A variety of global kinetic models are reviewed, including first-order, nth-order, nucleation, and sequential models as well as models having Gaussian, Weibull, and discrete activation-energy distributions. The important characteristics of these various models are outlined, with guidance in how to select the correct model. Some of the models have similar characteristics, and the parameter relationships among similar models are discussed. The comparison includes the relationship between conversion-dependent parameters determined by modified Friedman and Coats−Redfern isoconversion methods and reactivity distribution parameters determined by nonlinear regression of rate or fraction-reacted profiles. A new method for deriving discrete activation-energy distribution parameters having ln(A) = a + bE is also presented. Data accuracy requirements are discussed briefly. Kinetic analyses are given for a variety of materials, including synthetic polymers (polyethylene, polystyrene, polydimethylenenaphthalene, polysulfone, and polyvinyl acetate), petroleum sources rocks (including well-preserved algal kerogens and the Bakken and Monterey shales), oil shales (including kukersite), and the Illinois and Pittsburgh Premium coal samples.

We have measured the dispersion of the gas phase depolarization ratio of Rayleigh scattered light for 12 linear and symmetric top molecules. Combining these data with known refractive index data we obtain the frequency dependence of the polarizability anisotropy. For all molecules studied we find that the polarizability anisotropy increases more rapidly with increasing frequency than the bulk polarizability. We have correlated this behavior with the oscillator strength and direction of the first electronic transition. We have also compared our zero frequency extrapolated anisotropies with the anisotropies determined from static fields with the Kerr effect and the Stark effect in microwave spectroscopy.

While the broadness of the pyrolysis profile of most kerogens is described well by a parallel reaction model, the pyrolysis profile at a constant heating rate for certain well-preserved algal kerogens is narrower than can be described by a single first-order reaction. Further, these kerogens show an acceleratory period under isothermal conditions that is inconsistent with any parallel or nth-order reaction model. Three different models (serial, Bouster, and three-parameter) are tested against isothermal and nonisothermal pyrolysis data for a few samples, with the conclusion that the three-parameter model fits well and is the most stable and reliable. The three-parameter model reduces to a first-order model when the acceleration parameter is zero. The overall activation energy and frequency factor from this model are very close to those of the T max-shift method recommended earlier.

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