Study On Combustion Characteristics Of Bismaleimide And Its Composites

As an advanced composite material,the bismaleimide resin matrix composite has been widely used in fighters,transport aircraft,civil airliners,missiles and other aerobat.The bismaleimide resin and its carbon fiber composite are explored for its broad application in aerospace components,such as the wing and tail skins of fighter aircraft herein.The materials usually take special mission and undergo high temperature in diverse scenarios;hence,they will cause great losses to the aircraft and threaten the safety of the personnel on board seriously in case of fire.In this thesis,thermogravimetric method,cone calorimetry,limiting oxygen index method,horizontal and vertical combustion test method,smoke density test method and smoke toxicity test are used to analyze the combustion characteristics of bismaleimide resin and its carbon fiber composite systematically,including the thermal behavior,combustion behavior and flue gas characteristic parameters.Firstly,the properties of thermal behavior of the materials are revealed by TG curves and DSC curves respectively.Secondly,the pyrolysis kinetic models are established by the modeless FWO method and Starink method to discuss the reaction mechanism and calculate the apparent activation energy as well as average activation energy of the two kind of materials at different conversion rates.Thirdly,the ignition time,ignition temperature,heat release rate and mass loss parameters and so on are utilized to analyze the combustion behavior of the materials.Through establishing an ignition prediction model,the author calculate the critical thermal radiation intensity and ignition temperature,and verify the accuracy of the ignition prediction model furthermore.On the other hand,limit oxygen indexes are measured,and the combustion behavior classifications are confirmed by horizontal/vertical tests.As an important section,light transmittance,specific shading density,average smoke accumulation speed,smoke darkening index,maximum specific optical density correction value,CO and CO2 generation amount and toxic gas concentration are adopted together to explain smoke feature of the bismaleimide resin and its carbon fiber are analyzed.It is concluded that the usage of carbon fiber to toughen the bismaleimide resin can form a dense covering carbon layer largely when the bismaleimide resin's thermolysis occurs,which preventing heat and oxygen from entering the interior of the composite material so that playing an effective role in fire prevention,moreover,no obvious increase in toxic gas appears at last.