【作者】 王会；

【导师】 盛奎川；

【作者基本信息】 浙江大学 ， 农业电气化与自动化， 2010， 博士

【摘要】 本文以聚氯乙烯(PVC)和竹产业加工废弃物竹屑为研究对象,研究了原料特性和热模压工艺对复合材料性能的影响,在此基础上,着重考察了化学/水热增容对竹颗粒特性及复合材料性能的影响。结果发现：1)毛竹颗粒含水率为3%,复合材料中竹颗粒和PVC塑料的配比为5：5,竹颗粒粒径为0.9mm时,制备的竹颗粒增强PVC基复合材料的各项物理力学性能达到较佳。复合材料的较佳模压时间为8min,模压温度为180℃。2)5%硅酸钠处理的竹颗粒增强PVC基复合材料拉伸强度达到最大值,为15.72MPa。浓度为5%和2%氢氧化钠处理的竹颗粒增强PVC基复合材料弹性模量和静曲强度分别达到最大值,为4362.48 MPa和44.73MPa。0.5%的氢氧化钠处理的竹颗粒增强PVC基复合材料2h、24h厚度膨胀率分别达到最小值。采用不同溶液处理后竹颗粒和PVC的相容性改善,氢氧化钠和硅酸钠处理后的竹颗粒在PVC基体中的分布均匀性较亚硫酸氢钠差。3)高锰酸钾处理改善了毛竹颗粒在PVC基体中的分布,但高锰酸钾剂量过多会导致复合材料性能的降低。0.5%浓度的高锰酸钾修饰的竹颗粒增强PVC基复合材料的拉伸强度达到极大值,为13.79MPa。0.5%浓度的高锰酸钾修饰的竹颗粒增强PVC基复合材料的静曲强度和弹性模量分别达到极大值,为30.36MPa和3261.89MPa。高锰酸钾氧化处理增强了复合材料的弯曲变形率和断裂伸长率,改善了复合材料的耐水性。4)水热处理改善了毛竹颗粒表面结构,有效去除了半纤维素、木质素、果胶等物质,水热处理后毛竹颗粒在复合材料基体中的分布更为均匀。180℃水热处理复合材料的拉伸强度、静曲强度和弹性模量分别达到极大值,为15.79MPa、39.57MPa和6702.26MPa。200℃水热处理复合材料的拉伸断裂伸长率达到最大值,为3.75%±0.20%,140℃水热处理复合材料的弯曲最大变形率达到最大值,为36.22%±2.70%。280℃水热处理复合材料的2h和24h吸水率、2h和24h吸水厚度膨胀率分别达到极小值,为1.18%±0.08%、3.34%±0.20%、0.49%±0.13%和1.3%±0.41%。5)毛竹颗粒水热增容中,催化剂种类和浓度对毛竹颗粒特性及复合材料性能的影响显著。160℃时0.5%的硅酸钠催化水热处理毛竹颗粒的蛋白质、糖类、淀粉、果胶等物质的含量最小,为11.55wt%；120℃时0.5%硫酸催化水热处理毛竹颗粒的半纤维素含量最小,为7.58wt%；160℃下1%氢氧化钠催化水热处理毛竹颗粒的木质素含量略低,为11.31wt%。200℃下2%的硅酸钠水热处理毛竹颗粒增强PVC基复合材料的拉伸强度达到最大值,为26.98±4.69MPa。160℃下2%碳酸钾水热处理毛竹颗粒增强PVC基复合材料的弹性模量和静曲强度达到最大值,分别为6089.49±347.49MPa和52.16±2.54MPa。140℃下2%碳酸钠水热处理毛竹颗粒增强PVC基复合材料的拉伸断裂伸长率达到最大值,为4.41±0.03%。水热温度为160℃、浓度为2%氢氧化钠处理毛竹颗粒增强PVC基复合材料的弯曲最大变形率达到最大值,为91.92%±2.79%。120℃下催化剂浓度0.5%的硫酸水热处理毛竹颗粒增强PVC基复合材料的2h吸水率达到最小值,为1.61%±0.07%。180℃下催化剂浓度2%的硅酸钠水热处理毛竹颗粒增强PVC基复合材料的24h吸水率达到最小值,为3.43%±0.50%。,140℃下催化剂浓度0.5%的硅酸钠水热处理毛竹颗粒增强PVC基复合材料的2h厚度膨胀率达到最小值,为0.52%±0.15%。160℃下催化剂浓度1%的硅酸钠水热处理毛竹颗粒增强PVC基复合材料的24h厚度膨胀率达到最小值,为2.43%±0.13%。本论文在复合材料界面水热增容及复合材料耐水性机理方面进行了探索研究,本论文的研究成果为天然纤维的表面修饰及其增强树脂基复合材料的研究提供了新的思路和方法,为木塑复合材料的应用提供了参考。更多还原

