PREDICTION OF THE KINETIC PROPERTIES OF LOW-DENSITY POLYETHYLENE

This article presents the results of kinetic property prediction for low-density polyethylene using the Netzsch Kinetics Neo software, based on differential scanning calorimetry (DSC) data. The kinetic prediction includes a review of thermoanalytical data for chemical processes, process behavior, and temperature optimization. A multi-reaction model approach was applied, incorporating several types of reactions: an nth-order reaction, a diffusion-controlled reaction, an autocatalytic model, and the Avrami–Erofeev model. For each reaction, the activation energy and reaction order were determined, which define the heat flow under specific conditions. The DSC curve shows an endothermic peak at 118 °C, corresponding to the melting point of low-density polyethylene. The prediction of isothermal curves revealed behavior typical for processes governed by an autocatalytic or reaction-diffusion mechanism, where an initial induction period is followed by an increasing reaction rate, rapid heat release, and reaction completion. Isothermal lifetime simulations were performed at temperatures ranging from 10 to 160 °C for conversion degrees (α) from 0.02 to 0.8. Additionally, modeling of DSC curves under dynamic conditions at different heating rates (1–16 °C/min) produced DSC peaks that demonstrate the dependence of heat flow on heating rate. Analysis of adiabatic curves at various initial heating temperatures provides information about thermal runaway temperature and time, which is crucial for evaluating material performance under conditions without heat loss.