Influence Of Ultraviolet Accelerated Weathering On The Properties Of Wood Fiber/Polypropylene Composites

In this paper, the wood fiber/polypropylene composite (WF-PP) was prepared byextruding process. By adding coupling agent maleic anhydride grafted polypropylene (MAPP)and thermoplastic elastomer maleic anhydride grafted ethylene propylene diene monomerrubber (EPDM-MAH) to the formulation, the mechanical properties of composite wasincreased significantly. To improve the weathering resistance of composites, ultravioletabsorber UV531 was added to the composite and the effects of the additives on the weatheringproperties of composite was studied. The mechanical properties of the composites wereevaluated by Flexural and Unnotched impact test. The color loss was measured using aspectrophotometer. The surface chemical change and the micrographs change were studied byFTIR and SEM respectively.Adding coupling agents and thermoplastic elastomers improved the Flexural propertiesand Unnotched impact properties of composites, and the Flexural properties and Unnotchedimpact properties of the composite containing 5MAPP and 5EPDM-MAH increased by 21.9ï¼…and 80.3ï¼…respectively. The results of the ultraviolet accelerated weathering test showed thatthe mechanical properties retained decreased by increasing wood fiber content. By addingcoupling agent and thermoplastic elastomers, better interfacial adhesion between wood fiberand polypropylene was observed and this restricted the water to immerge into the interface,resulting in the improved mechanical properties of the composite after ultraviolet acceleratedweathering. Ultraviolet absorber UV531 significantly improved the weathering resistance ofcomposites, and the Flexural strength, Flexural modulus and Unnotched strength of compositesdecreased very little after ultraviolet accelerated weathering.Chromatism and FTIR analysis showed that the color loss and carbonyl index of thesurface of composites after ultraviolet accelerated weathering decreased when addingultraviolet absorber UV531. SEM micrographs showed that the surface cracks increased asultraviolet accelerated weathering time increased, the adhesion place of wood fiber andpolypropylene cracked more easily, and ultraviolet absorber UV531 was effective incontrolling the surface cracking of the composites in the ultraviolet accelerated weatheringprocess.