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51.
Ying‐Hung So Pamela Foster Jang‐Hi Im Philip Garrou Jack Hetzner Edmund Stark Kayla Baranek 《Journal of polymer science. Part A, Polymer chemistry》2006,44(5):1591-1599
Divinylsiloxane‐bisbenzocyclobutene (DVS‐bisBCB) polymer has very low dielectric constant and dissipation factor, good thermal stability, and high chemical resistance. The fracture toughness of the thermoset polymer is moderate due to its high crosslink density. A thermoplastic elastomer, polystyrene–polybutadiene–polystyrene triblock copolymer, was incorporated into the matrix to enhance its toughness. The cured thermoset matrix showed different morphology when the elastomer was added to the B‐staged prepolymer or when the elastomer was B‐staged with the DVS‐bisBCB monomer. Small and uniformly distributed elastomer domains were detected by transmission electron micrographs (TEM) in the former case, but TEM did not detect a separate domain in the latter case. A high percentage of the polystyrene–polybutadiene–polystyrene triblock copolymer could be incorporated into the DVS‐bisBCB thermoset matrix by B‐staging the triblock copolymer with the BCB monomer. The elastomer increased the fracture toughness of DVS‐bisBCB polymer as indicated by enhanced elongation at break and increased K1c values obtained by the modified edge‐lift‐off test. Elastomer modified DVS‐bisBCB maintained excellent electrical properties, high Tg and good thermal stability, but showed higher coefficient of linear thermal expansion values. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1591–1599, 2006 相似文献
52.
Siripon Anantawaraskul João B. P. Soares Preechathorn Jirachaithorn Jumras Limtrakul 《Journal of Polymer Science.Polymer Physics》2006,44(19):2749-2759
Four polyethylene samples (PE) with different molecular weight distributions (MWD) were analyzed by crystallization analysis fractionation (Crystaf) at several cooling rates to investigate the effect of MWD and cooling rate on their Crystaf profiles. Using these results, we developed a mathematical model for Crystaf that considers crystallization kinetic effects, which are ignored in all previous Crystaf models. The Crystaf model we proposed can fit the experimental Crystaf profiles of the 4 polyethylene resins very well. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2749–2759, 2006 相似文献
53.
J.-S. Kang G. Kim S.S. Lee S. Choi S. Cho S.W. Han H.J. Shin B.I. Min 《Journal of magnetism and magnetic materials》2006
The spatial concentration distribution and local electronic structure of ferromagnetic Ge1−xTx (T=Cr, Mn, Fe) DMS single crystals have been investigated by using scanning photoelectron microscopy (SPEM), X-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES). It is found that doped T ions in Ge1−xTx crystals are chemically phase-separated, suggesting that the observed ferromagnetism arises from the phase-separated T-rich phases in Ge1−xTx. 相似文献
54.
An element σ of An, the Alternating group of degree n, is extendible in Sn, the Symmetric group of degree n, if there exists a subgroup H of Sn but not An whose intersection with An is the cyclic group generated by σ. A simple number-theoretic criterion, in terms of the cycle-decomposition, for an element of An to be extendible in Sn is given here. 相似文献
55.
56.
利用谱线宽度测人发中的微量元素 总被引:2,自引:0,他引:2
通过实验证明了可以利用谱线宽度做永久工作曲线用于光谱定量分析。给出了用于测量人发中微量元素Cu,Zn,Fe和Ca的永久工作曲线,利用这些工作曲线对实际样品进行了测定,所得结果与用ICP-AES测得的结果相吻合。 相似文献
57.
João C. A. Barata 《Communications in Mathematical Physics》1990,129(3):511-523
This paper studies the vacuum overlap order parameter proposed by Fredenhagen and Marcu in the case of the compactU(1) gauge model with the Wilson action coupled to a Higgs field with fixed length ||=1. The existence of two distinct phases inD space-time dimensions (D4) is established. 相似文献
58.
59.
新显色剂对羧基苯基重氮氨基偶氮苯的合成及与镉显色反应的研究 总被引:4,自引:1,他引:4
本文报道了新色剂对羟基苯基重氮氨基偶氮苯的合成。 相似文献
60.
Borohydride exchange resin-transition metal(Co,Ni,Cu,)compoundsystems reduced C=C double to C-C single bond in ethanol. 相似文献