聚醚砜/热致液晶高分子原位复合材料的结构与性能

<正> 国际上关于热致液晶高分子(TLCP)原位复合材料的报道始于80年代,原位复合增强材料的增强形式不是在树脂加工前实际存在的,而是在加工过程中形成的,原位复合的方法是将TLCP掺入树脂基体,使其在特定的流场和应力场作用下,诱导取向并形成徽     

聚芳醚酮与液晶聚酯多嵌段共聚物的合成表征

近年来,以热塑性聚合物为基体,热致液晶聚合物(TLCP)作为增强剂的高分子原位复合材料由于其具有优异的机械性能和优良的成型加工性能,已引起各国工作者的普遍关注和极大兴趣．然而由于自聚集和相分离作用的影响,大部分液晶聚合物与通常的热塑性聚合物基体基本不相容或弱相容,这对于提高原位复合材料的力学性能不利．     

MWCNTs/PVA-co-PE纳米纤维膜导电性能的研究

通过原位自组装法制备MWCNTs/PVA-co-PE复合材料,将此复合材料与纤维素酯共混后,利用热塑性聚合物熔融共混相分离法制备了MWCNTs/PVA-co-PE复合纳米纤维。通过SEM和TEM分析表征了MWCNTs/PVA-co-PE复合纳米纤维的形态、结构以及多壁碳纳米管在纳米纤维中的分布状态;研究了多壁碳纳米管添加量对MWCNTs/PVA-co-PE复合纳米纤维导电性能的影响。结果表明,当多壁碳纳米管的添加量大于6%时,MWCNTs/PVA-co-PE复合材料的表面电阻会显著下降;提高MWCNTs的添加量会使MWCNTs/PVA-co-PE复合纳米纤维的表面电阻稍微下降,但是效果不大,这可能是由于MWCNTs在纳米纤维内部不能形成良好的导电通道。     

热塑性树脂的增强：从原位复合材料到原位混杂复合材料

综述了两类增强的热塑性树脂的基本方面。一类是由原位形成的热致液晶聚合物微纤增强的原位复合材料。从实验上研究了获得有效增强效果的两个关键因素；致热液晶聚合物的基体树脂中的成纤，以及在液晶聚合物与基体树脂不相容共混物中的增容作用。另一类是由作者发明的原位混杂复合材料，这一类材料是用直径在两个数量级上的纤维和原位形成的微纤混杂增强的。     

以热致液晶聚合物微纤增强的原位复合材料

用４种热致液晶聚合物分别与聚丙烯,聚对苯二甲酸丁二酯,聚碳酸酯,聚醚砜和聚砜搭配,在各聚合物对的“加工窗口“温度范围内熔融共混并挤塑得到６种共混物。藉流变仪,扫描电子显微镜,偏光显微镜,动态力学谱仪等重点研究了原位复合材料中微纤结构的形成,组分特性,熔体粘度,挤塑温度和浓度等因素对各向异性结构形成的贡献,以及液晶聚合物对聚合物结晶的诱导作用和两相间的相互作用。     

聚丙烯/尼龙6/聚丙烯接枝物原位复合材料的形态与力学性能——共混过程对体系的影响

聚丙烯／尼龙６／聚丙烯接枝物原位复合材料的形态与力学性能———共混过程对体系的影响黎学东陈鸣才黄玉惠丛广民（中国科学院广州化学研究所广州５１０６５０）关键词原位复合材料，成纤，相容性原位成纤复合材料是指在加工过程中增强相在基体中就地形成微纤，不...     

热致液晶共聚酯酰胺／PET共混物的流变性能和原位增强特性

采用Ｉｎｓｔｒｏｎ３２１１型毛细管流变仪研究了ＰＥＡ／ＰＥＴ共混物的流变性能，据此探讨共混物熔体的可纺性，讨论了共混物配比与复合纤维力学性能的关系，并且偏光显微镜，扫描电镜研究纤维的结构。结果表明，共混物的表观粘度低于ＰＥＴ的粘度，当ＰＥＡ为１０％，共混物的表观粘度达到最小值；且ＰＥＡ含量低于１０％时，共混物的可纺性即，表现出良好的原位增强效果。     

水辅助加工法制备聚丙撑碳酸酯/淀粉共混物

分别采用普通熔融共混法和水辅助加工法,制备了具有不同共混形态的聚丙撑碳酸酯(PPC)/淀粉共混物,并研究了淀粉分散形态对共混物的玻璃化转变温度(Tg)、流变以及力学性能的影响。研究结果表明,采用普通熔融共混法时,淀粉未发生糊化,并以原颗粒状分散于基体中;而采用水辅助加工法时,淀粉发生糊化,并在挤出过程中原位形成纤维结构。当淀粉以纤维形式分散于PPC基体中时,其与PPC间的界面接触面积显著增加,二者的相互作用增强,PPC/淀粉共混物的Tg、储能模量以及复合黏度显著提高。力学性能测试结果表明,当淀粉质量分数为30%,采用水辅助加工法制备的PPC/淀粉共混物的拉伸模量相比于纯PPC提高了67.7%。     

聚合物二元体系动态力学性能的估算

动态热机械分析是多相聚合物体系的一个重要研究手段.分析动态力学性能可以研究共混高聚物的相容性、复合材料的界面特性以及高分子运动机理等.本文综述了聚合物二元体系,即填充、纤维增强、共混体系动态力学性能的估算方法.在填充体系中,分别概述有无界面作用两种情况,当存在界面作用时,界面作用越强,模量越大,阻尼越小.对纤维增强体系,讨论了玻璃纤维有无取向的情况下模量和阻尼的估算.特别对于聚合物二元共混体系,分"海-岛"结构和双连续相两种情况,分别讨论了模量与阻尼的估算.     

