A Fluoropolymer Coating on Carbon Fibers Improves Their Adhesive Interaction with PTFE Matrix

Carbon fibers were treated in a HF glow discharge in tetrafluoroethylene and octafluorocyclobutane in order to improve their adhesion to poly(tetrafluoroethylene) matrix. As the result of the plasma treatment, a thin (20–140 nm) fluoropolymer coating was deposited onto the fiber surface. The structure of this coating was studied by means of IR spectroscopy, XPS, AFM and SEM techniques. The coating material appeared to be similar to PTFE in its chemical composition but distinguished by branched, partially crosslinked, amorphous structure and included unsaturated chemical bonds. The coating thickness of 70 nm was sufficient to effectively screen the field of molecular forces of the initial substrate, thus, decreasing the surface energy of the fibers and improving their compatibility with the PTFE matrix. The adhesive strength in the PTFE–carbon fiber systems, measured by means of the microbond test, more than doubled upon the plasma treatment (the local interfacial shear strength increased from 10.7 to 29.7 MPa, apparent IFSS from 4.3 to 7.8 MPa), and the interfacial frictional stress increased by 70%. The new composite material consisting of 20% short coated carbon fibers in the PTFE matrix showed better mechanical, thermal and tribological characteristics as compared with the composite reinforced with untreated fibers.     

Micromechanical properties of poly(butylene terephthalate) nanocomposites with single- and multi-walled carbon nanotubes

Polymer nanocomposites with carbon nanotubes (CNT) are becoming important structural materials because of their superior mechanical properties and easy processability. The objective of the work is to investigate the influence of small amounts of single walled carbon nanotubes (SWCNT), as well as multi-walled carbon nanotubes (MWCNT), on the microhardness of a thermoplastic polymer such as poly(butylene terephthalate) (PBT). The nanocomposites were obtained by introducing the CNT into the reaction mixture during the synthesis of PBT. The polymers without carbon nanotubes (reference material) and with carbon nanotubes were synthesized using an in-situ polycondensation reaction process. Weight percentages ranging from 0.01 to 0.2 wt% of the single walled and from 0.01 to 0.35 wt% of the multi-walled nanotubes were dispersed in 1,4-butanediol (BD) by ultrasonication and by ultra high speed stirring. The nanocomposites were extruded followed by injection molding. The samples were characterized by electron microscopy and microindentation hardness techniques. The variations of the micromechanical properties (indentation hardness) of the nanocomposites with nanotube content and with temperature are discussed in the light of the stress transfer between the polymer matrix and nanotubes, the degree of dispersion, the nature of the tubes and other structural parameters.     

葡萄糖水溶液中碳酸盐热力学研究 1.二氧化碳-碳酸氢钠-氯化钠-葡萄糖-水体系

在278.15～318.15K和一定离子强度范围内,测定了无液接电池Pt,(1-x)H~2+xCO~2│NaHCO~3(m~1),NaCl(M~2),.CO~2(m~3),葡萄糖(m~4)│AgCl-Ag的电动势,利用改进的Harned外推法和我们提出的多项式拟合法确定了二氧化碳在15%葡萄糖水溶液中的一级酸常数K 两种方法所得PK 值在实验误差范围内一致.PK 随温度变化符合经验方程PK =A~1+A~2/T+A~3T,并计算了二氧化碳在葡萄糖水溶液中解离过程的各热力学量.     

有机硼酸盐的化学II. 三烷基炔基硼酸锂与CO2反应过程中转移烷基的立体构型问题

本文研究了三烷基炔基硼酸锂与CO2 什应过程中转移烷基的立体构型问题,发现在该反应过程中烷基转移时其立体构型保持不变.这一特点对合成具有特定结构的有机化合物有一定意义.     

自溶液中的吸附XII.活性炭自水中吸附芳香化合物的热力学研究

测定了25℃和35℃时活性炭自水中吸附苯甲酸,邻苯二甲酸,邻羟基苯甲酸,间羟基苯甲酸,对羟基苯甲酸,苯酚和邻苯二酚共七种芳香化合物的等温线,计算了吸附过程的△G,△H和△S.七种芳香化合物的-△G都在5.9～7.7kcal.mol[-1]的范围内,差别不大;-△h都小于-△g的值;△s则都是正的。这些结果表明熵变是这类体系的吸附过程的重要驱动力,而且往往是主要驱动力,在液相吸附中,溶质的吸附必伴随着溶剂的脱附,前者是熵减少的过程,后者是熵增加的过程。因为上述芳香化合物的摩尔体积约是水(溶剂)的5～7倍,也就是说,吸附1摩尔的溶质将伴随5～7摩尔的水由表面脱附。因此,由于水的脱附引起的熵增加远远超过溶质吸附所引起的熵减少,这可以解释为何这类体系的吸附过程的熵变总是相当大的正值,根据这个理论,可以设想倘若溶剂的摩尔体积与溶质的相近或比溶质的更大时,吸附过程的熵变可能出现负值,文献中的一些数据支持了这一推测。     

聚(3-甲基噻吩)的电化学稳定性及电催化行为

用连续循环伏安法研究了电化学法制备的聚(3-甲基噻吩)(PMT)薄膜修饰玻璃碳电极在不同支持电解质溶液中的电化学稳定性。在易嵌入PMT的阴离子存在下, PMT电活性随扫描次数按表现二级反应降低; 在难嵌入PMT的离子存在下, PMT具有良好稳定性; 在含有氯、溴离子的水溶液中, PMT可将卤离子电催化氧化, 并引起PMT电活性迅速下降。光电子能谱分析表明氯已键合到PMT结构上。     

电化学活化碳纤维微电极和脑神经递质及抗坏血酸在体测定

本文采用一种简单电化学方法,即恒电流法处理自制碳纤维电极,在脑神经递质测定中显示了很高的灵敏度和分辨能力.活化后的电极对多巴胺的检测限达5×10^-8mol.dm^-3,对多巴胺和抗坏血酸的伏安峰分离达170mV.作者使用该电极,采用半微分伏安法测定了活体大鼠脑内抗坏血酸,3,4-二羟苯乙酸和5-羟吲哚乙酸的浓度分别为1.7×10^-4,2.1×10^-5和 3.3×10^-6mol·dm^-3.本文对电极的制作,活化条件,伏安峰判别,在体药物实验和电极活化机理等进行了研究和探讨.     

有机金配合物催化羰化胺制甲酰胺

Au(PPh3)2Cl,[Au(PPh3)]2S等有机金配合物催化羰化脂肪族二胺制相应二酰胺显示出非常好的活性,与同一类的有机钯催化剂相比,具有更好的催化转化能力和选择性。实验结果还表明适量分子氧的引入对反应有明显的促进作用。     

锆诱导的五元环化合物的新和成

由锆杂五元环化合物出发合成五元环有机化合物,只要求一个碳单元并且形成两个碳-碳链,从以下四个方面描述了利用锆杂环化物合成五元环有机化合物的新合成方法：(1)CO或RNC的插入反应;(2)与丙炔酸酯的加成反应-峡谷次的Michael加成;(3)与碘代丙烯酸酯或碘代环烯酮的偶联加成反应-先偶联后Michael加成;(4)与酰氯的取代加成反应-先亲核取代后亲核加成,每类反应都含有数个简单反应类型。     

超临界二氧化碳介质中有机化学反应研究

综述了本研究小组近年来在超临界二氧化碳介质中过渡金属催化的有机化学反应的研究结果,主要包括烯烃和炔烃的羰基化反应、氧化反应、自由基反应、低聚反应。