【Abstract】 Bamboo plastic composites were fabricated with polyvinyl chloride and moso bamboo sawdust from bamboo processing industry in this paper. And in order to obtain composites with outstanding mechanical properties, the influences of materials properties and moulding technical on the mechanical properties of moso bamboo particles reinforced PVC composites were studied. With this base, the roles of chemical/hydrothermal modification on characteristic of bamboo particles and properties of the composites were investigated. Results showed that:1) A better mechanical properties of moso bamboo particles reinforced PVC composites will be obtained when the particle size of moso bamboo particles is 0.9mm with a moisture content of 3%, and the weight ratio of bamboo and polyvinyl chloride is 50:50. Optimized parameters of molding technical is 8min compressing at 180℃.2) The highest tensile strength of the composites is 15.72MPa with 5wt% Na2SiO3 aqueous solution treatment. The best modulus of elasticity and modulus of rupture of the composites are obtained with 5wt% and 2wt% NaOH aqueous solution treated respectively, and the values are 4362.48 MPa and 44.73MPa. The lowest values of 2h and 24h thickness swelling and water absorption are obtained with 0.5wt% NaOH aqueous solution treatment. The compatibility of different content of the composites is improved with NaOH, Na2SiO3 and NaHSO3 solutions and the most uniform distribution of moso bamboo particles in PVC composites is observed with NaHSO3 solutions treatment.3) Tensile strength of moso bamboo particles reinforced PVC composites get its maximum value of 13.79MPa with 0.5% potassium permanganate treatment while modulus of rupture and modulus of elasticity reach their highest values of 30.36MPa and 3261.89MPa respectively at 0.2% concentration. Potassium permanganate treatment enhanced elongation at break and flexural deformation. A uniform dispersion of moso bamboo particles in PVC matrix was obtained after potassium permanganate treatment. Low concentration would oxidize hydroxyl groups of moso bamboo cellulose and too high concentration would make moso bamboo cellulose degrade.4) Hydrothermal modification improve the surface structure of moso bamboo particles and wipe out hemicelluloses, lignin, pectin and etc.. A uniform dispersion of moso bamboo particles in PVC matrix is observed with hydrothermal treatment. Tensile strength, modulus of elasticity and modulus of rupture of moso bamboo particles get their maximum values of 15.79Mpa, 6702.26MPa and 39.57MPa respectively with 180℃hydrothermal modification. The highest values of elongation at break and flexural deformation are 3.75%±0.20%(with 200℃hydrothermal modification) and 36.22%±2.70%(with 140℃hydrothermal modification). The lowest values of 2h and 24h of water absorption and thickness swelling are 1.18%±0.08%、3.34%±0.20%、0.49%±0.13% and 1.3%±0.41% respectively.5) The type and concentration of the catalyst have remarkable influence on characteristic of moso bamboo particles and the properties of the composites in the process of hydrothermal modification. A lowest content of protein, saccharine, amylum and pectin is obtained with 0.5wt% Na2SiO3 catalyzed. The lowest content of hemicelluloses is 7.58wt% which is catalyzed with 0.5% H2SO4 at 120℃hydrothermal modification. The lowest content of lignin is 11.31wt% which is catalyzed with 1%NaOH at 160℃hydrothermal modification. The largest tensile strength of the composites is 26.98±4.69MPa which is treated with 2wt% Na2SiO3 at 200℃. The highest modulus of elasticity and modulus of rupture are 6089.49±347.49MPa and 52.16±2.54MPa respectively which is treated with 2wt% K2CO3 at 160℃. The largest elongation at break of the composites is 4.41±0.03% which is catalyzed with 2wt% Na2CO3 at 140℃and the largest flexural deformation of the composites is 91.92±2.79% which is treated with 2wt% NaOH at 160℃. The lowest 2h water absorption of moso bamboo particles reinforced composites is 1.61±0.07% which is treated with 0.5wt% H2SO4 at 120℃hydrothermal condition. The lowest 24h water absorption of moso bamboo particles reinforced composites is 3.43±0.50% which is treated with 2wt% Na2SiO3 at 180℃hydrothermal condition. The lowest 2h thickness swelling of composites is 0.52±0.15% which is treated with 0.5wt% Na2SiO3 at 140℃hydrothermal condition and the lowest 24h thickness swelling of composites is 2.43±0.13% which is treated with lwt% Na2SiO3 at 160℃hydrothermal condition.The most important contribution of this research is surface modification of the composites with hydrothermal technology and the investigation of water absorption mechanism of the composites. The results of this manuscript will give an innovation thinking and method to surface modification of natural fibers and interface improvement of wood plastic composites. The results of our research also give some references to the applications of wood plastic composites.更多还原