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91.
92.
Ning-Fang Li Jiuyang Ji Wei Jiang Jia-Peng Cao Ye-Min Han Peng Yuan Yan Xu 《无机化学与普通化学杂志》2020,646(10):463-468
The usage of the achiral ligand, in lanthanide chemistry, successfully obtained two series of chiral lanthanide complexes, formulated d - and l -{Gd[IN][HIN][CH2OCH2O]}n (abbreviated as Gd ) and d - and l -{Dy[IN][HIN][CH2OCH2O]}n (abbreviated as Dy , HIN = isonicotinic acid). Crystallographic researches determined that four compounds are all one-dimensional (1D) chain structures and crystallized in a chiral space group. In addition, CH2OHCH2OH acts as not only solvent but also the bridge ligand. Besides, single crystal circular dichroism (CD) spectra conformed compounds Gd-L and Gd-D , Dy-L and Dy-D are enantiomers respectively. Magnetically, compound Gd showed predominant magnetocaloric effect (MCE) of 26.20 J · kg–1 · K–1 at 2.5 K for ΔH = 7 T, while there is ferromagnetic interactions in compound Dy . 相似文献
93.
Muhammad Usman Khan Muhammad Yasir Mehboob Riaz Hussain Zainab Afzal Muhammad Khalid Muhammad Adnan 《International journal of quantum chemistry》2020,120(22):e26377
The development of organic electron acceptor materials is one of the key factors for realizing high-performance organic solar cells (OSCs). Nonfullerene electron acceptors, compared to traditional fullerene acceptor materials, have gained much impetus owing to their better optoelectronic tunabilities and lower cost, as well as higher stability. Therefore, 5 three-dimensional (3D) cross-shaped acceptor materials having a spirobifullerene core flanked with 2,1,3-benzothiadiazole are designed from a recently synthesized highly efficient acceptor molecule SF(BR) 4 and are investigated in detail with regard to their use as acceptor molecules in OSCs. The density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed for the estimation of frontier molecular orbital (FMO) analysis, density of states analysis, reorganization energies of electron and hole, dipole moment, open-circuit voltage, photo-physical characteristics, and transition density matrix analysis. In addition, the structure-property relationship is studied, and the influence of end-capped acceptor modifications on photovoltaic, photo-physical, and electronic properties of newly selected molecules ( H1-H5 ) is calculated and compared with reference ( R ) acceptor molecule SF(BR) 4 . The structural tailoring at terminals was found to effectively tune the FMO band gap, energy levels, absorption spectra, open-circuit voltage, reorganization energy, and binding energy value in selected molecules H1 to H5 . The 3D cross-shaped molecules H1 to H5 suppress the intermolecular aggregation in PTB7-Th blend, which leads to high efficiency of acceptor material H1 to H5 in OSCs. Consequently, better optoelectronic properties are achieved from designed molecules H1 to H5 . It is proposed that the conceptualized molecules are superior than highly efficient spirobifullerene core-based SF(BR) 4 acceptor molecules and, thus, are recommended to experiments for future developments of highly efficient solar cells. 相似文献
94.
95.
Multicomponent polymer blends afford polymeric materials with specific properties for many applications. The effect of different chemical structures on the miscibility and compatibility of polymer blends composed of multicomponent acrylic and styrenic polymers was studied in this research. The influence of each component on the thermal, mechanical, and morphological properties, as well as optical transparency, was analyzed in poly (methyl methacrylate), homopolymer (PMMAh), or copolymer (PMMAe) blends where the minority constituents formed by polystyrene (PS), styrene-acrylonitrile copolymer (SAN) or acrylonitrile-butadiene-styrene terpolymer (ABS). The results showed significant changes in the properties of these mixtures due to the effect of the type of chemical structure and different elastomeric domains of the majority and minority components of polymer blends. 相似文献
96.
Although applied for several decades, production of hollow plastic parts by extrusion blow molding (EBM) is still over-dimensioned. To overcome this issue, a thorough investigation of the process-structure-property relationship is required. In this study, the local process-structure-property relationship for high-density polyethylene EBM containers is analyzed with differential scanning calorimetry and dynamic mechanic analysis microindentation. Local process-dependent crystallinity and complex modulus data at various processing conditions are supplemented with wide-angle X-ray diffraction and transmission electron microscopy (TEM). The crystallinities and the complex moduli clearly show lower values close to the mold side than at the inner side and the middle of the cross-section, which reflects the temperature gradient during processing. Additionally, the orientation of the polymer chain (c-axis) reveals a low level of biaxiality with a slight tendency towards transverse direction. The biaxiality increases for low mold temperature and high draw ratio. Finally, biaxiality is confirmed with TEM, which reveals no preferred lamellar orientation. 相似文献
97.
