Abstract
Outdoor exposure tests on wood plastic composites (WPCs) were conducted at seven sites in Japan. Fungal contamination was recognized on the surface of WPCs. Morphological and molecular biological analyses revealed that the contamination was derived from two species of surface contaminating fungi (Aureobasidium pullulans and Phaeococcomyces sp.). The degree of the contamination, that is, the total dark area caused by surface contaminating fungi, was quantified by using an image processing technique developed inhouse. The results showed a possibility that the propagation of the surface contaminating fungi was influenced by the temperature and precipitation at exposure sites, as well as the installation environment of WPCs. Furthermore, it was also found that the propagation of the surface contaminating fungi was saturated or decreased after 1-year exposure. The analysis of the number of dark area cluster and the average dark area revealed that surface contaminating fungi multiplied by repeating the random occurrence and the aggregation of surface contaminating fungi.
