Activation Energies of the Decomposition of Poly(methyl α-phenylacrylate) from Static and Dynamic TGA
It is shown that good agreement between activation energies, Ea, as determined by the two methods occurs only when the mechanism of degradation is invariant with extent of decomposition. In the case of poly(methyl α-phenylacrylate), which decomposes by random initiation and unzipping to monomer, this condition only applies with low-molecular-weight material. In polymers which contain long chains a termination step reduces Ea. As the amount of termination diminishes with average molecular weight (i.e., with extent of reaction) Ea from dynamic TGA is an average. Ea from static TGA (initial conditions) does not suffer from this disadvantage.
KeywordsMethyl Methacrylate Termination Step Polymer Decomposition Kinetic Chain Length Dynamic Thermogravimetric Analysis
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- 1.J. H. Flynn and L. A. Wall, General treatment of the thermo- gravimetry of polymers, J. Res. Nat. Bur. Standards U. S., 70A, 487 (1966).Google Scholar
- 2.H. Hopff, H. Lüssi, and L. Borla, Zur Polymerisation des Atropasäuremethylesters, Makromolek, Chem., 81, 268 (1965).Google Scholar
- 3.G. G. Cameron and G. P. Kerr, unpublished results.Google Scholar
- 4.K. Chikanishi and T. Tsuruta, Reactivity of a-alkylacrylic esters. Part 1. Homopolymerisation behaviors of methyl oalkylacrylates, Makromolek. Chem., 81, 198 (1965).Google Scholar
- 5.H. H. G. Jellinek and M. D. Luh, Thermal degradation of isotactic and syndiotactic poly(methyl methacrylate), J. Phys. Chem., 70, 3672 (1966)Google Scholar
- 10.L. A. Wall, Polymer decomposition: thermodynamics, mechanisms, and energetics, SPE J., 16, 810 (1960).Google Scholar
- 11.G. G. Cameron and G. P. Kerr, Simultaneous occurrence of chain-end and random initiation during thermal degradation of poly(methyl methacrylate), Makromolek. Chem., 115, 268 (1968).Google Scholar