炭黑分布对天然橡胶/顺丁橡胶并用胶性能的影响

研究炭黑在天然橡胶(NR)/顺丁橡胶(BR)并用胶中分布对并用胶性能的影响。结果表明:BR中炭黑的质量分数增大,NR/BR并用胶硫化胶的定伸应力、拉伸强度和拉断伸长率增大,耐磨性能提高,压缩生热和动态损耗因子减小,抗裂口增长性能变差;NR中炭黑的质量分数增大,NR/BR并用胶硫化胶的耐屈挠性能增强。     

炭黑N330在全钢载重子午线轮胎胎体胶中的应用

研究炭黑N330在全钢载重子午线轮胎胎体胶中的应用.结果表明:在胎体胶中以炭黑N330等量替代炭黑N326,胶料的MH增大,炭黑分散性提高,硫化胶的定伸应力增大,压缩生热升高,耐屈挠性能下降;以炭黑N330减量替代炭黑N326,并适当调整硫黄用量,胶料的MH减小,炭黑分散性改善,硫化胶的撕裂强度减小,压缩生热降低,耐屈挠性能提高,成品轮胎的耐久性能达到企业标准要求.     

炭黑对CR/TPI并用胶性能的影响

研究了炭黑种类及用量对CR/TPI并用胶的影响.结果表明:随着炭黑粒径的增大,混炼胶焦烧时间有增大的趋势,正硫化时间也随之延长;硫化胶交联程度降低;硫化胶的拉伸强度、断裂伸长率、压缩生热温升、屈挠性能和炭黑分散度随之降低;常温下回弹性能、磨耗性能提高;硫化胶的老化性能略有提高.添加炭黑N330硫化胶的综合性能最好.随着炭黑N330用量的增加,硫化胶拉伸强度先增大后减少,炭黑40份左右达到最大值,断裂伸长率减少,磨耗性能和屈挠性能降低,压缩生热温升、邵尔A硬度增大,常温下回弹性能提高.     

炭黑品种及用量对胎侧胶耐屈挠性能的影响

研究炭黑品种及用量对胎侧胶耐屈挠性能的影响。结果表明:固定胶料硬度(邵尔A型硬度为75度)时,随着炭黑粒径的增大,胶料的Payne效应减弱,热稳定性能下降,定伸应力增大,拉伸强度减小,压缩疲劳温升和耐屈挠性能降低;固定炭黑品种(N550)时,随着炭黑用量的增大,胶料的Payne效应增强,硬度提高,定伸应力增大,拉断伸长率减小,压缩疲劳温升和耐屈挠性降低;炭黑品种和用量相同时,添加环保芳烃油会降低胶料的压缩疲劳温升和耐屈挠性能。     

纳米粘土在半钢子午线轮胎胎侧胶中的应用

研究纳米粘土在半钢子午线轮胎胎侧胶中的应用。结果表明：以一定量的纳米粘土替代炭黑N660,胶料的加工性能和硫化特性变化不大,硫化胶的拉断伸长率和撕裂强度明显增大;随着纳米粘土用量的增大,硫化胶的密度增大,定伸应力减小,耐屈挠疲劳性能提高;以纳米粘土等量替代炭黑N660,填料分散性稍好,成品轮胎的高速和耐久性能达到企业标准要求,胶料成本下降。     

炭黑/蒙脱土/SBR纳米复合材料的性能研究

采用少量（0～5份）蒙脱土（MMT）等量替代炭黑，考察炭黑／MMT／SBR纳米复合材料的硬度、强伸性能、耐磨性能和耐屈挠龟裂性能。结果表明，随着炭黑／MMT并用比的减小，炭黑／MMT／SBR纳米复合材料的拉伸强度、撕裂强度和耐屈挠龟裂性能明显提高，耐磨性能有所下降，但降幅不大。     

超细大粒径硅质粉体材料对天然橡胶性能的影响

选用2种新型超细大粒径硅质粉体材料(牌号为N 90和N 98)填充天然橡胶(NR),考察了填料对NR混炼胶加工性能、硫化特性及硫化胶微观形貌、物理机械性能、耐曲挠疲劳性能的影响。结果表明,相比N 90,N 98的粒径分布窄,平均粒径较小,且表面接枝了硅甲基;添加适量的N 90和N 98均可改善NR混炼胶的加工性能,提高加工安全性; N 90和N 98在橡胶基体中均具有较好的分散性,改善了填料的网络结构;添加N 90和N 98均可使NR硫化胶的拉伸强度和耐磨性能降低,但N 90可提高硫化胶的撕裂强度,当N 90用量为5份时,扯断伸长率和撕裂强度最佳,N 98使硫化胶的撕裂强度降低;添加N 90和N 98均可提高NR硫化胶的耐屈挠疲劳性能,当N 90用量为5份或N 98用量为15份时,耐屈挠疲劳性能最佳。     

