【作者】 宋秋生；

【导师】 史铁钧；

【作者基本信息】 合肥工业大学 ， 材料学， 2009， 博士

【摘要】 聚合物/无机杂化材料是一种新型复合材料,具有聚合物和无机材料的综合性能。聚合物/无机杂化纤维结合了杂化材料与纤维材料的性能特点,越来越受到人们的关注。对杂化纤维的开展研究具有重要的理论意义和应用前景。本文研究了一系列聚合物/SiO₂（TiO₂）杂化溶胶的粘度特性及其杂化纤维的制备、机理、微观结构与性能。主要内容如下:1.采用溶胶凝胶方法,以正硅酸乙酯（TEOS）和钛酸四丁酯（TBOT）为原料,制备PVA/SiO₂、PAA/SiO₂、PAN/SiO₂、蔗糖/SiO₂、HPMC/SiO₂、PVA/SiO₂/TiO₂等杂化溶胶,系统研究了它们的粘度特性和成纤性能,并通过拉丝法制备杂化纤维。杂化溶胶粘度随时间的变化规律与纯SiO₂溶胶相似,粘度均呈现缓慢增加、逐渐加快、急剧上升等三个阶段。在粘度变化的第二阶段,杂化溶胶中聚合物具有适当的分子量和以线性分子为主的化学结构,赋予杂化溶胶良好的成纤性能。为聚合物杂化纤维的制备提供了实验基础。2.对制备PVA/SiO₂杂化纤维的杂化机理、化学结构和性能进行了研究。PVA中的-OH与TEOS的水解产物的-OH缩合形成了Si-O-C相连的化学键,耐热性能和耐水性能均得到明显改善,SiO₂网络使PVA的结晶受到限制,杂化纤维呈无规结构。为PVA纤维性能的提高提供了一种方法。3.对制备PVA/ SiO₂/TiO₂杂化纤维的杂化机理、化学结构和性能进行了研究。随着PVA含量的增加,PVA/SiO₂/TiO₂杂化溶胶的可纺性能明显改善;随着TBOT含量的增加,杂化溶胶的水解时间明显下降;制得的杂化纤维相分布十分均匀,具有良好的耐热和耐水性能。研究为PVA杂化纤维制备工艺改进和性能的提高具有重要的参考价值。4.用TEOS与乙烯基三乙氧基硅烷共缩聚,采用溶胶凝胶原位聚合法制备了PAA/SiO₂杂化纤维。对制备上述杂化纤维的杂化机理、化学结构和性能进行了研究。PAA/SiO₂杂化溶胶粘度在1400- 3000 mPa·s范围时,成纤性能好,杂化纤维表面光滑,尺寸均匀,透明度较好,PAA与SiO₂之间通过偶联剂形成化学键结合,杂化纤维具有良好的耐水和耐热性能。采用PAA/SiO₂杂化纤维的制备研究尚未见有报道。对水溶性的聚合物耐水和耐热性能的提高提供了一种新方法。5. SiC纤维介电常数和电阻率与玻璃纤维相近的,强度与模量与碳纤维相当的,具有碳纤维、芳纶等无法比拟的耐高温氧化性能,是高性能复合材料的理想增强剂,在航空航天、核工业等高科技领域有着广泛的应用。采用溶胶凝胶法制备了蔗糖/SiO₂杂化纤维,对其作为Si-C纤维的新型前躯体的可行性进行了初步研究。杂化纤维中蔗糖与SiO₂之间以化学键连接,形成了结构均匀的非晶杂化网络;杂化纤维经800℃处理后形成SiO₂与石墨微晶共存的结构。该研究未见报道,对拓展SiC纤维的制备新工艺具有重要的理论意义。6.分别采用溶胶凝胶共混法和溶胶凝胶原位聚合法两种工艺路线,分别制备了两种PAN/SiO₂杂化纤维。对两种溶胶的杂化机理与成纤性能及杂化纤维的结构进行了重点研究。两种不同制备方法对于杂化纤维的化学结构、微观形态和性能具有显著影响。其中,原位聚合法制得的杂化纤维中,PAN中的CN基团发生了水解且杂化纤维内部结构更加均匀。共混法制得的PAN杂化纤维中的CN基团基本不发生水解。两种杂化纤维的耐热性能均优于纯PAN。研究对于制备耐热型的PAN功能纤维具有重要的参考价值。7.采用TEOS和羟丙基甲基纤维素（HPMC）为主要原料、KH570为偶联剂,用溶胶凝胶法制备HPMC/SiO₂杂化溶胶。对其成纤性能和杂化纤维的结构与性能进行了研究。用HPMC/SiO₂杂化溶胶浸涂SiO₂凝胶纤维,制备了HPMC/SiO₂梯度结构杂化纤维。重点研究了杂化溶胶粘度对HPMC/SiO₂梯度结构杂化纤维的形成和表面形态的影响。HPMC/SiO₂杂化溶胶的粘度对于形成表面均一的梯度纤维影响显著,当杂化溶胶粘度为6000mPa·s左右时,浸涂效果较为理想。研究对于制备梯度结构的杂化纤维提供了新的思路。更多还原

