| The mechanics performance of Epoxy resin composite material is excellent, and this composite material has been widely used. It is very important for epoxy resin composite to be flame retarded, because the limited oxygen index of epoxy resin is only 18.6, which belongs to nonflammable grade. In this research, epoxy resin was flame retarded by several additive flame retardant reagents. The effects of flame retardant reagent on epoxy resin cure system,preparation procedure and mechanical properties were studied. Based on this study, cone calorimeter was applied on the products'combustion performance and flame retardant mechanism.The influences of ammonium polyphosphate,boracic acid and aluminium hydroxide on the combustion performance of epoxy resin were researched by testing limiting oxygen index, and the pyrolysis process of epoxy resin were researched by thermo gravimetric analysis. The results showed that the ammonium polyphosphate had good inflame-retarding effect for epoxy resin. When append mate of ammonium polyphosphate was 20%, the limiting oxygen index went to 28.1, which could meet the performance index requirement of the nonflammable material. Ammonium polyphosphate and boracic acid had synergetic effect, the limiting oxygen index reached 29.8 when the adding amount was 20%. Pyrolysis process of epoxy resin was changed because of the addition of flame retardant reagents. Pyrolysis temperature of epoxy resin increased to 407℃from 350℃, carbon yield ratio of epoxy resin increased to 75.1%from 28.2% with the addition of boracic acid; and pyrolysis temperature went to 336℃, carbon yield ratio increased to 67.3% with the addition of ammonium polyphosphate.The effects of curing agent and other factors on mechanical properties of glass fiber reinforced flame retarded epoxy resin composites were studied by testing the tensile strength and interlaminar shear strength. The results showed that either too much curing agent or a over heat curing temperature would lead to excessive curing and scorched phenomenon, and insufficient curing agent would lead to incomplete curing. Either excessive agent addition or insufficient would exert a negative influence on the performance of mechanical properties. Ammonium polyphosphate presented a promotion of curing reaction, and had a comparatively little effect on the mechanical properties of glass fiber reinforced flame retarded epoxy resin composites. With the 30% addition of boracic acid, tensile strength fell by 48.1% and interlaminar shear strength by 54.9%. Fiber content and molding pressure played determining roles in mechanical properties of glass fiber reinforced flame retarded epoxy resin composites. Decrease of mechanics performance by addition of flame retardant reagents could be ameliorated by adding coupling agent. Process improving experiment showed that tensile strength reached 348.2MPa, and interlaminar shear strength reached 27.7MPa when content of ammonium polyphosphate was 20%, curing temperature was 140℃, 8.0g dicyandiamide was added into every 100 g epoxy resin, molding pressure was 0.6 MPa, fiber content was 60%, the amount of titanate coupling agent was 3%.Cone calorimetry showed that heat flux was linear to root mean square countdown of time to ignition, y=338.14x+2.1638. Heat flux should not exceed 50kW/m2,because separating capacity decreased when the heat flux was over 50kW/m2. Total heat release of glass fiber reinforced flame retarded epoxy resin composites flame retarded by ammonium polyphosphate was 27.3MJ/m2, and smoke release was 2243m2/m2 Total heat release fell by 37%, and smoke release by 49%, both indicating the remarkable flame retardant and smoke suppression effect. Ammonium polyphosphate decomposed into phosphoric acid,polymetaphosphate and ammonia gas, etc. Phosphoric acid and polymetaphosphate catalyzed he process of epoxy resin's dehydration and carbonization, also served as a cover or protection on the same time, ammonia gas could dilute flammable gas, thereby reduced the release of heat,flammable gas and smoke.The study showed that the glass fiber reinforced flame retarded epoxy resin composites had many advantages, such easy to produce,cost effective and environmental friendly. Mechanical property and flame retardant property of glass fiber reinforced flame retarded epoxy resin composites could meet the requirements of manufacture of traffic tools and electronic devices. |
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