A novel phosphorus-containing epoxy with high heat resistance and low hydroxyl was synthesized from naphthoquinone,DOPO,phenolic epoxy and isocyanate.The glass transition temperature Tg and dielectric properties of the resin were measured by differential scanning calorimetry(DSC)and plate capacitance method,respectively.The results showed that the glass transition tempera-ture Tg was higher than 170℃,the dielectric constant and dielectric loss were lower,DK<3.50,Df<0.01,water absorption<0.2%,and the flame retardant was V0.When it was used as copper clad laminate base resin material,it had low dielectric,low dielectric loss,high Tg,low water absorption,V0 flame retardant and other excellent comprehensive properties.
The research progress of metal impurity removal for lithium iron phosphate cathodes were systematically summarized in this paper,the development trend of deep metal impurity removal technology were also put forward via briefly instruction of the principles,advantages and disadvantages of various metal impurity removal methods.Among them,solvent extraction method had some disadvantages such as high production cost in spite of simple operation.Pre-positioned acid pickling method was fit for dealing with the lithium iron phosphate materials containing trace impurities,had the advantages such as simple process,deep impurity removal and so on.However,pre-positioned acid pickling method also had the disadvantages of low selectivity and poor recovery.Dissolution inhibition method was applied for those lithium iron phosphate materials with high impurities,had the drawback of poor impurity removal.The complexation/precipitation method overcomed the shortcomings of dissolution inhibition method and had the advantages of easy control and sufficient impurity removal,indicated the prospect of industrial application.
随着聚烯烃产业的迅速发展,针对新型结构聚烯烃的研究也越来越深入.通过技术创新,采用专有聚合技术制备的长链支化线性低密度聚乙烯产品,各项性能优异,拓展了聚乙烯材料在发泡、高透膜、涂覆等高端领域的应用,同时可满足塑料轻量化和环保可回收等要求.这是国内首次在工业化聚乙烯装置上研发长链支化线性低密度聚乙烯产品,可为聚烯烃的结构调整与性能升级提供思路.
The particle size of CeO2 had a great impact on product performance.The effects of different precipitators,ammonium bi-carbonate concentration,feeding speed,reaction temperature,aging time,stirring speed and calcination temperature on the preparation and particle size of large-particle cerium dioxide were studied.The results showed that when the concentration of ammonium bicarbonate was 2.5mol/L,the droplet acceleration of ammonium bicarbonate was 1mL/min,the reaction temperature was 60℃,the aging time was 20h,the stirring speed was 80r/min,the calcination temperature was 950℃and the calcination time was 1.5h,the large particle CeO2 with D50 of 53.472µm were prepared.This method was simple and suitable for the preparation of other large-particle rare earth oxides.
At present,foam drainage technology was an economical and effective technology to solve the problem of liquid accumulation in gas wells,and foam drainage agent was the most critical part of foam drainage technology.The commonly used foaming agents in gas fields were introduced,the synthesis formulas,application conditions,effectiveness,advantages and disadvantages of conventional and applied foaming agents were discussed in detail.The current research progress on the application of silica particles in foaming agents,as well as the mechanism and advantages and disadvantages of their combination with various types of foaming agents,were reviewed.The problems in the preparation and application of foaming agents were analyzed,and the development trend and prospects of foaming agents in future foaming processes were proposed.
