热致性液晶聚芳酯初生纤维的热处理与表面修饰

发布时间：2018-03-31 23:29

本文选题：热致性液晶聚芳酯　切入点：后固相聚合宏观动力学　出处：《武汉纺织大学》2013年硕士论文

【摘要】：作为一种具有微纤自增强作用的高分子材料，热致性液晶聚芳酯（TLCP）具有高强度、高模量、低粘度、易加工等诸多优良特性，逐渐在尖端科技领域得到广泛应用，并引起了科学界和工业界极大关注。虽然近年来我国对TLCP的产业化进行了积极探索，但由于TLCP的关键生产技术全部被国外几家公司垄断，大部分重要的共聚单体和聚合技术依然依赖于进口，所以TLCP的产业化仍存在着原料价格昂贵、生产成本及纺丝工艺过程难以控制、工业化设备简陋等问题，TLCP纤维的研究和开发仍处于实验发展阶段。如何实现TLCP纤维的产业化生产，获得具有自主知识产权的生产技术，以较低成本获得高强高模、耐高温的TLCP纤维材料，依然是我国面临的主要问题，迫切需要进一步进行深入的研究与开发。本课题主要对热致性液晶聚芳酯初生纤维的后处理以及表面化学修饰进行研究。首先研究了TLCP纤维的后固相聚合宏观动力学，以及热处理工艺对纤维表面形态及热学性能的影响；第二部分研究TLCP纤维表面的化学修饰；最后，还研究了不同捻度对TLCP纤维拉伸性能的影响。主要的研究成果如下： (1)在220℃热处理温度下，纤维热处理前期强度增加显著，后期变缓，而纤维失重率持续增加并达到平衡。热处理过程的前期（9h前）纤维强度的增加主要受纤维结晶度提高以及分子量增长的影响，后期强度的提高则主要是聚芳酯分子量的增加所致。热处理温度对纤维失重率影响显著，热处理温度越高，TLCP纤维分子量增长越快；250℃左右为热处理的关键温度，TLCP纤维的后处理生产工艺中，在避免粘连的前提下，应尽可能提高热处理温度。TLCP纤维后固相聚合前期和后期的表观活化能分别为94.4kJ/mol和38.4kJ/mol。 (2)TLCP初生纤维的分解温度为509.7℃，初生纤维的热分解温度较高，耐热性好。相同的热处理温度下，随着时间的延长，TLCP纤维的熔点不断升高。热处理时间相同的条件下，随着热处理温度的升高，TLCP纤维的熔点也呈增长趋势，并且热处理温度对熔点的影响比热处理时间要明显的多。经热处理后TLCP纤维的表面变得粗糙、凹凸不平，这是由固相聚合时小分子副产物不断从纤维表面脱出造成的。在280℃下热处理9h时，纤维表面出现了原纤化，且受损严重，这是因为热处理温度过高时，单纤维间出现了粘结现象。由此也可知若热处理温度过高，时间过长，由于单纤维间出现粘结现象，纤维表面发生原纤化，且受损严重，将会严重降低纤维的强度。 (3)通过采用傅--克化学反应修饰TLCP纤维的表面，可以有效的提高TLCP单纤维/环氧树脂复合材料的界面剪切强度，相对于未修饰的纤维约提高了52%，表面化学修饰的最佳反应时间为40min。此外，经修饰的TLCP单纤维表面没有明显的刻蚀或受损现象，TLCP纤维的力学性能不会受到明显影响。 (4)对于TLCP纤维束而言，加捻对其力学性能影响很大，断裂强力随捻度的增大呈先增大后减小趋势；在最佳捻度时，其强度随线密度的增加呈先增大后减小趋势；当线密度为52.50tex，捻度为130Tm时，TLCP纤维的强度最大9.14cN/dtex。对于TLCP单纤维而言，加一定的捻度再退捻能够增强其断裂强力，，当超过捻度临界值时，由于加捻会对纤维造成一定程度的破坏，断裂强力反而减小。未加捻的纤维，断裂强力也随线密度增大而增大，当线密度为1.394tex时，强度最大11.3cN/dtex。
[Abstract]:As a kind of micro fiber self enhancement polymer materials, thermotropic liquid crystal polyarylate (TLCP) with high strength, high modulus, low viscosity, easy processing and other excellent properties, has been widely used in the field of cutting-edge technology, and caused great concern to the scientific community and industry in recent years. China's TLCP industry has actively explored, but because of TLCP's key production technologies are monopolized by a few foreign companies, most of the important monomers and polymerization technology is still dependent on imports, so the TLCP industry still has the high price of raw material, it is difficult to control the production cost and spinning process, industrial equipment simple and crude, the research and development of TLCP fiber is still in the experimental stage of development. How to realize the industrial production of TLCP fiber, with independent intellectual property rights of the production technology, at a low cost to obtain high strength Mould, high temperature resistant TLCP fiber material is still the main problem in China, and it is urgent to further study and develop it.
The main subject of TLCP protofibers postprocessing and surface chemical modification were studied. Firstly, after TLCP fiber solid phase polymerization kinetics, and the influence of heat treatment on fiber surface morphology and thermal properties; second surface chemical modification of TLCP fiber; finally, study effect of twisting on the tensile properties of TLCP fiber. The main results are as follows:
