Imide-aryl ether ketone block copolymers

Imide-aryl ether ketone block copolymers were prepared and their morphology and thermal and mechanical properties investigated. Two aryl ether ketone blocks were incorporated; the first was an amorphous block derived from bisphenol–A and the second block was a semi-crystalline poly(aryl ether ether ketone) prepared from a soluble and amorphous ketimine precursor. Bis(amino) aryl ether ketone and aryl ether ketimine oligomers were prepared via a nucleophilic aromaic substitution reaction with molecular weights ranging from 6,000 to 12,000 g/mol. The oligomers were co-reacted with 4,4′-oxydianiline (ODA) and pyromellitic dianhydride (PMDA) diethyl ester diacyl chloride in N-methyl–2-pyrrolidone (NMP) in the presence of N-methylmorpholine. The copolymer compositions, determined by H-NMR, of the resulting amic ester based copolymers ranged from 8 to 50 wt % aryl ether ketone or ketimine content. Prior to imide formation, the ketimine moiety of the aryl ether ketimine block was hydrolyzed (p-toluene sulfonic acid) to the ketone form producing the aryl ether ether ketone block. Compositions of this block were maintained low to retain solubility. Solutions of the copolymers were cast and cured to effect imidization, producing clear films with high moduli (ca. 2200 MPa) and elongations (33–100%). The copolymers displayed good thermal stability with decomposition temperatures in excess of 450°C. Multiphase morphologies were observed irrespective of the co-block type, block length or composition. © 1992 John Wiley & Sons, Inc.     

Synthesis and properties of amine‐containing poly(arylene ether sulfone) as an anion‐exchange matrix

Poly(arylene ether sulfone) (PSF), showing good thermal stability and excellent mechanical properties, was synthesized as an anion‐exchange matrix. It was synthesized by the condensation polymerization between bisphenol A and 4,4′‐dichlorodiphenylsulfone. 1°‐Amine‐containing poly(arylene ether sulfone) (1°‐APSF) was synthesized by the reduction reaction of a nitrated PSF. Then, it was transferred to 3°‐amine‐containing poly(arylene ether sulfone) (3°‐APSF) by the alkylation of the amine of 1°‐APSF. The properties of PSF, 1°‐APSF, and 3°‐APSF were investigated by Fourier transform infrared, ¹H NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The introduction of the 3°‐amine group into PSF increased the glass‐transition temperature but decreased thermooxidative stability. The ion‐exchange capacities of 1°‐APSF and 3°‐APSF were shown to be 2.24 and 2.86 mequiv/g, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4281–4287, 2002     

Synthesis of poly (ether-sulfone-amide)s by palladium-catalyzed polycondensation of aromatic dibromides containing ether sulfone structure,aromatic diamines,and carbon monoxide

A general method for the preparation of aromatic poly (ether-sulfone-amide)s has been developed. Polymerization is based on the palladium-catalyzed polycondensation of aromatic dibromides containing ether sulfone structural units, aromatic diamines, and carbon monoxide. Reactions were carried out in N, N-dimethylacetamide (DMAc) in the presence of palladium catalyst, triphenylphosphine, and 1,8-diazabicyclo [5,4,0]–7–undecene (DBU), and gave a series of poly (ether-sulfone-amide)s with inherent viscosities up to 0.86 dL/g under mild conditions. The polymers were quite soluble in strong acids, dipolar aprotic solvents, and pyridine. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 470°C in air. The glass transition temperatures of the polymers were around 230°C, which are higher than those of poly (ether-sulfone) analogues. These polymers also showed the good tensile strengths and tensile modulus. © 1994 John Wiley & Sons, Inc.     

