as C-Therm standardize their test methods in ensuring they meet the rigorous requirements set forth within consensus-building bodies as ASTM or ISO.
Figure 1. Sarah Ackermann is the Laboratory Manager and Application Specialist for TAL. She has an MSc in Chemistry and seven years of applied experience in thermal analysis. Currently, her research focuses on method development of new applications for established thermal testing techniques.
Interlab Study (ILS) Launched
In supporting the effort initiated by Yawney, I’ve agreed to lead the next step in this process with the generation of an Interlaboratory Study. The purpose of an ILS is to generate a stronger precision and bias statement based on data generated across several labs with several instruments for the effusivity method. These types of studies are an important part of the standardization process, as they’re designed to quantify the precision and bias associated with a proposed test method. By testing the same materials under the same conditions at several labs with several instruments and operators, data on the variation inherent to the method may be generated. This uncertainty estimate incorporates not only the uncertainty associated with the equipment itself, but also the effects of different users and different laboratory environments, and thus provides a more robust estimation of the uncertainty associated with a technique.
During the meeting, the sub-committee agreed to launch the necessary work item which formally launches the ILS within the ASTM framework. The work item number is WK57705
Candidate Reference Material Identified
In parallel with the Interlaboratory study, I have also been coordinating with other stakeholders on the committee in identifying a suitable candidate textile reference material for thermal effusivity. This action is complementary to the efforts on the ILS as such a material would ultimately be used in the ILS.
One of the global leaders in the provision of traceable reference standards for the textiles industry is Test Fabrics, Inc
. With the help of their Lab Manager, Shawn Meeks, a candidate reference material has been identified and presented to the sub-committee. Based on consultations with Meeks and others on the committee, a polyester duck fabric material was selected as a recommended candidate reference material subject to further testing as part of the approved ILS. Some of the characteristics that it made it a favorite for selection include;
– As a woven synthetic it is robust and can be consistently produced
– Polyester it is relatively hydrophobic and thus less likely to mould
– Is available in suitable thicknesses such that it can be tested as a single-layer
– Is relatively inexpensive and offers
This highly consistent and predictable test fabric sample will be thoroughly characterized for its performance as part of the ILS test.
Call for Expressions of Interest in Participating in ILS
I volunteered to lead the interlaboratory study on this test method. Right now, I am looking for volunteers interested in a part of the international standardization process.
Labs which participate in the ILS process are provided several benefits;
Reputation; All labs which partake in the ILS are listed as participants in the published report enhancing the technical profile and reputation of any participants. Participating in ILS studies speaks to the industry-leadership your lab is providing in such areas of characterization. (Note; the individual test results are not associated to the names of participants in the published reports. All results are published publicly in a sanitized anonymous format.)
Free advertising; You get the option of a free listing in ASTM’s online directory of labs, a database which averages 30,000 hits per month, where you can list up to 100 ASTM Standard test methods for your lab.
Share Results: All participants get a free copy of the standard and the ILS research report.
Self-Assessment: All participants will receive a confidential report indicating how your lab test results compared to those of other lab users, which offers valuable input to your internal QA/QC process.
If you’d like to participate, or if you’d like more information on this test method, please contact me either by phone (at +1-506-457-0498) or by email email@example.com