- Author
- Inaba, A. | Kashiwagi, T.
- Title
- Calculation of Thermal Degradation Initiated by Random Scission. Part 1. Steady-State Radical Concentration.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Journal
- Macromolecules, Vol. 19, No. 9, 2412-2419, September 1986
- Keywords
- thermal degradation | zip length | logarithmic normal distribution
- Abstract
- Changes in molecular weight distribution and in sample volume were calculated for thermal degradation of a polymer. The thermal degradation scheme consists of random scission initiation, depropagation, and disproportionation termination reactions. A steady-state radical concentration was used in this study. The initial molecular weight distribution of the sample was expressed by a logarithmic normal distribution. Results were obtained in two ways: one was by approximate analytical solutions describing changes in molecular weight and in the sample volume, including effects of initial polydispersity of the sample; the other was by numerical calculation. Comparison among the analytical solutions obtained in this study, previously published solutions, and the numerically calculated results indicates that the solutions obtained in this study can apply to more general initial molecular weight distributions and agree better with the numerical results than previously published results. Effects of initial molecular weight, average zip length, initial polydispersity, and order of the termination reaction on changes in molecular weight, polydispersity, and the volume of the sample are discussed. A method to determine values of kinetic constants of random scission initiation and average zip length is described using experimental data in conjunction with the calculated results.