【作者】 马晓宇；

【导师】 王子忱；

【作者基本信息】 吉林大学 ， 物理化学， 2012， 博士

【摘要】 随着世界经济的快速发展，对化石资源的依赖和消耗量不断增加，已经导致人类面临能源枯竭和环境污染等问题。因此，如何更有效利用化石资源、降低消耗速度成为决定人类生存和发展的重要课题。生物质是一种可以储存太阳能的可再生资源，它可以作为化石资源的补充和替代品，提取可再生的生物质材料代替化石资源原料，增加在高聚物中，可降低终端产品中高聚物的比例，从而间接地降低了石油、煤炭的消耗速度，为人类开发新能源、新资源争取时间创造条件。聚对苯二甲酸乙二醇酯（PET）作为石油化工的衍生品，是一种用途广泛、产量很大的重要聚合物材料，具有良好的机械物理性能、耐磨性、耐热性、耐化学药品性、绝缘性等特点，价格低廉，已广泛应用于涤纶纤维、薄膜及饮料包装和纺织服装生产等领域，因此需求量巨大。本论文首先以对苯二甲酸和乙二醇为原料，利用自行设计的连续式反应装置，采用直接酯化法制备PET，通过实验确定了反应条件与工艺流程，并针对PET的聚合特点对现有工艺条件进行了优化，制备出了大粘度、高分子量、高结晶度的PET聚合物。通过红外光谱分析，特性粘度和端羧基含量的测试表明，PET的特性粘度可以达到0.75dL g^-1，分子量为21100g mol^-1，端羧基含量为39.5mol t^-1，各项指标均达到国家标准。通过对TGA，DSC和外观颜色的分析对PET结晶动力学和发色机理进行了讨论，为后续的改性工作提供了理论基础和实验条件。本论文以稻壳灰为原料，利用化肥生产中的副产品、浓度为4mol/L氟化铵为溶硅剂，在温度393K反应2小时，制备出氟硅酸溶液，再将反应生成的副产物氨水加入到氟硅酸溶液中生成二氧化硅沉淀和氟化铵溶液，反应过程所使用的化学试剂均可循环利用，降低了成本，减少对环境的污染。采用透射电镜（TEM）、X射线衍射（XRD）、红外光谱（FTIR）、元素分析仪等对产品进行测定分析表明，在此条件下得到的最终产品是无定形的球状SiO₂，直径50⁶0nm，产品产率可以达到94.6%，具有纯度高，粒径小，分布均匀等优良特性。本工艺摆脱了在传统工艺中存在高温溶硅能耗大、排放二氧化碳污染环境、高品位硅砂资源缺乏的弊端，极大地降低了生产成本和投资成本，为二氧化硅的生产提供了可再生、高品位的原料，有利于大规模的生产。在本工艺的基础上，以稻壳为原料，完善了酸催化水解制备糖酸液、原位缩聚炭化制备胶体碳、再利用氟化铵制备SiO₂和木质素，所得到的纳米SiO₂和木质素产品纯度高，粒径小，尺寸分布均匀，最佳工艺条件的原料利用率达到了90%以上。整个实验流程优化、简化了稻壳综合利用的实验方法，实现了稻壳综合利用。通过原位聚合法制备了PET/SiO₂纳米复合材料和PET/木质素复合材料。SEM结果显示，SiO₂纳米粒子和木质素在复合材料中表现出了良好的分散性。木质素的加入使PET产生交联结构，形成弹性体，在出料时制备出多孔材料，起到交联剂和填充剂的作用。DSC，TGA结果表明，SiO₂纳米粒子的添加对PET的热稳定性和结晶速率均有明显的提高作用。这种原位聚合的方法可以进一步推广到木质素等有机材料，也可以通过改变高分子体系来扩展无机纳米粒子的应用领域。这极大的扩展了稻壳综合利用的研究工作。最后，在温和的水环境中，以稻壳灰为硅源，采用十六醇进行原位修饰改性提取出来SiO₂，并通过不同的热处理方式对其表面性质进行调控，制备出具有不同疏水性能的SiO₂粒子。并通过原位聚合法制备了十六醇修饰PET/SiO₂纳米复合材料。根据实验结果，我们提出了一个简单的模型，直观的表现十六醇对SiO₂的修饰，以及在PET基体中的分散机理。十六醇的加入通过形成有机硅结构降低纳米SiO₂的表面能和表面张力，减小了粒子之间的相互作用，导致其在复合材料中更好的相容性。SEM结果也显示，在PET和十六醇修饰过SiO₂纳米粒子之间无明显的相分离现象产生。PET,十六醇和SiO₂之间的相互作用是不产生相分离的主要原因。DSC，TGA结果表明，十六醇修饰过SiO₂纳米粒子的添加对PET的热稳定性和结晶速率均有明显的提高作用。这种原位修饰、原位聚合的方法可以进一步推广到其他无机纳米粒子的表面修饰，修饰剂也可以通过改变醇碳链的长短来改变无机物的表面浸润性，通过改变高分子体系来扩展无机纳米粒子的应用领域。整个实验流程优化、简化了制备纳米SiO₂、表面修饰改性、制备复合材料的方法。将修饰后的SiO₂粉末跟高分子材料复合，二氧化硅粉体较改性前，在高分子中实现了良好的分散，这极大的扩展了稻壳综合利用研究工作的应用技术研究。更多还原

