Multi-Sample UV Irradiator - Part 3 Correlation with Micro-UV Irradiator -

Importance of the Topic

The accelerated evaluation of polymer degradation under ultraviolet exposure is critical for predicting long-term material performance in applications such as outdoor coatings, packaging and automotive components. High-impact polystyrene (HIPS) is widely used in industry, making reliable and efficient UV degradation testing essential for quality control and material development.

Objectives and Overview of the Study

This study aims to compare the degradation behavior of HIPS when irradiated using a Multi-Sample UV Irradiator (UV-1048E) and a single-sample Micro-UV Irradiator (UV-1047Xe). The focus is on establishing a quantitative correlation between the two systems to enable high-throughput testing while maintaining consistency with standard single-sample results.

Methodology

• Sample Preparation: A 5 µL aliquot of HIPS in dichloromethane (20 µg/µL) was deposited into sample cups and dried to yield a 100 µg thin film.
• UV Irradiation: Five films were exposed simultaneously in the Multi-Sample UV Irradiator at 100 mm distance, and five films were irradiated sequentially in the Micro-UV Irradiator at 4 mm distance. Exposure durations ranged up to 12 h (multi-sample) and 2 h (micro-UV).
• Evolved Gas Analysis-MS: Post-irradiation degradation was assessed by recording EGA thermograms over a temperature ramp of 100–600 °C at 20 °C/min under helium flow (50 mL/min).

Used Instrumentation

• Multi-Sample UV Irradiator (UV-1048E)
• Micro-UV Irradiator (UV-1047Xe)
• EGA-MS system (EGA/PY-3030D) with deactivated metal capillary column (L = 2.5 m, i.d. = 0.15 mm)

Main Results and Discussion

Both irradiator systems produced broader EGA thermogram peaks with increasing exposure time, reflecting progressive HIPS degradation. The micro-UV setup exhibited a six-fold higher degradation rate due to its shorter irradiation distance. Despite this rate difference, there was a strong linear correlation between peak-width changes in the two systems. Reproducibility was excellent, with relative standard deviation (RSD) below 4.3 % for 0–12 h exposures in the multi-sample format.

Benefits and Practical Applications

The Multi-Sample UV Irradiator significantly increases testing throughput without sacrificing correlation to single-sample data, making it suitable for accelerated weathering tests in research and industrial QA/QC. Its reproducibility and correlation to established methods support its adoption in material stability screening and polymer formulation optimization.

Future Trends and Applications

Advances may include integrating real-time gas analysis, expanding to other polymer classes, coupling photothermal and oxidative degradation modes, and applying predictive modeling to forecast long-term performance. Automated sample handling and data processing will further enhance throughput and accuracy.

Conclusion

The comparative study demonstrates that the Multi-Sample UV Irradiator delivers reliable, reproducible HIPS degradation data that correlates closely with results from a single-sample Micro-UV system. This dual-system approach offers a practical balance between efficiency and methodological consistency for accelerated polymer aging studies.

References

1. C. Watanabe et al., Polymer Degradation and Stability, 94 (2009) 1467-1472.
2. T. Yuzawa et al., Polymer Degradation and Stability, 96 (2011) 91-96.
3. K. Matsui et al., Polymer Testing, 56 (2016) 54-57.