Study On The Preparation Of MH/MF And ATH/MF Microcapuses And Their Thermal Decomposition Kinrtics

Magnesium hydroxide (Mg(OH)2) and aluminum hydroxide (Al(OH)3) are halogen-free flame retardant for their smoke suppressibility,famle retardency and filling.However, Mg(OH)2and Al(OH)3are inorganic and the fatal disadvantage is their high loading lever, which would significantly affect the mechanical properties of flame-retardant polymeric material due to the poor compatibility.Melamine-formaldehyde resin microencapsulated magnesium hydroxide (MH/MF microcapsules) was prepared by in situ polymerization. Particle size as the inspection standard, the orthogonal experiment and the single factor experiment were used to ingvestigate the reaction, the results showed:effection of different factors on the microcapsules size was mMH/mMF> stirring speed> reaction time> reaction temperature; the appropriate conditions for the preparation of the MH/MF microcapsules:mMH/mMF was1.6, the reaction temperature was75℃, stirring speed was600r/min, reaction time was2h. MH/MF microcapsules successfully prepared in the above-mentioned appropriate conditions were investigated by SEM, FTIR, particle size analysis and TG, the results showed:the average particle size was2.66μm and its heat resistance significantly for the maximum weight loss temperature increased by about25℃than the pure magnesium hydroxide.Meanwhile, Melamine-formaldehyde resin microencapsulated aluminum hydroxide (ATH/MF microcapsules) was also prepared by in situ polymerization. Particle size as the inspection standard, the orthogonal experiment and the single factor experiment were used to ingvestigate the preparation, effection of different factors on the microcapsules size was mATH/mMF> reaction time> stirring speed> reaction temperature; the appropriate preparation conditions for the preparation of ATH/MF microcapsules:mATH/mMF was5.3, reaction time was2h, the reaction temperature was75℃, stirring speed was600r/min. Investigated by SEM, FTIR, particle size analysis and TG, ATH/MF microcapsules were successfully prepared in the above-mentioned appropriate conditions, the average particle size was5.09μm. FWO method, Kissinger method and Starink method to calculate the apparent activation energy E and preexponential factor A in thermal decomposition kinetics of MH/MF microcapsules and ATH/MF microcapsules were respectively studied; at the same time, Achar method and Coast-Redfer method to obtain the most probable mechanism function on the thermal decomposition kinetics of MH/MF microcapsules and ATH/MF microcapsules were analyzed by TGA with a combition of single scanning,conclusions were as follows:the most probable mechanism function on the thermal decomposition kinetics of MH/MF microcapsules:f(α)=1-α, G(α)=-ln(1-α) and its thermal decomposition process mechanism was random nucleation and subsequent growth; the most probable mechanism functions on the first stage thermal decomposition kinetics of ATH/MF microcapsules: f(α)=4(1-α)3/4,G(α)=1-(1-α)1/4; the most probable mechanism functions on the second stage thermal decomposition kinetics of ATH/MF microcapsules: f(α)=α-1/2,G(α)=α2and the thermal decomposition mechanism of the second stage was one-dimensional diffusion.