热塑性共聚聚酰亚胺薄膜的合成及性能研究

以2,2′-二甲基-4,4′-二氨基联苯(m-TB)为二胺单体,均苯四甲酸二酐(PMDA)和3,3′,4,4′-联苯四甲酸二酐(BPDA)为二酐单体,N,N′-二甲基乙酰胺(DMAc)为溶剂,采用常规的两步法制备了一系列不同二酐比例的热塑性聚酰亚胺,并通过红外光谱仪、X-射线衍射仪、热重分析仪、紫外光谱仪、动态热分析仪、溶解性测试等对共聚聚酰亚胺的结构和性能进行表征.结果表明:在1 780、1 720、1 500、1 380、1 050和725 cm~(-1)处出现明显的吸收峰,说明成功制备了聚酰亚胺材料;共聚聚酰亚胺只在PMDA与BPDA物质的量比为0.2∶0.8时存在结晶峰,其他比例时均为非晶聚合物;亚胺化后的共聚聚酰亚胺在DMSO、DMAc、DMF、NMP和m-cresol中有溶解性,证明成功制备出热塑性聚酰亚胺薄膜;热塑性共聚PI起始分解温度大于500℃,800℃时的质量保持率在50%以上,具有良好的热稳定性;随着聚合物中BPDA含量的提高,热塑性聚酰亚胺薄膜的玻璃化转变温度呈现下降的趋势.当紫外光波长达到400 nm时,薄膜的透光率高达57.6%,当波长为760 nm时,薄膜透光率均达到100%,成功制备了透光率较高的聚酰亚胺薄膜.     

一种可溶性双酮酐型共聚酰亚胺的合成及性能

以均苯四甲酸二酐(PMDA)和4,4’-对苯二甲酰二邻苯二甲酸酐(TDPA)为二酐单体,4,4’-(3-氨基苯氧基)二苯甲酮(BABP)为二胺单体,采用两步法低温溶液缩聚合成了系列双酮酐型共聚酰亚胺。采用红外光谱、X射线衍射、差示扫描量热分析、热重分析、拉伸测试和溶解性能测试对聚合物的结构与性能进行了表征,考察了TDPA/PMDA不同摩尔比对共聚酰亚胺溶解性、耐热性和力学性能的影响。结果表明,双酮酐型聚酰亚胺的玻璃化转变温度随TDPA摩尔含量的增加逐渐下降,溶解性能则逐渐提高,当TDPA/PMDA摩尔比为7/3时,共聚酰亚胺具有优良的耐热性能及力学性能,可溶于N,N-二甲基甲酰胺(DMF)等极性溶剂。     

2,5-双(4-氨基-2-三氟甲基苯氧基)叔丁基苯及其聚酰亚胺的制备和性能研究

通过两步反应制备得到2,5-双(4-氨基-2-三氟甲基苯氧基)叔丁基苯,将其分别与均苯四甲酸二酐(PM-DA)、3,3’,4,4’-四羧酸二苯醚二酐(ODPA)、3,3’,4,4’-二苯酮四酸二酐(BTDA)、3,3’,4,4’-联苯四酸二酐(BPDA)、双酚A二酐(BPADA)通过缩聚和热亚胺化制备得到5种性能优异的聚酰亚胺薄膜。结果表明薄膜的玻璃化转变温度(Tg)高于210℃,起始分解温度高于510℃;吸水率低于0.9%;介电常数介于2.90～3.15之间;杨氏模量在1.48～2.27GPa之间。     

可溶性含羟基聚酰亚胺的制备及其性能研究

合成了含羟基的二胺单体4,4′-二氨基-4″-羟基三苯甲烷(DHTM),并将该单体分别同六氟异叉丙基二苯四羧酸二酐(6FDA),3,3′,4,4′-二苯醚四羧酸二酐(ODPA)和4,4′,-二(4,4′,-异丙叉二苯氧基)四羧酸二酐(BPADA)反应制备了3种结构的聚酰亚胺。溶解性实验表明,这3种聚合物在非质子极性溶剂中均显示出良好的溶解性。此外,还对聚酰亚胺薄膜进行了拉伸和动态机械热性能测试。     

聚酰亚胺气凝胶的制备及其性能研究

以3,3’,4,4’-联苯四甲酸二酐(BPDA)和4,4’-氨基二苯醚(ODA)为合成单体,1,3,5-三(4-氨基苯氧基)苯(TAB)为交联剂,合成了聚酰亚胺溶胶,最后经CO2超临界干燥得到气凝胶。研究了溶胶配方对聚酰亚胺气凝胶密度、收缩率、孔结构、拉伸强度及热导率等性质的影响规律,制备得到低密度、小孔径、高比表面积、低热导率和较好柔韧性能的气凝胶。     

