Application of the Sestak-Berggren equation to organic and inorganic materials of practical interest

Reactions that have an initial acceleratory period are common in both organic and inorganic systems. The Sestak-Berggren equation, dx/dt= -kx(n)(1-x)(m)[-ln(x)](p), with p set to zero (also called the extended Prout-Tompkins (PT) equation) is an excellent empirical kinetic law for many of these systems. In this work, it is shown to fit both isothermal and constant heating rate pyrolysis data for a well-preserved algal kerogen in a petroleum source rock and two synthetic polymers (polycarbonate and poly-ether-etherketone), dehydration of calcium oxalate monohydrate, decomposition of ammonium percholorate, and diffusive release of gas implanted in materials. Activation energies derived by non-linear regression to multiple experiments are consistent with those derived by simple isoconversional methods. Errors caused by misapplication of first-order kinetics to single-heating-rate data are discussed briefly.