Synthesis,Structure Analysis,and Antitumor Activity of （R）-2,4-Dioxo-5-fluoro-l-[1-（methoxycarbonyl） Ethylaminocarbonylmethyl]-1,2,3,4-tetrahydropyrimidine

A new dipeptide compound, （R）-2,4-dioxo-5-fluoro-1-[1-（methoxycarbonyl） ethylaminocarbonylmethyl]-1,2,3, 4-tetrahydropyrimidine （5-FUAPM）, has been synthesized and identified by means of elemental analysis, IR, ^1H NMR and ^13C NMR spectra. The single crystal of compound 5-FUAPMoDMF was also obtained and characterized by DSC-TGA techniques. The crystal belongs to orthorhombic space group P212121 with the cell parameters： a= 0.4740（7） nm, b= 1.923（3） nm, c= 1.9229 nm, a=β=y=90°, V= 1.753 nm^3, Z=4, Dc= 1.312 g/cm^3, Mr=346.32, F（000）=728 and u=0.111 mm^-1. The final R and wR are 0.1378 and 0.2862, respectively. The result of the biological test showed that the compound 5-FUAPM has certain antitumor activities.     

New double negative and positive temperature coefficients of conductive EPDM rubber TiC ceramic composites

In this paper, we have successfully prepared ethylene-propylene-diene monomer (EPDM)/TiC composites as thermistors, with new double negative and positive temperature coefficients of conductivity (NTCC/PTCC). EPDM composites loaded with 50 phr HAF carbon black and different concentrations of TiC were prepared. This study focuses on the effect of TiC content on the vulcanization process, the network structure and the electrical and thermal properties of EPDM/TiC composites. The effect of TiC on the network structure was evaluated e.g. the curing process, the characteristic time constant during vulcanization, the volume fraction of rubber, gel fraction, interparticle distance between conductive particles, the extent of TiC reinforcement in the rubber matrix and molecular weight between cross-linking through experimental and affine-phantom models. The effects of TiC content on the percolation theory, electrical conductivity, conducting mechanism of conductivity, conducting hysteresis and I-V characteristics were also studied, as well as its TiC on the (NTCC/PTCC), thermoelectric power, dielectric constant and thermal conductivity. Stability and reproducibility of the thermal cycles for heating element applications was tested. Specific heat and the amount of heat transfer by radiation and convection as a function of TiC content was calculated using both the calorimetric technique and a theoretical model. It was proved that TiC improves the network structure, electrical and thermal properties of EPDM composites for practical applications.     

基于弹簧管悬臂梁的FBG压力传感的研究

提出了一种等强度悬臂梁与弹簧管结合的高灵敏度的光纤布拉格光栅(FBG)压力传感器。将FBG粘贴在悬臂梁的下表面,粘贴方向与悬臂梁轴线一致。理论分析了FBG中心波长相对偏移量与压力的关系,实验测得该传感器的压力灵敏度为2.767×10-4/MPa,是裸FBG压强灵敏度系数的142倍。压力灵敏度与悬臂梁和弹簧管的几何参数有关,改变参数,可获得不同灵敏度的压力传感器。     

功率型白光LED的热特性研究

大功率LED照明单元在光通量提高的同时伴随着散热，且普通功率型白光LED多采用蓝光芯片激发荧光粉的方法，随着温度的提升，荧光粉对应的波长会发生漂移。本文从功率型白光LED的发热原理出发，试验了其在脉冲源作用下，用于照明的可能性。试验表明，在此激励源的作用下，LED输出与散热很好，并从理论上进行了解释。     

环形腔高掺Er3 窄线宽光纤激光器实验研究

报道了采用光纤光栅（FBG）短直腔选频结构的环形腔窄线宽光纤激光器。采用约3m长高掺Er^3光纤，LD抽运阈值功率约为11mW，在25mW976nm有效抽运功率时输出信号功率为2．65mW，斜效率约为15％；输出激光3dB线宽小于0．01nm，20dB线宽小于0．04nm，边模抑制比（SMSR）为48dB；观察到输出信号光波长漂移范围为0．06nm。     

基于视频积累的距离扩展目标检测

正确提取目标强散射中心,并对强散射中心的能量进行有效的积累,是高分辨率雷达距离扩展目标检测的关键.本文先根据最大信噪比原则估计出目标窗口,然后在此窗口中利用门限检测方法提取目标强散射中心,最后利用广义似然比方法推导了自适应单扫频周期径向积检测器.仿真结果表明比文献[1]提出的SSD-GLRT检测器的性能有较大的改善.