粉末法制备聚酰亚胺泡沫塑料

以芳香二酐和二胺为单体,甲醇/四氢呋喃为溶剂,通过酯化法合成聚酯铵盐前驱体粉末、粉末法制备泡孔均匀的聚酰亚胺泡沫塑料.采用扫描电子显微镜照片、傅里叶变换红外光谱和热重分析表征泡沫材料结构及耐热性能,研究了初始加热温度、粉末粒径对泡沫密度的影响.结果表明:初始加热温度越高,泡沫密度越小.粉末粒径对泡沫密度影响较小.     

聚酰亚胺泡沫塑料制备与性能研究

采用一步缩聚法制备了聚酰亚胺(PI)泡沫塑料,并对其结构和性能进行了表征。经红外光谱测定,在1778、1720cm-1和1375cm-1处观察到PI特征峰。实验结果表明,所得PI泡沫塑料孔径均匀,平均密度小于0.30g/cm3,极限氧指数为38%,平均吸声系数为0.42,玻璃化转变温度为262.4℃,起始分解温度为549.7℃。     

聚酰亚胺泡沫塑料的合成路线及制备工艺

综述了主链聚酰亚胺泡沫塑料的各种合成路线和制备工艺中的发泡剂、发泡方法及泡孔结构的控制方法,分析对比了不同合成路线和制备工艺的技术特点;并介绍了侧链型聚酰亚胺泡沫塑料以及聚酰亚胺纳米泡沫塑料的合成路线和制备工艺。聚酰亚胺纳米泡沫塑料的纳米效应及其物理化学性能研究等也将是今后的重点。     

聚酰亚胺泡沫塑料开发研究概述

介绍了聚酰亚胺泡沫塑料的6种合成方法和制备工艺中所应注意的几个方面(发泡方法、泡孔大小和形状控制等)。并综述了聚酰亚胺泡沫塑料的高低温性、高抗拉强度、高弹性模量、耐辐射性、高介电性能等优异的性能及其在透波材料、阻尼材料、耐高温材料、低放气材料、低温材料、复合材料、介电材料等方面的应用。聚酰亚胺泡沫塑料的发展还应有更广阔的空间。     

PVFM泡沫塑料的研究及应用

介绍了PVFM泡沫塑料的性能、技术指标、成型方法及应用情况     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。     

聚乙烯醇缩甲醛泡沫塑料的研究

本文论述了用机械发泡法制备聚乙烯醇缩甲醛泡沫塑料的工艺及其影响因素。     

酯化法合成丙酸乙酯的动力学研究

以阳离子交换树脂Amberlyst 45为催化剂,在间歇搅拌釜式反应器中对酯化法合成丙酸乙酯的本征动力学进行研究,考察搅拌转速、催化剂用量、酸醇摩尔比、反应温度等因素对反应过程的影响。得出较好的反应条件为转速400 r/min,催化剂用量为丙酸溶液质量的6%,反应温度为358.15 K。酸醇摩尔比为1.4∶1。通过348.15—363.15 K下的实验数据进行拟合得到反应平衡常数,建立了拟均相反应模型,获得反应动力学方程。     

泡沫塑料熔体粘度的研究

在塑料熔体的发泡成型过程中,熔体的粘度是基本的流变性能之一,粘度影响到气泡的成核和长大,是制定发泡成型工艺和原料配方即设计发泡机头的重要依据,带有发泡剂的塑料熔体的粘度是温度、剪切速率和熔所含发泡剂种类、浓度及分布状态等的函数,对含有化学发泡 以ＣＯ２为发泡剂的泡沫塑料熔体粘度分别进行了探讨,介绍了相应的计算公式,分析了其影响因素 。     

