Novel Semi-Interpenetrating Polyimide Network Based on Acryl End Capped Oligoimides

Amino terminated oligoimides (AOIs) were prepared by the Michael addition reaction of various bismaleimides(1a–c) with excess of 4,4′-diamino diphenyl methane (DDM). These AOIs were characterized by elemental analysis, FT-IR spectral studies and number average molecular weight estimated by non-aqueous conductometric titrations. AOIs were then reacted with acrylol chloride and resultant acryl end capped oligoimides (AcOIs) sample were also characterized thermogravimetrically. Each of these AcOI was then combined with the commercially available thermoplastic polyamic acid solution in various proportions. The resultant suspensions were then heated in the presence of azobisisobutyronitrile (AIBN) as a initiator. The AcOI polymerized through double bond and polyamic acid is cyclized to form SEMI-IPN polymides, which were analyzed thermogravimetrically. The glass fibre reinforced composites were fabricated by using the suspensions of the AcOI and polyamic acid solution. The composites of SEMI IPN polymides were analyzed for their mechanical, chemical and electrical properties.     

新型环状聚酰亚胺齐聚物的基质辅

通过两步法以苯均四酸二酐和芳香二胺单体合成了芳香环状聚酰亚胺,并且用基质辅助激光解吸电离飞行时间质谱技术对其结构进行表征。以1,8,9-蒽三酚为基质,二甲基甲酰胺为溶剂,正离子方式记录谱图,谱图中可以观测到环状齐聚物的氢、钠、钾三组加合分子离子峰。质谱数据表明:环状聚酰胺酸室温放置时,部分三聚体转化为二聚体,可提高环状二聚体的收率。     

Semicrystalline polyimide matrices for composites: Crystallization and properties

New semicrystalline polyimide/oligoimide blends, designated for matrices in carbon fiber‐reinforced composites, were developed. A specific advantage of the proposed polyimides is their ability to crystallize from the melt, therein retaining their crystallinity throughout the manufacturing process. The generation of crystallinity after melting, referred to as recrystallization, was investigated here as affected by blending the polyimides with oligoimides of a similar chemical structure. Based on thermal analysis and enthalpy measurements, comparative X‐ray diffraction analyses, and polarized light microscopy of hot‐stage‐controlled crystallization, the recrystallization ability was determined for five different oligoimides. In some cases, the addition of oligoimides, both amorphous and crystalline, resulted in complete recrystallization. The main contribution of the oligoimides is suggested to be through plasticization, allowing segmental chain mobility during crystallization, and not via nucleation. A similar effect was obtained by lowering the molecular weight of the polyimide; this, however, generates mechanical property reduction, rendering the polyimide irrelevant to composite materials. Finally, it was shown that crystallization was also enhanced by carbon fibers, serving as a nucleating agent and generating transcrystallization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2873–2882, 2002; DOI 10.1002/app.10277     

基于低聚酰亚胺含氮介孔碳材料的制备

以低聚酰亚胺为氮源前驱体、交联酚醛树脂为碳源、嵌段共聚物为软模板剂,通过相分离自组装、交联和高温锻烧处理制备了新型高规整含氮介孔碳材料,并用FT-IR、SEM、TEM、热重分析和小角X光散射等测试方法表征介孔碳材料的组成与结构.结果表明,处理温度达350℃时嵌段共聚物模板可被成功移除,进而形成多孔结构;温度达600℃时体系完全碳化,可得到高规整的多孔含氮碳材料.通过调节体系中氮源、碳源及模板剂的相对比例可实现形貌由立方结构向柱状和层状结构的过渡,进而实现对含氮介孔材料形貌的有效调控.     

具有极低熔体黏度的苯乙炔封端热固性聚酰亚胺树脂

为了开发适于树脂传递模塑(RTM)成型的低熔体黏度热固性聚酰亚胺树脂,采用2,2′,3,3′-三苯二醚四甲酸二酐(3,3′-HQDPA)和3,3′,4,4′-三苯二醚四甲酸二酐(4,4′-HQDPA)的混合物与3种不同的二胺单体合成了3种系列的苯乙炔封端的热固性聚酰亚胺树脂,其中二胺为4,4′-二氨基二苯醚(ODA),4,4’-二氨基-2,2’-双三氟甲基联苯(TFDB)和2-苯基-4,4′-二氨基二苯醚(p-ODA)。文中系统地研究了酰亚胺预聚物的结构和相对分子质量对预聚物的聚集态结构、熔体黏度及对固化后薄膜的热性能、力学性能的影响。研究结果表明,与ODA和TFDB不同,p-ODA的特殊化学结构使得由它合成的酰亚胺预聚物(相对分子质量为750)表现为无定形态,并在低温区具有极低的熔体黏度。它在200℃至280℃区间内任意温度恒温2 h后,熔体黏度都低于1 Pa·s,更适宜RTM成型。     

Novel Semi-Interpenetrating Polyimide Network Based on Acryl End Capped Oligoimides

Amino terminated oligoimides (AOIs) were prepared by the Michael addition reaction of various bismaleimides with excess of 4,4′-diamino diphenyl methane (DDM). These AOIs were characterized by elemental analysis, FT-IR spectral studies, and number average molecular weight estimated by non-aqueous conductometric titrations. The AOIs were then reacted with acrylol chloride and the resultant acryl end capped oligoimides (AcOIs) were also characterized thermogravimetrically. Each of these AcOI was then combined with a commercially available thermoplastic polyamic acid solution in various proportions. The resultant suspensions were then heated in the presence of azobisisobutyronitrile (AIBN) as a catalyst. The AcOI polymerized through double bond and the polyamic acid was cyclized to form SEMI-IPN polymides, which were analyzed thermogravimetrically. Glass fiber reinforced composites were fabricated by using the suspensions of the AcOI and polyamic acid solution. The composites of SEMI IPN polymides were analyzed for their mechanical, chemical, and electrical properties.