Polyamide-6/vegetal fiber composite prepared by extrusion and injection molding

The interest for the use of vegetal fibers as polymers reinforcement has recently increased because of their unique environmental and technological advantages. This work evaluated the use of Curauá fibers in polyamide-6 composites aiming at glass fiber replacement. Fiber content of 20, 30 or 40 wt% and fiber lengths of 0.1 or 10 mm were studied. Fibers were treated with N₂ plasma or washed with NaOH solution, to improve their adhesion to PA-6. Samples with 20 wt% of short or long fibers, with or without pre-treatment, were compounded in two different co-rotating intermeshing twin-screw extruders. These samples were submitted to mechanical and thermal tests. In conclusion, non-dried raw materials improved fiber/matrix interfacial adhesion. Tensile and flexural properties of this composite are better than unfilled, but lower than glass fiber reinforced polyamide-6. However, its impact resistance and heat deflection temperature are similar to the glass fiber reinforced polyamide-6 and its lower density, enable it to replace this latter in specific non-critical applications.     

Flexural and Shear Rigidity of Composite Sheet Piles

The flexural and shear rigidity of pultruded composite sheet pile panels consisting of E-glass fiber-reinforced polyester are studied in this paper. The analysis consists of an experimental investigation and an analytical modeling to determine the resistance of the sheet pile panels to the deflections for design of composite sheet pile walls. Timoshenko’s beam theory was used to experimentally determine the flexural rigidity (EI) and shear rigidity (kAG) of the panel. Three- and four-point bending tests were performed on six different span lengths and the results were self-compared from the two independent tests. Analytical expressions for the flexural and shear rigidities were derived to allow the prediction based on the layered structure of pultruded shapes. The values computed from the analytical expressions were examined with the experimental results.     

铁水喷镁脱硫技术的应用

简述了涟钢铁水喷镁脱硫技术的设备概况、工艺流程和试生产情况。重点介绍处理过程的反应机理和控制方法，通过调整和改造，解决了钢水回硫的问题，实现了铁水脱硫-转炉-RH精炼炉-CSP的匹配。     

Finding feasible mold parting directions using graphics hardware

We present new programmable graphics hardware accelerated algorithms to test the 2-moldability of geometric parts and assist with part redesign. These algorithms efficiently identify and graphically display undercuts as well as minimum and insufficient draft angles. Their running times grow only linearly with respect to the number of facets in the solid model, making them efficient subroutines for our algorithms that test whether a tessellated CAD model can be manufactured in a two-part mold. We have developed and implemented two such algorithms to choose candidate directions to test for 2-moldability using accessibility analysis and Gauss maps. The efficiency of these algorithms lies in the fact that they identify groups of candidate directions such that if any one direction in the group is undercut-free, all are, or if any one is not undercut-free, none are. We examine trade-offs between the algorithms' speed, accuracy, and whether they guarantee that an undercut-free direction will be found for a part if one exists.     

Upper-bound analysis of the pressure-assisted injection forging of thick-walled tubular components with hollow flanges

An upper-bound analysis of the pressure-assisted injection forging (PAIF) of thick-walled tubular components with hollow flanges was conducted to predict the maximum forming-pressure requirements. The polymeric pressurizing material and the pure aluminium work material employed were assumed to obey the von-Mises’ yield criterion, the two materials being divided into three and six zones, respectively, and described using kinematically admissible velocity fields. An upper-bound solution was derived based on this model. Experiments were conducted to validate the solution. The results suggest that the upper-bound analysis has sufficient accuracy for the prediction of the forming-pressure requirements. Subsequently, a parametric analysis was conducted to study the effects of variation of the principal parameters of the process and the geometry, such as tube thicknesses, flange dimensions and friction, on the forming-force requirements, which showed other useful applications of the upper-bound solutions.     

Electrochemical chlorination of azulene derivatives: Insight into the mechanism of anodic oxidative chlorination

The cyclic voltammetry behavior of a series of five 1-substituted azulenes has been investigated as well as the electrochemical chlorination of these compounds. In the case of azulene compounds containing electron withdrawing groups which have higher oxidation potentials than that of the chloride ion, the electrochemical chlorination led usually to 3-chloro derivatives. The electrochemical chlorination fails for azulenes with lower oxidation potentials. Additionally some polyhalogenated compounds were obtained by controlled potential electrolyses. The paper also discusses the reaction mechanism of the electrochemical halogenation of 1-substituted azulenes.     

光孤子源的研制

报道了利用增益开关分布反馈半导体激光器，Ｆ－Ｐ光学滤波器及掺饵光纤放大顺研制成光孤子源的研究工作。光孤子源性能稳定，输出的超短光脉冲重复频率为２．５ＧＨｚ脉宽２４，谱宽０．１４ｎｍ，时间带宽积０．４１９，平均输出光功率２．４ｍＷ。     

Ammoxidation of methylaromatics over vanadium phosphate catalysts II. Catalyst formation, active sites and reaction mechanism

The interactions of VOHPO₄· 0.5H₂O and (VO)₂P₂O₇ with the ammoxidation feed and the single components such as ammonia, oxygen, water and component mixtures were studied in detail using XRD and temperature-programmed reaction spectroscopy. The aim of this work was to improve the knowledge of the formation of the active phases or active sites of the catalysts from their precursors under the condition of the ammoxidation reaction. Similar catalytic properties of various applied VPO materials were discussed in terms of the presence of similar structure elements (domains of adjacent edge-sharing VO₆ octahedra-units and P-O-NH₄ groups).     

强韧包装纸板用落叶松半化学浆的研究

主要研究一种可以替代传统硫酸盐化学木浆，来生产强韧包装纸板或瓦楞纸箱箱板纸的落叶松碱性亚硫酸盐－蒽醌半化学浆。这种采用碱性亚硫酸盐添加蒽醌助剂的制浆方法研制的落叶松半化学浆，当纸浆得率为５６．９％时，在低打浆度情况下纸浆强度性能可以达到我国２号未漂硫酸盐化学木浆的标准，而且有可能达到１号未漂硫酸盐化学木浆的标准，纸浆得率比落叶松硫酸盐木浆得率实际指标（４３％）绝对值提高１３％以上。用于制作强韧包装纸板或瓦楞纸箱箱板纸的落叶松碱性亚硫酸盐－蒽醌半化学浆，蒸煮终点宜于控制在得率约６２％、卡伯值１００左右。     

用纤维TiO2作光催化剂降解饮用水中腐殖质

用纤维状ＴｉＯ２作为光催化剂，采用间歇和连续两种操作方式，在Ｏ３／ＴｉＯ２／ＵＶ体系中处理含腐殖质的饮用水，使腐殖质去除率在９７％，纤维ＴｉＯ２可过滤回收，易于实际应用。