Discrete and continuous models for polymerization and depolymerization

• Published in: Chemical engineering science Vol. 56; no. 8; pp. 2831 - 2836
• Main Authors: McCoy, Benjamin J., Madras, Giridhar
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2001; Elsevier
• Subjects: Applied sciences; Chain end addition; Chain end scission; Continuous distribution kinetics; Discrete kinetics; Exact sciences and technology; Gamma distributions; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Similarity solutions; Similarity solutions; Chain end scission; Gamma distributions; Discrete kinetics; Chain end addition; Continuous distribution kinetics; Depolymerization; Kinetic model; Molecular weight distribution; Theoretical study; Polymerization; Modeling; Comparative study
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/S0009-2509(00)00516-9

A fundamental continuous model for the distribution kinetics of polymerization and its reverse, depolymerization, is shown to be consistent with the well-known discrete model. Solutions for discrete and continuous models are compared and shown to have identical expressions for molecular weight (MW) moments. Representing the continuous molecular-weight distribution (MWD) as a γ distribution compares well with exact polymerization and depolymerization MWD solutions of the discrete model, except when the number of repeat units in the polymer is small. None of the solutions for chain end polymerization or depolymerization has the self-similar form, for which the MW and time would appear together in the same similarity variable.