Physical Properties Important to Electrostatic and Non electrostatic Powder Transfer Efficiency in a Tumble Drum

ABSTRACT: Popcorn was oiled and coated in a tumble drum nonelectrostatically and electrostatically with sugar, cornstarch, salt, cellulose, maltodextrin, all-purpose flour, whole-wheat flour, or soy flour. Particle size, density, flowability, and chargeability were correlated to transfer efficiency using regression analysis. Of the various methods to measure chargeability, charge-to-mass and adhesion improvement were the most significant. For nonelectrostatic coating, small, dense, free-flowing powders were most efficient. Small, free-flowing highly charging powders were most efficient for electrostatic coating. Percent improvement was the highest for the least efficient powders. The greatest benefit with electrostatic coating was for low density, highly charging powders with no effect of size.     

YS-842催化剂在Hypol工艺PP中试装置上的应用

将Ziegler-Natta高效载体催化剂YS—842在Hypol工艺聚丙烯(PP)中试装置上进行应用考核，考察了该催化剂的适应性及共聚合性能。试验表明，YS—842催化剂活性高(达1．2Mg／g)、寿命长、氢调敏感性好：用YS—842催化剂生产的聚合物流动性好，粒径分布窄，细粉少，平均粒径为640μm；等规指数大于98．5％，堆密度大于0．45g／mL；试生产的F401、J340，其机械性能与使用进口催化剂生产的产品相当。     

UHMWPE/蒙脱土纳米复合材料结构与流动性的关系

采用甲基丙烯酰氧乙基三甲基氯化铵对微米尺度的蒙脱土进行离子交换，所得有机蒙脱土与少量引发剂和超高分子量聚乙烯(UHMWPE)共混后，在双螺杆挤出机上进行反应挤出，得到了具有一定流动性能的UHM—WPE／蒙脱土纳米复合材料。该纳米复合材料熔体的流动性能较UHMWPE高出许多；用X衍射、透射电子显微镜等表征方法研究了这种纳米复合材料的相结构，通过稳态和动态流变试验研究了其流变性能与蒙脱土含量的关系，分析了UHMWPE熔体大分子解缠结机理。     

提高铸造用酚醛树脂流动性的研究

用润滑剂改性的方法试制了改性酚醛树脂，使流动性从40～60mm提高到80～140mm。介绍改性树脂的合成工艺，覆膜砂的生产工艺，树脂性能及覆膜砂性能测试方法。与普通树脂覆膜砂相比，改性树脂覆膜砂的强度提高1～2倍，发气量和灼减量也降低。     

Effects of surface-activated coal gangue aggregates on properties of cement-based materials

Effects of calcined coal gangue （CG） aggregates treated by the surface thermal activation on the flowability and strength, and paste-CG aggregate interfaces of the cement-based material were investigated. The experimental results show that the compressive and flexural strength of the cement-based material with the calcined CG aggregates is much higher than that of the material with the natural CG aggregates, but the flowability of the material with calcined CG is significantly reduced with the calcined time. The strength of the material with the calcined CG aggregates only increases little with the calcined time at the same w/c ratio, but is reduced with the calcined time at the same flowability. The CG aggregates calcined by the surface thermal activation obviously overcomes the disadvantages of fully calcined CG.     

LaNi5 hydride powder flowability as a function of activation and hydrogen content

Volume expansion of hydrogen absorbing materials, together with inter-particle friction can cause tension accumulation in hydride containers during absorption. When hydride particles absorb hydrogen there is an important volume increase, in the order of 25%. Particles have to accommodate to the container geometry but this movement is opposed by inter-particle friction. Under certain conditions tensions can build up, compromising the mechanical integrity of the container. This phenomenon needs to be addressed at the design stage to avoid mechanical failure of the container.Flow behavior of powder materials is a relevant technological field, usually addressed by means of qualitative or quantitative flowability measuring devices. The rotating drum technique, while mainly qualitative, is well established and can be modified into a completely sealed unit. To determine the flowability of a hydride under different activation stages and hydrogen content levels we developed a rotating drum device that can be pressurized with hydrogen or depressurized. We report particle size evolution and flowability measurements of a hydrogen absorbing material (LaNi₅) at different stages of activation for both absorbed and desorbed states. The results of the present study show that the flowability of LaNi₅ in more dependent on the degree of activation of the sample than on hydrogen absorption state.     

振动搅拌对混凝土性能的影响

试验研究了振动搅拌对混凝土强度、含气量和工作性能的影响,结果表明:振动搅拌可以显著提高混凝土强度,但是随着养护时间增长,普通搅拌与振动搅拌混凝土试样强度差异减小;振动搅拌可以显著提高混凝土的含气量;振动搅拌对混凝土粘聚性和保水性影响不大,但是会降低混凝土的流动性。     

PP/竹粉复合材料的研究

分别将未处理和经过表面处理的竹粉填充到聚丙烯(PP)中,研究竹粉对PP性能的影响。当竹粉含量为30-40质量份时,复合材料的综合性能较好;PP／处理竹粉复合材料的流动性能、力学性能和热性能相对于未处理竹粉的复合材料均有不同程度的提高。     

聚四氟乙烯湿法造粒的研究现状

叙述了聚四氟乙烯湿法造粒料的应用范围、制造方法、性能特征以及前景展望。