【作者】 杨延华；

【导师】 姜振华；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2004， 博士

【摘要】 聚芳醚酮是一类半结晶性全芳香特种工程塑料。由于其优异的热稳定性和环境稳定性而广泛地应用于航空、航天、电子电工等高技术领域。因为一般聚醚醚酮的主链高度规整，结晶能力较强，其熔融温度较高，熔体粘度大，所以其加工中存在一定的困难。利用已有的高分子材料进行共混改性制备高性能材料不仅简捷有效，而且也相当经济。利用已有的液晶材料与PEEK原位复合，不仅能降低其熔体粘度，还能起到增强的作用。但是已有的PEEK与液晶的复合材料的相容性都很差，因此制备工程塑料与液晶高分子所组成的嵌段液晶共聚物用作二者共混的增容剂，从而制得高强度、高模量及加工性能优异的分子水平的原位复合材料，拓宽工程塑料的应用范围，将是嵌段液晶共聚物今后发展的主要方向。 通过分子设计，在聚酯液晶的主链上引入大体积侧基破坏了分子结构的规整性，使得分子链在晶体中的密堆砌效率降低，其熔点降到348℃，完全满足了其作为PEEK与TLCP原位复合材料中液晶分散相的条件。通过高温溶液缩聚反应得到了较高分子量（ηiv=0.92g/dl）的聚合物。FTIR、DSC、PLM和WAXD等结果表明，聚酯液晶为向列相液晶，具有典型的线链织构，PLM在390℃附近可观测到DSC测试中未出现的清亮点Ti。 <WP=122>合成了以HQ和DF单体羟基封端的三聚体。MS、FTIR的测试结果与预期结构相符。DSC测试结果表明其熔点为224.4℃。以三聚体、FH和TPC为单体采用与上相同的聚合方法制备了无规聚合物。DSC结果表明，样品呈现两个一级相转变，它们分别对应于结晶-液晶转变（282℃）和液晶-各向同性转变（331℃）。PLM和WAXD结果表明液晶相为向列相，并具有典型的向列相织构。以此液晶无规共聚物作为PEEK与TLCP共混体系的增容剂。合成了以BPA和DF为单体的羟基封端的聚芳醚酮齐聚物， GPC和DSC的结果分别得到=7797，分子量分布为1.2，Tg=121℃。以此活性端齐聚物与组成聚酯液晶的单体进行聚合。通过一步法合成了羟基封端的聚芳醚酮齐聚物与三种不同分子量聚酯的嵌段共聚物。以此液晶无规共聚物作为PEEK与TLCP共混体系的增容剂。FTIR和溶解实验结果表明，聚合物的结构为聚芳醚酮齐聚物和聚酯的嵌段共聚物，而不是而二者的共混物。DSC的结果表明，随着嵌段共聚物中TLCP段分子量的降低，熔点降低直至完全消失。所有嵌段共聚物都只有1个Tg且都出现在两个相应的齐聚物的Tg之间，说明无定形区二者有较好的相容性。PLM结果表明，共混物与TLCP有相似的液晶织构，但其在360℃处理有相分离发生，而所有嵌段共聚物的织构都相似，但它们与共混物和TLCP的不同。WAXD结果表明嵌段共聚物的衍射行为可以看作其相应齐聚物的衍射的叠加。SEM结果表明嵌段共聚物没有明显的相分离。对于原位复合材料，DSC和WAXD结果表明，随着TLCP的加入，共混体系中PEEK相的结晶度基本不变，TLCP的加入没有改变PEEK的结晶结构。由于TLCP的加入，共混物的熔体指数显著增加。共混物挤出的扭矩-时间曲线也表明，TLCP的加入使扭矩大幅度下降，从纯PEEK的60Nm降到85/15的<WP=123>25Nm，因而加入少量TLCP就能明显改善PEEK的成型加工性。以液晶嵌段共聚物做增容剂，增容后的共混体系的模压试片进行拉伸，性能测试表明，加入增容剂的两个体系，拉伸模量变化不大，拉伸强度均增加，说明加入增容剂后改善了共混物的界面粘结力。对以液晶嵌段共聚物做增容剂的共混体系的挤出样条的断面和剖面进行SEM测试。结果表明，TLCP分散相的尺寸随其含量的增加而增大，而相应对于加入增容剂的两个体系，增容后分散相的尺寸减小了一半；增容后两相的界面变得模糊，剖面图中微纤之间的界面也变得不清楚，这些都说明PEEK基体与TLCP共混物由于BCP的加入改善了二者的相容性。以液晶无规共聚物做增容剂，增容后共混体系的注射样条进行拉伸。试验结果表明，对于注射样条，随着TLCP的含量增加，拉伸模量和拉伸强度都增大，说明由于液晶分散相的取向对基体起到了增强作用。增容后的共混物的拉伸模量提高，拉伸强度基本不变，增容剂的含量变化对此体系的拉伸性能影响不大，断裂伸长率基本不变。形貌研究表明，液晶高分子原位复合材料内部可以明显地分为皮芯结构形貌。增容后的共混体系的两相界面变得模糊，分散相的尺寸变小。以上结果说明加入增容剂确实对共混体系起到了界面增容剂的作用。共混体系的结晶动力学研究表明，对于熔融态等温结晶过程来说，相同结晶温度下共混物95/5组分的t1/2都比纯PEEK小，TLCP为 15%组成的体系t1/2都大于PEEK的。随TLCP含量增加，结晶速率常数增加并越过一个最大值然后降低，这说明当液晶相参与PEEK结晶过程时，其对PEEK结晶过程中存在相反作用的竞争,即成核和稀释作用。在熔融态非等温结晶过程中，所有组成比的共混物的结晶活化能都低于比纯PEEK，说明添加了棒状链结构的TLCP组分促进了体系的成核作用。 <WP=124>更多还原

