Effect of morphology on brittle-ductile transition of HPDE/CaCO3 blends

In this paper, the results of a series of investigations of the effect of morphology on the brittle-ductile transition for HDPE/CaCO₃ blends are summarized: (1) It seems the critical ligament thickness increases with increasing matrix toughness; (2) the interphase adhesion is very important for the toughness of HDPE/CaCO₃ blends; (3) small particles are more effective than large ones; (4) CaCO₃ particle aggregation will reduce toughening efficiency; (5) uniform CaCO₃ particle size is more effective than heterogeneous size for the toughening of HDPE. It is expected that a polymer with higher modulus as well as higher toughness will be obtained by appropriately controlling the morphology of HDPE/CaCO₃ blends. © 1993 John Wiley & Sons, Inc.     

CaO-SiO2系玻璃的析晶动力学研究

利用溶胶-凝胶法制得CaO-SiO2系基础玻璃,通过差热分析曲线分析质量比为CaO-SiO2玻璃的析晶能力。经分析,其析晶活化能E=457.1kJ·mol-1,而晶化生长指数是随升温速率的不同而不同,速率越大,晶化生长指数越小。     

运动发酵单胞原生质球的形成和再生

运动发酵单胞(Zymomonas mobilis)ATCC29191菌株在含1～3g/L甘氨酸的液体培育12小时的菌体,用含20g/L的溶菌酶溶液处理12小时,可以稳定得到80％～90％的原生质球。原生质球稀释后在底层再生培养基上涂布,上面复盖一层半固体培养基,30℃培养5～7小时,再生率可达10~(-2)水平。     

Solvent fractionation of petroleum pitch for mesophase formation

Petroleum pitch (Ashland A240) has been subjected to thermal treatment and solvent fractionation to produce refined pitches to be evaluated as impregnants for C-C composites. The solvent fractions were obtained by sequential Soxhlet extraction with solvents such as hexane, benzene, and pyridine. Thermal treatment to 408 °C produced a mesophase pitch (≈50% mesophase); an appreciable portion of the mesophase was soluble in strong solvents. There were substantial differences in chemical composition and in pyrolysis behaviour of the fractions. As the depth of fraction increased, the pyrolysis yield and bloating increased, and the microstructure of the coke became finer until glassy microconstituents were formed in the deepest fractions.     

论刑罚个别化原则

刑事近代学派在批判刑事古典学派的基础上提出的刑罚个别化主张,对于预防犯罪和实现司法实践活动中的个别公正具有不可替代的作用.人身危险性是刑罚个别化原则的核心概念.分析了人身危险性与初犯可能性、主观恶性的关系,阐述了刑罚个别化原则的理论依据以及刑罚个别化原则与罪刑相适应原则的冲突,认为应该在罪与刑相适应的基础上,用人身危险性加以调整、修正,在一般预防和报应主义下,考虑刑罚的个别预防.     

VR技术对地下步行商业街心理环境辅助设计初探

文章力图以VR（虚拟现实）技术手段应用于城市地下步行商业街规划设计,来解决当前传统规划手段地下步行商业街规划中普遍存在的对其心理环境构筑的忽视和考虑不完善的诟病,以期最大限度消除规划设计中消极空间的产生,并对其关键技术进行了研究和探讨     

Practical Control of a Ball-Screw-Driven Stage for Long-Range Nanometer Positioning

A DC motor and ball-screw-driven stage is studied for long-range nanometer positioning.The closed-loop system with high-gain PID controller is specially designed for high-precision point-to-point (PTP) positioning.A particular input shape of the closed-loop system is proposed to avoid overshoot and vibration by taking into account the nonlinear characteristics of the feed drive.Friction modeling and identification are avoided and the effect of friction is greatly suppressed by the controller.Experimental and simulated results demonstrate long-range nanometer positioning is achieved without overshoot.In PTP positioning from 10 mm down to 5 nm,the positioning error is within ±5 nm and response dynamic is satisfactory.     

聚酯经营 风云变幻

回顾了 2 0 0 0年世界聚酯的发展状况 ,分析了 2 0 0 1年聚酯经营的现状 ,指出聚酯工业正面临着风云变幻的境地 ,并提出发展聚酯工业的建议。     

硬质聚氯乙烯管专用树脂

采用电镜分析、反相色谱、毛细管流变仪和布拉本达塑性仪研究了由锦西化工研究院生产的ＰＶＣ管用树脂的颗粒形貌、比表面积、流变性能和加工速率。结果表明，该树脂和疏松型树脂的形貌呈棉桃状不同，外形为球状，比表面积较大，约比普通ＳＧ－５型树脂增加１倍，最高可达１．００７ｍ＾２／ｇ；在从低剪切到高剪切速率范围内，该树脂的表观粘度均比ＳＧ－５型树脂低，不论是采用粒料还是粉料挤出，在聚合度相同时，该树脂的挤出速率     

ZrO2对CaO-SiO2系玻璃析晶的影响

通过DSC曲线研究了不同含量的ZrO2对CaO-SiO2系玻璃析晶的影响,根据JMA方程计算动力学参数(如析晶活化能E、频率因子ν、晶化指数n)。从计算结果可以看出,随着ZrO2含量的增加,析晶活化能E减少,而频率因子ν和晶化指数n增加。当ZrO2含量为7%时,E值最小:235.58kJ/mol;n值最大:4.70。说明ZrO2在CaO-SiO2玻璃体系是有效的晶核剂。