Identification of Pyrolysis Reaction Model of Linear Low Density Polyethylene (LLDPE)
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This paper described how to estimate the Arrhenius parameters as well as the pyrolysis reaction model of LLDPE from isothermal kinetic data. We used a custom-made thermobalance that is capable of monitoring a weight decrease with time under pure static condition and performed six isothermal kinetic experiments at 713, 718, 723, 728, 733, and 738 K that were chosen within a temperature range (710–740 K) where main decompositions were observed from non-isothermal kinetic results. Comparing experimental reduced-time-plots (RTPs) with theoretical ones, the pyrolysis reaction model of LLDPE is accounted for by "Avrami–Erofeev" model in the investigated temperature region, allowing its functional form to be 2(1 − α)[−ln(1 − α)]<SUP>1/2</SUP>. It is, hence, expected that the reaction order model adopted by the previous studies without verification is inappropriate to represent the pyrolysis reaction model of LLDPE. Bubble nucleation may be a major pyrolysis reaction mechanism of LLDPE. As heat is applied, the LLDPE is melted. Volatiles may be accumulated inside the melt until reaching a critical concentration where bubble nucleation sets forth. The rates of heat, mass, or momentum transfer in the LLDPE melt and its physico-chemical properties (especially viscosity) play an important role in characterizing the thermal decomposition kinetics of LLDPE.
- Chemistry Letters
Chemistry Letters 35(4), 446-447, 2006-04-05
The Chemical Society of Japan