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991.
Yong Wang Qiang Fu Qijun Li Gong Zhang Kaizhi Shen Yu‐Zhong Wang 《Journal of Polymer Science.Polymer Physics》2002,40(18):2086-2097
For a more complete understanding of the toughening mechanism of polypropylene (PP)/ethylene‐propylene‐diene rubber (EPDM) blends, dynamic packing injection molding was used to control the phase morphology and rubber particle orientation in the matrix. The relative impact strength of the blends increased at low EPDM contents, and then a definite ductile–brittle (D–B) transition was observed when the EPDM content reached 25 wt %, at which point blends should fail in the ductile mode with conventional molding. Wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to investigate the shear‐induced crystal structure, morphology, orientation, and phase separation of the blends. WAXD results showed that the observed D–B transition took place mainly for a constant crystal structure (α form). Also, no remarkable changes in the crystallinity and melting point of PP were observed by DSC. The highly oriented and elongated rubber particles were seen via SEM at high EPDM contents. Our results suggest that Wu's criterion is no longer valid when dispersed rubber particles are elongated and oriented. The possible fracture mechanism is discussed on the basis of the stress concentration in a filler‐dispersed matrix. It can be concluded that not only the interparticle distance but also the stress fields around individual particles play an important role in polymer toughening. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2086–2097, 2002 相似文献
992.
993.
994.
FuLinYAN AiXiaWANG ZhongJianJIA LeiHE 《中国化学快报》2003,14(12):1253-1254
A new isopropenyl benzofuran-type tetramer was isolated from the roots of ligularia stenocephala and its structure was established by spectroscopic methods. 相似文献
995.
Zhong‐Lu You 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(7):m339-m341
The title complex, [Cu(C11H14BrN2O)(N3)]n, is an interesting azide‐bridged polynuclear copper(II) compound. The CuII atom is five‐coordinated in a square‐pyramidal configuration, with one O and two N atoms of one Schiff base and one terminal N atom of a bridging azide ligand defining the basal plane, and another terminal N atom of another bridging azide ligand occupying the axial position. The {4‐bromo‐2‐[2‐(dimethylamino)ethyliminomethyl]phenolato}copper(II) moieties are linked by the bridging azide ligands, forming polymeric chains running along the b axis. Adjacent chains are further linked by weak Br⋯Br interactions into a sheet. 相似文献
996.
Microwave-assisted synthesis and electrochemical capacitance of polyaniline/multi-wall carbon nanotubes composite 总被引:1,自引:0,他引:1
Hongyu Mi Xiaogang Zhang Shuying An Xiangguo Ye Sudong Yang 《Electrochemistry communications》2007,9(12):2859-2862
Polyaniline/multi-wall carbon nanotubes composite (PANI/MWNTs) was rapidly synthesized by microwave-assisted polymerization. Transmission electron microscope (TEM) image revealed that this composite was a core–shell structure with PANI layers (50–70 nm). Electrochemical behavior of the composite was evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge tests with a two-electrode system. An enhanced specific capacitance of 322 F/g with a specific energy density of 22 W h/kg was about 12 times that of MWNTs. This composite also exhibited a good rate capability, retaining up to 87% of initial capacity at a current density of 5 mA/cm2. 相似文献
997.
Hiroaki Aikawa Tero Kilpeläinen Nageswari Shanmugalingam Xiao Zhong 《Potential Analysis》2007,26(3):281-301
We establish a scale-invariant version of the boundary Harnack principle for p-harmonic functions in Euclidean C
1,1-domains and obtain estimates for the decay rates of positive p-harmonic functions vanishing on a segment of the boundary in terms of the distance to the boundary. We use these estimates
to study the behavior of conformal Martin kernel functions and positive p-superharmonic functions near the boundary of the domain.
H. A. was partially supported by Grant-in-Aid for (B) (2) (No. 15340046) Japan Society for the Promotion of Science. N. S.
was partially supported by NSF grant DMS-0355027. X. Z. was partially supported by the Taft foundation. 相似文献
998.
Quantum Black Hole 总被引:1,自引:0,他引:1
Wu Zhong Chao 《General Relativity and Gravitation》1998,30(1):115-121
Creation of a black hole in quantum cosmology is the third way of black hole formation. In contrast to the gravitational collapse from a massive body in astrophysics or from the quantum fluctuation of matter fields in the very early universe, in the quantum cosmology scenario the black hole is essentially created from nothing. The black hole originates from a constrained gravitational instanton. The probability of creation for all kinds of single black holes in the Kerr-Newman family, at the semiclassical level, is the exponential of the total entropy of the universe, or one quarter of the sum of both the black hole and the cosmological horizon areas. The de Sitter spacetime is the most probable evolution at the Planckian era. 相似文献
999.
高斯光束在任意分布的径向梯度折射率介质中传输的计算方法 总被引:1,自引:0,他引:1
根据弱波导近似,本文建立了处理高斯光束在任意分布的径向梯度折射率介质中传输的计算方法,并具体计算和讨论了高斯光束腰斑在沿径向呈抛物型分布的介质中随传输距离的变化情况,其数值结果与解析近似符合。 相似文献
1000.
报道了以氯化钯作催化剂,区域选择性氧化9-烯丙基-1-氧代-4-氮杂双环(4.3.0)壬烷及10-烯丙基-1-氧代-4-氮杂双环(5.3.0)癸烷,制备了9-丙酮基-1-氧化-4-氮杂双环(4.3.0)壬烷及10-丙酮基-1-氧代-4-氮杂双环(5.3.0)癸烷。比较了不同催化条件和溶剂系统的反应收率,发现以PdCl2/对-苯醌为催化系统和以含水的DMF溶剂系统氧化收率最高。 相似文献