A series of octyltetramethyldisiloxane‐containing ethylene copolymers, poly(ethylene‐co‐OO7) (abbreviated as E‐co‐OO7), are prepared from vanadium catalyzed copolymerization of ethylene with 1‐oct(7‐en)yl‐3‐octyl‐1,1,3,3‐tetramethyldisiloxane (or OO7) macromonomer. The copolymers containing different silicone contents are employed as composite lubricants for high‐density polyethylene (HDPE). The influences of the silicone content in the copolymer and that of the added copolymer amount in the blend on the bulk and surface properties of the blends are systematically investigated. The results show that E‐co‐OO7 exhibits superior overall performance in comparison with conventional lubricants silicone masterbatch and polyethylene wax. Compared to HDPE control, 10 wt% E‐co‐OO7 addition increases the melt flow rates by 49%, increases the elongation at break from 740 to 860%, increases the water‐contact angle from 90° up to 108°, lowers the coefficient of friction from 0.072 to 0.049, lowers the specific wear rate from 11 × 10?3 to 5.6 × 10?3 mm3 Nm?1. The impact strength and high temperature thermal stability are also slightly improved. The measured Si/C atomic ratios demonstrate the sufficient silicone enrichment on surface of the blends. E‐co‐OO7 with 23.5 Si? O? Si per 1000 C gives the best internal lubrication, and E‐co‐OO7 with 29.7 Si? O? Si per 1000 C gives the best external lubrication.
The solid-phase extraction(SPE) technique applied to the extraction of organic compound was creatively used as the extraction of inorganic gold in the paper.Two types of techniques were proposed and explored,namely the SPE and the liquid–liquid extraction(LLE) of the quaternary ammonium surfactant [cetytrimethyl ammonium bromide(CTMAB),cetyl pyridine bromide(CPB),benzyl dimethyl dodecyl ammonium chloride(BDMDAC),and dodecyl trimethyl ammonium chloride(DTMAC)].The surfactant could react with Au(CN)_2~-to form the ionic complex,and the compound could be extracted by SPE column of reversed-phase bonded silica gel.Hence,a new method of SPE was proposed to extract gold with these features of the high selectivity,the reliability,and the simplicity.The experimental result shows that the recovery rate of gold is more than 98 %,and the solid-phase extraction column is not easily damaged and it can be repeatedly used.The new method can be used as the extraction process of gold from alkaline cyanide solution as well.Besides,the paper also puts forward a new process of gold extraction. 相似文献
The characteristics of surface feature and microstructure of the near-surface of nickel were investigated after high current pulsed electron beam (HCPEB) irradiation. Based on a physical model, the temperature profile was simulated. The depth of heat-affected zone, the initial melting position, heating rate and quenching rate were computed. The initial coarse-grained structure on the surface was refined, of which the size is about 70 nm. The TEM observations indicate that dislocation wall, sub-dislocation wall, twin and twin boundary steps were achieved on the surface of material after HCPEB irradiation. Furthermore, huge numbers of vacancy defect clusters including dislocation loops, stacking fault tetrahedras (SFT) and voids were also formed within the sublayer of the irradiated surface. The fact that supersaturation vacancies migrated towards the surface along grain boundaries and/or various dislocation configurations led to the formation of microporous feature on the irradiated surface. 相似文献