Effect Of NanoZnO On The UV Resistance Of Wood Plastic Composites

Wood plastic composites have many advantages such as decay resistance, and so on. Wood plastic composites are mainly used outdoor. Poor UV resistance performance of their products has limited its application. So it is necessary to use effective additives to improve the UV resistance properties of wood plastic composites. In this thesis, additives such as ZnO and NanoZnO have been used to improve the performance of WPC. The properties of wood composites with different content of ZnO and NanoZnO were tested after exposed to accelerated ultraviolet aging. The main results of the research are concluded as follows:Mechanical properties of wood plastic composites were changed with different content of wood flour. Too high or low content of wod flour have negative effect on mechanical properties of composites. Experiment results show that 50%-70% wood flour will be the ideal choose.The decay resistance of composites declined with an increase in the wood flour.ZnO and NanoZnO were choosed as additives to improve the UV resistance property of wood plastic composites. Adding ZnO or NanoZnO into the composites led to the decrease in mechanical properties of composites. XRD showed that ZnO or NanoZnO were indeed added into composites. Composites were treated for 1500h UV accelerated aging. Such characterization as SEM, FTIR and so on were to research the change of composites before and after aging.With ongoing of aging time △E increased, surface cracks came into being and gradually became more serious; Adding ZnO into the composites reduced AE comparing to the controller; Adding NanoZnO into the composites reduced AE and surface cracks increase comparing to the blank sample. In the meanwhile, bending performance also decreased, Adding ZnO and NanoZnO into the composites bending strength decreased less than blank sample.The results of FTIR show that the oxidation occurred on the surface during aging. The carbonyl index of composites continuously increased with the processing of UV aging time. Adding ZnO or NanoZnO into the composites reduced the carbonyl index increase comparing to the controller, this suggested that ZnO or NanoZnO could absorb ultraviolet light effectively to reduce the surface oxidation during ultraviolet aging. On the other hand, cellulose index of the composites decreased with the processing of UV aging time. Adding NanoZnO into the composites reduced the carbonyl index increase comparing to the controller, however adding ZnO into the composites increased the carbonyl index increase comparing to the controller, So, it is thought that the results may be due to the fact that the activity of ZnO did not play out in a short time.To conclude, adding ZnO or NanoZnO into the composites indeed improved the UV resistance of composites; They reduced fade and crack on the surface of composites, reduced the loss of bending performance, delayed the occuration of surface oxidation. The research indecated that the UV resistance effect of NanoZnO was better than ZnO.