A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styren...A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styrene/Cu （ABS/Cu） gradient polymeric composites were prepared successfully using this technique. The gradient structures, electrically conductive performance and mechanical properties of the ABS/Cu composites were investigated. Optical microscope observation shows that the gradient distribution of Cu particles in ABS matrix was formed along their thickness-direction. The electrically conductive testing results indicate that the order of magnitude of surface resistivity was kept in 10^15 Ω at ABS rich side, while that declined to 10^5 Ω at Cu particles rich side, and the percolation threshold was in the range of 2.82 vo1%- 4.74 vol% Cu content at Cu particles rich side. Mechanical test shows that the tensile strength reduced insignificantly as the content of Cu increases owing to the gradient distribution.展开更多
The solid-liquid separation is an important operation for the regenerated slurry of dual-alkali FGD system,and calcium sulfite could predominate in particle aggregates of the slurry.The settling velocity of calcium su...The solid-liquid separation is an important operation for the regenerated slurry of dual-alkali FGD system,and calcium sulfite could predominate in particle aggregates of the slurry.The settling velocity of calcium sulfite particles is a key parameter for the solid-liquid separation design.However,the settling velocity predicted by Stokes' Law could be suitable only for a spherical aggregate, but not for the irregular one.In this work,fractal geometry was introduced in order to characterize highly irregular geometric shapes.The sizes of calcium sulfite particle aggregates were analyzed using a metallographic phase microscope and image analysis.The results showed that particle aggregates had fractal features.The fractal dimensions could reveal the characteristics of the aggregates' geometry and aggregation process.An exponential relation between the fractal dimension D_2 and the particle size l was determined as A∝l^(D2). According to fractal theory,a parameter can be used to modify Stokes settling velocity close to actual settling velocity.The results could be valuable for the design of solid-liquid separation processes.展开更多
基金Funded by the National Natural Science Foundation of China(No.21274007)the Beijing Natural Science Foundation+1 种基金the Key Scientific Project of Beijing Municipal Education Commission(No.KZ201110011014)the Science and Technology Innovation Platform of Beijing Municipal Education Commission(No.PXM2012-014213-000025)
文摘A novel technique for preparing functionally gradient electrically conductive polymeric composites was developed by using of solution casting technique on the principle of Stokes＇ law. Acrylonitrile- butadiene-styrene/Cu （ABS/Cu） gradient polymeric composites were prepared successfully using this technique. The gradient structures, electrically conductive performance and mechanical properties of the ABS/Cu composites were investigated. Optical microscope observation shows that the gradient distribution of Cu particles in ABS matrix was formed along their thickness-direction. The electrically conductive testing results indicate that the order of magnitude of surface resistivity was kept in 10^15 Ω at ABS rich side, while that declined to 10^5 Ω at Cu particles rich side, and the percolation threshold was in the range of 2.82 vo1%- 4.74 vol% Cu content at Cu particles rich side. Mechanical test shows that the tensile strength reduced insignificantly as the content of Cu increases owing to the gradient distribution.
基金Supported by the National Hi-tech Research and Development Program (863 Program) of China (No.2001AA642030-1)New Century Excellent Scholar Program of Ministry of Education of China (No.NCET-04-0549)The Key Research Project of Zhejiang Province (No.010007037)
文摘The solid-liquid separation is an important operation for the regenerated slurry of dual-alkali FGD system,and calcium sulfite could predominate in particle aggregates of the slurry.The settling velocity of calcium sulfite particles is a key parameter for the solid-liquid separation design.However,the settling velocity predicted by Stokes' Law could be suitable only for a spherical aggregate, but not for the irregular one.In this work,fractal geometry was introduced in order to characterize highly irregular geometric shapes.The sizes of calcium sulfite particle aggregates were analyzed using a metallographic phase microscope and image analysis.The results showed that particle aggregates had fractal features.The fractal dimensions could reveal the characteristics of the aggregates' geometry and aggregation process.An exponential relation between the fractal dimension D_2 and the particle size l was determined as A∝l^(D2). According to fractal theory,a parameter can be used to modify Stokes settling velocity close to actual settling velocity.The results could be valuable for the design of solid-liquid separation processes.