【Abstract】 With the rapid development of world economy, a large number of fossilresources are consumed, which led to a series of problems such as energy depletionand environmental pollution.Therefore, how to use fossil resources more efficiently,reduce the rate of consumption becomes an important issue for human beings’survival and development.Biomass, as a kind of renewable resourcescan store solarenergy and be used as a complement and substitute for fossil resources. We canextract renewable biomass materials instead of fossil resources raw materials, increaseaccession to polymer and reduce the ratio of the polymer in products, thus can reducethe rate of consumption of oil and coal indirectly, and create the conditions for humanto develop new energy and new resources.Poly （ethylene terephthalate）（PET） as a petrochemical derivative, is aversatile production of polymer materials, which has good mechanical and physicalproperties, wear resistance, heat resistance, chemical resistance, insulation and lowprice, has been widely used in the field of polyester fiber, film, beverage packaging,textile and garment production, so the demand is huge.In this dissertation, PET was prepared by direct esterification with terephthalicacid and ethylene glycol using self-designed continuous reactor. The optimumreaction conditions and technological process were determined by experiment. Theresults showed that the productions had large viscosity, high molecular weight anddegree of crystallinity. By the tests of infrared spectroscopy, intrinsic viscosity andcontent of carboxyl end group showed that the intrinsic viscosity of PET could reachup to0.75dL g^-1, the molecular weight was21100g mol^-1, the carboxyl end groupcontent was39.5mol t^-1. The indicators were meet national standards. Crystallizationkinetics and the mechanism of hair color of PET were discussed by the tests of TGA,DSC, and the color, which provided a theoretical basis and experimental conditionsfor the follow-up of modified work.In this thesis, silica was extracted from the rice husk ash with ammoniumfluoride which was the by-product in fertilizer production as dissolved silicon agent by a recyclable method. It was found that silica could be synthesized at reactiontemperature of393K for2h, with NH4F concentration of4mol/L. All the chemicalreagents used in the reaction process were recycled to reduce costs and environmentalpollution. Transmission electron microscopy （TEM）, X-ray diffraction （XRD）,infrared spectroscopy （FTIR）, elemental analysis and other analysis results showedthat the final product SiO₂is spherical with the diameter of50to60nm, the yield ofproduct could reach up to94.6%. The final product has fine features of high purity,small particle size and uniform distribution. Compared with the traditional process,the process got rid of the drawbacks of high energy consumption, high carbon dioxideemissions and the lack of high grade silica sand, which greatly reduced the cost ofproduction and investment. Therefore, it was more suitable for large-scale production.On the basis of this process, the rice husk as raw material, improve theacid-catalyzed hydrolysis of the sugar acid, in situ polycondensation charringpreparation of colloidal carbon, and then the use of ammonium fluoride preparation ofsilica and lignin. The nano-SiO₂and lignin products were high purity, small particlesize and size distribution, the utilization of raw materials was more than90%. Thewhole experimental process had optimized and simplified the methodof the comprehensive utilization of rice husk.PET/SiO₂nanocomposites and PET/lignin composites were prepared via in situpolymerization. Composites containing SiO₂nanoparticles and lignin showed a gooddispersion from SEM results. Lignin and PET can produce cross-linked structure toform the elastomer. Porous materials were prepared when the material comes out.Lignin played the role of crosslinking agents and fillers in the material. DSC, TGAresults showed that the addition of SiO₂nanoparticles obviously increased thermalstability and crystallization rate of PET. In situ polymerization method can be furtherextended to lignin and other organic materials. The method can also be extend theapplications of inorganic nanoparticles by changing the polymer system. This greatlyextended the comprehensive utilization of rice husk.Finally, the SiO₂extracted from rice husk ash were modified in situ byhexadecanol under moderate water. SiO₂particles were prepared withdifferent hydrophobic properties by different heat treatment methods.PET/SiO₂nanocomposites were prepared by in situ polymerization. According to theexperimental results, we proposed a simple model, SiO₂were modified byhexadecanol and the mechanism of dispersion in the PET matrix was studied. The hexadecanol could reduce the surface energy and surface tension of SiO₂nanoparticles through the formation of organic silicon structure, which reduced theinteraction between the particles, resulting in better compatibility in thecomposite. SEM results also showed that there was no phase separation phenomenonbetween PET and modified SiO₂nanoparticles. The interaction between PET,hexadecanol and SiO₂was not the main reason for disappear of phaseseparation. DSC, TGA results showed that adding of SiO₂nanoparticles modified byhexadecanol significant increased thermal stability and crystallization rate ofPET. This method of modification and polymerization in situ could be furtherextended to surface modification of other inorganic nanoparticles, the surfacewettability of inorganic could be changed by changing the alcohol carbon chain lengthof modifiers. Application of inorganic nanoparticles could be expanded by changingthe polymer system. The entire experimental process optimized the preparation ofnano-SiO₂, surface modification and preparation of composite materials. ModifiedSiO₂composites with polymer materials showed good dispersion compared to theunmodified SiO₂, which greatly extended the application of technology research forcomprehensive utilization of rice husk.更多还原