聚酰胺酸酰亚胺化条件及其对聚酰亚胺力学性能的影响

采用均苯四酸二酐(PMDA)和4,4'-二氨基二苯醚(ODA)为单体,N-甲基吡咯烷酮(NMP)为溶剂,合成了黏度为1.87 dL/g的聚酰胺酸(PAA)。对聚酰胺酸分别进行了热酰亚胺化和化学酰亚胺化处理,研究了完全酰亚胺化所需的条件以及不同酰亚胺化方式对聚酰亚胺(PI)纤维条断裂强度的影响;对PAA初生纤维条进行拉伸和酰亚胺化处理的顺序不同,所得到的聚酰亚胺(PI)纤维条的力学性能不同,采用先酰亚胺化再拉伸的方法能得到力学性能更优异的聚酰亚胺(PI)纤维条。     

有机硅改性聚酰亚胺的合成研究

以双端氨基四甲基硅氧烷和芳香族二胺组成混合二胺,与芳香族四酸二酐反应得到有机硅改性聚酰亚胺溶液,经过热酰亚胺化得到有机硅改性聚酰亚胺薄膜,并对其性能进行了研究。     

系列聚酰亚胺的制备及其结构表征

以二苯醚四羧酸二酐（0DPA）为二酐单体,对苯二胺（PDA）和二胺基二苯基醚（ODA）为二胺单体,通过低温缩聚合成一系列聚酰胺酸（PAA）和聚酰亚胺（PI）薄膜,对其结构和力学性能进行表征,并比较ODPA—PDA和ODPA—ODA薄膜的力学性能。结果表明,PAA的酰亚胺化较完全;链节元素组成与空间构型对于PAA与PI薄膜的力学性能影响较大,其中,PI（ODPA—PDA）薄膜的拉伸强度达到450MPa。     

含苯并噁唑结构共聚酰亚胺的合成及其性能

联苯四羧酸二酐(BPDA)与4,4′-二氨基二苯醚(ODA)及自制的2,6-二(对氨基苯)苯并[1,2-d;5,4-d']二噁唑(DAPBBO)在二甲基乙酰胺中共聚,然后进行铺膜和热酰亚胺化,得到了含有双苯并噁唑的共聚酰亚胺薄膜,对其结构、热性能、力学性能及光学性能进行了表征。结果表明:杂环单体的引入提高了聚酰亚胺的力学性能,增加了聚酰亚胺的玻璃化转变温度,并且使聚酰亚胺薄膜具有良好的紫外吸收能力。     

热塑性聚酰亚胺薄膜的制备与性能研究

以自制的双[4-(4-氨基苯氧基)苯基]砜(BAPS)、4,4′-二氨基二苯醚(ODA)和3,3′,4,4′-二苯醚四甲酸二酐(ODPA)为主要原料,采用共聚法合成了较高黏度的聚酰胺酸(PAA)溶液;然后该PAA溶液经高温酰亚胺化后,制得了TPI(热塑性聚酰亚胺)薄膜。研究结果表明:所有样品均具有较好的尺寸稳定性和较低的吸水率,并具有一定的热塑性;当n(BAPS)∶n(ODA)=50∶50时,相应的TPI薄膜具有相对最好的综合性能,其基本完成了酰亚胺化的转变过程,具有较好的耐热性[玻璃化转变温度(Tg)约为249℃,热失重10%时的温度约为510℃,800℃时的残炭率约为18%]和优异的电绝缘性能(介电常数为2.5、介电损耗为0.001 2和体积电阻率为2.3×10~(13)Ω·m)。     

BAMPM基高可溶高透光聚酰亚胺的制备及表征

将3,3',5,5'-四甲基-4,4'-二胺基苯基-4'-甲基甲苯(BAMPM)与均苯四甲酸二酐(PMDA)、联苯四甲酸二酐(BPDA)、联苯醚二酐(ODPA)、六氟二酐(6FDA)通过一步高温缩聚法制备了四种新型聚酰亚胺(PI)。所得聚酰亚胺在普通有机溶剂中具有优异的溶解性。聚酰亚胺的玻璃化转变温度(Tg)超过332℃,10%热失重温度为530～537℃。溶液浇铸法制备的聚酰亚胺薄膜具有高光学透明性,UV截止波长为312～366 nm,80%透过率波长为382～436 nm。该薄膜的拉伸强度为60.5～84.7 MPa,弹性模量为1.7～2.4 GPa,断裂伸长率为5.9%～10.2%。     

