The Preparation, Structure And Property Of PVC/Wood Flour Composites

Recent years,wood-plastic composites(WPC) have gained popularity as a sort of novel and environment-friendly material.Although much efforts have been made for WPC by material scientists of our country,there are also many disadvantages limit their application.One of the disadvantages is that wood powder content is not high,which is generally not more than 50% of industrial production of WPC.Intensity of WPC with high wood powder content is not high which is still in the pilot phase.Another prominent issue is wood fiber and thermoplastics degradation in the process,which not only affects the appearance of beautiful color products,but also affectes the mechanical properties of wood-plastic composites.We were committed to investigate high wood powder content wood-plastic composites based on the research status and conditions of our laboratory. We have developed a novel method that preparing adhesive PVC to achieving better dispersion of wood flour into PVC matrix.We improved the processing flowability of WPC by adding complex plasticizer and CPE.We added wollastonite flour and modified resin into the wood plastic composites respectively in order to improve their mechanical property,thermal property and water-resistance.(1)The adhesive PVC was of benefit to wood flour and polymer matrix homogeneous mixing.we can achieve the best mixing effect which can meet requirment of compression molding process and functional performance when set the Mixing mill roll temperature at range from 175℃to180℃and mixing time at 15min.(2)The mechanical properties,processing behavior and the water resistance of wood-plastic composites were evaluated in order to optimize the moulding process. The experimental results indicated that wood-plastic composites with optimum properties can be made by seting compression molding temperature at 180℃, compression molding time at 25min and compression molding pressure at 10MPa.(3)According to scanning electron microscopy(SEM),CPE has significantly improved the interface compatibility of PVC-based wood-plastic composite;Interface compatibility of emulsion PVC based wood-plastic composite was better than suspension PVC based wood-plastic composite;The porosity of wood-plastic composite can be reduced by adding wollastonite flour;Wood flour treated with modified resin can significantly improved interfacial strength of wood-plastic composite.(4)The interface compatibility and mechanical properties of wood-plastic composites were significantly improved by the wood-flour silane treated by coupling agent KH550.The optimum concentration of silane coupling agent KH550 was 2% of wood flour.(5)Mechanical properties of emulsion PVC based wood-plastic composite was better than suspension PVC based wood-plastic composite;The addition of CPE into the PVC matrix significantly improved the unnotched impact strength,The optimum amount of CPE was around 10pbr,Mechanical properties of wood-plastic composites was improved by adding wollastonite flour,their tensile strength increased to 11.4MPa, flexural strength increased to 11.3MPa and flexural modulus increased to760MPa,the improvement of unnotched impact strength was not obvious;The addition of modified resin significantly improved their mechanical properties,the tensile strength increased to11.3MPa,flexural strength increased to 20.0MPa and flexural modulus increased to 1380MPa.(6)The result of water resistance studies show that adding wollastonite and modified resin can significantly improve the water resistance of wood-plastic composite materials,the effect of adding modified resin even more obvious,after 24 hours immersion,the tensile strength,flexural strength and impact strength retention rates respective were 96.5%,97.7% and 101.8%.(7)The thermal performance analysis indicates that the thermal decomposition temperature of wood-plastic composites was raised by adding both wollastonite flour and modified resin,which can raise the decomposition temperature by 17℃and 19℃.Half life temprature of wood-plastic composite added wollastonite flour increased by 58℃.