【作者】 万正龙；

【导师】 熊汉国；

【作者基本信息】 华中农业大学 ， 食品科学， 2010， 硕士

【摘要】 天然纤维具有价格低廉、低密度、高韧性、生物降解性等优点,使得天然纤维能被用于纤维增强材料。但是由于亲水的天然纤维与疏水的塑料之间的不相容,导致复合材料的强度的下降。针对这些问题,本文采用偶联剂改性竹粉来改善与聚氯乙烯(PVC)间的相容性,在微波条件下竹纤维接枝甲基丙烯酸甲酯(MMA)也是改善竹粉与PVC相容性的有效的方法之一,同时研究了纳米Ti02对复合材料抗菌性能的影响。主要结论如下：1.确定钛酸酯偶联剂的最佳用量为2%,DOP的最佳用量为10%,CPE的最佳用量为12%。竹粉经过偶联剂改性后,吸潮率低于未改性竹粉的吸潮率,且竹粉经钛酸酯偶联剂改性后的竹粉／PVC复合材料力学性能得到改善,拉伸强度和冲击强度明显提高。随着钛酸酯含量的增加,复合材料的拉伸强度和拉伸强度均升高,当钛酸酯含量为2%时,拉伸和冲击强度达到最大值,之后随偶联剂用量增加而降低。竹粉改性前后的红外光谱显示,钛酸酯、铝酸酯均可以对竹粉进行改性；SEM分析表明,钛酸酯对竹粉进行处理,改善了竹粉与PVC的相容性。2.采用响应面正交设计优化了微波接枝反应条件,其最佳接枝反应条件为：微波功率133.6W,引发剂浓度3.67×10-3mol／L,微波时间8.01min。同时得到了关于微波功率(X1),引发剂浓度(X2),反应时间(X3)的三元二次回归方程：Y=46.79667+1.07375X1+1.00000X2+0.28875X3-3.68583X1X1+0.07250X1X2+ 1.66500X1X3-6.05833X2X2+0.70750X2X3-0.64583X3X3对接枝共聚物进行表征,红外光谱和SEM分析表明,竹纤维的结构已经发生变化,MMA已经成功接枝到竹纤维上,接枝后的竹纤维结晶度降低,热重分析表明接枝后的竹纤维热稳定性增强,接枝后的吸潮率低于未改性竹纤维的吸潮率。将竹纤维接枝MMA与竹粉、PVC复合制备复合材料,与未处理竹粉的复合材料相比,加入接枝共聚物的复合材料的力学性能增加,SEM分析表明,接枝共聚物复合材料PVC相容性好。3.加入纳米Ti02后的竹粉／PVC复合材料力学性能得到改善。随着纳米Ti02含量的增加,复合材料的拉伸强度和拉伸强度均升高,当纳米Ti02添加量为3.2%时,复合材料的拉伸强度达到最大值。纳米TiO2对大肠杆菌的最小抑菌浓度为400mg／L,对金黄色葡萄球菌的最小抑菌浓度为800mg／L。随着纳米TiO2添加量的增加,竹粉／PVC复合材料的抗菌性能随之增加,当纳米TiO2添加量为1.2%时,复合材料对大肠杆菌和金黄色葡萄球菌的抗菌率就大于90%,抗菌效果显著；当纳米TiO2添加量为1.6%时,对大肠杆菌和金黄色葡萄球菌的抗菌率均超过了99%,复合材料具有强抗菌性能。复合材料经紫外光照老化实验后,实验结果表明复合材料具有良好的抗菌长效性。更多还原

【Abstract】 Natural cellulose has numerous advantages, such as low cost, low density, high toughness and biodegradability, and the cellulose can be used as reinforcements for thermoplastic matrix composites. But the incompatibility of the hydrophilic natural cellulose and the hydrophobic thermoplastic matrix can actually lead to a reduction in the strength of the composite material. Taking these aspects into account, the coupling agents are additives used in the cellulose reinforced thermoplastics, in order to increase the incompatibility of bamboo flour and PVC, grafting copolymerization of MMA onto cellulose under microwave irradiation is one of the most effective methods to improve the incompatibility of bamboo flour and PVC, and the effect of nano-TiO2 on the bactericidal activity of bamboo flour/PVC composites are investigated in this paper. The main contents and conclusions are as follows:1. The optimal level of DOP is 10%, the optimal level of CPE is 12%, the optimal level of titanate coupling agent is 2%.The tensile strength and impact strength have an increase with increasing titanate coupling agent content. The maximum tensile strength and impact strength are achieved at 2% titanate coupling agent, and then decrease. Treatment of bamboo flour with titanate coupling agent shows a decrease of the moisture absorption properties as compared to untreated bamboo flour. The modified bamboo flour is characterized by FTIR, and the result indicates that the surface of bamboo flour is modified successfully with titanate coupling agent. Scanning electron microscopy revealed good compatibility and adhesion between the plastic and the bamboo flour for crosslinked composites.2. The process of grafting is optimized by response surface methodology (RSM) to obtain the optimum conditions for grafting percentage. It is indicated that the optimum reaction condition is as follows:the microwave power,133.6 W; initiator concentration, 3.67×10-3mol/L; exposure time,8.01 min. The regression equation describing process of grafting is obtained by response surface methodology: Y= 46.79667+1.07375X1+1.00000X2+0.28875X3-3.68583X1X1+0.07250X1X2+ 1.66500X1X3-6.05833X2X2+0.70750X2X3-0.64583X3X3 The graft copolymer is characterized by FTIR, SEM, which elucidated the structure changes in comparison with bamboo cellulose, these results indicate that the surface of bamboo cellulose was grafted successfully with MMA copolymer. The crystallinity of the graft copolymers decrease in comparison with that of bamboo cellulose, and TGA revealed that copolymer had more thermal stability. Furthermore, the moisture absorption capacity of the graft copolymers decreased significantly with the increase in grafting percentage.A comparison with the composites filled with the untreated bamboo flour showed that the tensile strength and impact strength increased, with the incorporation of the graft copolymers into the bamboo flour/PVC composites. Scanning electron microscopy revealed good compatibility and adhesion between the plastic and the bamboo flour with the incorporation of the graft copolymers into the bamboo flour/PVC composites.3. The results exhibit that nano-TiO2 can obviously improve the mechanical properties of the composites. The tensile strength and impact strength have an increase with increasing nano-TiO2 content. Tensile strength reached the maximum value when the content of nano-TiO2 is at 3.2 wt%.The minimum inhibitory concentration of nano-TiO2 to E. coli and S. aureus are 400mg/L and 800mg/L respectively. The composites possess excellent bactericidal activity on the E. coli and S. aureus. The bactericidal activity of the composites is more than 90% when the content of nano-TiO2 is at 1.2 wt%. When the content of nano-TiO2 is at 1.6 wt%, the bactericidal activity of the composites is more than 99%. The prepared PE was treated by means of accelerated aging, and the results showed the composites had good long-time bactericidal activity.更多还原