Isokinetic Relationships to Evaluate Thermal Degradation Kinetics Parameters of MMA-St Copolymer and EPS Lost Foams

Methylmethacrylate-styrene (MMA-St) random copolymer was synthesized by suspension copolymerization. The thermal degradation of MMA-St copolymer and EPS lost foams was studied by non-isothermal thermal gravimetric analysis under nitrogen purge. It was found that EPS foam starts to decompose at higher temperatures than MMA-St copolymer foam in all heating rates. The apparent activation energy was calculated by the Flynn-Wall-Ozawa method. It has been concluded that the model fitting methods is unable to reveal the complexity of the pyrolysis process and the model-free methods can be suggested as a reliable way of determining the kinetic parameters. In this work the isokinetic relationship (IKR) was used to estimate a model-independent pre-exponential factor (lnA) corresponding to a given degree of conversion.

Keywords:

Lost foam , MMA-St copolymer , EPS , Degradation kinetics , IKR