含酮柔性共聚型聚酰亚胺性能研究

为了考察柔性二酐共聚对聚酰亚胺(PI)薄膜性能的影响,用含柔性基团的酮酐单体3,3',4,4'-二苯酮四酸二酐(BTDA)、刚性二酐单体均苯四甲酸二酐(PMDA)和芳香二胺4,4'-二氨基二苯醚(ODA)共聚,制得共聚聚酰亚胺薄膜.分别用FT-IR(ATR)、TMA、TGA、万能试验机对薄膜的结构、热性能及力学性能进行了测定.结果表明,聚合物亚胺化程度完全,且随着柔性二酐的加入聚合物的热性能得到明显改善,同时力学性能数据也表明,共聚物柔性增强,材料的加工性得到提高.     

以BAPP为原料的热塑性PI薄膜的合成及性能

以芳香长链二胺2,2-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)为二胺原料,与最具商业价值的四种酸酐均苯四甲酸二酐(PMDA)、3,3′,4,4′-联苯四酸二酐(BPDA)、3,3′,4,4′-二苯酮四酸二酐(BTDA)、3,3′,4．4′-二苯醚四酸二酐(ODPA)为二酸酐原料,采用二步溶液缩聚法制得了一系列均聚和共聚聚酰亚胺薄膜。利用FTIR表征了聚酰亚胺的结构,并用DSC、TOA、TMA DMA等手段测得了不同聚酰亚胺的Tg、5%与10%热失重温度、线膨胀系数、拉伸强度、断裂延伸率、热压粘接T型剥离强度等性能数据。     

溶液缩聚法含氟化聚酰亚胺的制备及薄膜性能研究(下)

本文以含三氟甲基为二胺单体,以含六氟为二酐单体合成了含邻扭结结构的新型聚酰亚胺。反应为高温溶液缩聚,反应通过常规的两阶段的过程,聚前体热酰亚胺化(酰胺酸)导致聚酰亚胺具有高的分子量。通过红外光谱(FT-IR)、核磁共振(NMR)表征手段对制备的含氟单体和相应的聚合物的结构进行了表征。该类聚酰亚胺表现出优异的溶解性能且表现出优异的热稳定性,耐温高达345 ℃。另外,所有的聚酰亚胺呈现良好的光学性能,透明度较高,截止波长较低。它们的聚集态特性及荧光光谱在有关化学结构的相关内容中讨论。通过被其表面与水的接触角测试,结果表明,这些含氟聚酰亚胺薄膜均具有的高疏水性,所有这些性能使其能在在光电子器件中用作透明柔性衬底。     

含苯并双咪唑高阻燃共聚聚酰亚胺薄膜的制备及其性能研究

以二胺单体2,2′-对苯基双-(5-氨基苯并咪唑)(PBABI)、 1,4-二氨基苯二胺(p-PDA)与二酐单体3,3′,4,4′-联苯四甲酸二酐(BPDA)进行共聚,制备高相对分子质量的聚酰亚胺(PI)前驱体聚酰胺酸(PAA),再通过热酰亚胺化的方式得到含苯并双咪唑重复单元的高阻燃共聚PI薄膜;研究了PI薄膜的聚集态结构、化学结构、热稳定性、阻燃性能和力学性能。结果表明:随着苯并双咪唑单体的增多,PI薄膜逐渐从有序堆积向无定型结构演变;苯并双咪唑结构促进了PI薄膜体系中形成分子间氢键作用;苯并咪唑的引入使PI薄膜的最大热分解温度提高5℃、玻璃化转变温度提升90℃、拉伸强度提高126 MPa,同时含苯并双咪唑的PI薄膜表现出优异的阻燃性能,极限氧指数提高到54%。     

PHASE SEPARATION OF POLY(AMIC ACID-CO-IMIDE) SOLUTION

Poly(amic acid-co-imide) (PA-I) is an intermediate for preparation of polyimide from polyamic acid (PAA). Phase separation does not appear for the solution until a certain imidization degree. The experimental results of a rotation viscometer and FT-IR analysis showed that the critical point of phase separation (CPPS) was related to the imidization methods (thermal or chemical imidization) and the backbone structures (flexible ODPA-ODA or semi-rigid PMDA-ODA). Phase separation time is shorted with the increase of the initial PAA concentration, acetic anhydride amount, or temperature. When phase separation occurs, the solution viscosity increases, while the imidization degree is almost constant as the initial PAA concentration rises. The greater the chain mobility, the higher the imidization degree at phase separation point. At CPPS, higher imidization degree and lower solution viscosity are obtained in the thermal imidization than in the chemical imidization; ODPA-ODA system exhibits higher imidization degree and better solubility than that of PMDA-ODA system.     