Quasi-static tensile test of UHMWPE fiber-reinforced composite laminate is challenging to perform due to low interlaminar shear strength and low coefficient of friction. Tensile tests proposed in the literature were conducted and limitations associated with each method led to the evolution of a new method. Tensile test of single-ply was realized as the best representative of tensile strength of a composite than tensile test of UHMWPE laminate. A fixture was developed for single-ply tests which increased friction and provided the mechanical constraint to slipping. The fixture is easy to fabricate and has provided repeatable results for eight grades of UHMWPE fiber-based (0/90) fabrics. Reported tensile strengths are in quite high range of 900–1500 MPa. 相似文献
98.
Natural fibers are inexpensive, biodegradable, and have similar specific properties to some synthetic fibers. Hardly any previous investigations exist of a composite made of multiple layers of pure Kevlar fiber fabric and pure Flax fiber fabric in a “sandwich structure”, but it only measured impact properties. The composite was made of 12 Flax/epoxy layers at the core in 3 possible configurations (i.e. [0]12F, [0/90]6F, or [±45]6F) that were sandwiched by 2 Kevlar/epoxy layers (i.e. plain weave) on each side. This study showed maximum change in the mechanical properties with respect to Flax/Epoxy for tension (+137.85% in ET, and +171.22% in σUT), compression (+171.22% in Ec, and −10.6% in σUC), 3-point bending (−11.54% in EB, and +2.19 in σUB), torsion (−5.31% in G, and 395.82% in τ), and water absorption (60.04%). This novel hybrid composite may be useful for research and industry applications. 相似文献
99.
Lithium-ion batteries have been developing intensively and earn an unprecedented reputation, yet advanced performance and safety issue still require considerable investigation. Separator is vital to comprehensive properties of batteries, where the mechanical properties are key to breaking through of new-type separator. Unfortunately, electrolyte submersion has caused damage to strength of cellulose separator. Whereupon, in this work, cellulose separator is optimized by introducing lignin particles to promote electrolyte-immersed mechanical strength. Experiments are conducted concerning surface morphology, contact angle, porosity, electrolyte uptake, mechanical properties and electrochemical performance. Molecular simulation is implemented to explore the mechanism of tensile behavior of cellulose and lignin subjected to electrolyte solvents. Experimental results confirm positive effect of lignin addition in improving mechanical properties and simultaneously maintaining impressive electrochemical performance of the cellulose/lignin composites separators. Besides, lignin addition amount of 2.5% and 5% is recommended to achieve promising overall properties. Molecular simulation has successfully unveiled that weakening of cellulose separator submerged in electrolyte is resulted by the deformed cellulose amorphous region and the promoting effect of adding lignin is contributed from the new hydrogen bonds generated between cellulose and lignin molecules. Hopefully, this work provides novel insight on preparing remarkable separator and mechanism of materials behavior. 相似文献
100.
Charlotte Menager Nathanaël Guigo Luc Vincent Nicolas Sbirrazzuoli 《Journal of polymer science. Part A, Polymer chemistry》2020,58(12):1717-1727
The curing of epoxidized linseed oil (ELO) with three different bio-based dicarboxylic acids (sebacic acid, suberic acid, and succinic acid) has been investigated. No accelerators or catalysts were used and the resulting thermosets are 100% bio-based. Structural investigations of the three crosslinked ELO resins were made using FTIR spectroscopy and TMA, that is, tensile tests, TGA, and DMA. As evidenced by FTIR measurements ELO and dicarboxylic acids reacts but no major differences can be distinguished between the dicarboxylic acids. Non-isothermal curing has been conducted by rheological and DSC measurements. Advanced isoconversional analysis applied to DSC data in association with the complex viscosity variations gives new insights into the polymerization mechanism. The length of dicarboxylic acid carbon chain modifies the reaction rate. Then, a correlation between reaction rate, activation energy, pre-exponential factors, polymerization mechanism, and change in rate-limiting step was shown. DMA and tensile tests highlight the relationship between the carbon chain length, reactivity, and thermomechanical properties. The use of succinic acid allows reaching a higher Tg and thermal stability. 相似文献