炭黑N234和深冷精细胶粉对天然橡胶/顺丁橡胶轮胎胎面胶性能的影响

研究炭黑N234和深冷精细胶粉对天然橡胶(NR)/顺丁橡胶(BR)轮胎胎面胶性能的影响。结果表明:随着炭黑N234用量增大,混炼胶的门尼粘度和硫化速率增大,硫化胶的300%定伸应力和拉伸强度增大,拉断伸长率和DIN磨耗量减小,撕裂强度、压缩生热和永久变形变化不大,耐屈挠性能提高;随着深冷精细胶粉用量增大,混炼胶的门尼粘度和硫化速率增大,硫化胶的300%定伸应力和DIN磨耗量变化不大,拉伸强度和拉断伸长率减小,撕裂强度、压缩生热和永久变形呈增大趋势,耐屈挠性能下降;深冷精细胶粉部分替代炭黑应用于轮胎胎面胶中可降低原材料成本,利于环保。     

生胶体系对胎侧支撑胶耐屈挠性能的影响

天然橡胶(NR)和顺丁橡胶(BR)并用用于胎侧支撑胶中,研究生胶体系对胎侧支撑胶耐屈挠性能的影响。结果表明:随着NR/BR并用胶中NR用量的增大,胶料的炭黑分散性变差,拉伸强度和拉断伸长率呈增大趋势,弹性降低,压缩疲劳温升增大;增大并用胶中BR的用量,可以提高胶料的耐屈挠性能。     

硅烷偶联剂KH-550对纳米晶纤维素/炭黑/天然橡胶复合材料性能的影响

试验研究硅烷偶联剂KH-550对纳米晶纤维素/炭黑/天然橡胶复合材料性能的影响。结果表明:加入硅烷偶联剂KH-550后,混炼胶的粘性模量和损耗因子减小,硫化胶的硬度和300%定伸应力增大,拉断永久变形减小,耐磨性能提高;当硅烷偶联剂KH-550用量为1~2份时,混炼胶的硫化特性和加工性能,硫化胶的交联密度、耐屈挠性能、压缩疲劳性能和耐磨性能明显改善。     

Polymorphism of LiGa5O8 and of LiGa5O8-MgGa2O4Solid Solutions

High-temperature X-ray diffraction and differential thermal analyses showed that LiGa₅O₈ exists in two polymorphs related by the first-order transition at 1138°±3°C of the low-temperature simple-cubic form, space group (probably) O⁷, to the high-temperature spinel (fcc) form, space group O _h ⁷. The transition is rapid, and the high-temperature form in pure LiGa₅O₈ could not be quenched to room temperature under the conditions used. However, the high-temperature polymorph can be quenched under equilibrium conditions when 40 mol% or more MgGa₂O₄ is present. The subsolidus equilibrium relations in the system MgGa₂O₄-LiGa₅O₈ are discussed.     

Magnetoresistance of CuxCo1-xFe2O4 Ferrites

Magnetoresistance measurements (Δ/R) were carried out on Cu _x Co_{1- x} Fe₂O₄ samples with x =1, 0.75, 0.50, 0.25 and cobalt ferrite in the range of magnetic intensity (H) from 1.0 to 4.5 kG. Linear plots were obtained between log (Δ/R) and log H for all compositions except that of cobalt ferrite. The values of n at x =0.5 do not agree with the results of some authors. The discrepancy may be attributed to the value of magnetic field intensity at which such measurements were carried out. The similarity of features of n and μ_D with composition leads us to believe that the magnetoresistance may arise from the scattering of conduction electrons by localized electrons involving the s-d exchange interaction.     

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.     

