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91.
Improving the impact property and heat‐resistance of PLA/PC blends through coupling molecular chains at the interface 下载免费PDF全文
The influences of both the molecular structure and the melt viscosity differences between Poly(lactic acid) (PLA) and polycarbonate (PC) on the interpenetration of molecular chains at the interface were investigated by comparing the dynamic mechanical properties and morphologies of the as‐prepared PLA/PC solution‐casting blends with those of their corresponding annealed (180°C, 8 h) samples or PLA/PC melt blends. Additionally, two chain extenders containing epoxy groups (ADR and TGDDM) were used to improve the interfacial strength. Subsequently, the interpenetration of PLA and PC molecular chains at the interface was also surveyed. Finally, the effects of the morphology formed by after adding ADR or TGDDM on the impact property, and heat resistance were discussed. The results showed that there was no interpenetration of molecular chains at the interface in PLA/PC melt blends because of the serious hindrance of the molecular structure and the melt viscosity differences. Although the interfacial strength achieved significant increase after adding ADR or TGDDM, the increase of the interfacial strength should be caused by the connection of ADR or TGDDM molecules with PLA and PC molecules at the interface through chemical bonds rather than the entanglements of PLA and PC molecular chains because of no interpenetration of PLA and PC molecular chains at the interface. Thus, the morphology formed after adding ADR or TGDDM is still the type of complete phase separation, which may be the most suitable morphology for achieving high impact and heat resistance PLA/PC blends because these two properties strongly depend on the crystallinity of PLA phase. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
92.
Arumugam Thangavel Marika Wieliczko Christopher Scarborough Birger Dittrich John Bacsa 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(11):936-943
In the crystal structure of the title homoleptic CrII complex, [Cr(CH3CN)6](C24H20B)2·CH3CN, the [Cr(CH3CN)6]2+ cation is a high‐spin d4 complex with strong static, rather than dynamic, Jahn–Teller distortion. The electron density of the cation was determined by single‐crystal X‐ray refinements using aspherical structure factors from wavefunction calculations. The detailed picture of the electronic density allowed us to assess the extent and directionality of the Jahn–Teller distortion of the CrII cation away from idealized octahedral symmetry. The topological analysis of the aspherical d‐electron density about the CrII cation showed that there are significant valence charge concentrations along the axial Cr—N axes. Likewise, there were significant valence charge depletions about the CrII cation along the equatorial Cr—N bonds. These charge concentrations are in accordance with a Jahn–Teller‐distorted six‐coordinate complex. 相似文献
93.
This note is denoted to establishing sharp distortion theorems for subclasses of α-Bloch mappings defined in the unit ball of Cn with critical points.Furthermore,the estimates of Bloch constant with respect to these subclasses are given. 相似文献
94.
卫星平台振动和反射镜震颤会引起遥感图像中的振荡畸变。这类畸变难以通过常用的几何校正方法消除。对此,提出了一种使用压缩感知的几何校正方法。该方法基于有理函数模型(RFM)进行几何校正。在校正过程中,利用初始的RFM计算出地面控制点(GCPs)在图像中的投影坐标与实际成像坐标之间的偏差(称为投影偏差),以地面控制点处的投影偏差作为采样值,使用压缩感知技术重构出所有像元处的投影偏差,并据此对RFM进行像方补偿;利用经过补偿的RFM进行遥感图像纠正。通过补偿,消除了振荡畸变引起的RFM模型误差,进而提高校正性能。利用实测数据验证了该方法的有效性,并通过仿真数据分析了地标点的数量与分布对该几何校正方法性能的影响。 相似文献
95.
In this paper, we continue our investigation of polyharmonic mappings in the complex plane. First, we establish two Landau type theorems. We also show a three circles type theorem and an area version of the Schwarz lemma. Finally, we study Lipschitz continuity of polyharmonic mappings with respect to the distance ratio metric. 相似文献
96.
This paper considers the class of all mappings of the form where h and g are analytic in the unit disk U, normalized by , and such that is logharmonic with respect to an analytic self‐map a of U. A distortion estimate and the radius of starlikeness are obtained for this class. Additionally, a solution to the problem of minimizing the moments of order p over the class is found, as well as an estimate for arclength. 相似文献
97.
Dr. Rüdiger W. Seidel Richard Goddard Constantin Hoch Iris M. Oppel 《无机化学与普通化学杂志》2011,637(11):1545-1554
Attempts to crystal engineer metallosupramolecularcomplexes from Cu(phen)2+ building blocks and the prototypical,rod‐like, exo‐bidentate ligand 4,4′‐bipyridine (4,4′‐bipy) by layering techniques are described. Reactions of Cu(phen)2+ (phen = 1,10‐phenanthroline) with 4,4′‐bipy in the presence of NO3– counterions yielded two distinct, discrete, dinuclear, Ci symmetric, dumbbell‐typecomplexes, [{Cu(NO3)2(phen)}2(4,4′‐bipy)] ( 1 ) and [{Cu(NO3)(phen)(H2O)}2(4,4′‐bipy)](NO3)2 ( 2 ), depending upon the mixture of solvents used for crystallization. In compound 1 , a mono‐ and a bidentate nitrato group coordinate to Cu2+, whereas in 2 the monodentate nitrato groups are replaced by aqua ligands, which introduce additional hydrogen‐bond donor functionality to the molecule. The crystal structure of 1 was determined by single‐crystal X‐ray analysis at 296 and 110 K. Upon cooling, a disorder‐order transition occurs, with retention of the space group symmetry. The crystal structure of 2 at room temperature was reported previously [Z.‐X. Du, J.‐X. Li, Acta Cryst. 2007 , E63, m2282]. We have redetermined the crystal structure of 2 at 100 K. A phase transition is not observed for 2 , but the low temperature single‐crystal structure determination is of significantly higher precision than the room temperature study. Both 1 and 2 are obtained phase‐pure, as proven by powder X‐ray diffraction of the bulk materials. Crystals of [Cu(phen)(CF3SO3)2(4,4′‐bipy) · 0.5H2O]n ( 3 ), a one‐dimensional coordination polymer, were obtained from [Cu(CF3SO3)2(phen)(H2O)2] and 4,4′‐bipy. In 3 , Cu(phen)2+ corner units are joined by 4,4′‐bipy via the two vacant cis sites to form polymeric zig‐zag chains, which are tightly packed in the crystal. Compounds 1 – 3 were further studied by infrared spectroscopy. 相似文献
98.
