高性能载重子午线轮胎天然橡胶/反式丁戊橡胶胎面胶的配方优化

研究高性能载重子午线轮胎天然橡胶(NR)/反式丁戊橡胶(TBIR)(并用比90/10)胎面胶的配方优化。结果表明:相比炭黑补强NR/TBIR并用胶,炭黑/白炭黑(并用比40/15)补强NR/TBIR并用胶的硬度、定伸应力、拉伸强度、撕裂强度和耐磨性能略有降低,抗湿滑性能保持不变,滚动阻力降低20%,压缩温升下降17%;在该配方基础上增大10%的促进剂和硫黄用量,得到优化配方。相比炭黑补强NR胎面胶,优化配方NR/TBIR胎面胶具有优异的力学性能和动态性能,在拉伸强度和抗湿滑性能基本不变的前提下,滚动阻力降低26%,压缩温升下降20%,耐磨性能提高5%。本优化配方适用于低滚动阻力高性能载重子午线轮胎胎面胶。     

TBIR改性NR硫化胶的研究

研究了两种牌号反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)改性天然橡胶(NR),结果表明,10~50份TBIR与NR共混,并用胶焦烧时间(t10)和工艺正硫化时间(t90)略有延长。相比NR硫化胶,NR/TBIR并用硫化胶力学强度保持在较高范围,屈挠疲劳性能大幅度提高,其中NR/TBIR-20=50/50硫化胶一级屈挠疲劳寿命可提高28.6倍,六级屈挠疲劳寿命可提高11.9倍。DMA结果表明,NR与TBIR具有优异的相容性。RPA及DMA 结果均表明NR/TBIR并用硫化胶具有更低的滚动阻力。综合可知,TBIR是一种高性能的合成橡胶新材料,可显著改善NR的综合性能。     

液体聚异戊二烯对天然橡胶/聚丁二烯橡胶硫化胶微观结构和性能的影响

研究了液体聚异戊二烯(LIR)作为增塑剂对天然橡胶(NR)/聚丁二烯橡胶(BR)硫化胶微观结构、弯曲疲劳性能、压缩疲劳性能和动态力学性能的影响,并与加入工业用增塑剂芳烃油的硫化胶进行了对比。结果表明,加入LIR较芳烃油有利于炭黑在NR/BR体系中的分散;随着LIR用量的增加,NR/BR硫化胶的耐屈挠疲劳性能基本不变;与芳烃油增塑的NR/BR体系相比,LIR增塑NR/BR体系的耐屈挠疲劳性能较优,压缩疲劳生热和压缩永久变形较低;加入LIR降低了硫化胶滚动阻力的同时减弱了其抗湿滑性。     

天然橡胶/高反式-1,4-丁二烯-异戊二烯共聚橡胶并用胶的性能研究

研究天然橡胶(NR)/高反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)并用胶的性能。结果表明:NR/TBIR并用胶的加工安全性能较好,物理性能保持较高水平,回弹性能改善,耐疲劳性能显著提高;TBIR与NR具有良好的相容性,NR/TBIR并用胶滞后损失和滚动阻力降低,耐低温性能提高;与NR/TBIR-40并用胶相比,NR/TBIR-20并用胶的物理性能和耐疲劳性能较好。NR/TBIR并用胶在轮胎胎面胶、胎侧胶、胎肩胶、上三角胶和减震、耐低温制品中应用前景广阔。     

白炭黑补强天然橡胶/高反式-1，4-丁二烯-异戊二烯共聚橡胶并用胶性能的研究

以天然橡胶(NR)/高反式-1,4-丁二烯-异戊二烯共聚橡胶(TBIR)并用胶为对比,研究白炭黑补强NR/TBIR并用胶的性能。结果表明:NR/TBIR混炼胶和白炭黑补强NR/TBIR混炼胶的强度分别较NR混炼胶和白炭黑补强NR混炼胶提高;随着TBIR用量增大,NR/TBIR硫化胶和白炭黑补强NR/TBIR硫化胶的压缩永久变形和DIN磨耗量分别较NR硫化胶和白炭黑补强NR硫化胶减小,耐屈挠疲劳性能和耐伸张疲劳性能大幅提高,静摩擦因数和动摩擦因数增大;白炭黑补强NR/TBIR硫化胶较白炭黑补强NR硫化胶的白炭黑聚集体平均粒径减小,白炭黑在橡胶基体中的分散性改善。     

