三元共聚液晶聚酯酰亚胺/PET共混体系结构与性能研究

通过熔融共混的方式,将实验室自行设计合成的三元共聚热致液晶聚酯酰亚胺(PPDI)与聚对苯二甲酸乙二酯(PET)进行共混,制备一系列不同液晶聚合物含量的共混体系.采用示差扫描量热仪(DSC)、广角X-射线衍射仪(WAXD)和动态力学性能分析仪(DMA)对共混体系的结构与性能进行表征.结果表明,共混体系中两组份之间具有良好...     

酸酐化聚砜对聚砜/液晶聚合物共混物的界面增容作用

首先合成了马来酸酐接枝改性聚砜.改性后聚砜材料的表面张力增大,其中的极性分量增加明显,并以此增容聚砜/液晶聚合物(VectraB950)为原位复合体系,研究了增容前后共混物的加工流变行为和界面性能.结果表明,酸酐化聚砜可增强聚砜与液晶聚合物之间的界面作用,引起共混物加工粘度的上升;漫反射FTIR研究表明,增容后共混体系中的特殊相互作用增大;XPS和PLM的研究表明,在熔融加工过程中改性聚砜与液晶聚合物组分之间存在一定的界面化学反应,并生成了接枝共聚物.共混物相容性的提高应归结于相间化学反应与物理作用共同作用的结果.     

混合方式对增容尼龙-6/聚苯醚体系的影响

研究了三种混合方式对于Nylon 6 PPO TPEg共混体系的影响 .混合是在双螺杆挤出机上进行的 .即(A)尼龙 6、聚苯醚和TPEg的混合物直接进行熔融挤出 ;(B)尼龙 6与TPEg的混合物预挤出 ,然后与聚苯醚熔融挤出 ;(C)聚苯醚和TPEg的混合物预挤出 ,然后与尼龙 6熔融挤出 .实验结果表明 ,混合方式不仅会影响共混物的形貌结构 ,而且会影响复合材料的最终性能 ,如力学性能、热性能和尺寸稳定性 .采用混合方式C所得的尼龙 6 聚苯醚复合材料的抗冲击强度高于用混合方式A和B所制备的复合材料 .这是因为聚苯醚和TPEg预共混时 ,聚苯醚上的OH基团和TPEg上的一部分马来酸酐发生化学反应 .然后预混物和尼龙 6熔融挤出时 ,剩下的马来酸酐再与尼龙分子上的NH2 基团反应 .这样就会形成一个好的界面层 ,它使复合材料的抗冲击强度大幅度提高 ,材料达到了超高韧性     

一种带肉桂酸酯基的聚酰亚胺液晶光定向材料研究

利用双酚A二胺单体(BISDA)与4,4-′(六氟异丙基)-双邻苯二甲酸酐(6FDA)的缩聚反应,制备了含有侧羟基的先驱聚合物PI-OH.通过PI-OH与肉桂酰氯的官能化反应,得到接有肉桂酸酯感光侧基的双酚A型聚酰亚胺PI-CI.用红外光谱(FTIR)、氢核磁共振(1H-NMR)分析、热分析(DSC)等方法表征了上述聚合物的结构和热性能.利用紫外-可见光谱(UV-Vis)对PI-CI的感光性能进行了研究.在线偏振紫外光辐照下,上述聚合物膜表现出二色向性.二向色性的强弱随光照能量的变化存在最大值.经线性偏振紫外光(LPUV)辐射后的PI-CI薄膜能诱导液晶盒中液晶分子发生均匀的定向沿面排列.上述实验表明,该聚酰亚胺是一类具有优良性能的潜在液晶光定向材料.     

由脂肪族二酰胺二醇合成聚酯酰胺及表征

利用脂肪族二元酸酯与乙醇胺反应容易获得的对称二酰胺二醇,经缩聚合成聚酯酰胺预聚体,并针对端羧基和端羟基同时扩链来提高分子量,获得可生物降解的聚酯酰胺.首先将N,N′-二(2-羟乙基)草酰胺(HEOA)或N,N′-二(2-羟乙基)己二酰胺(HEHA)与己二酸和丁二醇缩聚,制备同时带有端羧基及端羟基的脂肪族聚酯酰胺预聚体,通过1,4-双(2-噁唑啉)苯及己二酰双己内酰胺混合扩链剂扩链,获得高分子量脂肪族聚酯酰胺,并通过红外、1H-NMR、DSC及TGA对其结构和热性能进行了表征.结果表明,预聚体在制备过程发生了一定的酯-酰胺交换反应;扩链后聚合物的熔点、熔融焓和热稳定性有所下降;但热稳定性仍接近或略高于聚己二酸丁二酯.     

