聚(吡咯/二苯胺磺酸)/石墨烯复合材料的制备及其抗静电性能研究

采用化学氧化聚合法,以石墨烯(RGO)为掺杂剂,吡咯(Py)和二苯胺磺酸(SD)共聚制备导电复合材料。通过正交实验和分散性实验确定最佳合成条件为:以Fe Cl3·6H2O为氧化剂,n(氧化剂)∶n(单体)=1∶1,n(Py)∶n(SD)=7∶3(总量为0.01 mol),m(RGO)=0.05 g;在此条件下制备的复合材料电导率为12.05 S/cm,且具有良好的水分散性。用傅里叶变换红外(FTIR)光谱和X射线衍射(XRD)对其结构进行了表征,并使用热重分析仪(TGA)对复合材料的热稳定性进行了测试。结果表明,SD结构单元成功嵌入聚吡咯(PPy)的分子链中,RGO的掺杂使复合材料电导率和热稳定性都有了明显提升。将复合材料作为导电填料加入到水性聚氨酯中,考察了涂层的抗静电性能和机械性能,在添加量为4%时,涂层的综合性能较好,涂层表面电阻率可达8.65×107Ω。     

聚吡咯/海泡石一维纳米复合材料的制备及表征

以三氯化铁（FeCl3）为氧化剂,十二烷基磺酸钠（SDS）为掺杂剂,通过原位聚合的方法制备了聚吡咯/海泡石（PPy/SEP）纳米复合材料。研究了吡咯（Py）用量、聚合时间、氧化剂用量以及掺杂剂用量对复合材料电导率的影响,确定了制备导电复合材料的工艺条件。结果表明,在Py用量（以SEP质量计）为25 %,聚合温度为0 ℃,聚合时间为12 h,FeCl3/Py摩尔比为2.3/1,SDS/Py摩尔比为1/5的条件下制备的PPy/SEP复合材料电导率为2.15 S/cm。采用透射电镜、红外光谱、X射线衍射及热分析表征纳米复合材料的形貌与结构。结果表明,制备的PPy/SEP纳米复合材料为具有核壳结构的一维纳米复合材料,且PPy以非晶态的形式存在于SEP表面。     

超声辅助原位聚合聚吡咯/石墨烯纳米复合材料的制备及其性能研究

利用超声波的分散、粉碎、活化、引发等多重作用以及吡咯单体与石墨烯的π-π相互作用,在实现石墨烯均匀分散的同时,使吡咯单体在石墨烯表面进行原位聚合反应,制备出聚吡咯/石墨烯(PPy/RGO)纳米复合材料。运用扫描电子显微镜(SEM)、红外光谱(FTIR)、X射线光电子能谱(XPS)等测试手段对PPy/RGO纳米复合材料的表面特性、化学组成及结构等进行了表征。在此基础上,研究了制备过程中的各种因素(如氧化剂、反应温度、石墨烯含量等)对PPy/RGO纳米复合材料产率及导电性能的影响。并采用热重分析(TGA)和导电测试分析了石墨烯含量对其热稳定性及电导率的影响。     

聚吡咯/凹凸棒石纳米复合材料的制备及导电性能

以三氯化铁(FeCl_3)为氧化剂,十二烷基磺酸钠(sodium dodecylsulfonate,DSNa)为掺杂剂,使吡咯单体(pyrrole,Py)在凹凸棒石(attapulgite,ATP)的表面发生原位聚合反应,制备出聚吡咯/凹凸棒石(polypyrrole/attapulgite,PPy/ATP)纳米导电复合材料.研究了毗咯用量、聚合温度、聚合时间、FeCl_3用量以及DSNa用量对纳米导电复合材料体积电阻率的影响,确定了制备纳米导电复合材料的工艺条件.通过X射线衍射、热重-差热分析、Fourier红外光谱、Raman光谱和透射电子显微镜对纳米复合材料进行表征,结果表明:当吡咯用量(以ATP的质量计)为30%,FeCl_3与Py的摩尔比为2.3,DSNa的浓度为0.02g/mL时,20℃反应3h得到的PPy/ATP复合材料的体积电阻率可达7Ω·cm,聚吡咯以非晶态形式存在于凹凸棒石表面,两者之间的作用为物理作用.     

