Analysis of Ultraviolet-Degraded Plastic by Plastic Analyzer

Significance of the Topic

Analyzing the degradation state of plastic materials is critical for quality control in manufacturing, environmental monitoring and failure analysis. Ultraviolet (UV) and thermal exposure can alter polymer structures, generating oxidation products that interfere with identification efforts. A streamlined, accurate method to detect and characterize degraded plastics helps prevent contamination in production lines and supports research into microplastic aging.

Objectives and Study Overview

This application note demonstrates a rapid qualitative analysis of a plastic sample degraded by long-term indoor UV exposure. Using Shimadzu’s FTIR-based Plastic Analyzer, the study aims to identify polymer type and estimate degradation degree by comparing sample spectra against proprietary UV-damaged and thermal-damaged plastic libraries.

Methodology

The workflow employs ATR-FTIR measurement combined with automated library searching:

• Background scan acquisition on IRSpirit FTIR spectrophotometer
• Sample measurement using QATR-S single-reflection ATR accessory
• Spectrum search and report generation via the IR Pilot macro program

Three sample regions were analyzed: an unexposed interior fragment, an indoor side shielded from direct sunlight, and a window-facing side exhibiting yellowing.

Used Instrumentation

• IRSpirit™ Fourier Transform Infrared Spectrophotometer
• QATR™-S Single-reflection ATR Measurement Accessory
• Plastic Analysis Method Package with:
  
  • UV-Damaged Plastics Library (14 polymers, up to 550 h UV exposure)
  • Thermal-Damaged Plastics Library (13 polymers, heated to 200 °C–400 °C)
  • IR Pilot Macro for parameter control and reporting

Main Results and Discussion

Overlay spectra revealed that the interior fragment matched unaged polypropylene (PP). The indoor side aligned with PP after 40 h of UV exposure, while the yellowed window side corresponded to PP irradiated for 125 h. Degradation signatures included absorption bands near 3400 cm⁻¹ (O–H stretching), 1710 cm⁻¹ (C=O stretching) and 1150 cm⁻¹ (C–O stretching), consistent with oxidative chain scission and formation of hydroxyl and carbonyl groups.

Benefits and Practical Applications

The Plastic Analyzer system enables:

• Rapid, user-friendly identification of degraded polymers
• Automated parameter setup and reporting for routine analysis
• High accuracy through specialized UV and thermal damage libraries
• Support for contamination control in manufacturing and microplastic research

Future Trends and Potential Applications

Expanding spectral libraries to include additional polymer blends and environmental aging scenarios will improve identification robustness. Integration with microscopy and hyphenated techniques (e.g., µ-FTIR imaging) can advance microplastic characterization. Machine learning approaches may further automate degradation stage prediction and polymer classification.

Conclusion

Shimadzu’s Plastic Analyzer streamlines qualitative assessment of UV-degraded plastics by combining ATR-FTIR measurement with specialized damage libraries and automated workflows. The approach delivers rapid, accurate identification and degradation estimation, enhancing contamination analysis and materials research across industrial and environmental applications.