Identifying unified kinetic model parameters for thermal decomposition of polymer matrix composites

Abstract

Predicting thermal responses of composite materials requires accurate input parameters derived from reliable thermal property characterization and kinetic models. Composite material properties and decomposition kinetics vary with temperature and heating rate. Typically, conventional kinetic models derived from thermogravimetric analysis data result in multiple sets of kinetic model parameters, which are difficult to implement into numerical simulations under widely varying temperature and heating rate conditions. Here, a methodology was developed to reliably predict decomposition processes of composite materials with a single (i.e., unified) set of kinetic model parameters. The unified kinetic model parameters for each of four different composite materials were used to accurately predict decomposition kinetics observed over the entire range of experimental temperatures and heating rates. Furthermore, this broadly applicable methodology may predict decomposition from limited data sets, and is expected to extrapolate reliably measurable data to experimentally challenging heating rates and temperatures.

Pyrolysis Kinetics Analysis and Prediction for Carbon Fiber-Reinforced Epoxy Composites

“…After the pyrolysis degree exceeding 0.8, there was a deviation between the theoretical curves and the experimental curves. The results were consistent with previous research [7,9]. The possible reason for this result is that the reaction mechanism is complex at the end of the reaction, and there was a certain error when the second-order model was adopted to approximate the reaction mechanism.…”

“…Thermogravimetric analysis (TGA) has been used the most for the characterization of the thermal decomposition characteristics of materials. Some research has been conducted on the pyrolysis characteristics of CFRP matrix using the TGA method [7][8][9][10][11][12][13]. The kinetic parameters are obtained through the analysis of thermogravimetric data, and the mathematical relationship between conversion rate and temperature, also known as the conversion rate equation, is developed.…”

Methodology for Validation of Material Response Models Using In-Situ Ablation Sensing Methods

“…Utilizing the Kissinger equation instead of the Friedman equation will result in singular activation energy (EA) and reaction order (m) values while the pre-exponential (A) will change dependent on the heating rate. While the Kissinger decomposition equation may not provide adequate simulation data above α values of 0.7, it is significantly simpler to numerically optimize the KMPs and is less computationally intensive than the Friedman method [11].…”

“…The first heating rate of 50 °C/min was chosen to be as high as the given TGA instrument can safely handle, while subsequent heating rates are approximately half as much as the previous in order to ensure significant separation on a logarithmic scale. While these heating rates are not representative of the approximately 200 °C/sec peak heating rate experienced during OTB testing, the use of three or more TGA data sets from differing heating rates can be used to predict realistic KMPs for all heating rates as demonstrated by Sihn et al [11] The temperature versus normalized mass loss graph in an oxidizing environment is shown below in Figure 7.…”

“…KMPs for the three decomposition reaction chains based on the TGA data in an oxidative environment and the Kissinger method With the reaction order term for f(α) fixed, the slope of the curve fit (1/RT) and Y-intercept [ln(A)] give the EA and A terms as shown in Table1. While β is known and fixed for the OTB testing heating rate conditions and the Kissinger decay function, Sihn et al[11] describe how additional TGA data sets at different heating rates can be used to project variations in these parameters for any given heating rate β and any reaction model function.…”