Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《材料研究学报》
Abstract： The diatomite based flame-retardant materials for external thermal insulation board of exterior wall were preparedby sol-gels method with NaOH (2 mol稬-1) and Na2SiO3 (1 mol稬-1) simultaneously as the chemical activator, and then characterized by means of various methods. Results showed that aftera thin- plastering of the prepared flame- retardant diatomitewas applied on expandable polystyrene board, the limiting oxygen indexthe complex EPSboard can reached 36.8%, and itscombustion performance can meetthe requirement of UL- 94 V1. SEM results demonstrated that the NaOH and Na2SiO3 were benefit for the diatomite to form dense amorphous silica layer, XRD and FT-IR results showed that "depolymerization- reconstruction" of the diatomite structure occurred in the alkaline media, and which would further be reconstructed during firing.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： The phase change materials of fatty acid/SiO2 composite were prepared by sol-gel method with SiO2 as carrier material, fatty acid as phase change material, absolute alcohol and deionized water as solvent, Which then were characterized by scanning electron microscope (SEM), laser particle size analyzer (LPSA), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC) etc. The effect of the type of cores, the amount of phase change material and absolute alcohol and deionized water as well as the solution pH value and ultrasonic wave power on the texture of the prepared composites were investigated systematically. The results show that the texture of the phase change materials of fatty acid/SiO2 composite was greatly influenced by the type of cores, the amount of phase change material and absolute alcohol and deionized water, and also related to solution pH value and ultrasonic wave power. The optimal processing parameters for preparation a good composite are: decanoic acid-palmitic acid acts as core, the mole ratio of decanoic acid-palmitic acid to tetraethyl orthosilicate is 0.4, the mole ratio of absolute alcohol to tetraethyl orthosilicate is 5, the mole ratio of deionized water to tetraethyl orthosilicate is 9, solution pH value is 4 and ultrasonic wave power is 200 W.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Luminescent phosphors GdVO4: Eu3 + was prepared in solutions with different pH values by hydrothermal synthesis route using Gd2O3, NH4VO3 and Eu2O3 as precursors, and cetyl trimethyl ammonium bromide (CTAB) as surfactant. The synthesized products were characterized in terms of morphology, structure and luminescent performance by means of XRD, SEM, TEM, and PL. The results show that in an acid solution with pH=1, the size of synthesized GdVO4: Eu3 + crystal grains is of micron scale; in a solution with pH=4 , their size shrinks to nano-scale; it turned out well-dispersed nano-flakes of about 50 nm in solution with pH=7; besides, in solution with pH=10, a certain amount of impurity Gd(OH)3 was detected by XRD for the synthesized GdVO4: Eu3+ crystal grains. On the other hand, the surfactant affected obviously the final morphology of the synthesized GdVO4: Eu3 + crystal grains in terms of changes in the crystal growth direction and the aggregation shape, correspondingly, the luminescent properties were affected by grain size and crystallinity. It turned out that square GdVO4: Eu3+ nano-crystals with well crystallinity represented the optimal emission performance. But it is noted that the aggregation effect may weaken the luminescent property of the products.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-18 Cooperative journals: 《材料研究学报》
Abstract： Double-shell phase change nano-capsules were prepared by the emulsion interfacial polymerization method with phase change materials as core, polystyrene as inner shell, hydrophilic chitosan as outer shell, with a 1:1 ratio of core to shell, sodium dodecyl sulfate as emulsifier, hexadecane as co-emulsifier and azodiisobutyronitrile as initiator. The prepared capsules were characterized by fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), laser particle size analyzer (LPSA) etc. The results show that the morphology of the double-shell phase change nano-capsules was greatly influenced by the kind of cores, the amount of emulsifier, co-emulsifier and initiator, and also related to phacoemulsification time and mixing speed.
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