高性能/高温聚合物(Ⅴ)反应性端基聚酰亚胺齐聚物及固化技术

综述了高性能/高温聚合物中的反应性端基齐聚物与热固性聚酰亚胺及其固化技术,其包括PMR-15、PMR-Ⅱ,端乙炔基聚酰亚胺、苯乙炔封端聚酰亚胺、Thermcon聚酰亚胺、其它热固性聚酰亚胺、苯并环丁烯端基聚酰亚胺,对其化学结构与性能的关系也进行了讨论。     

热固性聚酰亚胺的研究进展及其在印制电路板上的应用

热固性聚酰亚胺作为一类先进的基体树脂,在航空航天、印制电路板、高温绝缘材料等领域的应用不断扩大.相对于热塑性聚酰亚胺来说,热固性聚酰亚胺具有更好的可加工性能.而且,其加工窗口温度可通过变换不同反应性端基来实现.若选用合适的反应性端基,其在固化时无小分子挥发物放出.对热固性聚酰亚胺的研究现状分类作了综述,对降冰片烯、烯丙基降冰片烯、乙炔基、苯乙炔基、马来酰亚胺、苯基马来酰亚胺、苯并环丁烯等封端型热固性聚酰亚胺的研究进展进行了重点阐述,对它们结构与性能的关系、齐聚物的固化机理等进行了讨论,并对其在印制电路板上的应用和发展趋势作了概述和展望.     

苯乙炔苯酐型热固性聚酰亚胺的合成与表征

热固性聚酰亚胺是一类先进复合材料基体树脂,相对于热塑性聚酰亚胺具有更高的耐温等级和更好的加工性能,因而作为树脂基复合材料和黏结剂在航空航天等领域应用更为成功。4-苯乙炔苯酐及其衍生物兼具有聚酰亚胺所必需的黏结性、耐热性和机械强度,其利用价值极高,是航空航天用复合材料母体树脂的原料。     

热固性聚酰亚胺展望

本文评述了降冰片烯、乙炔、苯并环丁烷和马来酸酐封端的热固性聚酰亚胺的发展现状,并介绍了他们的发展趋势及应用前景.     

苯乙炔苯酐型热固性聚酰亚胺的合成与表征

以4-溴代苯酐为原料,二(三苯基膦)二氯化钯为催化剂,三苯基膦为配体,三乙胺为反应副产物吸收剂,在非质子性溶剂N,N-二甲基乙酰胺中与苯乙炔进行交叉偶联反应,制得4-苯乙炔苯酐,然后以其为封端剂制备了聚酰亚胺;对苯乙炔苯酐及其封端的聚酰亚胺进行了结构及性能的表征.结果表明,用苯乙炔苯酐封端的聚酰亚胺,交联后薄膜的最高拉伸强度和最大断裂伸长率分别为112.9 MPa和20.7%,聚酰亚胺薄膜的玻璃化转变温度和5%的热分解温度分别为313.1℃和550.0℃.     

含苯乙炔基的酰亚胺低聚物及其复合材料研究

制备了一种侧链含苯乙炔基的二胺单体2,4-二氨基[4'-(4-苯乙炔基酞酰亚胺基)]二苯醚(DPED),并合成了基于2,3',3,4'-联苯四甲酸二酐(3,4'-BPDA)和DPED的酰亚胺低聚物,通过热重分析,示差扫描量热分析,1H NMR,熔点和力学性能测试研究了DPED的结构及固化行为,低聚物和其固化物及其碳纤维增强复合材料的性能。结果表明:在主链化学结构相同的情况下,将DPED引入到分子质量约为5 000 g/mol的低聚物中,低聚物熔体粘度会有显著降低,侧链苯乙炔基含量越高,其熔体粘度越低,含侧链苯乙炔基的树脂基复合材料的压缩强度高于不含侧链苯乙炔基复合材料,其值分别为570 MPa和415 MPa。     

高性能/高温聚合物的设计、性能和应用进展(Ⅵ)其他反应性端基及链内乙炔基齐聚物及其固化

综述了诸如星形支化苯乙炔封端苯并喹喔啉齐聚物、苯乙炔端基芳醚聚合物、烯丙基聚苯醚、含庞大芴基的聚芳醚等反应性端基芳醚齐聚物,主链含乙炔单元的聚(酰胺-酰亚胺)、马来酰亚胺端基聚合物,热塑性塑料增韧双马来酰亚胺和超支化聚醚酰亚胺的合成、性能和固化技术。     

2-(取代乙炔基)苯甲醛在有机合成中的应用

2-(取代乙炔基)苯甲醛是一类重要的有机中间体,因其较高的反应活性已被广泛用于构建各种化合物。该文综述了2-(取代乙炔基)苯甲醛衍生物在有机合成中应用的研究进展,如苯并碳环化合物、苯并氮杂环化合物、苯并氧杂环化合物、多元苯并杂环化合物的构建。并对其发展前景进行了展望,为今后2-(取代乙炔基)苯甲醛衍生物在有机合成中的应用提供了参考。     

