Some problems concerning the degradation of linear vinyl polymers and copolymers in nonisothermal conditions

A critical review of the experimental results concerning the thermal degradation of linear vinylic polymers in dynamic conditions shows that generally the use of a single thermogravimetric curve may lead to ambiguous conclusions concerning both the steps and the mechanism of the thermal degradation, as well as the corresponding evaluated kinetic parameters. The ultimate values depend not only on the transformation degree, but also on the heating rate used, so that extrapolations may be recommended. However, the significance of the extrapolated kinetic parameters is still arguable, so that to compare thermogravimetric results, standard working conditions must be used. In such conditions the relative thermal stability of the polymers and the influence of comonomer units on the thermal behavior of copolymers may be appreciated.