Three‐dimensionally braided carbon fiber–epoxy composites,a new type of material for osteosynthesis devices. I. Mechanical properties and moisture absorption behavior

In recent years, three‐dimensionally (3D) braided composites have attracted a great deal of attention because of their high‐impact damage tolerance and fatigue life, superior fracture toughness, and so forth, and have been used in aeronautics, military, and transportation. These advantages make them strong candidates for osteosynthesis devices. In this study, 3D braided carbon fiber–epoxy (C_3D/EP) composites were produced via a simple vacuum impregnation technique. The load‐deflection curve, mechanical properties, and influence of fiber volume fraction, braiding angle, and axial reinforcing fibers were examined to determine their suitability for internal fixation devices. It is found that the C_3D/EP composites have excellent toughness and do not show brittleness when fractured because of their relatively high void content. The flexural, shear, and impact strengths of the C_3D/EP composites are excellent. It was shown that a C_3D/EP composite with a stiffness similar to load‐bearing bones can be made while maintaining enough strength. It is concluded that a relatively higher void content and braiding angle is more suitable for the C_3D/EP composites from the viewpoint of requirements of fracture fixation materials. The moisture absorption behavior and changes in mechanical properties caused by moisture uptake were evaluated. Results show that absorbed moisture slightly decreases mechanical properties of the C_3D/EP composites. Contrary to the unreinforced epoxy, the moisture absorption behavior of the C_3D/EP composites cannot be described with Fick's law of diffusion, probably because of the presence of voids and/or 3D fiber structure. The exact mechanisms should be proposed in further investigations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1031–1039, 2002     

圆锥形零件冲压变形与成形载荷的分析

由于悬空侧壁部分的变形状态是圆锥形零件成形的关键，而径向拉应力是实现悬空部分成形的必要条件，同时也是该部分冲压成形成败的关键为此，经力学分析得出了侧壁部分径向拉应力的解析式和造成圆锥形零件破裂的最大径向拉应力的计算式。同时分析了圆锥形零件的成形载荷。     

塑钢包装箱材料贮存寿命预测

用热老化箱对4种塑钢包装箱用材进行了为期1个月的热老化试验，以材料的冲击强度作为判据指标，通过回归处理外推得到其常温下的贮存寿命预测评估结果。     

改进灰色神经网络模型在电量预测中的应用

研究过程中分析比较了人工神经网络和灰色模型的优缺点,尝试将人工神经网络模型与改进灰色模型进行有机结合,从而提出了改进灰色神经网络模型。新的耦合方式发挥了灰色预测方法中累加生成的优点,便于神经网络进行训练,又避免了灰色预测方法带来的误差,提高了预测精度,是一种新的有益探索;为实际工程应用提供了重要的参考。     

新抗生素B-3543的研究

对新抗生素B-3543进行了系统的研究,关键指标已达到工业化生产水平。确立了产生菌的分类地位,测定了抗生素的抗菌谱,获得效价达10000μg/ml的高产菌株,阐明了B-3543的化学结构,提出3种效价检定方法,制定了产品质量标准,完善了生产工艺,使产品总收率达60％。该项目还存在产品成本过高,产品稳定性不好等问题,有待研究解决。     

JSL系列电子计长仪及其在纺织设备上的应用

介绍了JSL系列电子计长仪的原理，特点以及在纺织行业多种设备计长控制方面的应用，可替代原已失效的机械式计长装置，运行可靠，计长准确，投资少，效率高。     

电脱盐工艺技术改造运行总结

中国石化股份有限公司济南分公司南常减压装置 2 0 0 1年防腐改造中首次采用了国产高速电脱盐设备 ,对电脱盐工艺进行了改造 ,通过近 1年的生产运行 ,不断进行摸索调整 ,适应了加工多品种原油的需要 ,取得了较好的脱盐效果 ,脱后原油含盐降到 0 .62mg/L ,脱盐污水油含量降至 5 0 μg/g ,为后续加工装置降低能耗、减轻设备腐蚀、安全平稳生产创造了条件     

Prediction of cracking within early-age concrete due to thermal, drying and creep behavior

To predict potential early-age cracking after concrete placing, a numerical simulation procedure has been completed based on a micromechanical model and empirical formulas on the property development of young concrete. The numerical model could account for the effects of hydration, moisture transport and creep. Environmental influences, such as removal of formworks, curing conditions and variations of surrounding temperature and relative humidity, have been investigated. In calculating stress field with age caused by these synthetic physical-mechanical processes, three-dimensional finite element and finite difference (3D-FE-FD) methods are combined together.     

丁腈橡胶/导电粒子复合材料的正温度系数(PTC)特性

将导电粒子碳黑和铜粉分别与丁腈橡胶混合制备导电聚合物复合材料，其中碳黑（Ｎ５５０）／丁腈橡胶复合材料的电阻率随温度的变化呈现较强的正温度系数（ＰＴＣ）效应。讨论了掺入导电粒子浓度、结构和表面性质以及混炼硫化工艺等对该类材料的室温电阻率及ＰＴＣ效应的影响。     

聚氧化乙烯—聚磷酸钠共混物的钠离子导电性

研究了聚氧化乙烯-聚磷酸钠共混物的钠离子导电性和低分子量多缩乙二醇对共混物导电性的改进作用。结果表明,降低多缩乙二醇的分子量以及增加其含量都有利于提高共混物的离子导电率。增塑剂改进共混物导电性的实质是提高共混物的非晶相含量,共混物内钠离子传导发生在非晶区,聚合物链段运动是离子传导的主要推动力。