[SY-F13] Studing thermo-oxidative degradation of polyimide in oxygen enviorment using MD simulations
Polyimides are important class of high-temperature polymers. These polyimides finds applications in diverse fields such as aerospace, electronics and automobiles. PMR-15 is one these polyimide which is extensively used as matrices for composite in the aerospace industry due to its high glass transition temperature, mechanical strength with high modulus of elasticity. However diffusion of oxygen in polymer and subsequent reaction with polymer leads to formation of oxidized layer. This layer drastically changes the mechanical properties of the polymer. Since these polyimide’s founds application in aircraft design, so thermo-oxidative degradation of polymer may prove fatal and catastrophic in oxygen rich environment. Crack initiation and damage growth also follows due to thermo-oxidative degradation. We will be studying thermo oxidative degradation of PMR-15 polymer through molecular dynamics(MD) simulation. Molecular simulations has been become quite popular tool to predict macroscopic properties of polymer through statistical study at atomistic level. However getting correct force field parameter to simulate an exact material is challenging and of utmost importance. We attempt to study PMR-15 polymer with its full atomistic details intact and predicting it micromechanical properties through MD simulation. Due to some computational and forcefield limitations, coarse grained model of polyimide had been previously studied. In our analysis, we don’t make any pre-assumption of course graining during sample preparation. We prepare our sample of PMR-15 with correct cross linking strategy such that we get density close to experimental value of 1.324. We will quantifies mechanical properties such as elastic constant and phenomenogical quantities such as diffusion constant and tries to predict the life of polymer due to thermo-oxidative degradation. We want challenge the time and scale limitations of MD simulation by attempting to simulate full scale atomistic model of the polymer PMR-15. This study will give more insight about capabilities of MD simulations and also provides reasons where it fails to give us valid results. This study will provide an alternative path to study the systems where experimental analysis is difficult to setup or too expensive and cumbersome.