Preparation And Property Study Of Polyurethane Foams/Expandable Graphite-Aluminum Hydroxide Flame Retardant

Polyurethane foams are widely used in various fields because of their good thermal insulation properties,excellent mechanical properties,excellent durability and dimensional stability.However,polyurethane foams are flammable and corrosive toxic gases are generated during combustion.With the development of science and technology and the rise of people's environmental awareness,the society has an urgent need for new environmentally friendly insulation materials.In order to improve the flame retardancy of the polyurethane foam,it is usually selected to enhance the flame retardant performance by adding a flame retardant,but the halogen-containing flame retardant releases a large amount of toxic gas during the burning process.In order to meet the needs of society,it is necessary to prepare a new green environmentally friendly flame retardant.In this paper,the composite flame retardant of expandable graphite/aluminum hydroxide was prepared by hydrothermal method,and then the expandable graphite/aluminum hydroxide composite flame retardant prepared by different hydrothermal conditions was separately added into the polyurethane raw material to prepare the flame retardant polyurethane sample.The effects of hydrothermal reaction conditions such as temperature,pH value and reactant ratio on the product were studied.The reaction mechanism of hydrothermal method for preparing expandable graphite/aluminum hydroxide composite flame retardant was elucidated.Through the structural analysis and micro morphology analysis of the new composite flame retardant,the flame retardant properties,mechanical properties and micro morphology of the flame retardant polyurethane can be analyzed as follows: the increase of hydrothermal temperature to the aluminum hydroxide phase The effect is obvious;the effect of pH change on the aluminum hydroxide phase is not obvious;the composite flame retardant will not participate in the foaming reaction of the polyurethane foam but will reduce the closed cell ratio of the polyurethane foam,and thus the mechanics of the polyurethane foam.The performance is deteriorated;the flame retardant performance of the composite flame retardant is excellent.When the addition amount is 20 g,the limiting oxygen index of the polyurethane reaches 28.5,and the self-extinguishing level.The effect of adding different quality composite flame retardants on the properties of polyurethane foams was also studied,and the flame retardant mechanism was analyzed.Through the analysis of the microstructure and properties of polyurethane samples with different amounts of composite flame retardants,the following conclusions can be drawn: the flame retardant properties and thermal stability of polyurethane foams will increase with the addition of composite flame retardants;polyurethane foams The closed cell ratio is gradually reduced as the new composite flame retardant increases,so that the compression properties of the polyurethane foam are lowered and the apparent density is increased.At the end of this paper,the mechanical properties of flame retardant polyurethane were improved by adding plasticizer DOA(dioctyl adipate).The effects of different addition amount of plasticizer DOA on the properties and structure of flame retardant polyurethane were explored.The following conclusions were obtained: DOA can significantly increase the compressive strength of the flame retardant polyurethane,and has no effect on the flame retardant properties,apparent density and thermal insulation properties of the flame retardant polyurethane.