Multi-Sample UV Irradiator - Part 2 Comparison of degradation degree by sample cup position -

Importance of the Topic

The development of a multi-sample UV irradiator enables simultaneous accelerated degradation testing of polymer materials, improving throughput and consistency in photo-thermal-oxidative stability studies. Uniform irradiation of multiple specimens is critical for reliable comparative analysis in material research and quality control.

Objectives and Study Overview

This study evaluated whether the position of sample cups in the new Multi-Sample UV Irradiator (UV-1048E) affects the degradation degree of high impact polystyrene (HIPS) films. Samples were placed along inner and outer circumferences, subjected to 6 hours of UV exposure, and then analyzed by evolved gas analysis-mass spectrometry (EGA-MS).

Methodology and Instrumentation

Sample Preparation and Irradiation Procedure

• HIPS films (100 µg) formed from dichloromethane solutions in quartz sample cups
• Five cups arranged on inner or outer circumference of a rotating holder (0.3 rpm)
• UV exposure: Xe-Hg lamp via fiber bundle at 100 mm distance, holder temperature 60 °C, air atmosphere, 6 hours

EGA-MS Analysis

• Instrument: EGA/PY-3030D multi-functional pyrolyzer in EGA-MS mode
• Furnace temperature program: 100–600 °C at 20 °C/min
• Carrier gas: helium, 50 mL/min, split ratio 1/50

Main Results and Discussion

UV-irradiated samples exhibited broader thermogram peaks compared to non-irradiated controls, indicating oxidative chain scission in HIPS. Comparison between inner and outer positions revealed negligible differences in peak width, with a relative standard deviation of 1.15% at 10% peak height (n=5). This uniformity confirms consistent irradiation across all sample positions as the holder rotates.

Benefits and Practical Applications

• Higher throughput by simultaneous irradiation of multiple specimens
• Reproducible degradation assessment regardless of sample placement
• On-line integration with GC/MS for real-time volatile product analysis
• Applicable to weathering tests and polymer stability screening

Future Trends and Potential Applications

Future developments may include integration of automated sample loading, expanded wavelength control for tailored photodegradation, coupling with advanced detectors for detailed product identification, and extension to other polymer types and composite materials.

Conclusion

The Multi-Sample UV Irradiator delivers uniform and reproducible photo-thermal-oxidative degradation of polymers across multiple positions, enhancing analytical throughput and reliability in material stability studies.

Reference

• C. Watanabe et al., Polym. Degrad. Stab., 94 (2009) 1467-1472
• T. Yuzawa et al., Polym. Degrad. Stab., 96 (2011) 91-96
• K. Matsui et al., Polym. Test., 56 (2016) 54-57