【Abstract】 Polymer/inorganic hybrid material is a kind of new composite, which has both merits of organic polymer material and inorganic material. Polymer/inorganic hybrid fiber combines merits of hybrid materials with fiber materials, whcih implies important theoretical significance and has vast application vistas.In this paper, a series of hybrid sols and hybrid fibers based on polymer/silica/（titania） were prepared by Sol-Gel and drawing method. The viscosity and spinnability of the hybrid sols were researched, the preparation, mechanism, microstructure, and property of the hybrid fibers was investigated systemically. The main investigations are compiled below.1. A series of hybrid sols of PVA/SiO₂, PAA/SiO₂, PAN/SiO₂, Sucrose/SiO₂, HPMC/SiO₂ and PVA/SiO₂/TiO₂ were prepared with tetraethorylsilane（TEOS） and tetrabutylorthotitanate（TBOT） as raw materials by Sol-Gel method respectively, and the change rules in viscosity versus aged time and spinnability of which were studied. The results showed that the hybrid sols were similar to SiO₂ sols in viscosity change rules, that is, three distinct change rate stages of viscosity were found in all the sols, the characteristic of which was changed slowly, quickly and drastically, respectively. Among these, in the second stage, polymers in the hybrid sols were almost linear molecules with proper molecular weight, and the hybrid sols were spinnable. The conclusion provided experimental foundations for the research on preparation of hybrid fibers.2. The hybrid mechanism, chemical structure and performance of PVA/SiO₂ hybrid fibers were researched. The results showed that PVA was linked with silica by Si-O-C bonds, which formed by the condensation between -OH groups of PVA and the hydrolysates of TEOS, the performance of resistance to heat and to water of PVA were improved greatly, the crystallinity of PVA was limited by SiO₂ networks, and the hybrid fibers were amorphous. The results will afford a new route of modification of PVA fibers.3. The hybrid mechanism, chemical structure and performance of PVA/SiO₂/TiO₂ hybrid fibers were studied. The results showed that spinnability of the hybrid sols were improved gradually with increasing of PVA content, and the hydrolysis time of the hybrid sols decreased markedly with increasing of TBOT content. In the interior of the hybrid fibers, the distribution of polymer and silica-titania was very homogeneous, the hybrid fibers had better resistance to heat and to water. The results are of important reference value for the preparation and modification of PVA/SiO₂ hybrid fibers.4. Continuous PAA/SiO₂ hybrid fibers were prepared by co-condensation reaction of TEOS and vinyl triethorylsilane（VTEOS） and Sol-Gel polymerization in situ processes. The hybrid mechanism, chemical structure and performance of PAA/SiO₂ hybrid fibers were researched. The results showed that the PAA/SiO₂ hybrid sol possesses well spinnability when its viscosity become 1400-3000mPa·s, the fibers had smooth appearance and their diameters were symmetric with well transparency, PAA were linked with SiO₂ networks by chemical bonds via coupling agents, and the hybrid fiber had good resistance to heat and to water. The results will suggest a new method for modification of water soluble polymers, especially, in heat resistance and water resistance.5. SiC fiber is a kind of excellent reinforcer for high performance composites, which has similar insulating constant and electric resistivity to glass fiber, similar strength and modulus to carbon fiber, and superior heat-oxidation resistance than carbon fiber and aromatic fiber. It has been widely used in high-technical areas as aviation, spaceflight and atomic energy industry. Continuous sucrose/SiO₂ hybrid fibers were prepared via Sol-Gel method by drawing, the feasibility of using it as a new candidate for the precursor of continuous SiC fiber was investigated preliminary. The results showed that sucrose was linked with silica by chemical bonds, in the interior of the fibers, homogeneous and amorphous networks were formed, and after the hybrid fibers had been heated to 800℃, co-existence of silica and micro-crystals of graphite were formed. Up till now, no reports about this research have been found. And this research will provide theoretical basis for new route of SiC fiber.6. Two kinds of hybrid sols of PAN/SiO₂ were prepared via sols blend and Sol-Gel in-situ polymerization respectively. The hybrid mechanism, the spinnability of the two kinds of hybrid sols and structures of the hybrid fibers prepared were researched. The results indicated that the chemical structures, the micro-morphology and the performance of the hybrid fibers were influenced greatly by their preparation method and conditions. Among these, CN groups hydrolyzed in the hybrid fibers via in-situ polymerization, and the interior structures of the hybrid fibers via in-situ polymerization were more homogeneous, the structure of PAN could be well kept via sols blend, and both of the hybrid fibers had better resistance to heat than pure PAN. The results will provide theoretical basis for the development of PAN fibers with good performance, especially, in heat-resistance.7. HPMC/SiO₂ hybrid sols were prepared via Sol-Gel method with TEOS and HPMC as raw materials and KH570 as coupling agent. In the basis of investigation on the spinnability of the hybrid sols and the structure and performance of HPMC/SiO₂ hybrid fibers, gradient HPMC/SiO₂ hybrid fibers were prepared with silica gel fiber and HPMC/SiO₂ hybrid sols as raw materials. The influences of viscosity on the micro-morphology and on formation of the gradient HPMC/SiO₂ hybrid fibers were investigated. The results indicated that the preparation of gradient hybrid fiber was greatly influenced by the viscosity of the hybrid sol, the gradient hybrid fiber could be well prepared when the viscosity of HPMC/SiO₂ hybrid sol was kept at about 6000mPa·s. The results provide a new idea for the preparation of gradient hybrid fiber.更多还原