Prediction of thermal degradation of thermoprotective materials on the basis of their composition and properties of components

Abstract

Thermal decomposition of thermoprotective materials based on phenolformaldehyde resin and carbon cloth with different contents of components is studied. Physical and mathematical models for the process are proposed. It is shown that the mass loss in carbon fiber reinforced plastics is determined by thermal degradation of the components and can be described by a generic kinetic scheme with a given set of thermokinetic constants. The mass loss of materials can be predicted by solving a system of ordinary differential equations taking into account the mass ratio of the components in the composite material.Carbon-fiber-reinforced composites have found application in thermal protection of the side surface of landers moving in dense atmospheric layers from intense heat flows. By varying the mass fractions of the polymer binder and the refractory filler in the composites, one can affect the heating and mass-loss processes in the thermoprotective coating and, after an analysis and simulation of the processes in heated carbon fiber reinforced plastics (CFP), predict the inflow of gaseous decomposition products into the boundary layer. The latter seems to be of extreme importance because this inflow affects heat and mass transfer, friction coefficients, and stability characteristics of a flying vehicle following a ballistic trajectory with different angles of attack. Moreover, variation of mass fractions of the components in a composite affects the thermophysical parameters of materials and, hence, the thickness of the heated, reacting, and coke layers of the thermoprotective coating.The high cost of certification and full-scale tests for new materials necessitates generalization of experimental data aimed at developing a technology for production of composite materials with prescribed (predictable) properties. This would substantially reduce the development costs and allow rapid introduction of new compounds into industry.The properties of thermoprotective materials based on phenolformaldehyde resin and carbon cloth were examined in [1][2][3][4].Schneider et al.[1] derived temperature dependences of thermophysical properties of CFPs under static conditions and kinetic parameters of its thermal decomposition process (activation energy E = 81 kJ/mole and preexponent k 0 = 3.15·10 4 sec −1 ) determined from thermogravimetric data by the chemical kinetics equationwhere ρ s and ρ c are the current and final densities of the material, t is the time, T s is the temperature, and R is the universal gas constant. The carbon fiber reinforced plastic contained ≈35% (by weight) of phenolformaldehyde resin and ≈65% (by weight) of carbon cloth.

Pyrolysis model for multiple compositions of a glass reinforced unsaturated polyester composite

“…This combination of matrix and reinforcement was chosen as the subject of this work because it is the most prevalent configuration in the composites market, it was the easiest system to procure, and provided the simplest procedure to fabricate samples. The majority of previous work to characterize reinforced polymer composites has been performed on pure materials or composites of a single composition; however, there have been a few notable efforts made to address the effect of composite composition on the burning behavior …”

“…One study that attempted to develop a pyrolysis model that predicted fire response while accounting for composition was conducted by Zinchenko et al . which investigated several compositions of phenol formaldehyde resin/carbon fiber cloth composites while focusing solely on the kinetic reaction mechanisms of thermal degradation . The mass loss model with the kinetic parameters determined for the individual constituents successfully predicted the experimentally measured relative mass of composites with compositions of 35 and 42 wt % resins, although parameters were varied for each configuration, resulting in a model that could not independently predict fire behavior.…”