Thermal and Thermo-oxidative Degradation

During the period a new international journal entitled Polymer Degradation and Stability has appeared. This started life as a quarterly, but already (1981) is moving into bimonthly publication. 

Apparatus and experimental techniques have been discussed in several papers. The techniques include thermal volatilization analysis, pyrolysis-gas chromatography, pyrolysis-molecular weight chromatography-i.r. spectrophotometry, and pyrolysis-mass spectrometry. Methods have also been described for collecting and separating pyrolysis products. -  

The great concentration of effort on three polymer types, the polyolefins, polystyrene, and poly(vinyl chloride), remains unchanged. Almost a third of the published papers relate to these three systems. 

Two review articles have been published, one relating to the thermo-oxidative degradation and stabilization of polyolefins and the other to the effect of thermal and thermo-oxidative breakdown of polyethylene and polypropylene upon overall properties. The latter paper specifically considers the effects of reprocessing. A 

Polypropylene has been pyrolysed in helium using programmed heating and flash pyrolysis techniques and the volatile products quantitatively analysed by interfaced gas chromatography. The major products formed under oxidizing conditions have 

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There have been many studies on the thermal and thermo-oxidative degradation of PMMA.23 24 It is well established that the polymer formed by radical polymerization can be substantially less stable than predicted by consideration of the idealized structure and that the kinetics of polymer degradation are dependent on the conditions used for its preparation. There is still some controversy surrounding the details of thermal degradation mechanisms and, in particular, the initiation of degradation.31... 

Table 2.7 Kinetic data obtained for the thermal and thermo-oxidative degradation of PET... 

Studies on thermal and thermo-oxidative degradation of poly (ethyleneterephthalate) and poly (butylene terephthalate). G. Gabriela Botelho, A. Arlete Queiros, S. Sofia Liberal, P. Pieter Gijsman/Po/vz er degradation and 5to/)z7z7y (2001),74 1 39-48. 

Hui, S., Chattopadhyay, S., Chaki, T. K., Thermal and thermo-oxidative degradation study of a model LDPE/EVA based TPE system Effect of nano silica and electron beam irradiation. Polymer Composites 2010,31(8), 1387-1397. 

S. Kuioda, 1. Mita, Degradation of aromatic polymers It. The crosshnking during thermal and thermo-oxidative degradation of a polyimide, Eur. Polym. J., 25, 611-620 (1989). 

The thermal and thermo-oxidative degradations of APP have been reported (Hornsby et al. 1996 Camino et al. 1984 Zhang et al. 1993) they are similar and consist of two steps. The degradation begins around 300 °C with the elimination of NH3, leading to the formation of a highly cross-linked polyphosphoric acid, whereas the second step above 550 °C corresponds to polyphosphoric acid evaporation and/or dehydration to P4O10 which sublimes. 

The electron beam irradiation is other type of energy that could produce degradation, in 2012 Tonny and Nemr reported the degradation of aciylonitrile/buta-diene/silica nanocomposite, the materials were electron beam irradiated at 25 and 100 kGy, finding that during the electron beam the thermal and thermo oxidative degradation are the principal reaction that occur confirmed by the fragments C-C of the polymer and volatiles as CO, CO2, CH4, H2O, etc. [69]. 

Thermal and thermo-oxidative degradation have been studied as a function of chemical structure in poly(phenylquinoxaline) and poly(naphthylimido phenyl-quinoxaline). The introduction of the naphthalene units is claimed to decrease thermal stability, but to increase thermo-oxidative stability. The thermal degradation of polyhexazocyclanes and suitable model compounds has been... 

Because of their potential for use in high-temperature environments the thermal and thermo-oxidative degradation behaviour of poly(pyromellitimides) continues to generate interest with e.s.r. studies on their thermal degradation behaviour and studies on the mechanism of thermal oxidation of bridging methylene groups in such polymers. 

The thermal and thermo-oxidative degradation of dimethyl siloxane-phenol-phthalein terephthalate block copolymers has also been studied. In inert atmosphere cross-linking occurred in the polyester blocks and changes in the infrared spectrum suggested the invoivement of the Fries rearrangement. In air, degradation was preferentially in the siloxane block. ... 

K. Chen and S. Vyazovkin, Mechanistic differences in degradation of polystyrene and polystyrene-clay nanocomposite Thermal and thermo-oxidative degradation. Macro-molecular Chemistry and Physics, 207 (2006), 587-95. 

TVA-FTIR allows method development for online detection and quantification of degradation products, as they are formed in the TVA experiment. Stevenson et al [944] have used TVA and SATVA as a platform for spectroscopic investigations of polymer degradation processes, as in case of PMMA and poly(bisphenol A, 2-hydroxypropylether). The kinetics of thermal and thermo-oxidative degradation and characterisation of the various degradation products of polystyrene alone and in the presence [949] of the flame retardant IDBP were investigated using TVA, FTIR and GC-MS. Other applications of TVA in problems in polymer chemistry have been reported [943,952]. The method is now near defunct. 

Differences Between Thermal and Thermo-Oxidative Degradation of Phosphorus Containing Polysulfones... 

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