Introduction
Flat roof membranes made of plastic are often used as waterproofing materials in construction. In this case, a PVC-based roof membrane was investigated that causes a strong odor nuisance when exposed to sunlight. The aim of the analysis was to characterize the material and to determine organic and inorganic pollutant emissions.
analysis and results
1. Material determination using FTIR spectroscopy
- The flat roof sheet consists of Polyvinyl chloride (PVC) with one plasticizer content of over 30% (diisononyl phthalate).
- Contains additional pigments and shows first signs of polymer damage.
2. Emission analysis using GC-MS
- diisononyl phthalate is already at 60 °C thermally desorbed, which indicates a high volatility of the plasticizer.
- decomposition products of polyenes were detected, which indicate a UV-induced material degradation indicate.
3. Environmental simulation in the xenon chamber
- With UV irradiation and heating to 60 °C there is a release of corrosive hydrogen chloride (dehydrochlorination).
- The material becomes brittle due to the loss of plasticizers, which leads to long-term impairment of the material properties.
Conclusion
The PVC flat roofing membrane is inadequately protected against weather-related degradation. Sunlight causes release of phthalates and hydrogen chloride, what a odor at adjacent workplaces.
Suggestions
- Improvement of UV stabilization of the material to avoid plasticizer release and dehydrochlorination.
- Use of alternative plasticizers with lower volatility or a lower plasticizer content.
- Regular review of the Long-term durability of the materials used in outdoor applications.
Figures: FTIR spectroscopy of the track (left) and that of the outgassing (right).