Expansive properties of the mixture C4ASH12 − 2CS III. Effects of temperature and restraint

The effects of temperature and restraint upon the hydration and the expansion of $\text{C}{}_4\text{A}\text{S}\text{H}{}_{12}\text{? 2}\text{C}\text{S}$ mixture compacts in different contact solutions have been investigated. Temperatures above 20°C do apparently hinder the formation of an impervious felt-like layer of ettringite around the $\text{C}{}_4\text{A}\text{S}\text{H}{}_{12}$ particles, thus greatly reducing the retarding effect of the lime. An uniaxial restraint of 1 Kg/cm² is enough to reduce sensibly the expansions which remain however high (about 100%). The results can be satisfactorily interpreted by the reaction and expansion mechanism hypothesized in our previous papers.     

Raman Study of Glasses of Ba2TiSi2O8 and Ba2TiGe2O8

Raman spectra are reported for fresnoite (Ba₂Ti(Si,Ge)₂O₈ glasses, and comparison is made between the Raman spectra of the corresponding crystalline powders and glasses of Ba₂TiSi₂O₈ and Ba₂TiGe₂O₈. The Ba₂TiGe₂O₈ glass spectra show correspondence with the Ba₂TiGe₂O₈ crystalline Raman spectra; the v _s(Ge–O–Ge) mode occurs at 518 cm⁻¹ in the glass and at 521 cm⁻¹ in the crystalline material. Five-fold coordinated titanium is the majority species present in the Ba₂TiGe₂O₈ glass as revealed by a strong band at 824 cm⁻¹ in the I glass spectrum. The Ba₂TiSi₂O₈ glass spectra are similar to the Ba₂TiSi₂O₈ crystalline spectrum; the strongest band is found at 836 cm⁻¹ in the I glass spectrum. Through comparison with the previous Raman data of other titania silicate glasses, we conclude that the Ba₂TiSi₂O₈ glass has a structure similar to the crystalline phase.     

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.     

Effects of metal-support interactions on the hydrogenation of CO over PdSiO2 and PdLa2O3

A study of CO hydrogenation over $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$ has been carried out for the purpose of identifying the effects of Pd dispersion, Pd morphology, and support composition on the catalytic activity of supported Pd. The specific activity of each catalyst for methanol and methane synthesis was determined from microreactor studies carried out at a fixed set of reaction conditions. Palladium dispersion was measured by H₂O₂ titration, and the morphology of the Pd crystallites, as expressed by the distribution of Pd(100) and Pd(111) planes, was determined from in situ infrared spectra of adsorbed CO. The crystallite morphology of the $\text{Pd}\text{SiO}{}_2$ catalysts is the same, independent of Pd weight loading: 90% of the surface is comprised of Pd(100) planes and 10% of the surface is comprised of Pd(111) planes. By contrast, the crystallite morphology of the $\text{Pd}\text{La}{}_2\text{O}{}_3$ catalysts changes with Pd loading. Primarily Pd(100) planes are exposed at low-weight loadings while Pd(111) planes are exposed at high-weight loadings. The Pd dispersion has little effect on the methanol turnover frequency over both $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$, for dispersions between 10 and 20%. On the other hand, the methane turnover frequency is independent of Pd dispersion over $\text{Pd}\text{SiO}{}_2$, but increases with decreasing dispersion over $\text{Pd}\text{La}{}_2\text{O}{}_3$. It is further observed that the Pd morphology influences the specific activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ for methanol synthesis: Pd(100) is nearly threefold more active than Pd(111). For a fixed morphology, the specific methanol synthesis activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ is a factor of 7.5 greater than that of $\text{Pd}\text{SiO}{}_2$.     

In situ laser raman spectroscopy of the sulfiding of Moγ-Al2O3 catalysts

Raman spectra of sulfided $\text{Mo}\text{γ-}\text{Al}{}_2\text{O}{}_3$ catalysts were obtained using in situ techniques for two sulfiding methods. For samples sulfided by 10% $\text{H}{}_2\text{S}\text{H}{}_2$ at 400 °C, MoS₂ structures were observed. A stepwise sulfiding using 10% $\text{H}{}_2\text{S}\text{H}{}_2$, with spectra recorded at 150, 250, and 350 °C, resulted in observation of molybdenum oxysulfide, reduced molybdate, and surface “MoS₂” phases. Reexposure of these samples to air led to radical modification of the oxysulfide structures as well as transformation of some sulfide phases. A model incorporating terminal and bridging MoS bonding and anion vacancies is proposed. This model is based on the conversion of isolated and aggregated molybdate and MoO₃ species to oxysulfide and reduced molybdenum phases. Conversion of reduced molybdenum phases to sulfides is observed to be slow.     

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.