非异氰酸酯法合成脂肪族热塑性聚氨酯及其性能研究

利用二氨酯二醇氨酯交换的非异氰酸酯法合成高分子量的脂肪族热塑性聚氨酯.以己二氨酯二醇(BHCH)的自缩聚,合成了Mn为29200的聚己二氨酯(PBHCH),其熔点为154.31℃,拉伸强度为28.41MPa,断裂伸长率为3.91%;利用己内酰胺与乙醇胺的共聚合成了同时带有端氨基及端羟基的尼龙-6低聚物,并与己内酯反应转化为端羟基尼龙-6低聚体,经与BHCH在170℃常压反应4 h及180℃减压反应6.5 h,获得了数种带有短尼龙-6段的酰胺型聚氨酯(s-PAUs),红外、核磁、GPC、广角X-射线衍射、DSC、TGA和力学性能表征表明,此类s-PAUs的Mn在26000以上、熔点在123.85~170.89℃之间、拉伸强度达28.53 MPa、断裂伸长率达299.0%.     

基于原子转移自由基聚合技术的偶氮苯星形液晶聚合物的合成与表征

利用原子转移自由基聚合(ATRP)技术合成了含不同端基取代基的偶氮苯三臂星形侧链液晶聚合物. 均苯三酚与2-溴异丁酰溴通过酯化反应制备三官能团引发剂, 引发偶氮苯单体6-[4-(4-甲氧基苯基偶氮)酚氧基]己基甲基丙烯酸酯(MMAzo)或6-[4-(4-乙氧基苯基偶氮)酚氧基]己基甲基丙烯酸酯(EMAzo)的ATRP反应. 利用核磁共振氢谱(¹H NMR)、凝胶色谱(GPC)、差示扫描量热法(DSC)和偏光显微镜(POM)等手段对星形聚合物进行表征. 星形聚合物的液晶性与相应均聚物相似, 但偶氮苯端基取代基的不同导致星形聚合物的液晶性差别显著. 在紫外/可见光照射下星形聚合物呈现明显的异构化转变.     

热致性液晶聚合物的种类对液晶/环氧树脂共混物固化反应动力学的影响

采用等温DSC固化动力学研究方法,用自催化动力学模型对反应型热致性液晶聚合物/环氧树脂共混体系进行研究.结果表明,EP/DDS未改性体系,在α＜40%范围遵循自催化反应机理;EP/DDS/LCPU共混改性体系,在α＜60%范围遵循自催化动力学反应机理,而且自催化反应速率和非催化反应速率均大于未改性体系,表明反应型热致性液晶聚合物的活性基团对固化反应起到了催化促进作用;EP/DDS/PHBHT共混改性体系能够较好符合n级反应机理,固化反应的活化能较大,说明没有反应基团的液晶聚合物(PHBHT)对固化反应无明显促进作用.     

PLA/PBS/DCP反应共混体系的结晶行为研究

通过熔融共混法制备了一系列聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)物理共混试样及PLA/PBS/过氧化二异丙苯(DCP)反应共混试样,采用示差扫描量热分析(DSC)法研究了物理共混试样结晶行为及反应共混试样的特殊结晶行为.结果发现,PLA与PBS的物理共混并未改善PLA的结晶性,而PLA/PBS/DCP反应共混时生成的交联/支化结构可起到异相成核作用,从而明显改善了反应共混体系的结晶性能,且随着DCP含量的增加,共混体系中两相结晶行为出现交替变化.     

新型含磺酸基Schiff碱型液晶化合物的合成与表征

对羟基苯甲醛与对氨基苯磺酸经缩合反应制得Schiff碱化合物(1).对羟基苯甲酸经醚化、酯化、酰氯化后再与1完成酯化反应合成了新型含磺酸基Schiff碱型液晶化合物--[4-(对磺酸苯亚胺基)甲苯基]-4-(ω-甲基丙烯酸乙氧基酯)-苯甲酸酯(5),其结构经1H NMR和IR表征.偏光显微镜与DSC检测结果表明,5具有近晶A型液晶特性,液晶变化范围189.45 ℃～267.65 ℃.     

Investigation into the morphology,crystallization and melting behaviour of nylon 6,6/LCP blends

Journal of Thermal Analysis and Calorimetry - The morphology, isothermal crystallization and melting behaviour of melt-mixed nylon 6,6/Vectra A950 liquid crystalline polymer (LCP) blends were...     