6FAPE基含氟聚酰亚胺的结构与性能研究

利用含氟二胺单体4,4'-双(4-氨基-2-三氟甲基苯氧基)二苯醚(6FAPE),分别与1,2,3,4-环丁烷四酸二酐(CBDA)、3,3',4,4'-二苯醚四酸二酐(ODPA)、3,3',4,4'-联苯四酸二酐(BPDA)、3,3',4,4'-二苯甲酮四羧酸二酐(BTDA)和均苯四甲酸二酐(PMDA)进行低温缩聚反应,经热酰亚胺化制备出5种聚酰亚胺(PI)薄膜,考察了其光学透明性和热性能,研究了聚酰亚胺分子结构与性能的关系.结果表明,CBDA基含氟PI薄膜在可见光波长范围内(400～700nm)具有优异的光学透明性,450nm处的透光率为84.6%,且5种含氟PI薄膜在光通讯波段(1.30μm和1.55μm)均无明显吸收;除CBDA外,含氟PI薄膜均具有良好的热稳定性,5%热失重温度超过530℃;5种含氟PT薄膜的玻璃化转变温度Tg均在200℃以上,且CBDA基舍氟PI薄膜的Tg最高,达到265.5℃.     

可溶性透明含氟聚酰亚胺薄膜的合成与性能

利用3种二胺单体1,4-双(4-氨基-2-三氟甲基苯氧基)苯、4,4’-双(4-氨基-2-三氟甲基苯氧基)二苯醚和4,4’-双(4-氨基-2-三氟甲基苯氧基)六氟丙烷分别与3种二酐单体1,2,3,4-环丁烷四酸二酐(CBDA)、均苯四甲酸二酐(PMDA)和3,3’,4,4’-二苯醚四酸二酐(ODPA)进行低温溶液缩聚反应,再经热酰亚胺化制备出9种聚酰亚胺(PI)薄膜。结果表明,这些PI具有较好的溶解性,可溶解于氨型强极性溶剂,在弱极性溶剂中也有一定的溶解性;CBDA和ODPA基PI在450 nm处的透光率超过80%,且CBDA基PI的紫外截止波长为310 nm,更接近无色,但其热稳定性最差,5%热分解温度在420℃左右,而PMDA和ODPA基PI的热稳定性较好。     

共聚物链结构对共聚型含氟聚酰亚胺薄膜性能的影响

以4,4'-二氨基-2,2'-双三氟甲基联苯(TFMB)、4,4'-(六氟异丙烯)二酞酸酐(6FDA)和3,3',4,4'-联苯四甲酸二酐(BPDA)为反应单体,改变非含氟BPDA单体在二酐中的配比和加料方式制备出一系列共聚型含氟聚酰亚胺(PI)薄膜并表征和分析其性能,研究了共聚物链结构对其性能的影响。结果表明,BPDA单体的加料方式及其在二酐单体中的比例均影响薄膜的性能。共聚型含氟PI薄膜在室温下均溶于非质子极性溶剂,且在可见光范围内有较高的透光率。随着非含氟二酐单体BPDA含量的提高薄膜的光学性能略有降低而其热性能和力学拉伸性能提高。非含氟二酐单体占二酐单体的比例为68.97%的共聚型PI薄膜,在500 nm处的透过率达到96.01%;非含氟二酐单体占二酐单体比例为35.71%的共聚型PI薄膜失重10%的热分解温度为595.23℃,拉伸强度为100.98 MPa。同时,BPDA加料方式的改变对共聚型PI薄膜的光学性能、热学性能和力学拉伸性能均有不同程度的影响。     

共聚制备低热膨胀透明聚酰亚胺薄膜

为了在尽量不影响其透光性的前提下解决含氟聚酰亚胺薄膜热膨胀系数(CTE)过大的问题,以4,4′-(六氟异丙烯)二酞酸酐(6FDA)、4,4′-二氨基-2,2′-双三氟甲基联苯(TFMB)和3,3′,4,4′-联苯四羧酸二酐(BPDA)为原料,通过两步法合成了5种BPDA掺杂量分别为0、10%、20%、30%和40%的共聚PI薄膜,并采用红外光谱分析(IR)、热重分析(TGA)、热机械性能分析(TMA)等方法对其性能进行了表征.分析表明:共聚薄膜的热性能相比均聚薄膜有所提高;薄膜的介电常数与BPDA的含量成正比,而其在可见光领域的透光率与BPDA的含量成反比;在BPDA含量较低时,薄膜的拉伸强度和弹性模量随BPDA含量的增加而增大,但当BPDA摩尔分数超过30%时其力学性能开始降低;随着共聚单体含量的上升,薄膜的热膨胀系数大幅减小.     

