NR／BR／OMMT纳米复合材料的研究（Ⅱ）纳米蒙脱土在工业配方中的应用

选用前期优选出的有机蒙脱土（OMMT）牌号,利用机械共混法制备了不同OMMT含量的天然橡胶（NR）/顺丁橡胶（BR）/OMMT纳米复合材料。利用透射电子显微镜研究了复合材料的亚微观结构,观察结果显示制备出了分散均匀的剥离型的NR/BR/OMMT纳米复合材料;力学性能测试表明,当OMMT的用量为3份时,其复合材料的综合力学性能最佳;耐溶剂实验表明,随着OMMT含量的逐渐增加,NR/BR/OMMT纳米复合材料的耐溶剂性能明显提高并不断提高;而OMMT在轮胎工业配方中的优异性能表明其在轮胎工业中具有良好的应用前景。     

NR/BR/OMMT纳米复合材料的结构与性能研究及其在轮胎胎面胶中的应用

采用机械混炼法制备了天然橡胶/顺丁橡胶/有机蒙脱土(NR/BR/OMMT)纳米复合材料,并对复合材料的结构与性能进行了表征。OMMT可明显提高橡胶基体的耐油性能和物理机械性能,降低混炼胶的焦烧时间(Ts)和正硫化时间(T90),起到了促进硫化作用。轮胎胎面胶配合显示,OMMT与炭黑并用补强NR/BR共混胶,明显改善其力学性能与耐磨耗性能。     

NR／BR／OMMT纳米复合材料的研究（Ⅰ）复合材料的制备及表征

选用自制的3种有机蒙脱土（OMMT）。利用机械共混法制备了天然橡胶／顺丁橡胶／有机蒙脱土（NR／BR／OMMT）纳米复合材料,测试了复合材料的力学性能,研究了复合材料的耐老化和耐溶剂性能。结果表明：3种OMMT对复合材料的补强效果明显不同,其中2#OMMT为最佳．其断裂强度和撕裂强度均提高近1倍,耐老化和耐溶剂性能也最优异。     

BR/CB/OMMT纳米复合材料的结构与性能研究

采用溶液插层法与双辊混炼法制备了顺丁橡胶/炭黑/有机蒙脱土（BR/CB/OMMT）纳米复合材料,用透射电子显微镜（TEM）以及X射线衍射（XRD）方法对复合材料的亚微观结构进行了表征,并研究了复合材料的力学特性、耐磨耗性能以及硫化特性。结果表明：BR/CB/OMMT为插层型纳米复合材料;在OMMT含量小于4份时,BR/CB/OMMT纳米复合材料具有优异的力学性能和耐磨耗性能;OMMT起到了硫化促进剂的作用,降低了BR的焦烧时间（TS）和正硫化时间（T90）;低填充量OMMT可提高复合材料的交联密度。     

天然橡胶/有机蒙脱土纳米复合材料的耐磨耗性能研究

采用4种不同牌号的有机化蒙脱土(OMMT),利用机械共混法制备出了NR/OMMT纳米复合材料,研究了复合材料的力学性能和耐磨性能,进行了透射电镜(TEM)和扫描电镜(SEM)分析。结果表明复合材料的力学性能和耐磨性都有不同程度的提高。TEM结果表明制备出了分散均匀的剥离型NR/OMMT纳米复合材料,通过纳米复合材料磨耗后的磨耗图纹及SEM表面形貌进行对比分析来探讨OMMT在橡胶中的耐磨机理。     

OMMT/NR纳米复合材料的性能研究

采用两种有机蒙脱土(OMMT)通过机械混炼法制备OMMT/NR纳米复合材科,并对复合材料的各项性能进行研究.结果表明,与NR相比,OMMT/NR纳米复合材料的加工性能、物理性能、热稳定性能和动态力学性能均有明显改善;以N,N'-二甲基-烷烃铵盐作为蒙脱土改性剂制备的OMMT/NR纳米复合材料的加工性能和物理性能较好.     

