分批加分散剂时苯乙烯悬浮聚合瞬间液滴直径和分布

在苯乙烯悬浮聚合中研究了分批加分散剂体系磷酸三钙(TCP)或 TCP 和聚乙烯醇(PVA)时的加入方式对瞬间液滴大小和分布的影响。考察了体系液滴分散和合一的特点。实验观察到分批加入分散剂体系时液滴大小分布的变化规律,呈由单峰分布过渡到双峰分布,最后又发展为单峰分布。这与分散剂体系一次加入相比,后者仅出现单峰分布逐渐过渡到双峰分布。     

极限电流型氧传感器的实验研究

本实验用8mol%Y_2O_3-ZrO_2固体电解质制成了极限电流型氧传感器,并测定了氧在0.23～28.70mol%,温度在550～800℃范围时,传感器的输出特性,观察到该传感器有较好的稳定性和电压电流特性曲线。实验验证了极限电流值与氧摩尔分数和温度的关系。     

Selective hydrogenation of oleic acid to 9-octadecen-1-ol: Catalyst preparation and optimum reaction conditions

A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%.     

滴加法制备铁黄颜料工艺研究

采用滴加法制备铁黄颜料，即采用硫铁矿烧渣直接制得的硫酸亚铁及硫酸亚铁结晶母液为原料。用空气作氧化剂，用氨水作沉淀剂制品种；在二步氧化中滴加氨水和硫酸亚铁结晶母液。探讨了亚铁浓度、空气流量等对晶种形成的影响，以及晶种比、空气流量、溶液pH、硫酸铵浓度等因素对铁黄生成的影响。确定了晶种制备和二步氧化的最佳工艺条件，即二步氧化中溶液pH控制在2．5～3．5，亚铁浓度控制在0．18～0．25mol／L的范围。检测结果表明：铁黄各项指标均达到原化工部HG／T2249--1991一级品标准。     

采用高速剪切反应器生产超细氧化铋工艺探讨

利用硝酸铋溶液和碳酸铵溶液为原料，采用高速剪切反应器，500℃煅烧后可以生产出高纯、超细的氧化铋粉末。该方法制备出的氧化铋平均粒度0．71μm且粒度范围分布窄，颗粒形貌为类球形，晶相为纯α相，指标达到电子压敏陶瓷要求。由于粒度细小，可以在电子压敏陶瓷球磨工艺减少球磨工艺，并具有更好的分散效果。本文对超细的氧化铋粉末形成机理也进行了探讨。     

对我国陶瓷企业实施品牌战略的思考

本文从品牌战略的内涵与其功能意义入手,探讨了品牌在企业营销过程中的作用,分析了我国陶瓷企业在实施品牌战略中存在的问题,并在此基础上提出了陶瓷企业实现品牌战略的建议。     

对51孔铂金坩埚结构变形和延长使用寿命问题的探讨

介绍了铂金拉丝坩埚在化学转化法制备BN纤维拉丝过程中,对铂金坩埚进行的加拼、焊接、横向内筋和调整铂(Pt)铑(Rh)掺合量,来延长铂金坩埚的使用寿命,提高铂合金材料的刚性强度、抗弯断面系数等方面进行了探讨.     

Analysis of the polyethylene glycol glucosides and FA esters thereof by atmospheric-pressure ionization MS

Polyethylene glycol (PEG) glucosides (PEGG) and the PEGG esters of lauric acid were analyzed by atmospheric-pressure ionization MS (API-MS) with electrospray ionization. Straightforward mass characterization of the complex mixtures could be achieved without prior chromatographic separation. The constituents were identified on the basis of quasi-molecular ions. Individual components could be observed as protonated molecular ions [M+H]⁺ and/or as their NH₄ ⁺, Na⁺, or K⁺ adducts in positive ion mode. The mass spectrometric investigation showed that mixtures of PEGG consisted of monoglucoside, diglucoside, polyglucoside, and free PEG. The esterification product is a mixture of two types of nonionic surfactants: PEG-laurates and PEGG-laurates. The reasons for distortion of the quasi-molecular ion intensities and the stabilization of adduct ions were discussed. The rapid and highly sensitive API-MS analysis technique proposed here is well suited for direct characterization of complex mixtures and suitable for development as a routine analytical method.     

Determination of Pipe Diffusion Coefficients in Undoped and Magnesia-Doped Sapphire (α-Al2O3): A Study Based on Annihilation of Dislocation Dipoles

The breakup of dislocation dipoles in plastically deformed samples of undoped and 30-ppm-MgO-doped sapphire (α-Al₂O₃) was monitored using conventional TEM techniques. Dislocation dipoles break up into prismatic dislocation loops in a sequential process during annealing; i.e., dislocation loops are pinched off at the end of a dislocation dipole. This pinch-off process is primarily controlled by pipe diffusion, and pipe diffusion coefficients at temperatures between 1300° and 1500°C were estimated by monitoring the kinetics of the dipole breakup process. We determined D _P^U= 8.1(_–4.3^+9.1) × 10^–3 exp [–(4.5 ± 1.3 eV )/ kT )] m²/s for the undoped material. The pipe diffusion kinetics for the MgO-doped crystal was determined at 1250° and 1300°C and was about 6 times higher than for undoped sapphire. Finally, climb dissociation of the dislocations constituting the perfect dipoles in sapphire is common; annihilation of one set of partials can result in the formation of faulted dipoles, which can pinch off to form faulted dislocation loops. D _P^U for faulted dipoles in the undoped material was determined at 1300° and 1350°C, and was about 4–10 times higher than for perfect dipoles.