In lost foam casting

the dynamic thermal degradation process of lost foam patterns under high temperature has a significant effect on molten metal filling appearance.The thermo-oxidative behaviors of EPS and St-MMA were investigated using Thermogravimetric analysis（TGA）in pure air atmosphere at multiple linear heating rates.The apparent activation energy of EPS and St-MMA was determined by the iso-conversional methods.The average apparent activation energy of EPS and St-MMA reaches 86.8 kJ·mol

-1

and 82.5 kJ·mol

-1

respectively.Furthermore

the master plot z（α）was adopted to compare experimental results and general reaction mechanism functions

and the reaction mechanism of EPS is determined by phase boundary controlled reaction model R3.While the St-MMA reaction mechanism function was acquired by the model fitting method using nonlinear least square method

reflecting its complicated degradation mechanism.The simulated kinetic reaction rate model of EPS and St-MMA can supply accurate theoretical dataset for modeling the dynamic thermal degradation process in lost foam casting.