有机蒙脱土对天然橡胶/顺丁橡胶纳米复合材料的增强及增容作用

采用机械混炼法制备了天然橡胶/顺丁橡胶/有机蒙脱土(NR/BR/OMMT)纳米复合材料,用透射电子显微镜以及广角X射线衍射仪研究了OMMT在纳米复合材料中的分布以及相结构,并对复合材料的力学性能、动态力学性能以及硫化热效应进行了研究。结果表明,OMMT多数分布于NR相以及NR和BR两相界面处,少数分散在BR相中;当OMMT少于6份时,OMMT片层呈剥离状态,并以纳米尺寸分散于橡胶基体中;纳米复合材料的硬度、拉伸强度和定伸应力随OMMT用量的增加而增大,但超过8份时,纳米复合材料的拉伸强度略有下降;与NR/BR复合材料相比,NR/BR/OMMT纳米复合材料的损耗因子降低,但具有相似的滚动阻力和更好的抗湿滑性能;OMMT能起增容作用,实现NR和BR两相的同步交联。     

OMMT/FKM纳米复合材料的结构和性能

采用机械混炼法制备有机蒙脱土（OMMT）／氟橡胶（FKM）纳米复合材料，研究复合材料的微观结构和性能。结果表明，OMMT／FKM纳米复合材料为剥离型复合材料；与FKM相比，OMMT／FKM纳米复合材料具有较优的物理性能、热稳定性和耐溶剂性能。     

有机蒙脱土对聚氯乙烯/丁腈橡胶纳米复合材料结构与性能的影响

采用熔融插层法制备了有机蒙脱土(OMMT)/聚氯乙烯(PVC)/丁腈橡胶(NBR)纳米复合材料,研究了复合材料的结构,考察了OMMT填充量对复合材料物理机械性能、耐热性能及耐溶剂性能的影响。结果表明,OMMT在复合材料中实现了纳米级分散,且极性PVC大分子在剪切力和热的作用下插入OMMT层间,形成PVC-OMMT纳米复合材料;随着OMMT填充量的增加,OMMT/PVC/NBR纳米复合材料的拉伸强度、300%定伸应力均先升高后降低,扯断伸长率降低,邵尔A硬度和永久变形呈增大的趋势,回弹性变化不大,耐溶剂性能先提高后降低;OMMT/PVC/NBR复合材料的耐热性能优于未填充OMMT复合材料。     

BR/炭黑/OMMT纳米复合材料的制备与性能研究

采用溶液插层法与两辊混炼法制备BR/炭黑/有机蒙脱土(OMMT)纳米复合材料,并对其微观结构和性能进行研究.结果表明,BR/炭黑/OMMT复合材料为插层型纳米复合材料,采用OMMT等量替代炭黑可明显降低胶料的门尼粘度,改善加工性能,提高胶料的硫化速度;OMMT用量不大于4份时可显著增大复合材料的拉伸强度、拉断伸长率和撕裂强度.     

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.     

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.     

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.     

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.     

The System Si3N4-SiO2-Y2O3

Subsolidus phase relations were established in the system Si₃N₄-SiO₂-Y₂O₃. Four ternary compounds were confirmed, with compositions of Y₄Si₂O₇N₂, Y₂Si₃O₃N₄, YSiO₂N, and Y₁₀(SiO₄)₆N₂. The eutectic in the triangle Si₃N₄-Y₂Si₂O₇-Y₁₀(SiO₄)₆N₂ melts at 1500°C and that in the triangle Si₂N₂O-SiO₂-Y₂Si₂O₇ at 1550°C. The eutectic temperature of the Si₃N₄-Y₂Si₂O₇ join was ∼ 1520°C.     

Compact Swelling in Bi1.4Pb0.6Sr2Ca2Cu3.6Oy During the Formation of High-Tc Superconducting Phase

Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T _c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T _c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed.