Synthesis And Surface Hydrophobic Modification Of152MHSH Whiskers In High Yield

As one of the novel reinforcement materials, Magnesium Hydroxide Sulfate Hydrate(abbreviated as MHSH) possesses the similar properties as the carbon fiber and siliconcarbide whisker, such as high strength and corrosion resistance, which shows excellenttoughening and strengthening performance. In addition, MHSH is also aenvironment-friendly flame-retardant having good application prospects.In this paper, the influence factors of different reaction system for synthesizing152MHSH were studied. The synthesis and surface polarity of the products could becontrolled via different additives and modifiers, and the yield and photoluminescenceproperties of the152MHSH whiskers were studied.The influences of the reaction condition on the morphology and yield of152MHSH were investigated in two different reaction systems, MgSO4-MgCl2-NaOHand MgSO4-NaOH, respectively. Results indicated that, in MgSO4-MgCl2-NaOHreaction system, needle-like152MHSH whiskers with the diameter of0.5~2μm andlength of30~100μm were fabricated when the molar ratio of n(MgSO4):n(MgCl2) is1:2and the concentration of NaOH is2.5mol/L. The corresponding whiskers displaysgood monodispersity with the maximum yield of86.65%. In MgSO4-NaOH reactionsystem, smooth surface and evenly distributed fibrous whiskers with diameter of1μm andlength of30~40μm were synthesized when the molar ratio of n(MgSO4):n(NaOH) is4:1and the concentration of NaOH is1mol/L, and the maximum yield is85.38%.Crystalline, purity and yield of the products were investigated using organic alcohols,organic acids and water-soluble polymer as additives respectively. The characterizationresults showed that the maximum yield of the whiskers is88.75%when1,2-propanediolwith the volume fraction of2.5%was applied as additives. The corresponding152MHSH whiskers featured high crystallinity, purity and draw ratio. The photoluminescenceproperties of152MHSH whiskers are characterized for the first time. It could be observedthat the yellow light could be excited using blue light, furthermore, the location andrelative intensity of the emission peak shifted when the additives was employed.Three modifiers, seventeen fluorine kwai triethoxy silane(AC-FAS), sodium dodecylbenzene sulfonate(LAS) and bis-[3-(triethoxysilyl) propyl] tetrasulfide (bis-sulfur silane),were employed to study the hydrophobic modification of152MHSH whiskers, and themodification effect have been analyzed in detail. The results found that the maximumwater contact angle of126°have been obtained with AC-FAS mass fraction of1.2%fortreatment1h at25℃, which was lipophilicity.