An aryl dicarboxylic acid amide compound TMB-5 is an efficient β-form nucleating agent for isotactic polypropylene （iPP）. Because of the solubility of TMB-5, superstructure and morphology of iPP crystals changed wi...An aryl dicarboxylic acid amide compound TMB-5 is an efficient β-form nucleating agent for isotactic polypropylene （iPP）. Because of the solubility of TMB-5, superstructure and morphology of iPP crystals changed with melting conditions. Effects of final heating temperature （Tf） on heterogeneous nucleation of iPP/TMB-5 were investigated. It was discovered that the crystallization temperature increased with decreasing Tf value. The optical microscopic images indicated that when TMB-5 partially dissolved in iPP melt, the remaining （non-dissolved） TMB-5 facilitated the recrystallization of dissolved nucleating agent from the melt, which promoted crystallization. Complete solubility of nucleating agent caused the decreasing efficiency. TMB-5 recrystallized in the form of tiny needles, whose aggregates induced dendritic iPP crystals.展开更多
Large size AlN bulk crystal has been grown on SiC heterogeneous seed by physical vapor transport (PVT). The properties of AlN wafer were characterized by high resolution X-ray diffraction (HRXRD), Raman spectroscopy, ...Large size AlN bulk crystal has been grown on SiC heterogeneous seed by physical vapor transport (PVT). The properties of AlN wafer were characterized by high resolution X-ray diffraction (HRXRD), Raman spectroscopy, etched method and atomic force microscope (AFM). Growth mechanism of AlN crystal grown on heterogeneous SiC seeds was proposed. Crystallization quality of AlN samples were improved with the growth process, which is associated with the growth mechanism. AlN single wafer has excellent crystallization quality, which is indicated by HRXRD showing the (0002),(1012) XRD FWHM of 76.3,52.5 arcsec, respectively. The surface of the AlN wafer is measured by AFM with a roughnessof 0.15 nm, which is a promising seed for AlN homogeneous growth.展开更多
以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)改性的硫酸钙晶须(CSW)为高密度聚乙烯(HDPE)的填料,采用熔融共混法制备了HDPE/CSW复合材料。通过SEM、XRD、TG、DSC表征了KH570改性的CSW对复合材料HDPE/CSW的性能影响。结果表明,改性CSW...以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)改性的硫酸钙晶须(CSW)为高密度聚乙烯(HDPE)的填料,采用熔融共混法制备了HDPE/CSW复合材料。通过SEM、XRD、TG、DSC表征了KH570改性的CSW对复合材料HDPE/CSW的性能影响。结果表明,改性CSW质量分数为20%时,HDPE/CSW的拉伸和弯曲强度比纯HDPE分别增加9.28%和33.04%,且易产生异相结晶,提升了HDPE/CSW复合材料的耐热性和结晶度。纯HDPE的热降解反应活化能为244.11 k J/mol,改性CSW质量分数为50%时,HDPE/CSW复合材料的热降解反应活化能降到236.99 kJ/mol,表明CSW提升了HDPE/CSW复合材料的热降解反应速率,扩展了复合材料的使用范围。展开更多
The polymer on modulating the crystal's habit is an evolving research in pharmaceutical crystallization.This study demonstrates the crystal habit modification of chlorzoxazone(CHZ)by heterogeneous crystallization(...The polymer on modulating the crystal's habit is an evolving research in pharmaceutical crystallization.This study demonstrates the crystal habit modification of chlorzoxazone(CHZ)by heterogeneous crystallization(HC)in the binary solvent acetonitrile-ethanol(A-E(1:1))in the presence of polyvinylpyrrolidine(PVP)at concentrations of 0.50,0.75,and 1.00 wt%.The A-E(1:1)and PVP in HC experiments influenced to change the shape of crystals from needle to plate shape and reduced the crystal size producing a lower aspect ratio(in the range of 1.5-2.3).In the presence of PVP,the CHZ size distribution is 65-78μm which tends to enhance the powder flow-ability of CHZ crystals and as the PVP concentration increases,the nucleation rate decreases.The solubility of size-reduced CHZ crystals at different pH is found to be improved by 1.2-1.4 times.Hence,HC is deemed effective in modifying the physicochemical attributes of CHZ.展开更多
The on-board methanol steam reforming(MSR) has long been considered as an effective approach to insitu produce hydrogen for fuel cell vehicles(FCVs). However, the conventional MSR catalyst pellets suffer from easy bre...The on-board methanol steam reforming(MSR) has long been considered as an effective approach to insitu produce hydrogen for fuel cell vehicles(FCVs). However, the conventional MSR catalyst pellets suffer from easy breakage during the vehicle movement, leading to increased pressure drop and reduced system stability. Herein, we introduce an integrated method to prepare the highly controlled structured catalysts based on coupled processes: direct prototyping the structured substrate using digital light processing(DLP) 3D printing technology, in-situ dynamic crystallization of active components assisted by magnetic resonance imaging(MRI) and calcination. The synthesized catalyst owns a gradient layer of active component, and exhibits better MSR performance, higher mechanical strength, reduced pressure drop, higher Cu dispersion and better adhesion of active compounds when compared with the conventional powder and pellet catalysts. The demonstrated successful application proves the feasibility of developed method,which has great potential to be used for preparing precisely other monolithic catalysts with customized structures.展开更多
文摘An aryl dicarboxylic acid amide compound TMB-5 is an efficient β-form nucleating agent for isotactic polypropylene （iPP）. Because of the solubility of TMB-5, superstructure and morphology of iPP crystals changed with melting conditions. Effects of final heating temperature （Tf） on heterogeneous nucleation of iPP/TMB-5 were investigated. It was discovered that the crystallization temperature increased with decreasing Tf value. The optical microscopic images indicated that when TMB-5 partially dissolved in iPP melt, the remaining （non-dissolved） TMB-5 facilitated the recrystallization of dissolved nucleating agent from the melt, which promoted crystallization. Complete solubility of nucleating agent caused the decreasing efficiency. TMB-5 recrystallized in the form of tiny needles, whose aggregates induced dendritic iPP crystals.
