Agilent 4300 Handheld Portable FTIR

Importance of the Topic

Understanding how environmental stressors—UV radiation, heat, and moisture—impact protective coatings is essential for predicting service life, minimizing maintenance costs, and ensuring structural integrity in industrial applications.

Objectives and Study Overview

This study applies a handheld FTIR spectrometer to monitor chemical and physical changes in a two-component epoxy resin coating on a standard Q-panel during a 56-day accelerated weathering cycle (ASTM G155). Key aims include capturing spectral markers of degradation, developing predictive multivariate models, and demonstrating a non-destructive workflow suitable for both laboratory and field environments.

Methodology and Instrumentation

A Q-panel coated with an industrial two-part epoxy finish underwent a continuous two-step cycle: 102 minutes of UV light (55 W/m² at 340 nm) followed by 18 minutes of UV light plus water spray, maintained at a black panel temperature of 70 °C, air temperature of 47 °C, and 50 % relative humidity. Spectra were recorded at 0, 3, 6, 10, 14, 21, 28, 35, 42, 49, and 56 days using:

• Agilent 4300 Handheld FTIR spectrometer with diffuse reflectance interface
• 64 scans per measurement at 8 cm⁻¹ resolution
• Non-destructive sampling, enabling repeated analysis of a single panel

Main Results and Discussion

Diffuse reflectance spectra revealed progressive chemical and physical transformations:

• Induction phase (0–21 days): Subtle spectral shifts indicating initial oxidation and moisture uptake
• Mid-term phase (21–35 days): Pronounced changes in binder-related bands and onset of matrix embrittlement
• End-of-life phase (35–56 days): Extensive degradation evidenced by visible pitting and cracking, correlated with spectral markers

Two partial least squares (PLS) models were developed:

• Model I (0–28 days): RMSE ≈ 1.0 day, strong linearity for early-term exposure
• Model II (28–56 days): RMSE ≈ 1.3 days, robust predictions for advanced aging stages

Benefits and Practical Applications

• Non-destructive monitoring allows repeated measurements on a single sample, reducing material use and variability
• Rapid analysis (< 30 s per measurement) supports efficient quality control in R&D and production
• Portable FTIR enables field assessment of large structures—bridges, vehicles, infrastructure—without sample removal
• Predictive PLS models inform maintenance schedules and optimize formulation durability

Future Trends and Potential Applications

• Extension to other aging protocols: salt spray, chemical exposures, high-temperature cycles
• Integration with advanced chemometric and machine learning algorithms for real-time diagnostics
• Automated field deployments for long-term asset monitoring and predictive maintenance
• Enhanced sampling interfaces (e.g., microspectroscopy) to probe microscale defects

Conclusion

The combination of handheld FTIR with diffuse reflectance sampling and accelerated weathering provides a powerful, non-destructive approach to study coating degradation. The developed PLS models deliver accurate predictions of exposure time, supporting better product development, quality assurance, and lifecycle management of protective coatings.

Reference

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