2-(取代乙炔基)苯甲醛衍生物在有机合成中的应用

作为一类具有特殊结构的重要有机合成中间体，2-(取代乙炔基)苯甲醛衍生物的化学结构是由苯环、取代乙炔基和醛基三部分活性基团构成的共轭体系. 因其具有较高的反应活性，而被广泛的用于构建各种具有新颖结构的苯并碳环或苯并杂环类化合物，如苯并碳环化合物、苯并氮杂环化合物、苯并氧杂环化合物、多元苯并杂环化合物等. 本文综述了2-(取代乙炔基)苯甲醛衍生物在有机合成领域的应用，并对其发展前景进行了展望，为今后2-(取代乙炔基)苯甲醛衍生物在有机合成中的应用提供参考.     

1,3,5-三（4-二苯胺基苯乙炔基）-2,4,6-三（4-腈基苯乙炔基）苯的合成及表征

利用微波反应合成了一种新型二阶非线性光学化合物1,3,5-三（4-二苯胺基苯乙炔基）-2,4,6-三（4-腈基苯乙炔基）苯,通过红外、核磁共振、元素分析等手段对产物结构进行了表征。紫外可见光的吸收光谱的研究表明,该产物有希望成为1064 nm激光的倍频材料。     

Synthesis and processing of PMR-15/LaRC-TPI semi-IPN systems

To improve the fracture toughness of PMR-15 polyimide and to alleviate its high susceptibility to microcracking induced by thermal cycling, a thermoplastic polyimide, LARC-TPI, was incorporated to form a sequential semi-interpenetrating polymer network (semi-2 IPN). The imidization kinetics of LARC-TPI in the semi-IPNs were studied using a thermal gravimetric analyzer. Both the solvent and the glass transition temperature of the semi-IPN were found to have significant effects on the imidization kinetics. The kinetics could be modeled by a two-step reaction: the first step being a second-order reaction followed by a second step, which is a first-order diffusion-controlled reaction. Differential scanning calorimetry was chosen to investigate the curing of PMR-15 and PMR-15/LARC-TPI semi-IPNs. The curing process was well correlated by a first-order reaction kinetics, which suggested that the reverse Diels-Alder reaction of the Norbornene end group was the rate controlling step. The glass transition temperatures of these semi-IPNs were again found to play important an important role in dictating the curing kinetics. A higher proportion of LARC-TPI or a higher glass transition temperature of the semi-IPN prepolymer tended to result in a slower curing reaction. The optimum molding cycle of PMR-15 and PMR-15/LARC-TPI semi-IPNs were then determined from the obtained kinetics. © 1995 John Wiley & Sons, Inc.     

Miscibility,crystallization, and morphology studies of thermosetting polyimide PMR-15/PEK-C blends

Miscibility, crystallization, and mechanical properties of blends of thermosetting polyimide PMR-15 and phenolphthalein poly(ether ketone) (PEK-C) were examined. With the exception of the 90/10 blend, which has two glass transition peaks, all the blends with PMR-15 less than 90 wt % are miscible in the amorphous state according to DMA results. Addition of PEK-C hindered significantly the crystallization of PMR-15, indicating that there must exist some kind of interaction between molecular chains of PMR-15 and those of PEK-C. The semi-IPN system of PMR-15/PEK-C blends exhibits good toughness. Two distinct microphases, interweaving at the phase boundaries, were found in the PMR-15/PEK-C 60/40 blend. The toughness effect of the blends is discussed in terms of the interface adhesion between the two distinct phases and the domain sizes of the phases. The relation between miscibility and toughness of the blends was investigated. © 1996 John Wiley & Sons, Inc.     

PMR-15/carbon fiber composites produced from powder-coated towpreg

An addition-type thermosetting polyimide, PMR-15, has a relatively high glasstransition temperature, T_g, of approximately 340°C and attractive high-temperature composite mechanical properties after postcuring. PMR-15 prepreg is typically produced by pulling carbon fibers through a methanol solution that contains the PMR-15 monomers. One of the monomers, methylene dianiline, is highly toxic, thereby making the solution-coating technique undesirable. To alleviate the toxicity problem in the prepregging step, “preimidized” PMR-15 is now available in powder form, and this material can be used to produce towpreg using a powder-coating method. The powder-coating method that has been used in this work involves the use of an aqueous foam as a carrier medium to continuously deposit the PMR-15 powder onto carbon fibers. The powder is slurried in a surfactant solution into which nitrogen is dispersed using a foam-generating device. A predetermined amount of this foam is then applied to a moving carbon fiber tow. The foam is collapsed and the powder fused to the fiber in a set of tubular ovens. The powder appeared to be particularly sensitive to the heat treatment, but towpreg was produced and composites were consolidated successfully. The mechanical properties of the composites formed from powder-coated towpreg compare favorably with the properties of composites fabricated from prepreg that was drum wound from a methanol solution.     

