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981.
982.
983.
    
For the production of polymer‐based conducting composites serving as positive temperature coefficient (PTC) materials with lower room‐temperature resistivity and sufficiently high PTC intensity, carbon black has been pretreated with acrylic acid and some initiator and then melt‐mixed with low‐density polyethylene. Because of the in situ formation of covalent bonding at the filler/matrix interface, the distribution status and thermally induced displacement habit of the conductive fillers have changed accordingly. As a result, the electrical performance of the composites can be tailored as desired. The amount of acrylic acid and the treatment sequence of carbon black exert an important influence on the effectiveness of the modification. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 127–134, 2003  相似文献   
984.
    
In this paper, a new catalyst system Cu‐Mn‐(M)/γ‐Al2O3 was developed for the directly synthesis dimethyl ether (DME) from synthesis gas in a fixed‐bed reactor. The catalysts with different n (Cu) : n (Mn) ratios, several promoter M (M is one of Zn, Cr, W, Mo, Fe, Co or Ni) were prepared and tested. The results showed the catalysts have a high conversion of CO and a high DME selectivity. The DME yield in tail gas reached 46.0% (at 63.27% conversion of CO) at 2.0 MPa, 275°C, 1500 h?1 with the Cu2Mn4Zn/γ‐Al2O3 catalyst.  相似文献   
985.
986.
    
The polymerization of cyclopentadiene (CPD) was effectively initiated by methylaluminoxane (MAO) to generate poly(cyclopentadiene) (polyCPD). The effects on the polymerization of some reaction parameters such as the monomer concentration, the initiator concentration, and solvents were investigated. The conversion of CPD was monitored with gas chromatography to investigate the reaction kinetics. The polymerization rate was proportional to the concentrations of MAO in the first order and of the CPD monomer in the second order, and a reasonable cationic polymerization mechanism was suggested on the basis of the kinetic study. PolyCPD obtained at a low temperature could be dissolved in toluene or chloroform, and this indicated lower cross‐coupling during the polymerization reaction. 1H NMR and IR analysis of the polymer indicated that there were almost equal amounts of 1,2‐enchainment and 1,4‐enchainment in the polymer chain. The measurement of polyCPD showed its unique properties as a potential candidate for stable wrappings or electronic packaging materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 264–272, 2006  相似文献   
987.
988.
    
Platelets play a fundamental role in thrombus formation and in the pathogenesis of arterial thrombosis. Patterning surfaces for controlled platelet adhesion paves the way for adhesion and activation mechanisms in platelets and detection of platelet functional defects. Here, a new and simple method based on controlled polymerization of 2‐methacryloyloxyethyl phosphorylcholine (MPC) on the surface of styrene‐block‐(ethylene‐co‐butylene)‐block‐styrene (SEBS) is shown. The competition between polymerization and degradation enables platelet adhesion on SEBS to be switched on and off. The adhesive sites of the platelets can be down to single cell level, and the dysfunctional platelets can be quantitatively detected.

  相似文献   

989.
    
A new 3D metal‐organic framework {[Ag4(btc)(bix)2] · H2O}n ( 1 ) [H4btc = biphenyl‐2, 2′,4, 4′‐tetracarboxylic acid, bix = 1, 4‐bis(imidazol‐1‐ylmethyl)benzene] was synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, infrared (IR) spectroscopy, thermal gravimetric analysis (TGA), and luminescence studies. The most remarkable structural feature of 1 is that the 1D chain and 2D network interpenetrated structures are further linked by parallel aligned 1D AgI chains to generate 3D metal‐organic framework.  相似文献   
990.
    
Two nickel(II) complexes, namely {[NiL(MeOH)(μ‐OAc)]2Ni} · 2CH2Cl2 · 2MeOH ( 1 ) and {[NiL(EtOH)(μ‐OAc)]2Ni} · 2EtOH ( 2 ) {H2L = 5, 5′‐dimethoxy‐2, 2′‐[(ethylene)dioxybis(nitrilomethylidyne)]diphenol}, were synthesized and structurally characterized. Two trinuclear NiII complexes are both hexacoordinate around the central NiII atoms, showing octahedral coordination arrangements, and each complex comprises three divalent NiII atoms, two deprotonated L2– ligands, in which four μ‐phenoxo oxygen atoms forming two [NiL(X)] (X = MeOH or EtOH) units, and coordinated and non‐coordinated solvent molecules. Complex 1 exhibits a 2D supramolecular network through intermolecular O–H ··· O, C–H ··· O and C–H ··· π interactions, whereas complex 2 forms an infinite 1D chain by intermolecular C–H ··· O hydrogen bonding interactions.  相似文献   
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