Effect of nonlinear viscoelastic properties on tack

The influence of rheological and surface properties on adhesive tackiness are studied. In particular, the importance of the elongational properties is emphasized in a model, which considers only the adhesive contribution while neglecting the importance of cavitation and surface roughness. This simple analysis allows us to recover the different types of curves (i.e., different adhesive materials) obtained in the literature on tack. Elastic, strain‐hardening, and viscous adhesive materials are considered. The question of the importance of surface properties is raised and discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3139–3149, 2003     

Quantum‐chemical approach to the solvatochromic transition in polysilane derivatives

We approached the solvatochromic transition observed in polysilane derivatives (poly[bis(4‐propoxybutyl)silylene] (PPBS)) from the standpoint of various quantum chemical treatments. It was found from conventional geometry optimizations at the levels of semiempirical and ab initio molecular orbital methods that a protonation to polysilane oligomers with side chain R = ? OCH₃ results in the conformational change of Si‐backbone to a trans‐zigzag structure. Using the Elongation method, which was developed for efficient calculations of huge systems, it was demonstrated that a protonation could change the conformation of Si‐backbone to a trans‐zigzag structure over 10–14 Si atoms. In addition, ab initio calculations showed that the positive charge of a proton can delocalize into the Si‐backbone through a long side chain in PPBS. Positively charged polysilane oligomers provide a rotational barrier that prefers a trans‐zigzag structure, whereas neutral oligomers have a barrier that results to a random structure. This unique behavior of the charged polysilane oligomers should not be disregarded in understanding the mechanism of the solvatochromic transition in PPBS. In ab initio configuration interaction/Mφller‐Plesset through‐space/bond interaction analysis, it was found that such a unique behavior of the rotational barrier in polysilane oligomers could be explained by the effect of orbital delocalization through σ‐conjugation on the Si‐backbone. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 119–133, 2006     

Homologation of ethylene without metathesis on silica supported ruthenium catalyst

A 1:1 mixture of ¹²C₂-C₂H₄ (H₂C=CH₂) and ¹³C₂-C₂H₄ (H₂ ¹³C=¹³CH₂) was contacted on Ru/SiO₂at 200^oC. Propylene (homologation) was observed without ¹³C₁-C₂H₄ formation (metathesis reaction). This might at least be corroborating evidence for discrimination of active sites in regard with the homologation and the metathesis. This revised version was published online in August 2006 with corrections to the Cover Date.     

圆锥形弹簧的劲度系数和静伸长

从理论上导出了圆锥形密圈弹簧的劲度系数计算公式，给出了圆锥形密圈弹簧竖直悬挂时，由于自重而引起的静伸长量．     

新型齿形链磨损机制及其温度和速度特性的实验研究

在给定的试验条件下，通过对比磨损试验研究了新型齿形链与普通外啮合齿形链的磨损机制，分析了销轴的磨损表面形貌，研究了不同油温和交变速度下新型齿形链的磨损特性．结果表明，新型齿形链的耐磨性能明显优于普通外啮合齿形链，新型齿形链在交变速度下的磨损伸长率大于非交变速度下的磨损伸长率；随着试验油温的升高，新型齿形链的磨损伸长率明显增大．     

脱胶工艺对丝织物穿着性能的影响

本文讨论了脱胶工艺对真丝织物服用性能的影响,并测试了其服用性能最重要的指标,如:丝织物的白度、亮度、断裂强度、断裂延伸、动摩擦系数和粗糙程度等。实验结果表明:纯碱是真丝织物脱胶的主要用剂;丝织物的脱胶率与脱胶液内的纯碱浓度有关,但最好采用纯碱和表面活性剂作为混合脱胶剂;丝织物在纯碱2—3g/L 和油酸钠3g/L 溶液中脱胶1小时,所得白度、亮度较高,断裂强度和断裂延伸下降较少,并可减少丝织物动摩擦系数和降低其粗糙程度,改善其表面性能。     

用移位法弥补金属材料延伸率测定中的误差

介绍金属材料延伸率的测定中，断位位于试样一端时，用移位法减少测量误差的方法。     

茼蒿幼苗根——茎过渡区的初步研究

通过对茼蒿幼苗的连续切片观察，对茼蒿根、茎过渡以及维管组织的一系列变化有了一定的认识。一方面证实了子叶区的客观存在，另一方面也为菊科植物的起源和演化及各属之间的关系积累了新的资料。     

Morphology development in PS/LLDPE blend during and after elongational deformation

The morphology development within a PS/LLDPE blend with 5 wt % of LLDPE at various stages of uniaxial deformation and after cessation of the flow was studied. Under given deformation conditions the dispersed LLDPE particles stretch and form highly elongated fibrils in agreement with a modified capillary number model. The morphology development after deformation was investigated for two different modes—relaxation and recovery. It was found that the stress in the sample is the crucial parameter determining the morphology development. During the first part of relaxation the stress in the sample is sufficient to hold the particles in the highly elongated state and, therefore, Rayleigh breakup takes place according to the Tomotika theory. It results in considerably finer phase structure. Contrary to this, in the absence of the stress in the sample, that is, in the recovery mode, the fibrils start to shrink immediately after the deformation and after a certain time the spherical morphology is restored. During elongation and recovery no evidence of coalescence was observed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 16–27, 2008     

用HVI测试中国棉纤维性能的比较研究

本文分析了目前世界上主要产棉国和棉纺织品生产国中,较广泛使用的两种类型的大容量棉花测试系统(HVI)的特征.用两种 HVI 和常规单项仪器测试了取自全国的有代表性的36个棉花样品的纤维性能,分析了两种类型的 HVI 及其与单项仪器测试结果间的相关性,对 HVI 测试中国棉纤维作出了评价。