T.F. Qi M. Ge O.B. Korneta S. Parkin L.E. De Long G. Cao 《Journal of solid state chemistry》2011,184(4):893-898
Correlation between structure and transport properties are investigated in high-quality single-crystals of Ca2Ru1−xCrxO4 with 0<x<0.14 using single crystal X-ray diffraction and by electronic studies. The parent compound was known to exhibit an intriguing first-order structurally driven metal-insulator (MI) transition at 357 K. Upon chromium doping on the ruthenium site, the metal-insulator transition temperature (TMI) was drastically reduced, and is related to the competition between structural changes that occur upon Cr doping and with decreasing temperature. A strong suppression of structural distortions with increasing Cr substitution was identified. No clear TMI can be observed when x>13.5% and the system behaves as an insulator. Such a large, sharp metal-insulator transition and tuneable transition temperature may have potential applications in electronic devices. 相似文献
99.
Stephen E Huang D Shaw JL Blake AJ Collison D Davies ES Edge R Howard JA McInnes EJ Wilson C Wolowska J McMaster J Schröder M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(37):10246-10258
The NiII complexes [Ni([9]aneNS2‐CH3)2]2+ ([9]aneNS2‐CH3=N‐methyl‐1‐aza‐4,7‐dithiacyclononane), [Ni(bis[9]aneNS2‐C2H4)]2+ (bis[9]aneNS2‐C2H4=1,2‐bis‐(1‐aza‐4,7‐dithiacyclononylethane) and [Ni([9]aneS3)2]2+ ([9]aneS3=1,4,7‐trithiacyclononane) have been prepared and can be electrochemically and chemically oxidized to give the formal NiIII products, which have been characterized by X‐ray crystallography, UV/Vis and multi‐frequency EPR spectroscopy. The single‐crystal X‐ray structure of [NiIII([9]aneNS2‐CH3)2](ClO4)6?(H5O2)3 reveals an octahedral co‐ordination at the Ni centre, while the crystal structure of [NiIII(bis[9]aneNS2‐C2H4)](ClO4)6?(H3O)3? 3H2O exhibits a more distorted co‐ordination. In the homoleptic analogue, [NiIII([9]aneS3)2](ClO4)3, structurally characterized at 30 K, the Ni? S distances [2.249(6), 2.251(5) and 2.437(2) Å] are consistent with a Jahn–Teller distorted octahedral stereochemistry. [Ni([9]aneNS2‐CH3)2](PF6)2 shows a one‐electron oxidation process in MeCN (0.2 M NBu4PF6, 293 K) at E1/2=+1.10 V versus Fc+/Fc assigned to a formal NiIII/NiII couple. [Ni(bis[9]aneNS2‐C2H4)](PF6)2 exhibits a one‐electron oxidation process at E1/2=+0.98 V and a reduction process at E1/2=?1.25 V assigned to NiII/NiIII and NiII/NiI couples, respectively. The multi‐frequency X‐, L‐, S‐, K‐band EPR spectra of the 3+ cations and their 86.2 % 61Ni‐enriched analogues were simulated. Treatment of the spin Hamiltonian parameters by perturbation theory reveals that the SOMO has 50.6 %, 42.8 % and 37.2 % Ni character in [Ni([9]aneNS2‐CH3)2]3+, [Ni(bis[9]aneNS2‐C2H4)]3+ and [Ni([9]aneS3)2]3+, respectively, consistent with DFT calculations, and reflecting delocalisation of charge onto the S‐thioether centres. EPR spectra for [61Ni([9]aneS3)2]3+ are consistent with a dynamic Jahn–Teller distortion in this compound. 相似文献
100.
ABSTRACT The mixed metal fluorides containing alkali metals have a range of important applications in optical and electronic devices. Raman spectrums of two such fluorides were examined. Raman spectrum of KCuF3 at 300 K exhibited bands at 261, 295, 363, 468, 519, and 549 cm?1, indicating site symmetry (orthorhombic) lower than the tetragonal symmetry as observed from the powder X-ray diffraction pattern. Cubic KNiF3 showed bands at 410, 468, and 657 cm?1. The first two bands were attributed to the second-order phonon scattering, and the band at 657 cm?1 was assigned to two-magnon peak. 相似文献