橡胶熔体在不同生产工艺下流动的数值分析

膨胀干燥机是橡胶后处理的重要设备,可脱去橡胶熔体中质量分数为90%的水分。基于FLUENT软件,对橡胶熔体在膨胀干燥机流道中的流动进行数值分析,在不同进出口压力差、螺杆转速等生产工艺条件下,根据速率分布云图、压力分布云图,分析橡胶熔体在膨胀干燥机流道中的流动规律,从而改善橡胶质量。     

Aluminum assisted electrodeposition of europium in LiCl-KCl molten salt

Cyclic voltammetry (CV), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to investigate the electrodeposition of Eu and Al in an LiCl-KCl eutectic melt containing Eu²⁺ and Al³⁺ at 450 °C. In order to deposit a pure Eu and Al alloy, the stoichiometrically lower concentration of Al³⁺ than that of Eu²⁺ and Al wires as a counter electrode was introduced into the bath of LiCl-KCl melt for the electrodeposition. The electrodeposition takes place at a potential more negative than −1.95 V vs. Ag|Ag⁺ while the deposit is oxidized at more positive potential than −1.92 V. Two new reduction peaks and an anodic peak on a W working electrode were observed at −2.39 V, −2.42 V, and −2.1 V, vs. Ag|Ag⁺, respectively, suggesting that the potential window of the Al system in LiCl-KCl melt can be extended to −2.43 V vs. Ag|Ag⁺. The EDS analysis indicated that AlEu can be deposited at the potential more negative than −2.37 V.     

Experimental studies on extrudate swell behavior of PS and LLDPE melts in single and dual capillary dies

Extrudate swell behavior of polystyrene (PS) and linear low‐density polyethylene (LLDPE) melts was investigated using a constant shear rate capillary rheometer. Two capillary dies with different design configurations were used, one being a single flow channel and the other being a dual flow channel. A number of extrudate swell related parameters were examined, and used to explain the discrepancies in the extrudate swell results obtained from the single and dual flow channel dies, the parameters including output rate and output rate ratio, power law index, wall shear rate, wall shear stress, melt residence time, pressure drop induced temperature rise, flow channel position relative to the barrel centerline, and the flow patterns. It was found in this work that the power law index (n value) was the main parameter to determine the output rate ratio and the extrudate swell between the large and small holes for the dual flow channel die: the greater the n value the lower the output rate ratio and thus decreased extrudate swell ratio. The differences in the extrudate swell ratio and flow properties for PS and LLDPE melts resulted from the output rate ratio and the molecular chain structure, respectively. The extrudate swell was observed to increase with wall shear rate. The discrepancies in the extrudate swell results from single and dual dies for a given shear rate were caused by differences in the flow patterns in the barrel and die, and the change in the melt velocities flowing from the barrel and in the die to the die exit. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1713–1722, 2003     

熔体的粘度，亚稳相，相变和相图——Ⅲ．合金液相相图

对Sn（x）Bi（1-x）11种组分（x=0.10％，20％…80％，90％，100％）的熔体的粘度进行了测量，给出了它们的相变点Tt，相区和相参数；根据这些参数作出了一个二元合金液相相图；为了表明相区的划分和每个相区的结构特征提出两种相图的形式；第1，温度一组分（T-X）图，第2，结构-组分（df-x）图。     

熔体的粘度,亚稳相,相变和相图Ⅰ.熔体的粘度理论和亚稳相

用Einstein-Debye粘度的流团扩散理论和流团振动的量子理论给出了熔体粘度的微观公式,并用熔体的结构模型和流团的扩散模型分析了熔体粘度的微观本质是分子间相互作用.发现熔体中存在多个亚稳相相区,指出了表征熔体亚稳相特征的有宏观相参数η0,ε和微观相参数df.     

熔体的粘度,亚稳相,相变和相图Ⅱ.熔体中的不连续结构相变

实验和理论表明,粘度是一个能明确表征和反映熔体中存在的亚稳相和这些相之间转变特征的“好”物理量.表征熔体中亚稳相特征具有宏观参量(η0,ε)又有微观参量(df);是一类有别于其它有液-液相变液体的(例如4He,液晶)新的液相.熔体中亚稳相之间的转变是一类新的LLPT:第1,是可逆的一级相变:在相变点两相平衡并服从相律;第2,是不连续结构转变并有两种突变形式:热缩(吸收蒸发热),热胀(放出凝结热).对任意组分的熔体均有相似的亚稳相特征和相变特征.     

Development of CAD software package of intellectualized casting technology

Based on the numerical simulation of solidification, a computer aid design(CAD) software package of casting technique was developed to design the rising system intelligently. The software can calculate the size and locate the situations of the isolated melts. According to the liquid shrinkage of each isolated melts and the standard parameters of risers in the database, the riser‘s situation and the size can be identified intelligently as long as the riser‘s shape is selected. 3-D software and simulation analysis of CAST soft/computer aid engineering(CAE) software show that the design of the riser and the running system is feasible.     

膨胀干燥机橡胶熔体流动数值模拟分析

膨胀干燥机是橡胶后处理的重要设备,通过膨胀干燥机可脱去橡胶熔体中90%的水分。基于FLUENT软件,对橡胶熔体在膨胀干燥机流道中的流动进行数值分析,并根据速度分布云图及压力分布云图,分析橡胶熔体在流道中的流动规律。研究结果可为进一步研究工艺参数对橡胶质量的影响奠定基础。     

Electrochemical formation of Sm-Co alloys by codeposition of Sm and Co in a molten LiCl-KCl-SmCl3-CoCl2 system

Electrocodeposition of Sm and Co on a Cu substrate was investigated in a molten LiCl-KCl-SmCl₃ (0.5 mol.%)-CoCl₂ (0.1 mol.%) system at 723 K. Phase of the deposited Sm-Co alloys could be controlled by electrolysis potential. SmCo₃ was formed on a Cu substrate by potentiostatic electrolysis in the potential range of 0.20-0.90 V (vs. Li⁺/Li). Sm₂Co₁₇ was obtained in the potential range of 0.90-1.50 V.     

交联聚乙烯/丙烯酸/蒙脱土纳米复合材料的制备与表征

在制备交联聚乙烯／蒙脱土纳米复合材料的过程中,利用交联聚乙烯的特征,通过在与蒙脱土熔融复合的过程中加入单体丙烯酸作为相容剂,制得交联聚乙烯／蒙脱土纳米复合材料。用XRD、TEM进行表征,并对材料的力学性能进行测试。结果显示：复合材料的拉伸强度与原基材相比有所上升,而冲击强度有所下降。