New Advances in Chemical Research in 2021. In heterogeneous catalysis, catalysts provide a surface to which reactants bind in a process of adsorption. The reactant in an enzyme-catalyzed reaction is called a substrate. 10465-78-8, Name is N1,N1,N2,N2-Tetramethyldiazene-1,2-dicarboxamide, molecular formula is , belongs to benzoxazole compound. In a document, author is Dai, Xuemin, SDS of cas: 10465-78-8.
A series of high-performance polyimide copolymer (co-PI) fibers containing phenylenebenzoxazole moiety with one hydroxyl group are synthesized based on the copolymerization of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) with two diamine monomers, namely, p-phenylenediamine (p-PDA) and 5-anino 2 (2 hydroxy-4-aminobenzene)-benzoxazole (p-mHBOA), through a two-step method. The molar ratio of p-PDA/p-mHBOA varies from 10/0 to 0/10. Influences of the p-mHBOA moieties on the thermal stability, crystal structure, crystal orientation, microvoid morphology, and mechanical properties are systemically investigated. Fourier transform infrared results confirm that intra/inter molecular hydrogen bonds come from the OH group and nitrogen atom of the benzoxazole group and/or OH group and the oxygen atom of the carbonyl group of cyclic imide. The glass transition temperatures (T(g)s) of coPI fibers are in the range of 290 degrees C-325 degrees C. The prepared fibers show excellent thermal stabilities, and their T5% is within 528 degrees C-542 degrees C in air. Two-dimensional wide-angle X-ray diffraction spectra indicate that homo-PI and co-PI fibers present a regularly arranged polymer chains along the fiber axial direction. Moreover, the ordered molecular packing along the transversal direction of fibers is destroyed by the copolymerization. Small-angle X-ray scattering results show that co-PI fibers with optimal mechanical properties exhibit the shortest average length (L) and the smallest radius (R) of microvoids. When the pmHBOA/p-PDA molar ratio is 5/5, the fracture strength and initial modulus can reach approximately 30.31 cN/dtex (4.40 GPa) and 894.88 cN/dtex (129.8 GPa), respectively. The relationship between structure and mechanical properties is also discussed. (C) 2018 Published by Elsevier Ltd.
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Reference:
Benzoxazole – Wikipedia,
,Benzoxazole | C7H5NO – PubChem