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51.
Yuan-Jyh Lee 《Polymer》2004,45(18):6321-6331
We have successfully synthesized a novel benzoxazine ring-containing polyhedral oligomeric silsesquioxane (BZ-POSS) monomer by two routes: (1) hydrosilylation of a vinyl-terminated benzoxazine using the hydro-silane functional group of a polyhedral oligomeric silsesquioxane (H-POSS) and (2) reaction of a primary amine-containng POSS (Amine-POSS) with phenol and formaldehyde. The benzoxazine-containing POSS (BZ-POSS) monomer can be copolymerized with other benzoxazine monomers through ring-opening polymerization under conditions similar to that used for polymerizing pure benzoxazines. Thermal properties of these POSS-containing organic/inorganic polybenzoxazine nanocomposites have been improved over the pure polybenzoxazine analyzed by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The BZ-POSS monomer is poorly miscible with the benzoxazine monomer and tends to aggregate and forms its own domains, both before and after polymerization. At a higher BZ-POSS content, gross aggregation occurs and results in a lower than expected improvement in the thermal properties. 相似文献
52.
53.
试验以解决带材中凸度过大为目的,制定了把带材中凸度控制在1%以下的试验目标。重点关注两点:弯辊调整对板形中凸度的影响和不同工作辊凸度对板中凸度的影响。 相似文献
54.
55.
接枝法制备聚苯乙烯/笼型倍半硅氧烷复合材料 总被引:1,自引:0,他引:1
以工业级的3-氯丙基三氯硅烷和七聚(苯基)倍半硅氧烷三硅醇钠为原料,通过顶端封角法合成了含有一个3-氯丙基、七个苯基的单官能团POSS(3-氯丙基POSS),并以其作为聚苯乙烯的添加剂,采用化学接枝的方法制备POSS/PS复合材料.利用傅立叶转变红外光谱(FT-IR)、核磁共振(1H-NMR、29Si-NMR)和X-射... 相似文献
56.
从合成八苯基硅倍半氧烷(OPS)出发,通过控制硝化条件制备了不同多官能度硝基苯基硅倍半氧烷(NPS),然后对NPS催化还原得到相应的多官能度氨基苯基硅倍半氧烷(APS).利用红外、核磁、元素分析、热失重对多面体低聚硅倍半氧烷(POSS)化学结构和热性能进行了表征.元素分析发现OPS硝化时间越长,硝基越多,但是不是正比关... 相似文献
57.
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... 相似文献
58.
Development of nano-composite lead-free electronic solders 总被引:1,自引:0,他引:1
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. 相似文献
59.
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. 相似文献
60.
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. 相似文献