Rheological behavior and prediction for blending conditions of a thermotropic liquid crystalline polyester with nylon

The dynamic rheological behavior of a liquid crystalline polymer (LCP), Vectra™ A, and nylons was investigated. The viscosities of nylon 66 and nylon 6 decrease slowly with an increase in temperature, while the viscosity of Vectra A drops dramatically at 280 °C, but remains slightly changed above 300 °C. At constant frequency and above 300 °C, the mean value of the activation energy of Vectra A is about 87.0 kJ/mole, but jumps to a much higher value of about 407.0 kJ/mole if the melt temperature is below 300 °C. The activation energy of Vectra A above 300 °C is lower than nylon 66, which shows that the viscosity of nylon 66 has a greater temperature dependence than Vectra A. The viscosity ratio of Vectra A to Nylon 66 is less than 1 at temperatures higher than 290 °C, which indicates that Vectra A can form the fibrils in the nylon 66 matrix and reinforce nylon 66 when blending them above this temperature. Experimental data confirm our prediction. Copyright © 2000 John Wiley & Sons, Ltd.     

Mutual influence of the morphology and capillary rheological properties in nylon/glass‐fiber/liquid‐crystalline‐polymer blends

Nylon‐6/glass‐fiber (GF)/liquid‐crystalline‐polymer (LCP) ternary blends with different viscosity ratios were prepared with three kinds of nylon‐6 with different viscosities as matrices. The rheological behaviors of these blends were characterized with capillary rheometry. The morphology was observed with scanning electron microscopy and polarizing optical microscopy. This study showed that although LCP did not fibrillate in binary nylon‐6/LCP blends, LCP fibrillated to a large aspect ratio in some ternary blends after GF was added. The addition of 5 wt % LCP significantly reduced the melt viscosity of nylon‐6/GF blends to such an extent that some nylon‐6/GF/LCP blends had quite low viscosities, not only lower than those of neat resins and nylon‐6/GF blends but also lower than those of corresponding nylon‐6/LCP blends. The mutual influence of the morphology and rheological properties was examined. The great reduction of the melt viscosity was considered the result of LCP fibrillation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1619–1627, 2004     

热处理对尼龙6及其与聚酰胺嵌段共聚物共混体系晶体熔融行为和结晶结构的影响

采用溶液共混-共沉淀的办法获得尼龙6及聚酰胺嵌段共聚物/尼龙6共混体系粉末,样品在260℃下熔融之后经程序降温的方法得到非淬火样品,然后分别在190℃下高温退火不同时间(0~48 h),采用示差扫描量热仪(DSC)、广角X射线衍射仪(WAXD)、偏光显微镜(POM)等表征手段研究热处理对体系晶体熔融行为和结晶结构的影响.结果表明,(1)在相同的热历史条件下,嵌段共聚物的存在影响了尼龙6的结晶行为及结晶结构;(2)退火处理对两种样品有着不同的影响,对于尼龙6体系,退火处理促进了非晶相向晶相的转变,大大提高样品的结晶完善程度和结晶度;对于共混体系,退火处理同样促进了非晶相向晶相的转变,同时形成新的α型和γ型结晶,体系的结晶完善程度明显提高,退火48 h后,结晶度比原始样品提高约84%.     

Improvement of the properties of polyarylate reinforced with liquid crystalline polymers

Blends of polyarylate of bisphenol A, PAr, with two commercial main chain liquid crystalline polymers, Vectra A950 and Vectra B950, are studied. From dynamic viscoelastic measurements it is deduced that both systems (PAr/Vectra A950 and PAr/Vectra B950) are immiscible and scanning electron microscopy (SEM) micrographs show the presence of spherical domains of the liquid crystalline polymer when PAr constitutes the matrix. Extrusion capillary measurements reveal that, under conditions of temperature and shear rate similar to those of processing, the viscosity is reduced to approximately 10% of its value when the content of liquid crystalline polymer is only 20%. This great improvement of the rheological properties is observed in both PAr/Vectra A950 and PAr/Vectra B950 blends. The effect of draw ratio on Young's modulus for different compositions is also analyzed, pointing out the reinforcing action of both liquid crystalline polymers on polyarylate: for instance, 20% of Vectra B950 in the blend gives rise to a 700% increase of the modulus of fibres prepared at a draw ratio of 50. SEM of the extrudates reveals that the spherical domains are elongated at the entrance of the capillary giving rise to a microfibrillar morphology which is related to the excellent rheological and mechanical properties of the blends.     

