碳纳米管/白炭黑/炭黑补强溶聚丁苯橡胶纳米复合材料导电性能的研究

研究碳纳米管(CNTs)/白炭黑/炭黑补强溶聚丁苯橡胶(SSBR)纳米复合材料的导电性能。结果表明,当白炭黑用量小于50份时,白炭黑的阻隔效应占主导,CNTs/白炭黑补强SSBR纳米复合材料的导电性能较差;当白炭黑用量达到70份时,白炭黑的体积排除效应占主导,复合材料的导电性能较好。炭黑和CNTs的协同作用可提高CNTs/白炭黑/炭黑补强SSBR纳米复合材料的导电性能。偶联剂Si747改性复合材料的导电性能优于未添加偶联剂Si747的复合材料。     

白炭黑/炭黑/SBR复合材料的结构和抗静电性研究

采用高温共混技术制备白炭黑/炭黑/溶聚丁苯橡胶(SSBR)和白炭黑/炭黑/乳聚丁苯橡胶(ESBR)复合材料,并分别对其结构和性能进行研究.结果表明,在填充剂总量不变的前提下,随着白炭黑用量的增大,白炭黑/炭黑/SSBR和白炭黑/炭黑/ESBR复合材料物理性能呈现加和效应的特点,动态性能提高,表面电阻和体积电阻率增大;白炭黑/炭黑/SSBR复合材料物理性能与白炭黑/炭黑/ESBR复合材料差别较小,但前者动态性能较好;添加导电炭黑使复合材料抗静电性提高、物理性能下降;当白炭黑/炭黑并用比为35/35、导电炭黑用量不大于5份时,白炭黑/炭黑/SSBR复合材料的综合性能较好.     

酚醛树脂改性淀粉/NR复合材料的性能研究

采用间苯二酚-甲醛(RF)树脂改性淀粉,通过乳液共沉法制备淀粉/NR复合材料,研究改性淀粉用量对复合材料性能的影响,并与相同体积分数的炭黑和偶联剂Si69改性的白炭黑填充的NR复合材料进行对比。试验结果表明,RF树脂的加入增强了淀粉与NR之间的交联作用,提高了淀粉/NR复合材料的物理性能;当淀粉用量为20份、经3.6份RF树脂改性后,复合材料的综合性能最佳;随着改性淀粉用量的增大,复合材料的硬度和300%定伸应力增大。当填料体积分数相同时,改性淀粉对NR的补强效果与炭黑接近,且优于白炭黑。     

导电炭黑/三元乙丙橡胶电磁屏蔽复合材料的性能研究

以三元乙丙橡胶(EPDM)为基体、导电炭黑为导电填料,并添加增塑剂,制备可挤出加工的炭黑/EPDM电磁屏蔽复合材料,研究炭黑和增塑剂的品种和用量对复合材料性能的影响.结果表明:添加结构度高、粒径小的导电炭黑有利于形成导电网络;随着炭黑用量的增大,复合材料的体积电阻率逐渐降低,当炭黑用量达到18份时,可以得到体积电阻率小于10Ω·cm的导电橡胶复合材料;添加20份石蜡油时,能有效降低胶料的门尼粘度.     

乳聚丁苯橡胶/白炭黑/偶联剂体系挤出流变特性的研究

本工作研究了白炭黑含量及偶联剂种类对填充丁苯橡胶挤出流变特性的影响,并分析了三种偶联剂的接枝效率。结果表明：在低剪切速率下,白炭黑填充体系的非牛顿指数n与其填充量关系不大;在高剪切速率下,胶料的非牛顿指数随填充量增加而增大。当填充量为40phr时,偶联剂Si747胶料粘度大,Payne效应大,挤出物外观粗糙,有较好的挤出温度稳定性;偶联剂Si69与Si75对白炭黑的改性效果差别不大。     