(1) 220 degrees in the heat treatment temperature, heat treatment of fiber early strength increased significantly, the late slow, while the fiber loss rate continued to increase and reached equilibrium. Pre heat treatment process (9h) to increase the strength of fiber is mainly affected by the crystallinity of fiber increased and the molecular weight growth effect, improve the late strength it is mainly polyarylate molecular weight due to the increase of heat treatment temperature. The weight loss rate of the fiber, the higher the temperature, the faster growth of the molecular weight of TLCP fiber; 250 degrees around the critical temperature of thermal treatment, TLCP fiber postprocessing in the production process, in the premise of avoiding adhesion, should do may improve the heat treatment temperature of.TLCP fiber after solid phase polymerization of early and late apparent activation energy were 94.4kJ/mol and 38.4kJ/mol.
(2) the decomposition temperature of TLCP nascent fiber is 509.7 DEG C, higher decomposition temperature of PAN fiber heat, good heat resistance. The same temperature, with the extension of time, the melting point of TLCP fiber increased. The heat treatment time under the same conditions, with the heat treatment temperature increases, the melting point of TLCP fiber also showed a rising trend, and the influence of heat treatment temperature on the melting point of the heat treatment time is more significant. The surface of TLCP fiber after heat treatment became rough and uneven, which is composed of solid phase polymerization of small molecular by-products from the surface of the fiber extrusion. In the heat treatment of 9h at 280 DEG C, fiber surface the fibrillation, and seriously damaged, this is because of the heat treatment temperature is too high, the single fiber between the bond phenomenon. So if the heat treatment temperature is too high, too long, because bond phenomenon of single fiber, fiber surface of the original Fiber, and the damage is serious, will seriously reduce the strength of the fiber.
(3) by using Friedel - Crafts reaction modification of TLCP fiber surface, can effectively improve the TLCP single fiber / epoxy resin composite material interface shear strength, compared to the unmodified fiber increased by about 52%, the optimal reaction time of surface chemical modification of 40min. in modified TLCP single fiber surface without obvious the etching or damage phenomenon, the mechanical properties of TLCP fiber will not be significantly affected.
(4) for the TLCP fiber bundle, twisting has great influence on its mechanical properties, tensile strength increases while the twist was first increased and then decreased; in the best twist, its strength was first increased and then decreased with the increase of the line density; when the line density is 52.50tex, twist is 130Tm, the tensile strength of TLCP fibers the maximum 9.14cN/dtex. for TLCP single fiber, with a twist and untwisting can enhance the tensile strength, twist when more than the critical value, the twisting will cause damage to the fiber, the breaking strength decreases. Untwisted fiber breaking strength with line density increases, when the line density is 1.394tex when the maximum intensity of 11.3cN/dtex.

【学位授予单位】：武汉纺织大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TS102.5

【参考文献】