微波辐射合成聚酰胺酸和聚酰亚胺的研究

在N,N’-二甲基甲酰胺溶剂中,以均苯四甲酸酐和3,3’,4,4’-二苯酮四羧酸二酐为二酐单体,4,4’-二氨基二苯醚和4,4’-二氨基二苯甲烷为二胺单体,采用微波辐射低温溶液共缩聚,合成了聚酰胺酸(PAA)预聚体,然后亚胺化脱水、环化,生成共缩聚聚酰亚胺(PI)。通过红外光谱(FT-IR)、特性粘度[η]和热重分析(TG)等对聚合物进行了一系列的结构表征和性能测试。结果表明,微波辐射溶液聚合能够提高PAA的特性粘数及产率,微波的引入大大缩短了反应时间;FT-IR表明,在1 775 cm-1和1 724 cm-1处观察到聚酰亚胺特征峰;TG表明,PI的5%热失重温度(Td5%)为477℃,10%热失重温度(Td10%)为553℃。     

Visualization study of foaming process for polyimide foams and its reinforced foams

In this article, the foaming processes of polyimide foams and its reinforced foams were observed by a self‐made visualization device at different heating rates ranging from 10°C/min to 120°C/min. Contributing factors such as chemical structure of polyimide, fillers, and heating rate were investigated to determine the effects on the inflation onset temperature and morphological change of polyimide foam precursor powders. The results showed that the powder might grow into a single bubble mesostructure at a lower heating rate or a multibubble mesostructure at a higher heating rate. Because of the filling of reinforcing fillers, the inflation morphology of reinforced polyimide foam precursor powders show a different change trend with the increase of temperature compared to the pure polyimide foam precursor powders. For all kinds of polyimide foam precursor powders investigated in this article, the inflation morphologies showed a similar variation trend with different heating rates, and the final inflation degrees were slightly different. The inflation onset temperatures of all polyimide foam precursor powders studied decreased with increasing heating rate. POLYM. COMPOS., 2010. © 2008 Society of Plastics Engineers     

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。     

酯化工艺塔EG循环量对酯化工艺的影响

改变酯化工艺塔EG循环量,测试工艺塔回流水中的非水分（有机物）含量,酯化热井中EG水含量及切片中端羧基和DEG含量,探讨酯化EG循环量变化对酯化反应的影响,为更高负荷生产扩展空间。     

Carbon foams prepared from polyimide using urethane foam template

Polyimide and carbon foams were successfully prepared using polyurethane foams as a template. Impregnation of polyimide precursor, poly(amide acid), followed by imidization at 200 °C gave polyurethane/polyimide (PU/PI) composite foams, which resulted in PI foams by heating above 400 °C and then carbon foams above 800 °C. Foams carbonized at 1000 °C were graphitized by the heat treatment at 3000 °C, keeping foam characteristics. Two applications of these carbon foams, i.e., an adsorbent of ambient water vapor and a substrate of photocatalyst anatase TiO₂, were experimentally confirmed. For the former application, the present foam could be characterized by prompt adsorption of ambient water vapor. Some of carbon foams prepared were floating on water, even after loading photocatalyst anatase, which might be advantageous for photodecomposition of pollutants in water in respect to the UV rays efficiency.     

Characterization of polyimide foams after exposure to extreme weathering conditions

The weathering degradation of three closely related polyimide foams was studied by X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FT-IR) spectroscopy, Raman spectroscopy, Thermogravimetric Analysis (TGA) and Thermomechanical Analysis (TMA) after exposure at the NASA Kennedy Space Center's (KSC) Beach Corrosion Site. These foams were developed by NASA Langley Research Center for applications such as cryogenic insulation, flame retardant panels and structural subcomponents. The degradative environmental conditions at the KSC corrosion site include exposure to sunlight, exposure to changes in temperature and humidity, mechanical erosion by wind and rain, and high sodium chloride content due to the close proximity of the ocean. Other possible atmospheric contaminants include hydrogen sulfide and hydrogen chloride (the latter originating with exhausts from the launching of space vehicles). The foams were studied for a total of 17 months exposure, with samples taken at 3, 9 and 17 months. Data analyses of the weathered foams showed that chemical structure and density effects were the key variables in weathering performance. The carbonyl linkage in the dianhydride of the TEEK-L series polyimide foams is the most important factor in degradation. TEEK-H series foams, which contain an ether linkage in the dianhydride, showed much less degradation or more resistance to weathering in comparison to the TEEK-L series. In the same chemical series, the lower density foams were more degraded in comparison to higher density foams.     