UHMWPE/炭黑抗静电复合材料的研究

制备了导电炭黑(CB)填充UHMWPE抗静电复合材料。实验结果表明,在经表面固相接枝改性的UHMWPE/CB复合体系中,炭黑渗滤区含量为5%~7%,表面电阻ρs从1014Ω下降到107Ω,较低的炭黑含量确保了复合材料优异的耐磨性;同时扫描电镜(SEM)表征证明炭黑在改性UHMWPE中达到纳米分散,形成双重纳米导电网络结构,这种双重纳米导电结构提高了复合材料的抗静电性能、力学性能和热变形温度。     

华光导电炭黑填充硅橡胶的研究

研究了华光导电炭黑填充硅橡胶的工艺性能、导电性能及物理机械性能。实验表明：在不添加软化剂的情况下，华光导电炭黑在硅橡胶中的填充量应小于30phr；在硅橡胶中填充20phr时，加工性能和综合性能较好，表面电阻率为23Ω·cm，体积电阻率为100～101Ω·cm，拉伸强度则可达5．7MPa，可见，华光导电炭黑在较低填充份数下，硫化胶的电阻率较低，而拉伸强度较高，极具有应用前景。     

硅烷偶联剂对白炭黑Z1165MP填充SSBR/BR性能的影响

研究了硅烷偶联剂NXT、Si747改性白炭黑Z1165MP填充SSBR/BR的硫化特性、物理性能及动态性能,并与Si69进行了对比。结果表明,与偶联剂Si69和Si747相比,NXT具有较好的抗焦烧性能,当偶联剂用量较高时,这种优势更加明显,3种偶联剂的抗焦烧能力顺序为NXTSi69Si747。Si69和Si747改性体系,当偶联剂用量分别达到3.2份和6.4份后,硫化胶的拉伸强度明显下降,拉断伸长率逐渐降低;NXT改性体系,拉伸强度在实验用量范围内变化不大,拉断伸长率明显降低,当用量达到1.6份后,降低程度明显减小。3种改性体系的撕裂强度均有所改善,压缩疲劳温升和阿克隆磨耗体积明显降低。混炼胶和硫化胶的G′0.56%和G′0.56%-G′100%均随着偶联剂用量的增加明显降低,当偶联剂用量达到4.8份后NXT和Si747改性体系的Payne效应较Si69改性体系小。     

纳米氧化锌/EPDM复合材料的性能研究

试验研究纳米氧化锌/EPDM复合材料的物理性能和导热性能,并与炭黑和白炭黑补强的EPDM胶料进行对比.结果表明,纳米氧化锌的导热性能明显优于炭黑和白炭黑等传统补强填料,其对EPDM具有较好的补强作用,纳米氧化锌/EPDM复合材料的生热较低;采用偶联剂Si69对纳米氧化锌进行原位改性可以改善纳米氧化锌粒子与EPDM间的界面作用,提高其分散性,从而显著提高复合材料的物理性能,降低生热;改性纳米氧化锌/EPDM复合材料的物理性能和导热性能良好,可用于动态工况下使用的橡胶制品.     

改性碳纳米管在不同补强填充体系丁腈橡胶中的应用研究

研究改性碳纳米管（CNTs）在碳酸钙、白炭黑、炭黑N330补强填充体系丁腈橡胶（NBR）中的应用。结果表明：随着改性CNTs用量增大,碳酸钙补强填充体系和白炭黑补强填充体系NBR的MH－ML逐渐增大,t90缩短;炭黑N330补强填充体系NBR的MH－ML增大,t90延长;3种补强填充体系NBR的硬度、100%定伸应力、撕裂强度逐渐增大,碳酸钙补强填充体系NBR的拉伸强度提高,白炭黑补强填充体系和炭黑N330补强填充体系NBR的拉伸强度稍有降低;碳酸钙补强填充体系和白炭黑补强填充体系NBR的表面电阻率（ρs）和体积电阻率（ρv）变化较小,变化规律不明显;炭黑N330补强填充体系NBR的ρs和ρv较小,导电效果较好;3种补强填充体系NBR的导热性能均有所提高,炭黑N330补强填充体系胶料的热扩散率最大。     

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.