4,4'-对苯二甲酰二邻苯二甲酸酐和均苯四甲酸酐共聚酰亚胺的合成与性能

以4,4'-对苯二甲酰二邻苯二甲酸酐(TDPA)和均苯四甲酸酐(PMDA)为芳二酐单体,与4,4'-二氨基二苯醚(ODA)经溶液缩聚、热亚胺化制得PMDA/TDPA共聚酰亚胺薄膜,并用红外光谱、热重分析、差示扫描量热分析、力学性能测试等对薄膜的结构和性能进行表征。结果表明,在聚酰亚胺分子主链引入双酮基结构单元后,共聚酰亚胺树脂玻璃化转变温度(Tg)随着TDPA比例的增加逐渐下(Tg为322~285℃),溶剂流延成膜的加工性能得到显著改善,薄膜仍具有优良的热氧化稳定性和力学性能,5%热分解温度(Td5%)为517~550℃,拉伸强度为111~148 MPa。     

共聚低热膨胀聚酰亚胺薄膜的制备与表征

以4,4′-(六氟异丙烯)二酞酸酐(6FDA)为含氟二酐,4,4′-二氨基-2,2′-双三氟甲基联苯(TFMB)为含氟二胺,通过引入分子结构相对对称的刚性单体1,2,4,5-均苯四甲酸二酐(PMDA)进行共聚合成了5种含氟比例不同的透明聚酰亚胺薄膜,并对其性能进行了表征。分析表明:引入刚性单体共聚后薄膜的热稳定性和耐热性有所提高;薄膜的介电常数随着PMDA含量的上升而增加;共聚薄膜在可见光领域的透光率低于均聚薄膜;拉伸实验显示在添加少量PMDA后,薄膜的拉伸强度和弹性模量有所增大,但当PMDA含量过高时其力学性能反而下降;随着PMDA含量的增加,薄膜的热膨胀系数明显降低。     

一种耐高温聚酰亚胺胶粘剂的合成

以醚胺(ODA)、砜胺(DDS)和醚酐(ODPA)、酮酐(BTDA)为原料,采用冷却法和加热法分别合成了一种耐高温聚酰亚胺胶粘剂。通过搭接试验和聚酰亚胺膜结构表征,比较了两种不同合成方法所得聚酰亚胺胶粘剂的性能差异。通过试验选择了亚胺胶的搭接工艺和固化工艺,从而使聚酰亚胺胶粘剂的粘接性能达到最佳。     

含偶联剂的聚酰亚胺/SiO2杂化膜的制备与性能

采用二酐(HQDPA)和二胺(ODA)合成了聚酰亚胺,以正硅酸乙酯(TEOS)为无机前驱体,通过溶胶-凝胶法在溶剂DMF中制备出SiO2不同含量的PI/SiO2杂化膜,偶联剂GOTMS用来加强聚酰亚胺与SiO2的相容性。采用SEM及万能拉力实验机对膜材料的微观结构和力学性能进行了表征。结果表明,质量分数为10%SiO2的杂化膜力学性能得到加强,20%,30%的膜力学性能下降;加入偶联剂有效地抑制了SiO2的团聚,20%,30%的杂化膜力学性能得到了改善。     

Polyimide/sepiolite nanocomposite films: Preparation, morphology and properties

Polyimide/sepiolite nanocomposite films have been prepared via an in situ polymerization method. The process involves the dispersion of sepioite in N,N-dimethylacetamide, polycondensation of 2,2′-bis [4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride and 4,4′-oxydianiline in the presence of sepiolite suspension to form poly(amic acid), and the thermal imidization of poly(amic acid)/sepiolite nanocomposite. The morphology, thermal and mechanical performance, and water absorption of nanocomposite films were systematically studied with various sepiolite contents. The results indicated that sepiolite was dispersed homogeneously at a nanometer scale in polyimide matrix. Owing to such nanodispersion of sepiolite, the polyimide/sepiolite nanocomposite films exhibit dramatic improvements on the mechanical properties and the coefficient of thermal expansion while fine thermal stability and low water absorption capacity were also maintained. When the sepiolite content increased to 16% the polyimide/sepiolite nanocomposite film achieved as much as 41% and 94% increase on the tensile strength and modulus respectively, and 50% decreased in coefficient of thermal expansion.     