Investigation of oxidation profile in PMR-15 polyimide using atomic force microscope (AFM)

Nanoindentation measurements are made on thermosetting materials using cantilever deflection vs. piezoelectric scanner position behavior determined by atomic force microscope (AFM). The spring model is used to determine mechanical properties of materials. The generalized Sneddon's equation is utilized to calculate Young's moduli for thermosetting materials at ambient conditions. Our investigations show that the force-penetration depth curves during unloading in these materials can be described accurately by a power law relationship. The results show that the accuracy of the measurements can be controlled within 7%. The above method is used to study oxidation profiles in PMR-15 polyimide. The thermo-mechanical profiles of PMR-15 indicate that the elastic modulus at the surface portion of the specimen is different from that at the interior of the material. It is also shown that there are two zones within the oxidized portion of the samples. Results confirm that the surface layer and the core material have substantially different properties.     

Interpenetrating polymer network approach to tough and microcracking resistant high temperature polymers. Part II. LaRC-RP41

Recently, we reported on the interpenetrating polyimide network (IPN) approach to develop tough and microcracking resistant high temperature matrix resins for use in aircraft/aerospace structural components. One such polymer developed is designated LaRC-RP40. This new simultaneous semi-IPN was prepared from easy-to-process but brittle crosslinking PMR-15 and tough but difficult-to-process linear NR-150B2. Significantly improved toughness, microcracking resistance, and glass transition temperature over PMR-15 were realized from the combination. These property improvements were achieved without compromising ease of processing, high temperature mechanical performance, and cost effectiveness compared to PMR-15. These results encouraged us to further explore this approach for the development of a wider range of polymers of basic technological and economic interest. In the present work, we combine crosslinking PMR-15 and linear LaRC-TPI to provide a new sequential semi-2-IPN called LaRC-RP41. The physical and mechanical properties of the neat resin and composite reinforced with graphite fibers are presented. The phase morphology and phase stability of the neat resin and composite studied by various techniques are also discussed.     

PMR-15 processing,properties and problems—a review

The frontrunner in the race to develop a high temperature resin for use in advanced composites intended for high temperature applications is the NASA developed polyimide PMR-15. One of the key factors in the success of the material is the relatively easy processing which is due mainly to the use of the PMR approach (Polymerisation of Monomeric Reactants). Prepreg and high quality composite laminates (glass or carbon) can be prepared with ease. Laminate properties compare well with conventional epoxy based systems but thermal stability is much greater. Continuous use temperatures are in the range 280-300°C, some 150-170°C higher than epoxy systems. Applications of PMR-15 composites include aero-engines, missiles, spacecraft and military aircraft. Despite being the leading system available today PMR-15, like all materials, has a number of limitations affecting its widespread use. Included in these are reliable methods of quality control, prepreg batch to batch variability, microcracking from thermal cycling, health and safety hazards and high temperature processing. This paper reviews the present status of PMR-15 development and outlines work designed to identify and where possible overcome these limitations.     

Effect of degree of cure and fiber content on the mechanical and dynamic mechanical properties of carbon fiber reinforced PMR-15 polyimide composites

A unidirectional continuous carbon fiber reinforced polyimide composite is fabricated using the PMR-15 polyimide as a matrix. Mechanical and dynamic mechanical properties of the composite are studied. The effect of variation of the fiber content ranging from 55% to 70% by volume on the properties of the composite is determined. The effects of the laminate thickness and degree of curing of the matrix on the Izod impact strength are examined. The effect of the degree of curing of the matrix on the dynamic mechanical spectrum is studied. Finally, variables such as humidity, environment temperature, vacuum, and pressure during laminate processing, and variation of monomer composition are discussed in terms of change in matrix structure, which is reflected in a variation of Tg between batches.     

开孔聚酰亚胺泡沫粘接性能研究

探讨了BHPI-J-2010胶粘剂的固化度、耐热性、固化工艺、粘接铝的拉剪强度及粘接聚酰亚胺泡沫的可行性;研究了BHPI—J-2010胶粘剂粘接聚酰亚胺泡沫／45号钢的拉伸性能及固化工艺;考查了开孔聚酰亚胺泡沫／45号钢粘接试样高温拉伸和蠕变性能及胶粘剂的使用寿命。结果表明,BHPI—J-2010胶粘剂对开孔聚酰亚胺泡沫具有良好的粘接性能。