Agilent 4300 Handheld Portable FTIR

Importance of the Topic

The durability and performance of protective coatings under environmental stress are critical for sectors ranging from infrastructure to transportation. Accelerated weathering tests help predict long-term behavior by simulating UV exposure, temperature, and moisture cycles in a controlled timeframe. Non-destructive analysis during these cycles enables continuous monitoring of chemical and physical changes on a single sample, improving efficiency and reducing material costs.

Study Objectives and Overview

This study evaluates the Agilent 4300 Handheld FTIR with a diffuse reflectance interface for in-situ monitoring of a two-component epoxy resin coating subjected to 56 days of accelerated weathering per ASTM G155. Measurements were taken at eleven time points from 0 to 56 days to track subtle spectral changes and to build multivariate models correlating spectral features with exposure time.

Methodology and Instrumentation

The coated Q-coupon panels were aged in a xenon-arc weatherometer under a two-step cycle: 102 minutes of UV light (55 W/m2 at 340 nm) followed by 18 minutes of light plus water spray, maintaining black-panel temperature at 70 °C, air at 47 °C, and 50 % humidity. Diffuse reflectance spectra (64 scans, 8 cm–1 resolution) were acquired in under 30 seconds at each interval, without any sample preparation.

Instrumentation details:

• Agilent 4300 Handheld FTIR spectrometer
• Diffuse reflectance interface for non-destructive surface analysis
• ASTM G155-compliant xenon-arc weatherometer

Main Results and Discussion

Spectral analysis revealed three aging phases: an induction period (0–21 days) with mild chemical changes, a mid-term phase (21–35 days) with combined chemical and physical alterations, and an end-of-life stage (35–56 days) dominated by physical degradation. More than 100 spectra were divided into 80 % calibration and 20 % validation sets. Two partial least squares (PLS) models were developed: Model I (0–28 days) achieved ±1.01 days accuracy and Model II (28–56 days) ±1.25 days. High linearity in actual vs. predicted plots confirmed robust predictive performance.

Benefits and Practical Applications

• Non-destructive, repeatable measurements on a single coupon throughout aging
• Rapid data acquisition (< 30 s per measurement) with minimal training
• Field portability for on-site monitoring of large or fixed structures
• Formulation screening by comparing multiple coating variants in a single weathering cycle
• Correlation of laboratory and real-world aging through multivariate models

Future Trends and Applications

Advancements may include adapting the approach to other coating chemistries (e.g., polyurethanes, acrylics), integrating real-time data analytics for adaptive sampling intervals, and deploying handheld FTIR for continuous outdoor weathering farms. Combining non-destructive spectroscopy with remote sensing and IoT connectivity could further enhance predictive maintenance strategies for infrastructure assets.

Conclusion

The Agilent 4300 Handheld FTIR with a diffuse interface proved effective for non-destructive, time-resolved analysis of epoxy coatings under accelerated weathering. The developed PLS models reliably predicted exposure time based on spectral changes, demonstrating the method’s value for formulation development, quality control, and in-service condition monitoring.

References

• Leung Tang and Alan Rein. Agilent Application Note 5991-6976EN, 2016. Coatings Analysis: Non-Destructive Testing of an Industrial 2K Epoxy Resin-coated Panel under ASTM G155 Weathering. Agilent Technologies.