Postdoctoral Fellow; PREP

Johns Hopkins, founded in 1876, is America's first research university and home to nine world-class academic divisions working together as one university.

$82,000 - $89,000

Johns Hopkins University:
Whiting School of Engineering:
Office of Research and Translation

This position is part of the National Institute of Standards (NIST)
Professional Research Experience (PREP) program. NIST recognizesthat its research staff may wish to collaborate with researchers atacademic institutions on specific projects of mutual interest andthus requires that such institutions be the recipients of a PREPaward. The PREP program requires staff from a wide range of backgrounds to work on scientific research in many areas. Employee sin this position will perform technical work that underpins the scientific research of the collaboration.

Postdoctoral Researcher on Civil Infrastructure Polymer Durability

The PREP Researcher will conduct laboratory accelerating weatheringexposure experiments on various polymer systems used ininfrastructure applications, which will include building envelopematerials, protective coatings, crack repair materials, and fiberreinforced polymer composite (FRP) retrofits. The PREP Researcherwill help to identify select polymeric infrastructure materials inwidespread use based on current limitations of these materials,identified research gaps, and identified durability issues.

Accelerated weathering experiments will primarily take place on thestate-of-the-art NIST SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) device which allows precise control of temperature and relative humidity while exposing samples to highlyuniform ultraviolet (UV) exposure. Other weathering exposureexperiments in humidity chambers, a freeze/thaw chamber, acorrosion chamber, commercial UV-weathering devices, or at twooutdoor weathering fields may be conducted. The PREP researcherwill collect material property change data resulting fromdegradation and develop test configurations and methods to measureperformance changes of an infrastructure material with respect toits given application (e.g., increased water penetration of abuilding envelope material).

Alongside structural engineers,weathering data criteria will be collaboratively incorporated intodesign equations and structural models.

Key responsibilities will include but are not limited to:

• Review literature and sample degradation results from previousSPHERE and outdoor weathering experiments.
• Help identify a select few polymeric infrastructure materials fordurability assessment that will have a high impact forstakeholders. Identification efforts should involve literaturereviews, stakeholder engagement, and market research. Buildingenvelope materials will be highest priority.
• Conduct accelerated weathering exposure on the NIST SPHERE and onother weathering devices, as appropriate.
• Characterize the chemical, optical, and mechanical propertychanges of weathered infrastructure polymer samples usingtechniques such as ATR-FTIR, Raman, UV-Vis, color and gloss tests, DSC, TGA, pull-off testing, three-point bending tests, moisture absorption tests, infrared thermography, andmicroscopy.
• Develop test configurations and test methods to measureperformance changes of a material within a given infrastructureapplication. This may include water vapor transmission tests,corrosion tests, tensile tests, impact and tear resistance tests,etc.
• Maintain the NIST SPHERE in collaboration with NIST technicians:this includes collecting, recording, and analyzing irradiancedata.
• Construct a UV-degradation database for correlatingmaterials-structure-performance properties. Contribute to a NISTSPHERE metadata database.
• Present results within the group and other related meetings,write protocols, technical reports, and prepare manuscripts forhigh impact, peer-reviewed publications.
• Ensure that results, protocols, software, and documentation havebeen archived.

The ideal candidate will possess a deep background in materialsscience, strictly focused on the fundamental degradation of polymers in outdoor service environments. A Ph.D. degree in Materials or Chemical Engineering, Mechanical Engineering,Environmental Engineering, Chemistry, or a related polymer science field.

• Demonstrated hands-on laboratory experience with at least four ofthe following techniques: tensile tests, DMA, nanoindentation, DSC,TGA, FTIR spectroscopy, Raman spectroscopy, UV-Vis spectroscopy,color and gloss tests, optical microscopy, scanning electronmicroscopy, infrared thermography, pull-off tests, three-pointbending tests, moisture absorption tests.
• Experience evaluating long-term degradation of polymericmaterials and/or the use of accelerated weathering techniques inprior research efforts.
• Experience using analysis software (e.g., Excel, Origin,Solid…