PA封端型聚酰亚胺的合成与表征

以均苯四甲酸二酐(PMDA)和自制的1,3-双(4-氨基苯氧基)苯(TPER)在邻苯二甲酸酐(PA)封端的情况下溶液缩聚得到聚酰胺酸(PAA),通过溶液亚胺化和固相亚胺化相结合得到聚酰亚胺(PI).用傅立叶变换红外光谱仪、乌氏粘度计和热失重分析仪对PI进行了结构表征和性能测试,分析了封端剂加入量、亚胺化方式对PI性能的影响.结果表明,封端剂的加入可有效降低PI的粘度,两种亚胺化方式的结合可以降低PI的最终亚胺化温度,得到的PI热稳定性高.     

Dry-jet wet spinning of aromatic polyamic acid fiber using chemical imidization

A solution of about 15% polyamic acid (PAA) prepared from 4,4′-oxydianiline and pyromellitic dianhyride in N,N-dimethyl acetamide (DMAc) was used for fiber spinning. To obtain a high draw ratio of the PAA fiber during spinning, acetic anhydride or acetic anhydride and pyridine were added to the PAA solution to make it slightly gelled; such gelling contributed to high drawing of the PAA fibers during spinning. Before spinning the properties of the solution after acetic anhydride or acetic anhydride and pyridine were added, and the diffusion property of DMAc into various coagulants were examined. Even though acetic anhydride was only added to the spinning solution, the diffusion rate became slower and the solution viscosity increased, because PAA was converted to the corresponding polyimide (PI). Pyridine affected the rate dramatically. The mechanical properties of the PAA fibers obtained in this system were examined. Solid PI fibers were also obtained by annealing of the PAA fibers. The ultimate stress and initial modulus of the PAA fiber were around 268 MPa and 4.1 GPa, respectively. After the fiber was annealed at 350°C without tension for 30 min under nitrogen, these values increased to around 399 MPa and 5.2 GPa, respectively.     

静电纺聚酰亚胺非织造布的制备与表征

以N,N-二甲基乙酰胺(DMAc)为溶剂,3,3',4,4'-二苯醚四甲酸二酐(ODPA)和4,4'-二氨基二苯醚(ODA)为单体,利用高压静电纺丝技术,制备了聚酰胺酸(PAA)和聚酰亚胺(PI)非织造布,并采用扫描电镜(SEM)对PAA及PI非织造布的表面形态进行表征,研究了PI非织造布的力学性能。结果表明:经300℃热亚胺化处理得到的PI非织造布,纤维平均直径减小到500nm以下,纤维的带状形貌与PAA明显不同,并且出现了收缩、弯曲等现象。静电纺丝法制得的PI非织造布的力学性能仍然比较优越。     

The retarding effects and structural evolution of a bio-based high-performance polyimide during thermal imidization

The thermal imidization evolution of a bio-based high-performance polyimide, namely adenine-containing polyimide (API), was investigated by thermogravimetric analysis (TGA), in situ Fourier transform infrared spectroscopy (in situ FTIR), and wide-angle X-ray diffraction (WAXD), in contrast to an adenine-free 4,4′-oxydiphthalic anhydride (ODPA)/4,4′-oxydianiline (ODA) PI. The influence derived from adenine was focused. At precursor stage of API (polyamic acid, PAA), the H-bonding interaction of PAA–PAA type as well as the especial interaction between the secondary amine of adenine and solvent (dimethylacetamide, DMAc) was discovered. Structural evolution of API was traced by in situ FTIR and multistage WAXD from PAA stage to PI stage. Compared with OPI, the retarding effects were found in the process of thermal imidization of API, partly due to the formation of H-bonding derived from the extra secondary amine of adenine moieties, which complicated the H-bonding form in API. Finally, a hypothesis of evolution of thermal imidization process about API molecule was proposed in contrast with adenine-free ODPA ODA PI. Compared with the consistency of both API and ODPA ODA PI in PAA stage, API possessed a more delicate thermal imidization process. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46953.     

