Evolution of the decomposition mechanisms as a function of heating rate of a biosourced polymers reinforced with carbon fibers.
ASENSIO V. 1, REBILLAT F. 1, DAMIANI D. 1,2, COSCULLUELA A. 1,3
1 Laboratory of Thermostructural Composites (LCTS) - University of Bordeaux, (UMR 5801 : CNRS, CEA, SAFRAN, UB), Pessac, France; 2 French Alternative Energies and Atomic Energy Commission (CEA), Le Ripault, France; 3 French Alternative Energies and Atomic Energy Commission (CEA), Cesta, France
Aeronautical and space applications require the use of composite materials that can withstand very high heat flows with a limited ablation rate. The materials of this study are carbon fiber reinforced biosourced polymer matrix (biosourced CFRP). During a heating step, the material is progressively transformed into carbon through a pyrolysis process. The resulting carbon/carbon composite will undergo ablation, in the considered applications.
The objective of this work is to identify the mechanisms of decomposition during the pyrolysis process of a biosourced CFRP and quantify the progression rates of each, as a function of the heating rate.
The effect of temperature on the physico-chemical behaviour of the materials (the composite or the resin alone) has been analysed at different heating rates (from 5 to 100°C/min). A characterization of the degraded materials has been carried out to facilitate the understanding of the pyrolysis mechanisms. Through coupled FTIR, TMA and DSC analyses, it is possible to identify: the pyrolysis products, the level of energy exchange and the volume variations to describe the reaction mechanisms [1]. One single global reaction could not be used to correctly represent this whole process and a multi-step pyrolysis reaction has to be considered. The kinetic coefficients of each step are determined using iso-conversion methods [2]. The thermal and morphological properties of the composite and the resin alone, are analysed before and after pyrolysis (porosity, diffusivity, cracking, etc.). A global strategy for monitoring pyrolysis will be described. In the long term, ways could be identified to develop composite materials with high-performance mechanical and thermal properties.
[1] Bessire, B. K., Lahankar, S. A. et Minton, T. K. Pyrolysis of Phenolic Impregnated Carbon Ablator (PICA). ACS Applied Materials & Interfaces, 7(3), 1383?1395. 2015.
[2] Vyazovkin, S. et Wight, C. A. Model-free and model-fitting approaches to kinetic analysis of isothermal and nonisothermal data. Thermochimica Acta, 340?341, 53?68. 1999.