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41.
The unusual eutectic crystallization behavior in the poly(ε‐caprolactone) (PCL) and 3‐pentadecylphonel (PDP) binary blends was investigated by differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy. A eutectic system was found with the eutectic composition at 60 wt % PDP and the eutectic melting temperature at 35 °C. The melting process of the blend at the eutectic composition was studied by in situ FTIR. The concurrence of the melting of PCL and PDP crystallites and the sequential formation of hydrogen bonding interaction between PDP molecules and PCL chains were traced. It was also found that a further increase in temperature above the eutectic melting temperature would impair the hydrogen bonding and increase the content of nonassociated phenol hydroxyl group. The semicrystalline morphology of blends affected by the composition was also investigated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1015–1023, 2009 相似文献
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Qipeng Guo Alexia Habrard Yoosup Park Peter J. Halley George P. Simon 《Journal of Polymer Science.Polymer Physics》2006,44(6):889-899
Thermosetting blends of an aliphatic epoxy resin and a hydroxyl‐functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 4,4′‐diaminodiphenylmethane (DDM) as the curing agent. The phase behavior and morphology of the DDM‐cured epoxy/HBP blends with HBP content up to 40 wt % were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The cured epoxy/HBP blends are immiscible and exhibit two separate glass transitions, as revealed by DMA. The SEM observation showed that there exist two phases in the cured blends, which is an epoxy‐rich phase and an HBP‐rich phase, which is responsible for the two separate glass transitions. The phase morphology was observed to be dependent on the blend composition. For the blends with HBP content up to 10 wt %, discrete HBP domains are dispersed in the continuous cured epoxy matrix, whereas the cured blend with 40 wt % HBP exhibits a combined morphology of connected globules and bicontinuous phase structure. Porous epoxy thermosets with continuous open structures on the order of 100–300 nm were formed after the HBP‐rich phase was extracted with solvent from the cured blend with 40 wt % HBP. The DSC study showed that the curing rate is not obviously affected in the epoxy/HBP blends with HBP content up to 40 wt %. The activation energy values obtained are not remarkably changed in the blends; the addition of HBP to epoxy resin thus does not change the mechanism of cure reaction of epoxy resin with DDM. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 889–899, 2006 相似文献
46.
In this communication, we present novel nanofilled polymer composites prepared using a poly(l-lactic acid) (PLLA) matrix and amyloid fibers. Amyloid fibers are made from protein sources’ and share many of the same material properties as spider silk, but exist at significantly smaller length scales with diameters of 5–10 nm. This work highlights the potential use of amyloid fibers as nanofillers in the development of renewable polymeric materials with tuneable properties. Improvements in the glass transition temperature (Tg), elongation at break and Young’s modulus was measured, while the yield strength of the new materials was not seriously hampered. 相似文献
47.
We define a particular type of automorphisms called transvections on a finite finite abelian p-group Hp. It is proved that the subgroup E of the automorphism group Aut(Hp) of Hp generated by those transvections is normal in it, and that Aut(Hp) can be written as the product of E and some abelian subgroup K. The center of Aut(Hp) is also determined. 相似文献
48.
An Effective Method to Construct Cluster‐based Frameworks with Multifarious Structures,Luminescence, and Sorption Properties
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An effective method was developed for the synthesis of three cluster‐based frameworks with multifarious secondary building units (SBUs) and various structures, which were formulated as [Me2NH2]2[Zn10(BTC)6(μ3‐O)(μ4‐O)(H2O)5] · 3DMA · 9H2O ( FJI ‐ 3 ), [Me2NH2]2[Zn9(μ3‐OH)2(BTC)6(H2O)3] · 5DMA · 6H2O ( FJI ‐ 4 ) and [Me2NH2][Zn3(μ3‐OH)(BTC)2DMF] · H2O ( FJI ‐ 5 ) (H3BTC = 1,3,5‐benzenetricarboxylic acid, DMA = N,N′‐dimethyl acetamide and DMF = N,N′‐dimethyl formamide), respectively. X‐ray structural analysis reveals that FJI ‐ 3 displays 3D highly porous metal‐organic framework with four kinds of microporous cages constructed by two paddle‐wheel Zn2(CO2)4, trimeric Zn3O(CO2)6, and tetrameric Zn4O(CO2)6 SBUs. FJI ‐ 4 exhibits 3D microporous MOFs with a dodecahedral cavities built by paddle‐wheel Zn2(CO2)4 and trimeric Zn3O(CO2)6. FJI ‐ 5 shows 3D microporous MOFs with an 1D channel assembled by the Zn3O(CO2)6 SBUs. In addition, the fluorescence and sorption properties in these cluster‐based frameworks were also investigated. Furthermore, the method employed in this work may provide an useful approach to the design and synthesis of novel cluster‐based frameworks. 相似文献
49.
Haifeng Zheng Sixun Zheng Qipeng Guo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(15):3161-3168
The miscibility and thermal properties of polyethylene oxide(PEO)/oligoester resin (OER) blends and PEO/crosslinked polyester (PER) blends were studied by differential scanning calorimetry (DSC). The effect of quenching process on the crystallization behavior of PEO for these two systems were investigated and discussed in details. It has been found that a single, composition dependent glass transition temperature (Tg) was observed for all the blends, indicating that the two systems are miscible in the amorphous state at overall compositions. From the melting point depression of PEO, the interaction parameter χ12 for PEO/OER blends and that for PEO/PER blends were found to be −1.29 and −2.01, respectively. The negative values of χ12 confirmed that both PEO/OER blends and PEO/PER blends are miscible in the molten state. Quenching process has a greater hindrance on the crystallization of PEO/OER blends than on that of PEO/PER blends. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3161–3168, 1997 相似文献
50.
Sixun Zheng Jinyu Huang Yongcan Li Qipeng Guo 《Journal of Polymer Science.Polymer Physics》1997,35(9):1383-1392
The miscibility of blends of phenolphthalein poly(ether ether sulfone) (PES-C) and poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. Differential scanning calorimetry (DSC) studies showed that the PES-C/PEO blends prepared by casting from N,N-dimethylformamide (DMF) possessed a single, composition-dependent glass transition temperature (Tg), and thus that PES-C and PEO are miscible in the amorphous state at all compositions at lower temperature. At higher temperature, the blends underwent phase separation, and the PES-C/PEO blend system was found to display a lower critical solution temperature (LCST) behavior. The phase separation process in the blends has also been investigated by using DSC. Annealed at high temperatures, the PES-C/PEO blends exhibited significant changes of thermal properties, such as the enthalpy of crystallization and fusion, temperatures of crystallization and melting, depending on blend composition when phase separation occurred. These changes reflect different characteristics of phase structure in the blends, and were taken as probes to determine phase boundary. From both the thermal analysis and optical microscopy, the phase diagram of the blend system was established. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1383–1392, 1997 相似文献