Tuesday, 7 September 2021

Sensing Water Absorption in Hygrothermally Aged Epoxies with Terahertz Time-Domain Spectroscopy

 Lin, Hungyen, Benjamin P. Russell, Prince Bawuah, and J. Axel Zeitler. "Sensing water absorption in hygrothermally aged epoxies with terahertz time-domain spectroscopy." Analytical Chemistry 93, no. 4 (2021): 2449-2455.

Abstract 

In the field of non-destructive testing, terahertz sensing has been used to analyze a wide range of materials where the most successful applications have involved materials that are semi-transparent to terahertz radiation. In this work, we demonstrate the sensitivity of terahertz time-domain spectroscopy to quantify water absorption in hygrothermally aged simple and commercial epoxy systems supported by conventional gravimetric analysis.


...................We performed transmission terahertz spectroscopy using a commercial THz-TDS setup (Terapulse 4000, TeraView Ltd.,Cambridge, U.K.) shown in Figure 1c. For the measurements, we selected the high-resolution scanning mode with 20 waveform averages, which took approximately 40 s per measurement. Given the sharp and distinct absorption features due to the rotational transitions of water molecules in the gas phase, all terahertz measurements were performed under a continuous purge with dry nitrogen in the sample chamber of the spectrometer................................


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