Flame retardation of banana fiber reinforced epoxy composites using melamine pyrophosphate and pentaerythritol as intumescent flame retardants and the influence of mechanical properties were investigated. The effects of IFR contents and the ratio of MPP and PER on limiting oxygen index (LOI) and UL94 rating of banana fiber reinforced epoxy composites has been studied. It was found that the combustion performance of the composites increases with increasing IFR contents,and the composites at the ratio of MPP/PER=2:1(weight ratio) at the same loading 40% showed the best combustion performance with IFR contents increasing,the limiting oxygen index (LOI) increased and UL94 rating reached, but the mechanical properties of composites significantly decreased. In order to increase the comprehensive properties, the flame retarded fiber was used to prepared the composites,the limiting oxygen index (LOI) of the composites significantly increased. the best complex properties were the IFR contents was 40%, the ratio of MPP/PER=2:1 (weight ratio), by the spraying method with 20g the fire retardant liquid of every 30g banana fiber.
As the matrix of sisal fiber, thermoplastic tapioca starch(TPS) was prepared with the mixed plasticizer, formamide and urea (mass ratio 2:1). X-ray diffractograms showed that with increasing fiber content(below 30phr), cellulose crystallinity at 22.5° gradually got stronger but starch crystallinity at 15.3°, 17.1°, 18.2°, 23.5° already disappeared, showed that this matrix still restrained the retrogradation of starch. SEM micrographs showed good dispersion and adhesion between starch and fiber. Studies in the dependence of mechanical properties of reinforced TPS on the fiber content from 0 to 30phr, the initial tensile strength was quadrupled up to the maximum 21.83MPa at 20phr fiber content, while the elongation at break was reduced from 72% to 0.44%. TG mass loss curves showed that thermal stability of this composites had great improved under 500°C.
A novel zero-dimensional dinuclear zinc complex, di-μ-acetato-1:2κ4
O:O′-(μ-2-acetyl-6-{[(Z)-2-bromo-3-oxoprop-1-en-1-yl]azanidyl}phenolato-1κ2
O
1,O
2:2κ3
O
1,N,O
6)(N,N-dimethylacetamide-1κO)dizinc(II), [Zn2(C11H8BrNO3)(CH3COO)2(C4H9NO)] or [Zn2(L)(CH3COO)2(DMA)], 1, was synthesized using (Z)-3-[(3-acetyl-2-hydroxyphenyl)amino]-2-bromoprop-2-enal (H2
L), which was synthesized from 1-(3-amino-2-hydroxyphenyl)ethanone and 2-bromomalonaldehyde. H2
L and 1 were characterized by single-crystal X-ray diffraction, FT–IR spectroscopy and elemental analysis. Theoretical calculations of the bond orders and excited state of H2
L confirmed that there is extensive electron delocalization in the H2
L molecules. Single-crystal X-ray diffraction shows that the two Zn atoms are pentacoordinated in distorted trigonal bipyramidal configurations in the crystals of 1. The thermogravimetric analysis of 1 shows that the main frame of the complex remains stable to about 190 °C. Powder X-ray diffraction (PXRD) analysis shows that 1 possesses high purity and acid and alkali resistance. The intermolecular interactions of H2
L and 1 were analyzed using Hirshfeld surface analysis and the results indicate that the H...H and O...H interactions of H2
L and 1 play a considerable role in stabilizing the self-assembly process.
Pure Al2O3-2SiO2 powders with alkali-activation reactivity were prepared by a sol-gel method. The effects of preparation conditions on alkali-activation reactivity were studied and the optimum preparation conditions were obtained. The results show that calcination temperature is a key factor affecting the alkali-activation reactivity of the powders, while other preparation conditions such as synthetic temperature, the molar ratio of solvents to starting materials and drying time have fewer effects on alkali-activation reactivity than calcination temperature. The structure of the powders was investigated by 27Al magic-angle spinning nuclear magnetic resonance spectra. The data show that the Al2O3-2SiO2 powders with the high alkali-activation reactivity are of high content of 5-coordinated Al and the peaks attributed to 5-coordinated Al are strengthened with the rise of calcination temperature of the powders.
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