Thermal debinding behavior of a low-toxic DMAA polymer for gelcast ceramic parts based on TG-FTIR and kinetic modeling

In this work, the pyrolysis characteristics of a low-toxic N, N-dimethylacrylamide (DMAA) gel polymer was investigated through nonisothermal thermogravimetry (TG) and TG-FTIR analyses. Moreover, the thermal debinding kinetics of gelcast SiAlON ceramic parts was studied through three different kinetic models: the Coats-Redfern (C-R) method, distributed activation energy model (DAEM) and three-Gaussian-DAEM-reaction model (3-DAEM). The rationality and adaptability of the three models to the thermal debinding kinetics study were analyzed by comparison with experimental data. The results showed that three mass loss zones were observed in the temperature ranges of 100-320 degrees C, 320-520 degrees C and 520-600 degrees C, respectively, and the main pyrolysis gas products were CO2, H2O and CH4. The conversion rate (alpha) curves calculated by 3-DAEM were more consistent with the experimental values than those calculated with the C-R and DAEM methods. The fitting quality parameter (Fit%) was less than 2.63%, and the reaction rate (d alpha/dT) curves calculated by 3-DAEM were bimodal distribution curves, which were in good agreement with the experimental results. The kinetic parameters (E-0,E-i, k(0,i) and sigma(i)) of the global thermal debinding process calculated by 3-DAEM were 116.00-145.79 kJ mol(-1), 1.10 x 10(9) s(-1) and 1.67-43.25 kJ mol(-1), respectively. It is anticipated that the study achievements can be used to help predict the thermal debinding behavior and design a reasonable debinding technology for the gelcasting of ceramic parts.