Pyrolysis Kinetics of Nylon 6–6, Phenolic Resin, and Their Composites

Abstract

A multistep kinetic process is postulated to describe the pyrolysis of nylon 6-6, phenolic CTL-91LD (a phenolic novalac resin), and their composites. Kinetic coefficients are derived from thermogravimetric analysis data (TGA) at heating rates varying from 3-60°C/min for each component. Three correlation techniques are used to obtain consistent coefficients. A two-step kinetic equation is derived to describe the phenolic pyrolysis and a single-step kinetic equation is found to adequately represent nylon 6-6 pyrolysis. These equations are then combined to obtain an overall pyrolysis rate equation for the composite.The derived rate equations for the individual components and the 1 : 1 composite are verified by comparing them with TGA data taken at rates of sample temperature rise varying from 3-1 OO"C/min. Predictions are made for isothermal pyrolysis of a 1:l composite. Weight-loss data for the nylon-phenolic composite, during both isothermal pyrolysis and pyrolysis at programmed rates of temperature rise, are accurately correlated by the multistep pyrolysis rate equation.

Competitive kinetic model for the pyrolysis of the Phenolic Impregnated Carbon Ablator

“…The proposed competitive model is compared to two other traditional devolatilization mechanisms [11,12] for PICA, that feature parallel reactions schemes. First is the model of Lachaud et al [11] developed for the Porous Material Analysis Toolbox (PATO) is based on a two-equation model built upon legacy data on the decomposition of phenolic [7][8][9]. Previous studies…”

“…In these processes, the long polymeric chains of the solid phenolic break up with the consequent release of gases and leading to a carbonaceous char. In ablator response models for PICA, pyrolysis has been traditionally modeled assuming the presence of several solid phases of density ρ i that decompose following a set of independent parallel reactions [7][8][9][10][11][12]. Arrhenius-type reactions are used and reaction constants are calibrated based on experimental measurements of mass loss versus temperature from thermogravimetric analysis (TGA) [13].…”

“…This shift towards lower temperatures suggests that several reactions consuming the same reactant are occurring simultaneously, or in other words, that two (or more) reactions are in competition. Legacy pyrolysis mechanisms do not account for such behavior because of their parallel and independent reaction formulation [8][9][10][11][12]. Effects of competitive reactions are not only observed in the degradation of carbon/phenolic composites, but also in the pyrolysis of biomass materials [20].…”

Pyrolytic and Elemental Analysis of Decomposition Products from a Phenolic Resin

“…Studies of the effect of heating rate on the thermal decomposition of phenolic resin have been performed using thermogravimetric analysis (TGA) . TGA experiments on phenolic resin suggest that the residual weight percentage associated with the upper temperature of decomposition can be taken as a nominal 50% . A limitation of TGA is the precise interpretation of the events on a TGA curve and their relationship with the chemical mechanism of solid state decomposition .…”

Porous-material Analysis Toolbox based on OpenFOAM-extend and Applications

“…This is correct for one-dimensional steady-state problems with an impermeable back face; in other configurations, the direction and velocity of the flow has to be determined by resolution of the momentum-conservation equation (see subsection III.B). The pyrolysis gas production -Π -is traditionally obtained by fitting thermogravimetry analysis of the resin decomposition using one or several Arrhenius laws [11]. For example, for phenolic polymers, it has been shown that the pyrolysis degradation process follows four steps [3], that may be described by four heterogeneous decomposition reactions [4].…”