A rapid technique for monitoring volatile organic compound emissions from wood–plastic composites

Abstract

Wood–plastic composites (WPCs) have numerous indoor applications, including framing, decoration and flooring. However, the impact of WPCs on indoor air quality has not been widely studied. Proton-transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) was utilized to monitor the release of volatile organic compounds (VOCs) from a commercial WPC for 41 days since its day of manufacture. Additionally, the emission rates of VOCs from seven different WPC samples were compared and converted into air concentrations to evaluate whether the odour thresholds would be exceeded. The VOCs studied were formaldehyde, acetaldehyde, acetic acid, cyclohexene, furan, furfural, guaiacol and monoterpenes. The results from the 41-day test revealed that the emission rates of monoterpenes, guaiacol, furfural and acetaldehyde declined by 75%–93%, whereas an opposite phenomenon was observed for cyclohexene (nearly a threefold increase). The comparison of VOC emission rates from seven WPC samples indicated that none of the samples had the lowest or highest emission rate for every VOC studied. The present results are significant in at least two aspects; this study shows that the VOC emission rates from WPCs can be determined by using PTR-TOF-MS. Furthermore, it seems that guaiacol and acetaldehyde exceed their odour thresholds and therefore humans will be able to detect these compounds from the WPCs studied.