Preparation Of Wood Fiber/polypropylene Composites Reinforced By Nano-TiO₂ And The Study On Its Resistance To Uv-aging

Due to its excellent performance and low cost,PP-based wood-plastic composite materials are widely used in building decoration materials,outdoor buildings,etc.while outdoor materials are often exposed to sunlight,and the aging of materials after exposure to ultraviolet rays reduces their service life.Performance is reduced.In order to overcome the aging caused by UV to composite materials,nano-TiO2 particles treated with silane coupling agent KH-570 were added into wood fiber/PP composite system to prepare PP-based wood-plastic composite materials,and artificial UV accelerated aging test was carried out.The mechanical properties,surface color and surface morphology of composites before and after aging were tested,analyzed and characterized.The effect and mechanism of nano-TiO2 particles on UV-resistant aging of PP-based wood-plastic composites were investigated.Experimental results show:(1)The modified nano-TiO2 particles were found to be successfully grafted on the surface of nano-TiO2,which improved the surface properties and dispersion.And a suitable wood to plastic ratio can improve the mechanical properties of the composite,and the pretreatment method of the wood fiber also affects the properties of the material.(2)The mechanical properties of PP-based wood-plastic composites prepared by surface-modified nano-TiO2 showed a first increase and then decrease,mainly due to the effect of trace amounts of TiO2 particles on the mechanical properties of the composites,but TiO2 particles.When the content exceeds a certain limit,the nanoparticles will agglomerate in the material to reduce or even eliminate the nano-characteristics.(3)After the prepared TiO2-PP-based wood-plastic composite material is accelerated by ultraviolet aging,the mechanical properties of the composite material will decrease.The mechanical properties of TiO2 composites have a small reduction range,mainly due to the properties of nano-TiO2,which can shield the ultraviolet light and reduce the aging of the material.However,when the content of nano-TiO2 is too high,the particles begin to agglomerate,thereby hindering the exertion of its nano-effects and reducing the aging resistance of the material.When the composite material was added with 3 wt%of nano-TiO2,the obtained composite had the best anti-aging UV aging effect.(4)Combined with Fourier transform infrared spectroscopy,scanning electron microscopy and aging mechanism of composite materials,the anti-aging mechanism of nano-TiO2 on PP-based wood-plastic composites was analyzed as follows:nano-TiO2 has absorption and shielding effect on ultraviolet light,and it is added to composite materials.In the whole process of ultraviolet aging,due to the characteristics of nano-TiO2,the energy absorbed by the composite material does not reach the energy required for the molecular chain breakage and wood fiber degradation of the polymer inside the material,so that their degradation reaction is delayed,thereby Obvious aging inhibition of the composite material is obtained.