Application of Continuous Kinetics to Polymer Degradation

Abstract Degradation of polydisperse polymers is studied in the framework of continuous kinetics which is directly based on continuous distribution functions which depend on the molecular weight and the time. A firstorder formalism is presumed. A Schulz-Flory distribution (with time-dependent parameters) is assumed to be valid during the entire time of degradation. Thus, an essential simplification of the solution procedure of the continuous rate equation is achieved. As a proof of accuracy, the approximation solution and the exact solution are compared for the case of “random scission.” Furthermore, the developed method is shown to be suitable for describing the experimental data of dextran degradation caused by acid hydrolysis, by ultrasonic irradiation, and by enzymatic attack. The model parameters fitted to the experimental data allow the evaluation of the scission probability as a function of the molecular weight and of the location of the bond to be broken within the molecule.

[1]  O. Saito.  On the Effect of High Energy Radiation to Polymers I. Cross-linking and Degradation , 1958 .

[2]  H. Kehlen,et al.  Continuous Thermodynamics of Polymer Solutions: The Effect of Polydispersity on the Liquid-Liquid Equilibrium , 1985 .

[3]  B. Wolf,et al.  Degradation of chain molecules. 1. Exact solution of the kinetic equations , 1981 .

[4]  W. Kuhn,et al.  Über die Kinetik des Abbaues hochmolekularer Ketten , 1930 .

[5]  D. Browarzik,et al.  Refined Continuous Thermodynamic Treatment for the Liquid-Liquid Equilibrium of Copolymer Solutions , 1989 .

[6]  A. M. Basedow.  Studies on the enzymatic hydrolysis of dextran , 1980 .

[7]  Robert M. Ziff,et al.  The kinetics of cluster fragmentation and depolymerisation , 1985 .

[8]  B. Wolf,et al.  Degradation of chain molecules. 2. Thermodynamically induced shear degradation of dissolved polystyrene , 1984 .

[9]  Robert M. Ziff,et al.  New solutions to the fragmentation equation , 1991 .

[10]  P. J. Blatz,et al.  Note on the Kinetics of Systems Manifesting Simultaneous Polymerization-Depolymerization Phenomena , 1945 .

[11]  Klaus H. Ebert,et al.  Kinetic Studies on the Acid Hydrolysis of Dextran , 1978 .

[12]  E. Montroll,et al.  Theory of Depolymerization of Long Chain Molecules , 1940 .

[13]  Robert M. Ziff,et al.  Kinetics of polymer degradation , 1986 .

[14]  H. Kehlen,et al.  Continuous kinetics of first order degradation reactions in polydisperse mixtures , 1988 .

[15]  A. Keller,et al.  The extensibility of macromolecules in solution; A new focus for macromolecular science , 1985 .

[16]  K. Ebert,et al.  Effects of mechanical stress on the reactivity of polymers: activation of acid hydrolysis of dextran by ultrasound , 1979 .

[17]  H. Kehlen,et al.  Continuous thermodynamics of polymer systems , 1989 .

[18]  H. Kehlen,et al.  Application of Continuous Thermodynamics to the Stability of Polymer Systems. III , 1987 .