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Termination Kinetics of Methyl Acrylate and Dodecyl Acrylate Free‐Radical Homopolymerizations up to High Pressure
Author(s) -
Buback Michael,
Kuelpmann Albrecht,
Kurz Caroline
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20020501)203:8<1065::aid-macp1065>3.0.co;2-f
Subject(s) - monomer , chemistry , methyl acrylate , polymerization , polymer chemistry , acrylate , plateau (mathematics) , diffusion , bar (unit) , analytical chemistry (journal) , thermodynamics , polymer , organic chemistry , mathematical analysis , physics , mathematics , meteorology
The single pulse (SP) – pulsed laser polymerization (PLP) technique has been applied to measure k t / k p , the ratio of termination to propagation rate coefficients, for free‐radical bulk homopolymerizations of methyl acrylate (MA) and dodecyl acrylate (DA) between 10 and 50°C at pressures from 10 to 2 500 bar. k t / k p is obtained from experimental monomer concentration vs. time traces that are determined via time‐resolved (μs) near infrared monitoring of monomer conversion induced by single excimer laser pulses of about 20 ns width. With k p being known from PLP–SEC experiments, chain‐length averaged k t is immediately obtained from k t / k p . For MA, k t remains constant up to about 15% monomer conversion and clearly decreases upon further polymerization. For DA at pressures of 100 bar and above, a plateau value of constant k t is observed up to about 60% monomer conversion whereas at lower pressure, e. g. at 10 bar, k t slightly increases in the very initial conversion region, but also exhibits a plateau k t value at moderate and high conversions. The occurrence of such plateau k t values and their pressure and temperature dependence are consistent with the view that plateau regions of k t are best understood in terms of diffusion control via segmental mobility.