Hebei Meixi Biotechnology said that at present, the flame retardants of polymer materials are developing in the direction of high efficiency, low smoke and low toxicity, so the application of various halogen-free flame retardants and the research of their flame retardant mechanism will become the most active research field of flame retardant polymers. Basic magnesium carbonate has good thermal stability, non-toxic, non-volatile, does not produce corrosive gases, does not produce secondary pollution and is inexpensive. It is an environmentally friendly flame retardant material, but there are not many reports on its application in flame retardant epoxy resins. The flame retardant properties and flame retardant mechanism of basic magnesium carbonate flame retardant epoxy resin were analyzed.
Flame retardant performance analysis: combustion performanceWith the increase of alkaline magnesium carbonate filling, the dripping produced by the combustion of epoxy resin alkaline magnesium carbonate composite materials decreases, the combustion capacity is weakened, and the self-extinguishing time becomes shorter. In the filling volume reached 52At 4%, there is no dripping, and the combustion is pyrolyzed into charcoal, and the combustion changes from a molten state to a cohesed state, and quickly self-extinguishes. From this point of view, basic magnesium carbonate filled epoxy resin has good flame retardant properties and will not cause secondary pollution.
With the increase of the basic magnesium carbonate filling, the oxygen index of the sample increased, and the flame retardant effect was improved, which was consistent with the results obtained by the combustion test. When the basic magnesium carbonate content is 33At 3%, the LOI value of epoxy resin is 19 when it is blank8% rises to 229%, which has reached the standard of self-extinguishing (226%)。With the increase of basic magnesium carbonate addition, the limiting oxygen index of the sample also increased, when its content reached 52At 4%, the LOI value of the sample has reached 270%, which has exceeded the standard for flame retardancy (26.).8%)。When the basic magnesium carbonate content is 56At 5%, the LOI value of the sample is already close to 30%. From the above, it can be seen that basic magnesium carbonate is a relatively good inorganic flame retardant, and a better flame retardant effect is achieved when the addition amount is not too large.
The basic magnesium carbonate separates the thermal decomposition of the gas and epoxy resin, and the sample shrinks, forming cracks. The decomposition of basic magnesium carbonate to produce activated magnesium oxide may catalyze the thermal-oxygen cross-linking reaction of epoxy resins to form a stable carbon-containing residue. Activated magnesium oxide and carbon-containing residue particles have a strong adsorption force, adsorbing carbon particles on the surface of the combustion residue. In addition, there is no topography of the cooling liquid on the surface of the combustion residue, which indicates that the basic magnesium carbonate can enhance the resistance of the epoxy resin to melt droplets, so the sample does not dissolve during combustion. The surface layer of this combustion residue blocks and isolates the heat flow and mass flow, acting as a flame retardant. In a word, basic magnesium carbonate has multiple flame retardant functions and is a good flame retardant for epoxy resins.
Hebei Meixi Biotechnology said that the addition of basic magnesium carbonate in epoxy resin is 56At 5%, its limiting oxygen index reached 297%, the thermal decomposition termination temperature is reduced by about 100%. Basic magnesium carbonate has dilution, cooling, isolation, catalytic flame retardant effects. Basic magnesium carbonate enhances the resistance of epoxy resins to melt droplets.