Madras, Giridhar and Chattopadhyay, Sujay (2001) Effect of Hydrogen Donor on the Thermal Degradation of Poly(vinyl acetate) in Solution. In: Journal of Applied Polymer Science, 81 (8). 1996 -2000.
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The thermal decomposition of poly(vinyl acetate) (PVAc) in solution was investigated both in the presence and absence of a hydrogen donor (H-donor). Thermal degradation experiments at 220-250°C were conducted in a batch reactor by dissolving PVAc in diphenylether. The molecular weight distributions were measured as a function of reaction time. Experimental data indicated that the polymer degrades by random chain scission. The random scission degradation rate coefficient was between $9.01 \times 10^-^4$ and $6.12\times10^-^3 min^-^1$. The activation energy, determined from the temperature dependence of the rate coefficient, was 31.5 kcal/mol. The effect of an H-donor, diphenylamine, was also investigated by varying the concentration from 0 to 0.472 mol/L. The data indicated that the presence of diphenylamine increases the PVAc degradation rate from $3.67\times10^-^3$ to $4.59 \times 10^-^3 min^-^1$ at 240°C. This is in contrast to the reduction in the degradation rate of polystyrene in the presence of diphenylamine. Continuous distribution models have been developed by treating molecular weight as a continuous variable. The experimentally observed variation of the degradation rates with H-donor concentration is satisfactorily explained by a continuous distribution model based on the radical mechanism that involves the elementary reactions including the hydrogen abstraction steps.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to John Wiley & Sons, Inc.|
|Keywords:||polymer degradation; Polymer solution; Continuous distribution kinetics; Thermal cracking; Hydrogen donor|
|Department/Centre:||Division of Mechanical Sciences > Chemical Engineering|
|Date Deposited:||16 Mar 2007|
|Last Modified:||19 Sep 2010 04:36|
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