本文選題：熱致性液晶聚芳酯　切入點(diǎn)：后固相聚合宏觀動(dòng)力學(xué)　出處：《武漢紡織大學(xué)》2013年碩士論文

【摘要】：作為一種具有微纖自增強(qiáng)作用的高分子材料，熱致性液晶聚芳酯（TLCP）具有高強(qiáng)度、高模量、低粘度、易加工等諸多優(yōu)良特性，逐漸在尖端科技領(lǐng)域得到廣泛應(yīng)用，并引起了科學(xué)界和工業(yè)界極大關(guān)注。雖然近年來我國對(duì)TLCP的產(chǎn)業(yè)化進(jìn)行了積極探索，但由于TLCP的關(guān)鍵生產(chǎn)技術(shù)全部被國外幾家公司壟斷，大部分重要的共聚單體和聚合技術(shù)依然依賴于進(jìn)口，所以TLCP的產(chǎn)業(yè)化仍存在著原料價(jià)格昂貴、生產(chǎn)成本及紡絲工藝過程難以控制、工業(yè)化設(shè)備簡(jiǎn)陋等問題，TLCP纖維的研究和開發(fā)仍處于實(shí)驗(yàn)發(fā)展階段。如何實(shí)現(xiàn)TLCP纖維的產(chǎn)業(yè)化生產(chǎn)，獲得具有自主知識(shí)產(chǎn)權(quán)的生產(chǎn)技術(shù)，以較低成本獲得高強(qiáng)高模、耐高溫的TLCP纖維材料，依然是我國面臨的主要問題，迫切需要進(jìn)一步進(jìn)行深入的研究與開發(fā)。 本課題主要對(duì)熱致性液晶聚芳酯初生纖維的后處理以及表面化學(xué)修飾進(jìn)行研究。首先研究了TLCP纖維的后固相聚合宏觀動(dòng)力學(xué)，以及熱處理工藝對(duì)纖維表面形態(tài)及熱學(xué)性能的影響；第二部分研究TLCP纖維表面的化學(xué)修飾；最后，還研究了不同捻度對(duì)TLCP纖維拉伸性能的影響。主要的研究成果如下： (1)在220℃熱處理溫度下，纖維熱處理前期強(qiáng)度增加顯著，后期變緩，而纖維失重率持續(xù)增加并達(dá)到平衡。熱處理過程的前期（9h前）纖維強(qiáng)度的增加主要受纖維結(jié)晶度提高以及分子量增長(zhǎng)的影響，后期強(qiáng)度的提高則主要是聚芳酯分子量的增加所致。熱處理溫度對(duì)纖維失重率影響顯著，熱處理溫度越高，TLCP纖維分子量增長(zhǎng)越快；250℃左右為熱處理的關(guān)鍵溫度，TLCP纖維的后處理生產(chǎn)工藝中，在避免粘連的前提下，應(yīng)盡可能提高熱處理溫度。TLCP纖維后固相聚合前期和后期的表觀活化能分別為94.4kJ/mol和38.4kJ/mol。 (2)TLCP初生纖維的分解溫度為509.7℃，初生纖維的熱分解溫度較高，耐熱性好。相同的熱處理溫度下，隨著時(shí)間的延長(zhǎng)，TLCP纖維的熔點(diǎn)不斷升高。熱處理時(shí)間相同的條件下，隨著熱處理溫度的升高，TLCP纖維的熔點(diǎn)也呈增長(zhǎng)趨勢(shì)，并且熱處理溫度對(duì)熔點(diǎn)的影響比熱處理時(shí)間要明顯的多。經(jīng)熱處理后TLCP纖維的表面變得粗糙、凹凸不平，這是由固相聚合時(shí)小分子副產(chǎn)物不斷從纖維表面脫出造成的。在280℃下熱處理9h時(shí)，纖維表面出現(xiàn)了原纖化，且受損嚴(yán)重，這是因?yàn)闊崽幚頊囟冗^高時(shí)，單纖維間出現(xiàn)了粘結(jié)現(xiàn)象。由此也可知若熱處理溫度過高，時(shí)間過長(zhǎng)，由于單纖維間出現(xiàn)粘結(jié)現(xiàn)象，纖維表面發(fā)生原纖化，且受損嚴(yán)重，將會(huì)嚴(yán)重降低纖維的強(qiáng)度。 (3)通過采用傅--克化學(xué)反應(yīng)修飾TLCP纖維的表面，可以有效的提高TLCP單纖維/環(huán)氧樹脂復(fù)合材料的界面剪切強(qiáng)度，相對(duì)于未修飾的纖維約提高了52%，表面化學(xué)修飾的最佳反應(yīng)時(shí)間為40min。此外，經(jīng)修飾的TLCP單纖維表面沒有明顯的刻蝕或受損現(xiàn)象，TLCP纖維的力學(xué)性能不會(huì)受到明顯影響。 (4)對(duì)于TLCP纖維束而言，加捻對(duì)其力學(xué)性能影響很大，斷裂強(qiáng)力隨捻度的增大呈先增大后減小趨勢(shì)；在最佳捻度時(shí)，其強(qiáng)度隨線密度的增加呈先增大后減小趨勢(shì)；當(dāng)線密度為52.50tex，捻度為130Tm時(shí)，TLCP纖維的強(qiáng)度最大9.14cN/dtex。對(duì)于TLCP單纖維而言，加一定的捻度再退捻能夠增強(qiáng)其斷裂強(qiáng)力，，當(dāng)超過捻度臨界值時(shí)，由于加捻會(huì)對(duì)纖維造成一定程度的破壞，斷裂強(qiáng)力反而減小。未加捻的纖維，斷裂強(qiáng)力也隨線密度增大而增大，當(dāng)線密度為1.394tex時(shí)，強(qiáng)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.

【學(xué)位授予單位】：武漢紡織大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TS102.5

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