Degradation kinetics of poly vinyl

Application of the Computer to Degradation Kinetics of Poly(vinyl Halides)... 

Computer programs have been used to correlate the degradation kinetics of poly(vinyl halides) assuming a kinetic model that is based on the zipper mechanism. Best fit values of the parameters of the kinetic model allow reproduction of a degradation with an error that is usually less than 0.6% per point. 

The storage of voluminous run data in a readily available form and the obtaining of best fit values of kinetic parameters have been useful in the better understanding of the degradation kinetics of poly(vinyl halides). ... 

M.T. Taghizadeh, A. Bahadori, Degradation kinetics of poly (vinyl-pyrrolidone) under ultrasonic irradiation. J. Polym. Res. 16, 545-554 (2009)... 

Degradation of Poly(vinyl chloride) According to Non-Steady-State Kinetics... 

Some very recent studies by Lewis at al. (Ref. 52, 53) have provided an initial report on the use of crown ethers for the replacement of the labile chlorine atoms of poly(vinyl chloride) by acetate ions. In this ongoing study, the authors are studying the kinetics of the modification process and the relative stabilities of the modified polymers under pyrolytic conditions, in an attempt to determine ideal conditions for the substitution of the labile chlorine atoms only, as more extensive substitutions result in some polymer degradation. 

Recently Madras et al. [17], studying the degradation of styrene and poly(vinyl acetate) in chlorobenzene have analysed their data using a continuous distribution kinetics model. 

Poly(vinyl chloride) has been shown to degrade thermally by a chain mechanism that is best represented by non-steady-state kinetics (NSSK). Degradations are initiated at a very few sites within a chain, and the subsequent zip reaction which accounts for substantially all of the evolved hydrogen chloride is confined to a single chain. 

Thermal decomposition of a y-irradiated poly( vinyl fluoride) occurred in two main steps firstly, elimination of hydrogen fluoride and secondly, main chain scission to yield unsaturated hydrocarbons." Polytetrafluoroethylene and the copolymer of tetrafluoroethylene and hexafluoropropene were degraded in various atmospheres and the decomposition products analysed." - For an inert atmosphere over twenty different fluorinated products were identified. For air the major products were COF, CF , and COj with minor amounts of fluorocarbons. The gaseous and solid decomposition products have also been analysed from the thermal degradation of poly(carbon monofluorides) containing different proportions of fluorine. Kinetic data were also obtained. 

Study of the kinetics of HCl evolution during UV, thermal and photo-thermal degradation shows that the amounts of produced HCl differ significantly depending on the treatment of the poly(vinyl chloride) samples [1792]. 

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