Mechanically strong, flexible polyimide aerogels cross-linked with aromatic triamine

Polyimide gels are produced by cross-linking anhydride capped polyamic acid oligomers with aromatic triamine in solution and chemically imidizing. The gels are then supercritically dried to form nanoporous polyimide aerogels with densities as low as 0.14 g/cm(3) and surface areas as high as 512 m(2)/g. To understand the effect of the polyimide backbone on properties, aerogels from several combinations of diamine and dianhydride, and formulated oligomer chain length are examined. Formulations made from 2,2'-dimethylbenzidine as the diamine shrink the least but have among the highest compressive modulus. Formulations made using 4,4'-oxydianiline or 2,2'dimethylbenzidine can be fabricated into continuous thin films using a roll to roll casting process. The films are flexible enough to be rolled or folded back on themselves and recover completely without cracking or flaking, and have tensile strengths of 4-9 MPa. Finally, the highest onset of decomposition (above 600 °C) of the polyimide aerogels was obtained using p-phenylene diamine as the backbone diamine with either dianhydride studied. All of the aerogels are suitable candidates for high-temperature insulation with glass transition temperatures ranging from 270-340 °C and onsets of decomposition from 460-610 °C.     

Processing and properties of carbon fiber/Triple-A polyimide composites fabricated from imide oligomer dry prepreg

Triple-A polyimide (TriA-PI) concept, “amorphous, asymmetric, and addition type”, was originally proposed by Yokota in 1999 for high temperature polymer matrix composites. The first version polyimide “TriA-PI-1” was developed from a-BPDA (2,3,3′,4′-biphenyltetracarboxylic dianhydride), 4,4′-oxydianiline (4,4′-ODA), and phenylethynyl phthalic anhydride (PEPA). The cured polyimide exhibits excellent mechanical properties with high glass transition temperature.In this study, a new prepreg system, namely imide-oligomer dry prepreg was developed by impregnating imide-oligomer into unidirectional carbon fiber bundles directly. Carbon fiber/TriA-PI-1 composites were fabricated from the imide-oligomer dry prepreg, and mechanical properties were evaluated. It was demonstrated that the TriA-PI-1 composite exhibits excellent compressive and tensile strengths at 300 °C as well as room temperature. It was easy to make a high quality composite laminate without complicated process using imide-oligomer dry prepreg.     

笼型聚倍半硅氧烷增韧3层聚酰亚胺薄膜的制备与性能

以3,3′,4,4′-联苯四酸二酐(BPDA)-对苯二胺(PDA)/4,4′-二苯醚二胺(ODA)型聚酰亚胺为芯层,将2,2′-双(4-(4-氨基苯氧基)苯基)丙烷(BAPP)-BPDA型聚酰胺酸涂覆于芯层的上、下表面并热亚胺化得到3层聚酰亚胺薄膜。为提高3层聚酰亚胺薄膜的韧性,将降冰片烯二酸酐-马来酰亚胺基七异丁基聚倍半硅氧烷交替共聚物(poly(MIPOSS-alt-NA))作为BPDA的共单体引入到上、下表层的热塑性聚酰亚胺中。结果表明,当poly(MIPOSS-alt-NA)的质量分数为6.0%时,3层聚酰亚胺薄膜的断裂伸长率从7.2%提高到14.5%,热膨胀系数则从27.0×10-6 K-1降低至23.6×10-6 K-1,与铜箔制备的柔性覆铜板剥离强度达到12.0 N/cm,针对拉伸断面电镜照片的变化对增韧机理进行了分析。     

Surface properties of aromatic polymer film during thermal treatment

Aromatic polyimide films are processed from polyamic acid solutions. This process involved the simultaneous loss of solvent and chemical conversion of polyamic acid to polyimide, and implied structural reorganization which led to changed physical properties. Polymer films generated from benzophenonetetracarboxylic dianhydride and 4,4′-diamino-3,3′-dimethyl diphenylmethane have been investigated at different stages of thermal treatment. The surface polarity, which was determined by the presence of polar COOH and CONH groups, changed during polyamic acid thermal treatment. These polar groups were removed step by step by imidization process leading to the modification of the physical properties of the polymer film.     

低介电常数聚酰亚胺薄膜的制备与性能研究

用单体4,4′-二胺基二苯醚（ODA）和均苯四甲酸二酐（PMDA）添加纳米SiO2,在溶剂N,N-二甲基乙酰胺（DMAC）中,采用原位聚合法合成SiO2/聚酰亚胺（PI）复合薄膜。用氢氟酸刻蚀SiO2纳米粒子,引入纳米微孔,形成含有微孔的PI薄膜。造孔剂含量为15%时,薄膜的介电常数从纯聚酰亚胺的3.54降低至3.05（1kHz）。用透射电镜表征微孔结构,分析了微孔孔径和造孔剂（SiO2）含量对薄膜介电常数、耐热性、疏水性和机械强度等性质的影响。