酯化工艺塔的改造

阐述了聚酯酯化反应以及工艺塔的工作原理,分析实际运行中存在的问题,通过对原设备改造,提高了酯化各项工艺稳定性,降低了生产污水的化学需氧量。     

Structures and properties of closed‐cell polyimide rigid foams

Closed‐cell polyimide rigid foams with different Calculated Molecular Weight (Calc'd M_n) and foam density (ρ) have been prepared by thermal foaming of nadimide‐endcapped imideoligomers (NAIO) powder. The NAIO powder was obtained by thermally treating of a PMR poly(amide ester) solution derived from the reaction of diethyl ester of 2,3,3′,4′‐biphenyltetracarboxylic dianhydride (α‐BPDE) and p‐phenylenediamine (p‐PDA) using monoethyl ester of cis‐5‐norbornene‐ endo‐2,3‐dicarboxylic acid (NE) as reactive endcapping agent in ethyl alcohol. Effect of Calc'd M_n and foam density (ρ) on mechanical and thermal properties of the polyimide rigid foams have been systematically investigated. It was found that the thermal foaming properties of NAIO powders were affected by the Calc'd M_n. The appreciate Calc'd M_n could yield polyimide foams with both high closed‐cell content (C_c) (>80%) and outstanding mechanical properties. Moreover, the thermal properties were reduced by increasing of Calc'd M_n and the mechanical properties improved gradually by increasing foam densities. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3282–3291, 2013     

Preparation and characterization of high‐temperature resistance polyimide foams

A new high‐temperature resistance polyimide foam was synthesized from 2,3,3′,4′‐biphenyltetracarboxylic dianhydride (α‐BPDA) and p‐phenylenediamine (p‐PDA). The structures and foaming process of polyimide precursor powders were characterized by wide‐angle X‐ray diffractometer (WXRD) and the self‐made visualization device, respectively. The imidization degree, thermal mechanical properties and thermal stability of the polyimide foams with different post‐treatment temperatures were also measured by fourier transform infrared spectrometer spectrum (FTIR), dynamic thermal mechanical anaylsis (DMTA), and thermogravimetric analysis (TGA). Results showed that the inflation onset temperatures of polyimide precursor powders ranged from 122 to 135°C with varying the heating rate. And the increase in the imidization degree, glass transition temperatures (T_g) and temperatures for 5 wt% mass loss of high‐temperature resistance polyimide foams can be achieved with increasing post‐treatment temperature. It was quite surprising to find that T_g of high‐temperature resistance polyimide foam post‐treated at 420°C was up to above 450°C, and the char yield at 800°C was more than 60%. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

含氰基聚酰亚胺的合成

通过对3,3′,4,4′-联苯四甲酸二酐(BPDA)进行酯化、溴代、氰基取代、水解以及脱水闭环系列反应,合成了侧链含氰基的新型对称二酐——2,2′-二氰基联苯四甲酸二酐,将其与4,4′-二氨基二苯醚(ODA)通过两步法制备了侧链含氰基的聚酰亚胺(PIDC).PIDC的结构与性能由傅里叶变换红外光谱仪、差示扫描量热仪和热重分析仪表征.结果表明:直接由BPDA和ODA通过两步法制备的聚酰亚胺在大多数有机溶剂中不溶,而室温下PIDC在极性非质子溶剂N-甲基吡咯烷酮、二甲基亚砜、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺中溶解性能良好;氰基的引入使聚酰业胺的玻璃化转变温度由266℃增至303℃,氮气氛围下失重5％的温度提高至523℃.