Session: MF-02-03 Materials for Hydrogen Service-Polymers 2

Paper Number: 123905

123905 - Evaluation of Common Thermoplastic Polymers in High-Pressure Cycling Hydrogen Under Ambient and Cold Environments Applicable to the Hydrogen Infrastructure 

Thermoplastics and elastomeric polymeric materials are commonly used in the hydrogen infrastructure, with polyethylene as liners for hydrogen storage tanks, poly (phenylene sulphide) and polyoxymethylene as pipeline liners for high pressure hydrogen distribution systems, polytetrafluoroethylene as seals in mechanical compressors, and Viton and nitrile butadiene rubbers as seals and gaskets in valves.   Transport properties in polymers, under different pressure and temperature conditions, have been well investigated with the goal of understanding gas-polymer interactions in thermoplastics and elastomers [1-4]. Permeability, diffusivity, and solubility data with regards to hydrogen transport show that hydrogen diffusivity in glassy polymers is [approximately] an order of magnitude lower than elastomers, whereas the solubility is not very different for the two classes. While most studies have focused on defining the behavior of elastomeric polymers in hydrogen, an example of early studies on thermoplastic materials was the work by Castagnet et.al.  Pressurized hydrogen and nitrogen at 30 MPa pressure was used to study gas sorption and tensile behavior of semi-crystalline polyethylene (PE) and polyamide (PA11) compared to experiments at atmospheric pressure [5].

In the work described here, we evaluated the effect of high-pressure cycling on select thermoplastics under ambient and cold (-40°C) conditions. Thermoplastics applicable to the hydrogen infrastructure (e.g., PEEK, PTFE, PA-11, HDPE, and POM, including different commercial grades of these polymers) were exposed to hydrogen under isothermal conditions and characterized for polymer changes ex-situ using conventional polymer characterization techniques. These included density measurements for impact of hydrogen retention, hardness changes using nanoindentation, storage modulus and glass transition changes using dynamic mechanical and thermal analysis (DMTA), and general polymer microstructural changes in the polymer using solid-state nuclear magnetic resonance (NMR), attenuated total reflectance Fourier transform infra-red spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and X-ray CT. Mechanical testing included tensile testing of thermoplastics before and after hydrogen exposures. Findings from a high-pressure cycling study involving PTFE, Nylon-11, and PEEK with [or at]varying rates of depressurization (1 through 40 MPa/min) are also presented here. The overall impact of these evaluations is to establish a technical basis for the behavior of common thermoplastics in cycling hydrogen environments under ambient and cold temperatures while establishing the relationship between polymer structure-based properties and hydrogen transport effects.

 References

1. Sandia 2013-8904, October 2013, R. Barth, Polymers for Hydrogen Infrastructure and Vehicle Fuel Systems: Applications, Properties, and Gap Analysis.

2. Kane, M.C., WSRC-STI-2008-00009-Rev0, Permeability, Solubility, and Interactions of Polymers – An Assessment of Materials for Hydrogen Transport.

3. Stodilka, D.O., et al., A tritium tracer technique for the measurement of hydrogen permeation in polymeric materials. Int. J. Hydrogen Energy, 2000. 25: p. 1129- 1136.

4. Klopffer, M., Flaconneche, B., Odru, P. Plastics, Rubbers and Composites 36 (2007): p. 184-189. 8. Jones, Parry, E. and D. Tabor, Effect of hydrostatic pressure on the mechanical properties of polymers: a brief review of published data. J. Mater. Sci., 1973(8): p. 1510-1516.

5. Castagnet, et. al., Hydrogen influence on the tensile properties of mono and multi-layer polymers for Gas Distribution. Int. J. Hydrogen Energy, 2010. 35(14): p. 7633-7640.

Presenting Author: Nalini C. Menon Sandia National Laboratories

Presenting Author Biography: Ms. Nalini Menon is a Principal member of Technical Staff at Sandia National Laboratories in Livermore, California. Prior to joining Sandia, she worked for 20 years as a polymer chemist/materials scientist and has extensive background in formulating adhesives, paint/coatings, encapsulants, and potting compounds for the automotive and aerospace industries. Her specialties include leading long-term materials-focused R&D projects with emphasis on characterization and evaluation of mechanical, thermal, and rheological properties of organic materials. Nalini leads the polymer compatibility in hydrogen effort at Sandia in support of the Fuel Cell Technologies Office, DOE’s overall goals of building a hydrogen infrastructure and economy here in the US. Her work, as part of a consortium including National Labs and industry partners (PNNL, SRNL, ORNL and Ford), has been recognized by the DOE with a “Team award 2018 DOE Award for exceptional contribution to FCTO/EERE (Fuel Cell Technology Office/Office of Energy Efficiency and Renewable Energy) goals”. As part of this effort, she has played a significant leadership role in the development of the Canadian Standards Association (CSA)’s CHMC2 standard for the compatibility of polymers in hydrogen environments, for use by the hydrogen community. She was an Invited speaker at the International Symposium of Hydrogen, Japan in the year 2018 where she presented on “Compatibility of polymeric materials in hydrogen service”.

Authors:

Nalini C. Menon Sandia National Laboratories
April Nissen Sandia National Laboratories
Keri Mcarthur Sandia National Laboratories
Bernice Mills Sandia National Laboratories
Fitzjames Ryan Sandia National Laboratories
Kevin Simmons Pacific Northwest National Laboratory