基金supported by National Key Research and Development Plan of China (No. 2017YFB0404103)National Natural Science Foundation of China (No. 51702297)Tianjin Science and Technology Plan Project (No. 17YFZCGX00520)
文摘Large size AlN bulk crystal has been grown on SiC heterogeneous seed by physical vapor transport (PVT). The properties of AlN wafer were characterized by high resolution X-ray diffraction (HRXRD), Raman spectroscopy, etched method and atomic force microscope (AFM). Growth mechanism of AlN crystal grown on heterogeneous SiC seeds was proposed. Crystallization quality of AlN samples were improved with the growth process, which is associated with the growth mechanism. AlN single wafer has excellent crystallization quality, which is indicated by HRXRD showing the (0002),(1012) XRD FWHM of 76.3,52.5 arcsec, respectively. The surface of the AlN wafer is measured by AFM with a roughnessof 0.15 nm, which is a promising seed for AlN homogeneous growth.
文摘以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)改性的硫酸钙晶须(CSW)为高密度聚乙烯(HDPE)的填料,采用熔融共混法制备了HDPE/CSW复合材料。通过SEM、XRD、TG、DSC表征了KH570改性的CSW对复合材料HDPE/CSW的性能影响。结果表明,改性CSW质量分数为20%时,HDPE/CSW的拉伸和弯曲强度比纯HDPE分别增加9.28%和33.04%,且易产生异相结晶,提升了HDPE/CSW复合材料的耐热性和结晶度。纯HDPE的热降解反应活化能为244.11 k J/mol,改性CSW质量分数为50%时,HDPE/CSW复合材料的热降解反应活化能降到236.99 kJ/mol,表明CSW提升了HDPE/CSW复合材料的热降解反应速率,扩展了复合材料的使用范围。
文摘The polymer on modulating the crystal's habit is an evolving research in pharmaceutical crystallization.This study demonstrates the crystal habit modification of chlorzoxazone(CHZ)by heterogeneous crystallization(HC)in the binary solvent acetonitrile-ethanol(A-E(1:1))in the presence of polyvinylpyrrolidine(PVP)at concentrations of 0.50,0.75,and 1.00 wt%.The A-E(1:1)and PVP in HC experiments influenced to change the shape of crystals from needle to plate shape and reduced the crystal size producing a lower aspect ratio(in the range of 1.5-2.3).In the presence of PVP,the CHZ size distribution is 65-78μm which tends to enhance the powder flow-ability of CHZ crystals and as the PVP concentration increases,the nucleation rate decreases.The solubility of size-reduced CHZ crystals at different pH is found to be improved by 1.2-1.4 times.Hence,HC is deemed effective in modifying the physicochemical attributes of CHZ.
基金supported by the Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Key Technical Personnel of Chinese Academy of Sciences+1 种基金the STS Program of Chinese Academy of Sciences (No. KFJJ-STS-SCYD-302)the National Natural Science Foundation of China (22108288)。
文摘The on-board methanol steam reforming(MSR) has long been considered as an effective approach to insitu produce hydrogen for fuel cell vehicles(FCVs). However, the conventional MSR catalyst pellets suffer from easy breakage during the vehicle movement, leading to increased pressure drop and reduced system stability. Herein, we introduce an integrated method to prepare the highly controlled structured catalysts based on coupled processes: direct prototyping the structured substrate using digital light processing(DLP) 3D printing technology, in-situ dynamic crystallization of active components assisted by magnetic resonance imaging(MRI) and calcination. The synthesized catalyst owns a gradient layer of active component, and exhibits better MSR performance, higher mechanical strength, reduced pressure drop, higher Cu dispersion and better adhesion of active compounds when compared with the conventional powder and pellet catalysts. The demonstrated successful application proves the feasibility of developed method,which has great potential to be used for preparing precisely other monolithic catalysts with customized structures.
