Molecular characterizations, mechanical properties and anti-algal activities for PVC and wood/PVC composites containing urea- and triazine-based algaecides

Material behaviors and anti-algal performances of PVC and wood PVC composites (WPVCs) were examined after adding commercial algaecides of different types and contents. Three different wood types commonly found in tropical climates - namely, Xylia kerrii Craib and Hutch.; Hevea brasiliensis Muell.; and Mangifera indica Linn. - were of interest. Isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea), a urea-based algaecide, and Terbutryn (N-2-tert-butyl-N-4-ethyl-6-methylthio-1,3,5-triazine-2,4-diamine), a triazine-based algaecide, were used as anti-algal agents in this study; concentrations in the specimens varied from 0 to 1500 ppm. Surface color, thermal properties, chemical structure and mechanical properties of the materials were also monitored. The results revealed that addition of Isoproturon tended to considerably change the surface color of the materials, particularly for PVC which had the highest Delta E* value, whereas addition of Terbutryn did not. The effect of wood types was found to influence the initial surface color of the materials. Evidence based on DSC, FT-IR and contact angle testing indicated that Isoproturon had a strong molecular interaction with PVC and could induce PVC degradation. The mechanical properties of PVC and WPVC were affected by the addition of wood, but not by algaecide addition. The results of the growth inhibition zone and chlorophyll-a content in Chlorella vulgaris TISTR 8580 suggested that Terbutryn exhibited better anti-algal performance than Isoproturon with a recommended dosage of 1000 ppm while Isoproturon at 1500 ppm could act as an effective coupling agent in WPVC composites. (C) 2013 Elsevier Ltd. All rights reserved.