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Title: Degradation kinetics of polymers in solution: Dynamics of molecular weight distributions

Abstract

Polymer degradation occurs when macromolecular chains are broken under the influence of thermal, mechanical or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here the authors develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of MWDs. The governing integrodifferential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably describe experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of macromolecular degradation processes, particularly how bimodal MWDs can evolve during degradation.

Authors:
;  [1]
  1. Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
Publication Date:
Sponsoring Org.:
USDOE Pittsburgh Energy Technology Center, PA (United States); Environmental Protection Agency, Washington, DC (United States)
OSTI Identifier:
460566
DOE Contract Number:  
FG22-94PC94204
Resource Type:
Journal Article
Journal Name:
AIChE Journal
Additional Journal Information:
Journal Volume: 43; Journal Issue: 3; Other Information: PBD: Mar 1997
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; POLYMERS; DECOMPOSITION; THERMAL DEGRADATION; EROSION; MOLECULAR WEIGHT; MATHEMATICAL MODELS; THEORETICAL DATA

Citation Formats

McCoy, B J, and Madras, G. Degradation kinetics of polymers in solution: Dynamics of molecular weight distributions. United States: N. p., 1997. Web. doi:10.1002/aic.690430325.
McCoy, B J, & Madras, G. Degradation kinetics of polymers in solution: Dynamics of molecular weight distributions. United States. https://doi.org/10.1002/aic.690430325
McCoy, B J, and Madras, G. 1997. "Degradation kinetics of polymers in solution: Dynamics of molecular weight distributions". United States. https://doi.org/10.1002/aic.690430325.
@article{osti_460566,
title = {Degradation kinetics of polymers in solution: Dynamics of molecular weight distributions},
author = {McCoy, B J and Madras, G},
abstractNote = {Polymer degradation occurs when macromolecular chains are broken under the influence of thermal, mechanical or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here the authors develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of MWDs. The governing integrodifferential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably describe experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of macromolecular degradation processes, particularly how bimodal MWDs can evolve during degradation.},
doi = {10.1002/aic.690430325},
url = {https://www.osti.gov/biblio/460566}, journal = {AIChE Journal},
number = 3,
volume = 43,
place = {United States},
year = {Sat Mar 01 00:00:00 EST 1997},
month = {Sat Mar 01 00:00:00 EST 1997}
}