全芳香族热致液晶聚合物与热塑性树脂聚砜的原位复合材料

用自制的四种全芳香族热致液晶聚合物ＢＰ ＬＣＰ、ＢＰＭ ＬＣＰ、ＢＰＡ ＬＣＰ、ＢＰＳ ＬＣＰ与热塑性树脂聚砜（ＰＳＦ）熔融共混，制备了一系列原位复合材料．研究了所得材料的微观形态、热性能、力学性能等，结果显示：四种液晶聚合物中，ＢＰ ＬＣＰ，ＢＰＳ ＬＣＰ在所用加工条件下可在ＰＳＦ中取向成纤，而且这两种共混物断面上存在皮 核效应；ＢＰＭ ＬＣＰ和ＢＰＡ ＬＣＰ未成纤，均以球状存在于ＰＳＦ中．这四种液晶聚合物与ＰＳＦ的相容性较差，各共混物的Ｔｇ均分别接近于二纯组分的Ｔｇ值，ＳＥＭ照片上明显的相界面也能说明以上问题．液晶聚合物对ＰＳＦ有增强作用，但增强效果不很显著，这可能是二者相容性较差所致     

THE EFFECT OF BLENDING SEQUENCE ON PHASE MORPHOLOGY OF NYLON 6/ABS/SMA BLENDS

The preparation process-dependent phase morphology of blends composed of nylon 6 and acrylonitrile-butadiene- styrene(ABS)over a composition range of 30-70 wt% using a styrene-maleic anhydride(SMA)copolymer as the compatibilizing agent with a constant content(5phr)was investigated.The results of the scanning electron microscope (SEM)observation revealed that compared with the binary blends of nylon 6 and ABS,the existence of SMA caused a composition shift of phase inversion to a higher weight fraction of...     

界面相互作用对尼龙6／聚乙烯共混物形态结构和流变行为的影响

利用扫描电子显微镜和动态力学分析仪研究了马来酸酐熔融接枝聚乙烯（ＰＥ－ｇ－ＭＡ）对尼龙６／聚乙烯（ＰＡ６／ＰＥ）共混物形态结构和动态力学行为的影响．结果表明，ＰＥ－ｇ－ＭＡ使ＰＡ６／ＰＥ共混物中ＰＡｅ的玻璃化转变峰向低温例偏移，这主要归因于ＰＥ－ｇ－ＭＡ改善了ＰＡ６和ＰＥ二者的相容性；但随着ＰＥ分散相中ＰＥ－ｇ－ＭＡ所占比重的增加，ＰＥ－ｇ－ＭＡ与ＰＡ６之间界面化学键合密度增大，使得ＰＡ６的玻璃化转变温度反而提高．同时，利用平行板流交仪研究了ＰＥ－ｇ－ＭＡ对ＰＡ６／ＰＥ共混物熔体流变行为的影响．ＰＥ－ｇ－ＭＡ使共混物熔体粘度和动态储能模量增大，这应归因于ＰＡ６／ＰＥ－ｇ－ＭＡ之间在熔融共混过程中的界面化学键合．     

尼龙1212/尼龙6共混体系的非等温结晶行为

用DSC研究了尼龙 12 12 ,尼龙 6及其共混体系的非等温结晶行为 .结果表明 ,加工历史对尼龙的结晶和熔融行为影响很大 .经双螺杆挤出机挤出的尼龙 12 12和尼龙 6 ,由于应力诱导分子链取向 ,其结晶温度都有不同程度的提高 ,且表现出多重熔融现象 .在共混体系中 ,尼龙 12 12分子在共混物的界面上异相成核结晶 ,提高了其结晶温度 ,但酸酐化SEBS的加入抑制了分子链的运动又使其结晶温度降低 .共混体系降低了尼龙12 12的熔融温度 ,并使得其高熔点的熔融峰逐渐消失 ;而尼龙 6的熔融行为基本上没有变化 .     

Reactive blending of poly(ethylene 2,6-naphthalate) and Vectra A

In situ composites based on poly(ethylene 2,6-naphthalate) (PEN) and a thermotropic liquid crystal polymer (Vectra A950) were prepared by melt blending under different processing conditions. Thermal behaviour, mechanical and physical properties and morphology of the blends were investigated. The DSC analysis indicates that, as expected, Vectra enhances the crystallization process of PEN. Moreover, mechanical and thermal tests evidence the significant role of 20 wt% Vectra on increasing the material performances; tensile properties, coupled with SEM, show that strength and modulus of PEN are significantly improved when Vectra domains are long and continuous fibrils. The overall results can be attributed to the compatibilisation of the system induced by the mixing conditions that affect the extent of transreactions occurring in the melt. To deepen this aspect, the soluble and insoluble fractions in a PEN solvent were isolated and thoroughly characterized: both the fractions contain PEN/Vectra copolymers. The results underline the potentiality of the PEN/Vectra system for different high-performance applications requiring superior strength and modulus, heat stability or barrier properties.