【Abstract】 PEEK is semicrystalline aromatic engineering plastics with balanced properties as excellent thermal stability widely applied in aerospace, automobile and electrical industries. The systems of PEEK blended with TLCP are considered to reduce the melt viscosity of PEEK and reinforce with the rigid TLCP as suggested by the concept of “in-situ composites to form a new kind of composites material. But the compatibilities between PEEK and TLCP are poor even in the case of in-situ fibrils. The common approach of compatibilization of polymer blends is to decrease the interfacial tension between the blend partners. Compatibilization by block or random copolymers containing segments chemically similar to the blend partners is the route used in this study.By introducing bulky pendent group onto the polyester, the regularity of chain structure was destroyed. Tm was reduced to348℃, which satisfied the processing conditions of in-situ composites. The polymer with higher molecular weight was obtained by high temperature solution condensation. The liquid crystallinity, texure of polyester were investigated by using a variety of experimental techniques including DSC, PLM and WAXD. It was found that polyester showed the typical nematic texture under Ti which was observed only by PLM.Hydroxy-terminated trimer was synthesized using HQ and DF. Random copolymer was synthesized using trimer, FH and TPC. DSC, PLM and WAXD <WP=126>results showed copolyester was nematic thermotropic liquid crystalline. The random copolymer was used to be compatibilizer of the blends.Multi block copolymer containing different lengths of thermotropic liquid crystalline polyesters (TLCP) and poly(aryl ether ketone) (PAEK) units were prepared for the first time by high temperature solution polymerization of TLCP monomers and hydroxy terminated PAEK containing BPA and DF. The chemical structure, thermal properties and liquid crystallinity of the block copolymers were investigated by FTIR, DSC and PLM respectively. A single glass transition revealed the two blocks had good compatibility. The TLCP segment length of the copolymers had a significant influence on their melting points. The block copolymer PAEK (7797)-b-TLCP (7691) and PAEK (7797)-b-TLCP (5497) showed typical nematic threaded texture which differed from the texture of polyester. When the molecular weight of TLCP reducing to 2965, liquid crystallinity of copolymer disappeared. The influence of synthetic conditions on its properties were investigated. For in-situ composites, DSC and WAXD results showed the crystallinities and crystal structure of PEEK in blends were not changed with the increment of TLCP content. The melt viscosity considerablely decreased after the addition of TLCP. The toque-time plot in the extruding process also showed the same results. The small amout TLCP improved the processability of PEEK distinctively.The compatibilizing effects of random and multi block copolyesters were studied. Tesile properties were measued for blends compression sheet containg multi block copolymer as compatibilizer. The tensile modulus of two blend systems were not changed, tensile strength increased after addition of block copolymer. SEM results of fracture surface of extrudates showed the dimension of TLCP dispersion phase became smaller and the interface became indistinct. These results showed the interface adhesion between two phases. <WP=127>Tesile properties were measued for blends molding speciemen containg random copolymer as compatibilizer. The results showed tensile properties of molding speciemen was better than the compression ones with the same TLCP content because the TLCP tended to align along the molding flow direction under appropiate processing conditions. The increment in the tensile modulus with increasing TLCP content led to improvements in tensile strength. After addition of compatibilizer to the blends, the tesile modulus increased, tensile strength and enlongation at break were not changed. These results showed the random copolymer served as compatibilizer. The crys更多还原