The Roles of 3- and 4-Isopropylbiphenyls in the Isopropylation of Biphenyl over a H-Mordenite

The isopropylation of mixtures of 3- and 4-isopropylbiphenyls (3- and 4-IPBPs) was examined over a dealuminated H-mordenite (HM) to elucidate the role of 3- and 4-IPBPs in the isopropylation of biphenyl (BP). 4-IPBP was consumed much faster than 3-IPBP in all cases. 4-IPBP was an exclusive precursor to diisopropylbiphenyls (DIPBs), particularly 4,4-DIPB, and 4,4-DIPB was found in encapsulated products during the reaction. These results show that 4-IPBP can allow establishment of an active complex with propylene and acid site in HM pores, whereas 3-IPBP cannot. It is concluded that the isopropylation of BP over HM occurs through a reactant selectivity mechanism, and through a restricted transition state mechanism, but not through a product selectivity mechanism.     

不同促进剂对NR平衡硫化体系的影响

研究了促进剂的种类，促进剂并用及硫化温度等条件对平衡硫化体系（ＥＣ）硫化天然橡胶（ＮＲ）的影响。结果表明，噻唑类促进剂具有较低的硫化返原率，尤其是促进剂ＤＭ，在１３０～１７０℃的硫化温度范围内，硫化２小时的硫化返原率均为０；当促进剂ＮＯＢＳ或ＣＺ与ＤＭ并用时，可缩短正硫化时间；当ＤＭ摩尔分数分别为４０％和５０％左右时，不仅使硫化２小时的硫化返原率为０，而且可使３００％定伸应力保持恒定；以ＮＯＢＳ或ＣＺ为主促进剂时，正硫化时具有较高的拉伸强度和撕裂强度，但硫化２小时时的降低幅度比ＤＭ大。     

硫酸根/氧化钛—氧化镧催化合成苯甲醛1,2—丙二醇缩醛

以稀土改性固体超强酸SO_4~(2-)/TiO_2—La_2O_3为催化剂,通过苯甲醛和1,2—丙二醇反应合成了苯甲醛1,2—丙二醇缩醛,探讨了SO_4~(2-)/TiO_2—La_2O_3对缩醛反应的催化活性,研究了醛醇物质的量比、催化剂用量、反应时间等对产品收率的影响。实验表明,SO_4~(2-)/TiO_2—La_2O_3是合成苯甲醛1,2—丙二醇缩醛的良好催化剂,在n(醇):n(醛)=2.25:1,催化剂用量为反应物料总质量的0.50％,环己烷为带水剂,反应时间50min的优化条件下,苯甲醛1,2—丙二醇缩醛的收率可达80.8％。     

Interfacial shear strength of C/C composites

Fiber-bundle push-out, single-fiber push-in, and single-fiber push-out tests were conducted in order to examine the applicability of these methods for determining the interfacial shear strength of carbon-carbon composites. The fiber-bundle push-out test resulted mostly in fractures along the fiber/matrix interface but created a small amount of fractures in the matrix. Hence, the evaluated strength was regarded as an approximate value. In order to precisely evaluate the interfacial strength, push-in and push-out tests for a single fiber were performed using a micro-Vickers indentation tester. In these tests, the load has to be placed within a target fiber, and the indentation should not extend to the matrix. This condition restricted the load that could be applied to a carbon fiber. Within this limit, a single carbon fiber could not be pushed-in. For the sake of load reduction, single-fiber push-out tests were conducted using thin specimens. The thickness appropriate for a single-fiber push-out specimen was estimated based on the interfacial shear strength obtained by the bundle push-out tests. Below this thickness, single-fiber push-out tests could be successfully performed.     

Effect of Pt Incorporation into Ni/ZrO2–SO 4 = /Al2O3 Catalyst for n-Butane Isomerization

Three Ni/ZrO₂–SO₄⁼/Al₂O₃ catalysts with different concentrations of platinum (0.2, 0.3 and 0.4 wt%) were prepare and tested for n-butane isomerization reaction at 338 K, in absence and in presence of hydrogen. The results shown that, at low temperature, platinum contributes to the olefin or butyl ion formation and the reaction follows a bimolecular pathway. However, when the reaction occurs in the presence of hydrogen, the formation of butyl ions is inhibited. The main feature of platinum addition is the stabilization of the catalytic activity, which is indicated by the slow deactivation constants compared to that of the unpromoted catalyst.     

热处理制度对高ZnO含量的Li2O-Al2O3-SiO2系统玻璃析晶及热膨胀系数的影响

以TiO2 ZrO2 P2O5为复合成核剂,采用传统熔融冷却法获得了高ZnO含量的Li2O-A l2O3-SiO2系统的基础玻璃。通过差热分析确定了该玻璃的热处理条件、晶化性能,利用梯温炉实验、X射线衍射分析和扫描电镜对晶化试样的物相和微观结构进行了研究,讨论了热处理制度对玻璃的析晶及热膨胀系数的影响。研究结果表明:含10%(质量分数)ZnO的LAS系统样品玻璃最佳核化温度为(710±2)℃,玻璃的晶化活化能E为(275±2)kJ/mol,晶化指数n为3.11±0.2,样品玻璃在较低温度下失透,并且随着晶化温度升高,样品的热膨胀系数加大。     

环境保护与汽车涂装

叙述了与汽车涂装相关的国际环保法规及汽车涂装的公害,重点介绍了汽车用环保型涂料、5R活动和3C1B涂装技术等环保达标措施.     

蓝色荧光碳点的制备及检测、防伪应用

以柠檬酸钠为碳源、氨水为氮源,采用一步水热法制备了氮掺杂碳点(NCDs),对其制备条件进行了优化.采用荧光光谱仪、TEM、AFM、XPS及FTIR对制备的NCDs进行了表征,并探索了NCDs在Fe3+检测及荧光防伪中的应用.结果表明,NCDs的最优制备条件为柠檬酸钠浓度为0.1 mol/L、氨水浓度为1.8 mol/L、反应温度为200℃、反应时间6 h、装载体积25 mL.在最优条件下制备的NCDs的荧光为典型的非激发波长依赖型,最佳激发波长为343 nm,最佳发射波长为443 nm,荧光量子产率可达54.9％.NCDs为球形结构,平均粒径为4.96 nm,碳核为类石墨烯结构且其表面含有—NH2、—OH及—COOH.NCDs的荧光可被Fe3+选择性猝灭,且荧光猝灭程度与Fe3+浓度在0.1～87.5μmol/L范围内线性关系良好,检测限为50 nmol/L.此外,将NCDs配制成荧光墨水,利用喷墨打印机打印出的图案整体饱满、边缘细节清晰具有很强的可识别性.     

高分子和盐对3-十二烷氧基-2-羟丙基三甲基溴化铵泡沫性能的影响

测定了3-十二烷氧基-2-羟丙基三甲基溴化铵(C12TAB)在PVP、PEG和溴化钠存在下的泡沫性能。结果表明：含量相同时，C12TAB／NaBr混合体系的起泡性能高于C12TAB／高分子体系，而稳泡性能低于后者。含量相同的C12TAB／高分子体系，PVP对C12TAB的影响好于PEG。     

异佛尔酮二异氰酸酯三聚体的合成

合成了3－异氰酸酯基亚甲基－3，3，5－三甲基环己基二异氰酸酯（IPDI）三聚体，对合成中催化剂，反应温度、反应时间等进行了探讨，并用红外光谱进行了表征。结果表明，采用醋酸钾化催化剂，在50－90℃下反应，再经脱催化剂处理，可制得IPDI三聚体。