Hebei Messi Biology Co., Ltd. stated that at present, flame retardants for polymer materials are developing in the direction of high efficiency, low smoke, and low toxicity. Therefore, the application of various halogen-free flame retardants and the research on their flame retardant mechanisms will become an important issue in the development of flame retardants. The most active research field of burning polymers. Basic magnesium carbonate has good thermal stability, is non-toxic, non-volatile, does not produce corrosive gases, does not produce secondary pollution and is low in price. It is an environmentally friendly flame retardant material, but there are not many reports on its application in flame retardant epoxy resin. The flame retardant properties and flame retardant mechanism of basic magnesium carbonate flame retardant epoxy resin were analyzed.
Flame retardant performance analysis: Combustion performance As the filling amount of basic magnesium carbonate increases, the dripping produced by the combustion of the epoxy resin/basic magnesium carbonate composite material decreases, the combustion ability weakens, and the self-extinguishing time becomes shorter. When the filling amount reaches 52.4%, there is no dripping matter, the combustion material is pyrolyzed into char, the combustion changes from a molten state to a coke state, and it self-extinguishes quickly. From this point of view, basic magnesium carbonate filled epoxy resin has good flame retardant properties and will not cause secondary pollution.
As the filling amount of basic magnesium carbonate increases, the oxygen index of the sample increases and the flame retardant effect improves, which is consistent with the results obtained from the combustion test. When the basic magnesium carbonate content is 33.3%, the LOI value of the epoxy resin increases from 19.8% in the blank to 22.9%, reaching the self-extinguishing standard (22.6%). As the addition amount of basic magnesium carbonate increases, the limiting oxygen index of the sample also increases. When its content reaches 52.4%, the LOI value of the sample has reached 27.0%, which has exceeded the flame retardant standard (26.8% ). When the basic magnesium carbonate content is 56.5%, the LOI value of the sample is close to 30%. It can be seen from the above that basic magnesium carbonate is a relatively good inorganic flame retardant, and it can achieve a relatively good flame retardant effect when the added amount is not too large.
Basic magnesium carbonate decomposes to release gas and the thermal decomposition of the epoxy resin causes the sample to shrink and form cracks. The active magnesium oxide generated by the decomposition of basic magnesium carbonate may catalyze the thermal oxygen cross-linking reaction of epoxy resin to generate a stable carbon-containing residue. Activated magnesium oxide and carbon-containing residue particles have strong adsorption force, and the carbon particles are adsorbed on the surface of the combustion residue. In addition, there is no cooling liquid morphology on the surface of the combustion residue, which indicates that basic magnesium carbonate can enhance the anti-dropping ability of the epoxy resin, so the sample does not produce droplets during combustion. The surface layer of this combustion residue blocks and isolates the heat flow and mass flow, and plays a flame retardant role. In short, basic magnesium carbonate has multiple flame retardant functions and is a good flame retardant for epoxy resin.
Hebei Messi Biology Co., Ltd. stated that when the amount of basic magnesium carbonate added to the epoxy resin is 56.5%, its limiting oxygen index reaches 29.7%, and the thermal decomposition termination temperature is reduced by about 100°C. Basic magnesium carbonate has dilution, cooling, isolation, catalytic and flame retardant effects. Basic magnesium carbonate can enhance the anti-drip ability of epoxy resin.