聚吡咯/二氧化硅复合材料的制备及导电性的研究

以三氯化铁(FeCl3)为氧化剂,对甲苯磺酸钠(TSANa)为掺杂剂,在水中使吡咯(Py)单体在二氧化硅(SiO2)粒子表面发生化学氧化聚合反应,制备了具有良好导电性的聚吡咯/二氧化硅(PPy/SiO2)复合材料。结果表明:当FeCl3与Py的摩尔比为2 5,Py与SiO2的质量比为0 3,TSANa的浓度为0 020g·ml-1,在10℃下反应4h,得到的复合材料具有最高电导率12 6S·cm-1。FT-IR结果表明:在形成复合材料过程中PPy与SiO2发生了一定的物理和化学作用。     

聚吡咯/有机蒙脱土纳米复合材料的制备及其导电性

以三氯化铁(FeCl3)为氧化剂,对甲苯磺酸钠(TSANa)为掺杂剂,使进入经有机插层剂改性的有机蒙脱土(OMMT)层间的吡咯(Py)发生氧化聚合反应,制备了具有良好导电性的聚吡咯/有机蒙脱土(PPy/OMMT)纳米复合材料。结果表明,采用插层剂为十八烷基三甲基氯化铵(OTAC)改性的有机蒙脱土OMMT-O,FeCl3与Py的摩尔比为2 14,Py与OMMT-O的质量比为0 24,TSANa的浓度为0 023g·ml-1,在20℃反应6h,得到的PPy/OMMT-O纳米复合材料的电导率达到3 07S·cm-1。XRD测试表明,在形成复合材料过程中PPy已经插层进入到蒙脱土的片层中。     

聚吡咯/凹凸棒土纳米复合材料的制备及结构表征

以十二烷基磺酸钠为掺杂剂,FeCl3·6H2O为氧化剂,引发吡咯单体（Py）发生化学氧化聚合,制备出聚吡咯/凹凸棒土纳米复合材料（PPy/ATP）,并通过XRD、TG-DTA、FTIR和TEM等技术手段对所得的复合材料进行了表征。体积电阻率测量表明,随着Py用量的增大,纳米复合材料的体积电阻率逐渐变小,当Py/ATP的质量比≥0.25时体积电阻率变化不大。XRD和TEM显示,聚吡咯以非晶态形式包覆在凹凸棒土单晶的表面,形成核-壳棒状纳米结构,包覆层厚度约为2 nm。TG-DTA表明凹凸棒土纳米复合材料的耐热性能与纯聚吡咯相比明显提高。FTIR表明纳米复合材料中聚吡咯与凹凸棒土之间存在物理作用。     

PLA/PPy复合材料的制备及表征

以吡咯(Py)为原料,通过原位聚合法合成聚吡咯(PPy)导电粒子,通过PPy粒子对聚乳酸(PLA)进行改性,制备PLA基导电复合材料,并对其形貌、力学性能及导电性能进行测试。结果表明:PPy可以与PLA基体呈现一种紧密结合的状态;PLA/PPy(5%)导电复合材料综合性能最佳,其拉伸强度为51.2 MPa、断裂伸长率为163.5%、电导率为4.12×10~(-5) S/cm。     

PEDOT/石墨烯复合材料的制备及其抗静电性能研究

采用原位聚合法,以氧化石墨烯(GO)为掺杂剂,将3,4-乙烯二氧噻吩(EDOT)原位聚合在氧化石墨烯的表面,制备了部分还原氧化石墨烯/聚3,4-乙烯二氧噻吩(rGO/PEDOT)导电复合材料。实验表明:当m(EDOT):m(GO)=1:1时制备的复合材料具有良好的水分散性,电导率为2.56S/cm。用全反射红外光谱和拉曼光谱对其结构进行了表征,并使用透射电镜(TEM)对复合材料在水中的分散性进行了表征。结果表明:PEDOT成功聚合在GO的表面上,且PEDOT的聚合使氧化石墨烯得到了部分还原。将复合材料作为导电填料加入到水性聚氨酯中,测试了涂层的抗静电性、机械性能和热稳定性,在添加量为10%时,涂层的综合性能较好,涂层表面电阻可达1.27×10~9Ω。     

聚吡咯/羧酸化细菌纤维素复合材料的电学性能研究

基于细菌纤维素的多羟基结构，对其进行羧酸化改性；接着以羧酸化细菌纤维素为模板，原位复合聚吡咯（PPy），得到PPy/羧酸化细菌纤维素导电复合材料。并对其微观形貌、化学结构、热稳定性等进行测试表征，重点研究了用不同浓度的氧化剂处理后，复合材料电学性能的变化。结果表明，电子电导率随氧化程度的提高而升高，最高可达10^-3 S/cm，编号为0.04-48h的样品具有最佳的离子电导率。     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.