PC/POSS复合材料的制备及热性能

合成及表征了八苯基倍半硅氧烷（PH-POSS）、γ-甲基丙烯酰氧丙基倍半硅氧烷（MA-POSS）,并利用差示扫描量热（DSC）和热重分析（TGA）分别研究其在聚碳酸酯（PC）体系中对体系热性能的影响。研究结果表明,复合材料Tg随着PH-POSS含量的增加而降低;而随着MA-POSS含量的增加基本不受影响。在氮气中,复合...     

Development of nano-composite lead-free electronic solders

Inert, hybrid inorganic/organic, nano-structured chemicals can be incorporated into low melting metallic materials, such as lead-free electronic solders, to achieve desired levels of service performance. The nano-structured materials technology of polyhedral oligomeric silsesquioxanes (POSS), with appropriate organic groups, can produce suitable means to promote bonding between nano-reinforcements and the metallic matrix. The microstructures of lead-free solder reinforced with surface-active POSS tri-silanols were evaluated using scanning electron microscopy (SEM). Wettability of POSS-containing lead-free solders to copper substrate was also examined. Steady-state deformation of solder joints made of eutectic Sn-Ag solder containing varying weight fractions of POSS of different chemical moieties were evaluated at different temperatures (25°C, 100°C, and 150°C) using a rheometric solids analyzer (RSA-III). Mechanical properties such as shear stress versus simple shear-strain relationships, peak shear stress as a function of rate of simple shear strain, and testing temperature for such nano-composite solders are reported. The service reliability of joints made with these newly formulated nano-composite solders was evaluated using a realistic thermomechanical fatigue (TMF) test profile. Evolution of microstructures and residual mechanical property after different extents of TMF cycles were evaluated and compared with joints made of standard, unreinforced eutectic Sn-Ag solder.     

Some results on fuzzy (digital) convexity

The definition of fuzzy convexity is reviewed and some results on projections of convex and fuzzy convex sets are established. Digital fuzzy convexity is defined and relationships among alternative definitions are investigated.     

Geometric Methods for Shape Recovery from Line Drawings of Polyhedra

Using structural geometric arguments, Whiteley showed that a line drawing is a correct projection of a spherical polyhedron if and only if it has a cross-section compatible with it. We here enlarge the class of drawings to which this test applies, including those of polyhedral disks, possibly with perforations. This extension is helpful, as it makes the test applicable to verify and reconstruct drawings from usual scenes with opaque objects.The presented results rely on geometric constructions, thus offering an alternativeapproach to line drawing interpretation, complementary to the algebraic-combinatorial treatment given in the classic work by Sugihara.Lluís Ros was born inVilafranca del Penedès (Catalonia), on June 30, 1968. He is currently a research scientist at the Institut de Robótica i Informàtica Industrial of the Spanish High Council for Scientific Research, where he holds a Ramón y Cajal position since February 2003. He received a M.Sc. degree in mechanical engineering in 1992, and a Ph.D. degree (with honors) in advanced robotics in 2000, both from the Polytechnic University of Catalonia. His research interests are in geometry, with applications to machine vision, robot kinematics and computer graphics.Federico Thomas was born in Barcelona, on October 5, 1961. He received the B.S. degree in telecommunications engineering in 1984, and the Ph.D. degree (with honors) in computer science in 1988, both from the Polytechnic University of Catalonia. Since March 1990, he has been a research scientist in the Institut de Robòtica i Informàtica Industrial of the Spanish High Council for Scientific Research. His research interests are in geometry and kinematics, with applications to robotics, computer graphics and machine vision.     

A robust, real-time ellipse detector

In this paper, we present an improved ellipse detector that may be used in real-time face detection. In this algorithm we first extract edges from the image using a robust edge detector, which is then followed by a rule-based method. Finally, we decompose the parameter space of the Hough transform to achieve computational efficiency. Our extensive experimental results show indeed that the proposed detector is capable of detecting ellipse features with an excellent accuracy under various image conditions at a high speed (10 frames per second on a Pentium-III PC).     