Simulation of polyimide fibers with trilobal cross section produced by dry‐spinning technology

As one type of high performance fibers, polyimide fibers can be prepared from polyamic acid (PAA) solution by dry‐spinning technology. The transformation from the precursor of polyamic acid to polyimides via thermal cyclization reaction in the dry‐spinning process is a main distinguishing feature, which is very different from other fibers produced by dry‐spinning such as cellulose acetate fiber and polyurethane fiber. In this report, the dry‐spinning formation of polyimide fibers with trilobal cross section from PAA solution in N,N‐dimethylacetamide is simulated via a one‐dimensional model based on a viscoelastic constitutive equation, combined with profile degree equation of cross section and imidization kinetics equation. The glass transition temperature, imidization degree and profile degree of the filament along the spinline are predicted by the model, as well as relative parameters such as solvent mass fraction and temperature. As a simulated result, solidification of polyimide fibers take place about 150 cm from the spinneret which is farther than for cellulose acetate fiber (70 cm). Moreover, the final profile degree of fiber is affected by many spinning parameters, such as spinning temperature, surface tension, spinning solution concentration, major, and minor axis length of the spinneret hole. POLYM. ENG. SCI., 55:2148–2155, 2015. © 2015 Society of Plastics Engineers     

Study on morphology control and how to affect mechanical properties of polyimide/silica hybrid films

A series of polyimide (PI)/silica hybrid films were prepared by sol–gel method, using hydrolyzed tetraethoxysilane and poly amic acid‐imides (PAA‐Is), which were different imidization degree controlled by chemical imidization method. The imidization degree was characterized by Fourier transform infrared spectra and their corresponding morphology was characterized by scanning electron microscopy. The results show that there are two kinds of silica particles and their formative morphology obeys the double phase separation mechanism. According to the increase of PAA‐I imidization degree, amount of nano silica particles decreased and the diameter of macro silica particles increased in the hybrid films. Tensile testing, dynamic mechanical analysis, and thermal mechanical analysis results show that, according to the amount of nano silica particles increasing, the hybrids have the higher the mechanical properties, glass transition temperature (T_g), and thermal expansion coefficient. Through controlling PI/silica hybrid films microstructure, its mechanical properties can be controlled. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚酰亚胺前驱体化学亚胺化研究进展

聚酰亚胺是一类高性能的聚合物,它可由其前驱体聚酰胺酸经热或化学亚胺化而得到。化学亚胺化是在较温和的条件下,经脱水剂和催化剂作用而进行的。综述了聚酰胺酸化学亚胺化的研究进展,对其脱水体系进行了归纳总结,分析了不同脱水体系下的反应机理,对乙酸酐／吡啶和乙酸酐／三乙胺体系下聚酰胺酸化学亚胺化的动力学进行了讨论与比较,并简要介绍了聚酰胺酸化学亚胺化法在光纤纺纱、塑料零件和型材、挠性覆铜板及微电子用聚酰亚胺材料的制备中的应用。     

Polyamic acid: nanoprecipitation and electrophoretic deposition on porous supports

Polyamic acid (PAA, a precursor of polyimide) was synthesized from 4,4′-oxydiphthalic anhydride and 4,4′-oxydianiline. PAA, dissolved in dimethylsulfoxide (DMSO), was precipitated into colloidal particles after its injection into acetone. The resulting particle size distribution was found to depend on aging time of PAA solutions, their concentration, and the manner in which the solutions were mixed with acetone. PAA particles of any size down to 10 nm appeared to be achievable by decreasing the acetone/DMSO ratio. Particles in DMSO/acetone suspensions were found to have a significant negative zeta potential. Therefore, there was no need to add organic bases to form PAA anions, in contrast to all previously published studies on the PAA electrodeposition. EPD was performed onto porous stainless-steel or alumina disks, which are suitable supports (reinforcements) for membranes. The slow evaporation of DMSO residue yielded dried polymer layers, comprised of 50–100 nm PAA globules. The outer surface of layers was usually covered with a very thin, continuous PAA skin. Such supported PAA layers—after a simple imidization step via a heat treatment—could be applied as thermally resistant membranes for gas separation.     

Ion beam-induced positive imaging of polyimide via two step imidization

The preparation of ion track membranes of thermally stable polyimide films has been performed by ion beam irradiation of partially imidized polyamic acid (PAA) films followed by alkaline etching and final imidization. No discernible positive hole patterns were observed on the irradiated films of partially imidized PAA containing sulfonyl linkages, although sulfonyl group is known to be highly sensitive to ion beams. In contrast, positive hole patterns appeared on the irradiated films of the partially imidized PAA with 68-89% imidization degrees that contains sulfonyl linkages along with a methylene group in the main chain. The most contrasty hole patterns with 0.3 μm diameter were observed on the irradiated PAA films of 89% imidization degree. The irradiated PAA film with the hole patterns was then transformed to the corresponding polyimide film with curing at 350 °C for 1 h. From the structural comparison of the polyimides, the possible mechanism for the hole pattern formation is suggested.