Number: 2000-001-1-400
Title: Critically Evaluated Propagation Rate Coefficients for
Free-Radical Polymerizations of Methacrylic Acid Esters with Functional,
Cyclic and Branched Ester Groups
Task Group
Chairman: S. Beuermann
Members: M. Buback,
T. Davis, R.
Hutchinson, B.
Klumperman, A. Kajiiwara, I.
Lac�k, G. Russell
Completion Date: 2003 - project completed
Objective:
Critical evaluation of propagation rate coefficients for free-radical
polymerization of functional methacrylic acid esters with this kp
data being derived from pulsed-laser initiated polymerizations in conjunction
with polymer molecular weight analysis by size-exclusion chromatography
Description:
Modeling of free-radical polymerizations is important for science
and industry. Unfortunately rather different parameter values are reported
for ostensibly the same systems. For measurement of individual propagation
rate coefficients, kp, the IUPAC Working Party on
"Modeling of Polymerisation Kinetics and Processes" recommended pulsed-laser
initiated polymerization (PLP) in conjunction with size-exclusion chromatography
(SEC) as the method of choice. This technique has been successfully
used to determine reliable propagation rate coefficients for several
monomers. After having established benchmark value data of kp
for styrene, methyl methacrylate, and other alkyl methacrylates in three
previous publications of the IUPAC Working Party, the intention of the
present project is to continue this task and to collate reliable kp
data for methacrylates with functional, cyclic, and branched ester groups.
The knowledge of kinetic data for these monomers is of great importance,
as they are frequently used in technical polymerizations, e.g. in the
automotive industry.
Special attention has to be paid to the determination of absolute molecular
weight distributions (MWD), because propagation rate coefficients are
calculated from characteristic (inflection) points of the MWDs. Therefore,
the accuracy of kp is directly determined by the accuracy
of SEC calibration. Usually SEC calibration standards are not available
for these systems, and thus, the knowledge of Mark-Houwink constants
is required to apply universal SEC calibration. kp results from ESR
spectroscopy and rate measurements will be collected, too. These data
are independent of SEC calibration. After critical evaluation of the
existing rate coefficients, and after perhaps carrying out several additional
experiments, benchmark value data for the functional methacrylates will
be published.