Two novel epoxy resins; namely, R1 and R2 were synthesized and characterized. These two resins were isomers and both contained naphthalene units and two symmetric flexible aliphatic ester chains terminated by epoxy groups. To investigate the influence of different structural isomers on the performance of these epoxy resins, they were both cured with various curing agents which results in the choosing of 4,4′-diaminodiphenylmethane (DDM) as the optimized curing agent. The curing technical temperature was obtained from extrapolated plots of T– β curve at different heating rates. The kinetic parameters, the activation energy ( E
a ) and the reaction order ( n ) were deduced by Kissnger’s isoconversional method and Crane equation. The moisture absorption and mechanical and thermal properties of the cured epoxy resins were investigated. Experimental results indicated that the R1/DDM and R2/DDM epoxy resins displayed improved mechanical performance without significant decrease in their important inherent properties, e.g., temperature of glass transition ( T
g ), moisture absorption and thermal properties when compared with the corresponding commercial biphenyl-type epoxy resins. The average inter-segment distances in R1/DDM and R2/DDM systems were 4.46 and 4.88 Å, respectively, which were measured by wide-angle X-ray diffraction. The result showed R1/DDM (1,5-di-substituted) was strongly hindered in comparison with R2/DDM (2,7-di-substituted) and E
a and T
g values of the R1/DDM were slightly higher than those of R2/DDM. Furthermore, mechanical properties and moisture absorption of the R1/DDM were lower than those of R2/DDM. Nevertheless, the position of the substituent only weakly affected the thermal properties and the reaction order ( n ).
Da Xu,Chenyi Zhou,Yunhe Zhang,Jinhui Pang,Zhenhua Jiang,Haibo Zhang
Polyaramid is an indispensable high-performance material for its excellent thermal stability and mechanical strength . But its ultra high melting temperature which is higher than its decomposition temperature and the strong solvent resistance makes it difficult to process. In this work, we prepared a new series of soluble polyamides , poly(arylene ether naphthalene amide)s (PENA), by introducing both naphthalene and phenyl ether groups to the main chain of the polyaramid. The relationship between phenyl ether content and properties of PENAs were investigated. These PENAs have good solubility and can be made into strong and tough films by solvent casting method. Among them, poly(mono arylene ether naphthalene amide)PMENA, which contains mono-ether structure in the polymerization unit, shows the best performance with a tensile strength of 118 MPa and an elongation at break of 45%. Furthermore, PMENA also has good and stable dielectric properties with a high permittivity of 4.7, and low dielectric loss of 0.03 at 1 kHz, at room temperature .
A fluorescent probe for selective detection of mercury based on an azobenzene derivative bearing naphthalene units has been synthesised and its cation recognition abilities examined by UV-Vis and fluorescence spectroscopy. The fluorescent probe exhibits a highly selective response of fluorescence enhancement toward mercury in DMF aqueous media (DMF: H2O, v/v = 1:1).
Wei Ting Gao,Xue Lang Gao,Wei Wei Gou,Jia Jun Wang,Zhi Hong Cai,Qiu Gen Zhang,Ai Mei Zhu,Qing Lin Liu
The development of high-performance anion exchange membranes (AEMs) has become more urgent for fuel cells. One of the critical challenges is to prepare AEMs with sufficient ion conductivity and robust alkaline endurance. In this work, bulky twisted binaphthyl units are introduced into the backbones of AEMs by a one-pot superacid-catalyzed polymerization to enhance both the conductivity and stability. The binaphthyl unit can depress the chain packing density and enlarge the free volume of the AEMs, conducing to form well-defined microphase separation and to build well-developed ion-conductive highways. The poly(binaphthyl piperidinium)-based AEM (QABNP) shows the highest OH − conductivity of 135.25 mS cm −1 superior to the poly(quaterphenyl piperidinium)-based AEM (QAQPP) (109.12 mS cm −1 ). Meanwhile, the QABNP AEM exhibits about 90% conductivity retention after being tested in a harsh alkaline environment (2 M NaOH at 80 °C) for 1080 h. Importantly, the QABNP based single cell possesses the highest peak power density (PPD) of 1.16 W cm −2 at a high current density of 2.37 A cm −2 with a low high frequency resistance (HFR) of 0.04 Ω cm 2 . This study demonstrates the merits of bulky twisted binaphthyl incorporated in a polymer backbone for improving AEM performances.
危险品化学品经营许可证（带存储）