Laser-flash-initiated polymerization as a tool for evaluating (individual) kinetic constants of free-radical polymerization—5. Complete analysis by means of a single experiment
✍ Scribed by O.F. Olaj; I. Schnöll-Bitai
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- English
- Weight
- 575 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0014-3057
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✦ Synopsis
A~tract--Three systems, styrene in bulk (a), styrene-toluene 1 : 1 (b), and methylmethacrylate in bulk (c) have been subjected to a pseudostationary polymerization initiated by periodic laser flashes at 25 ° at various pulse separations to in the range of 0.1~, sec. The kinetic analysis, which can be carried out separately and independently for each experiment, is based on molecular mass distributions evaluated by GPC, gravimetric determination of polymer yield and evaluation of P, from the GPC-curves. Rate constants of propagation kp were determined from the points of inflection in the GPC-curves while k2/kt was calculated from the product of rate of polymerization and/5 w. Combination of kp and k~/k t finally yielded k t. In addition, rough estimates could be obtained for the contribution of disproportionation to overall bimolecular termination. The results were: system (a): kp = 77 + 41 mol-t sec i; kt = (0.78 + 0.12). 108 l mol t sec-l; system (b): k o = 79 __+ 5 1 mol -t sec -~, k t = (0.96 _+ 0.09). 1081 mol -~ sec-t; system (c): kp = 313 + 8 lmol-~ sec -1, k t = (0.39 + 0.04). 10s I mol-t sec-i.