多面齐聚倍半硅氧烷改性环氧的制备及表征

以八苯基多面齐聚倍半硅氧烷为原料通过溴代,格氏试剂与丙酮加成等反应制备了八多羟基苯基多面齐聚倍半硅氧烷,并对产物进行了FTIR表征。采用该产物改性环氧树脂,并通过热失重分析仪、示差扫描量热仪对其固化物的热性能进行了研究。结果表明:该合成具有活性官能团的多面齐聚倍半硅氧烷的方法可行。在环氧树脂中加入八多羟基苯基多面齐聚倍半硅氧烷对其固化物热稳定性影响不大,但可以显著提高材料的玻璃化转变温度,当其质量分数为5.13%时,Tg可达183.2℃。     

Poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxane) hybrid nanocomposites: Preparation,thermal properties,and Tg improvement mechanism

A series of poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxanes) (PVP‐POSS) organic–inorganic hybrid nanocomposites containing different percentages of POSS were prepared via free radical polymerization and characterized by FTIR, high‐resolution ¹H‐NMR, solid‐state ²⁹Si‐NMR, GPC, DSC, and TGA. POSS contents in these nanocomposites can be effectively controlled by varying the POSS feed ratios which can be accurately quantified by FTIR curve calibration. On the basis of ²⁹Si‐NMR spectra, average numbers of reacted vinyl groups of each octavinyl‐POSS macromer are calculated to be 5–7, which depends on POSS feed ratios. Both GPC and DSC results indicate that these nanocomposites display network structure and the degree of crosslinking increases with the increase of the POSS content. The incorporation of POSS into PVP significantly improves their thermal properties (T_g and T_dec) primarily due to crosslinking structure and dipole–dipole interaction between POSS cores and PVP carbonyl groups. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

笼型倍半硅氧烷增韧环氧树脂的机理研究

为提高环氧树脂的韧性,采用氨基笼型倍半硅氧烷(POSS-NH2)改性环氧树脂。分别添加不同质量百分含量的POSS(5%、10%、20%和30%)到双酚A型环氧树脂中,经反应得到一系列杂化树脂;然后采用4,4’-二氨基二苯砜(DDS)作为固化剂固化得到含POSS的有机无机杂化材料。通过对杂化材料的冲击强度、弯曲强度进行研究,并采用SEM进行机理分析。结果表明:随着POSS含量的增加,冲击强度和弯曲强度呈先增大后下降的趋势,当POSS含量为10%时,冲击强度和弯曲强度达到最大值。SEM分析表明"裂纹钉锚"和"裂纹诱导"两种增韧机理同时存在。     

差动式板材凸度在线激光检测技术的研究

本文提出了一种基于激光检测技术的高精度、稳定性好的板带凸度在线检测技术的方法,给出了工作原理,并完成了初步实验验证.研究对于提升我国板带生产线的自动化程度、改进与提高板带的产品质量、增强市场竞争力具有重要的的学术意义和工程意义.     

八氨基倍半硅氧烷改性聚酰胺酰亚胺基润滑涂层的性能研究

为开发苛刻服役环境下高性能、长寿命的有机润滑涂层,以氨基丙基三乙氧基硅烷（KH550）为原料制备了八氨基倍半硅氧烷（ NH₂-POSS）,并将其添加到聚酰胺酰亚胺基涂层（ HM-1100A）中,研究了改性前后涂层的结构、力学性能和摩擦性能。结果表明：经 NH2-POSS改性后的 HM-1100A涂层相比原始涂层具有更高的硬度、内聚强度及较低的表面能,并且涂层的摩擦性能有显著提高。通过对比 HM-1100A、KH550改性 HM-1100A及 NH₂-POSS改性 HM-1100A 3种涂层的热重、硬度、表面能和摩擦性能,研究了其作用机理,分析发现 NH₂-POSS独特的中空笼形结构和八官能团的引入有效提高了涂层的物理机械性能和摩擦性能。