Behavior of protonated cyclopropyl intermediates during polyalphaolefin synthesis: Mechanism and predicted product distribution

A new mechanism for the origin of multiple skeletal isomers observed in the cationic dimerization of 1‐decene is proposed, and products that should form based on this mechanism are predicted. A protonated cyclopropyl intermediate appeared to form directly from combination of 2‐decyl carbocation with 1‐decene; formation of this intermediate did not appear to occur via ring closure of a branched secondary carbocation. The authors propose that rapid, repeated isomerizations of the protonated cyclopropyl intermediates lead to multiple skeletal isomers in decene dimers. The proposed mechanism can account for structures previously identified in mixtures of decene dimers and butene dimers. Copyright © 2012 John Wiley & Sons, Ltd.     

An Experimental Investigation of Liquid Jet Impingement and Single-Phase Spray Cooling Using Polyalphaolefin

Experiments on triangular and rectangular array jet impingement and single-phase spray cooling have been performed to determine the effect of both cooling techniques on heat transfer coefficient (h) and the coolant mass flux required for a given cooling load. Experiments were performed with circular orifices and nozzles for different H/D values from 1.5 to 26 and Reynolds number range of 219 to 837, which is quite lower than the ranges employed in widely used correlations. The coolant used was polyalphaolefin. The experiments simulated the boundary condition produced at the surface of the stator of a high power low-density generator or motor. For the custom fabricated orifices, commercial nozzles, and conditions used in this study, both cooling configurations showed enhancement of heat transfer coefficient as H/D increases to a certain limit after which it starts to decrease. The heat transfer coefficient always increases with Reynolds number. In keeping with previous studies, single-phase spray cooling technique can provide the same heat transfer coefficient as jets at a slightly lower mass flux, but with much higher-pressure head. Special Nu_d correlations that account for the range of parameters and coolant studied in this work are derived.     

吗啉衍生物摩擦学性能研究

合成了一系列吗啉衍生物；利用四球摩擦磨损试验机考察了合成产物作为添加剂对聚α-烯烃减摩抗磨作用的影响；采用扫描电子显微镜和X射线光电子能谱仪分析了钢球磨损表面形貌和典型元素的化学状态．结果表明，所合成的吗啉衍生物作为添加剂可以有效地改善聚α-烯烃对钢-钢摩擦副的抗磨作用，但对其减摩作用影响不大．含添加剂的润滑油在摩擦过程中同钢发生了摩擦化学反应，形成了由有机含氮化合物、氧化铁和其它含氮有机化合物组成的边界润滑和防护薄膜，从而使得钢-钢摩擦副的摩擦磨损性能得以改善．