石墨烯对天然橡胶硫化胶性能的影响

采用少量石墨烯部分替代NR胶料中的炭黑,通过熔融混炼法制得石墨烯/NR胶料。试验结果表明,3份石墨烯虽然降低了NR的加工安全性、硫化速度、交联密度和撕裂强度,但却提高了胶料的拉伸强度、定伸应力、硬度和耐磨性能,同时也降低了胶料的压缩疲劳温升和压缩永久变形,并使NR硫化胶有较好的耐热老化性能和耐伸张疲劳性能、一定的抗湿滑性能和较低的滚动阻力。     

天然橡胶/杜仲胶并用胶的交联密度与结晶度的关系及其对性能的影响

通过调整硫黄用量,研究天然橡胶(NR)/杜仲胶(EUG)并用胶的交联密度与结晶度的关系及其对并用胶性能的影响。结果表明：NR/EUG并用胶的交联密度与结晶度呈负相关;随着硫黄用量的增大,NR/EUG并用胶的交联密度增大,t₁₀略有缩短,t₉₀变化不大,硬度、耐屈挠性能和抗湿滑性能先提高后降低,滚动阻力和生热下降,储能模量波动减小;当硫黄用量为2～2.5份时,NR/EUG并用胶的交联密度和结晶度较大,物理性能、耐磨性能和抗湿滑性能较好。     

液体二烯烃橡胶在NR/SBR胎面胶中的应用研究

采用4种液体二烯烃橡胶和环保芳烃油（TDAE）作为增塑剂,研究对比其在天然橡胶（NR）/丁苯橡胶（SBR）胎面胶中的应用。结果表明：含液体橡胶的混炼胶的加工流动性较含TDAE的混炼胶略变差,焦烧时间和正硫化时间略延长;与含TDAE的硫化胶相比,含液体橡胶的硫化胶的定伸应力、撕裂强度、回弹值增大,耐磨性能提高,耐屈挠疲劳裂纹引发性能和耐热空气老化性能降低;含液体异戊橡胶LIR-50的硫化胶的拉伸强度和回弹值最大,耐压缩疲劳性能和耐6级裂口屈挠疲劳性能最佳,滚动阻力最低;含液体顺丁橡胶LBR-305的硫化胶的耐磨性能最佳;含液体丁戊橡胶LBIR-390的硫化胶的综合物理性能介于含液体异戊橡胶LIR-50的硫化胶与含液体顺丁橡胶LBR-305的硫化胶之间;含液体丁苯橡胶LSBR-820的硫化胶的抗撕裂性能最佳,耐屈挠疲劳性能最差。     

石墨烯用量对天然橡胶/反式聚异戊二烯复合材料性能的影响

以石墨烯代替部分炭黑制备了天然橡胶(NR)/反式聚异戊二烯(TPI)复合材料,研究了石墨烯用量对NR/TPI复合材料硫化特性、微观结构、力学性能、耐老化性能、耐伸张疲劳性能、耐磨性能及动态力学性能的影响。结果表明,加入石墨烯降低了NR/TPI复合材料的交联密度、邵尔A硬度和耐老化性能;3份石墨烯提高了材料的拉伸强度和撕裂强度;加入3份或5份石墨烯均可在改善材料的耐伸张疲劳性能、耐磨性能和抗湿滑性能的同时,降低其滚动阻力;3份石墨烯在改善材料的抗湿滑性能方面效果更明显,5份石墨烯在降低材料的滚动阻力方面效果更明显。     

工程轮胎胎面胶用黏土/炭黑/天然橡胶纳米复合材料的性能

在工程轮胎胎面胶配方中,用黏土替代部分高耐磨炭黑,利用机械共混工艺制备了黏土/炭黑/天然橡胶(NR)纳米复合材料,研究了复合材料的综合性能.结果表明,黏土的加入不会对胶料的硫化特性产生太大影响;少量黏土的加入增强了混炼胶的填料网络作用,改善了炭黑/NR硫化胶的物理机械性能,耐磨性能提高了15%～30%,降低了滚动阻力,提高了耐屈挠疲劳破坏性能,当黏土填充量为4份时,复合材料的综合性能最优.     

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.