环氧树脂/玻璃纤维复合界面的电子能谱化学分析

采用化学分析用电子能谱技术分别对机械剥离后的玻璃纤维布和短切玻璃纤维增强环氧树脂试样的玻璃纤维面作了对比分析,发现树脂残留物表面上有富裕的环氧基,证明剥离不是发生在树脂／玻璃纤维（布）粘结界面上,而是发生在粘结界面附近的树脂层里;环氧树脂／玻璃纤维布界面比环氧树脂／短切玻璃纤维界面有更强的界面增强效应。     

热致液晶聚酯共混物与复合材料研究

评述了热致液晶聚酯的共混物与复合材料的研究新进展,揭示了热行为与相容性、流变性与加工性以及形态结构与多种性能之间的内在联系,展望了应用于高强高模纤维与塑料、低热膨光纤涂层及低透气包装膜等高性能材料的前景.     

Rheology,morphology and tensile properties of thermotropic liquid crystalline polymer/polypropylene in‐situ composites

Blends of various grades of polypropylene (PP) with a thermotropic liquid crystalline polymer (TLCP), namely a copolymer of p‐benzoic acid and ethylene terephthalate (60/40 mole ratio) were prepared as extruded films. A thermoplastic elastomer styrene (ethylene‐butylene) styrene (SEBS) was used as a compatibilizer. Melt viscosities of all specimens were measured using a plate‐and‐plate rheometer with oscillating mode in the shear rate region of 1 ‐ 200 rad/s. Addition of SEBS compatibilizer resulted in an increase of the blend viscosity. Observation of the blend morphology revealed an improvement of TLCP dispersion. The TLCP fiber aspect ratio (length to diameter) in the extruded film also increased after addition of SEBS. As a result, the film modulus in extrusion direction was enhanced. The tensile strength of the film specimen was also increased due to an improvement of interfacial adhesion.     

A rheological and morphological study of a copolyester liquid crystal/polypropylene blend system

The effects of composition and shear rate on the rheology and morphology of blends of LC–3000, a thermotropic liquid crystalline polymer consisting of 60/40 of hydroxybenzoic acid and poly(ethylene terephthalate), with polypropylene were studied. It was found that the rheological properties depend in a complex manner on composition and applied shear. Both positive and negative deviations from the log-additivity rule were observed at low shear rates. Significant viscosity reduction was measured when the dispersed phase was a nematic TLCP. The accompanying microstructural transitions were characterized a posteriori, and it was found that the state of dispersion of the TLCP phase also influences the viscosity reduction phenomenon. A nematic, fibrillar TLCP phase shows a viscosity reduction of the order of fourfold with respect to the viscosity of the matrix. Another important finding was that the stability of these fibers would not be expected from work on other non-TLCP-containing immiscible blends. This suggests that the unique rheology of the TLCP minor phase is relevant to the formation of stable fibers. © 1996 John Wiley & Sons, Inc.     

Mechanical Properties and Dynamic Mechanical Analysis of Thermoplastic-Natural Fiber/Glass Reinforced Composites

The mechanical properties and dynamic behavior of thermoplastic composites based on polypropylene/glass fibers and polypropylene/natural fibers (i.e. kenaf, hemp, flax) are presented. A survey is given on some aspects, crucial for the use of these composites in structural and non-structural components such as their vibration-damping response, in relation to the composite compaction level and the manufacturing procedure. In order to investigate a wide vibration frequency range, including acoustic frequencies, different testing techniques, both with forced and free vibrations, were applied. A comparison between natural fiber and glass fiber reinforced laminates is presented. Compaction levels, allowing to obtain the best compromise between mechanical performance and damping response, are investigated.     

Investigations on the interactions between Li-TFSI and glass fibers in the ternary PP/GF/Li-TFSI composites

The polypropylene/glass fiber(PP/GF) composites with excellent antistatic performance and improved mechanical properties have been reported by incorporation of a very small amount of the organic salt, lithium bis(trifluoromethanesulfonyl)imide(Li-TFSI), into the PP/GF composites. It was considered that GF could play the role as the pathways for the movements of ions in the ternary composites. In this work, the interactions between Li-TFSI and glass fiber and the effects of such interactions on the physical properties of the composites have been systematically investigated. Three types of glass fibers with different ―OH group concentrations have been prepared in order to compare the interactions between GF and Li-TFSI. It was found that the ―OH group concentrations on the surface of glass fiber have significant effects on interactions between glass fibers and Li-TFSI. Such interactions are crucial for both the antistatic and mechanical performances of the final PP/GF/Li-TFSI composites. The investigation indicated that the GF with high ―OH group concentrations confined the movement of TFSI-, which decreased the antistatic properties of PP/GF/Li-TFSI composites. On the other hand, the GF with low ―OH group concentrations inhibited the absorption of Li-TFSI onto the GF, which also hindered the formation of Li-TFSI conductive pathway. The best antistatic performance of the ternary composites can be achieved at the intermediate ―OH concentrations on the GF.     

The comparison of relaxation events with spectroscopic properties of polymer composites with fibrillar dopings on the basis of low density polyethylene and polypropylene

In this study, the mechanical and electrical degradation properties of the composites of polypropylene (PP)+PP fibers, low-density polyethylene(LDPE)+PP fiber, and PP+fiber glass have been investigated and the validity of Zhourkov's thermofluctuation theory has been shown.     

废旧聚丙烯塑料回收利用的研究

聚丙烯制品在加工和使用过程中受光、热和氧的作用，产生光氧降解，从而使聚丙烯的物理、化学、机械等性能明显下降。本文通过添加新聚丙烯、乙丙橡胶、玻璃纤维与其进行共混，从而提高废聚丙烯的物理、化学、机械等性能，达到回收利用之目的。