Polymer stabilization thermal degradation

Frequently, different classes of light stabilizers are combined to optimize stabilizing efficiency [112]. For example, UVAs and HALSs, used in combination, often provide better photostability than either class alone. Light stabilizers are also used in combination with additives that protect the polymers against thermal degradation during processing, such as hindered phenols and phosphates [113]. Consequently, various bifunctional and trifunctional photostabilizers have been synthesized and some have been selected for use in commercial applications (see Chart 9.15). 

Thermal stability of nine polymer systems Thermal degradation of blends using TG-DTG-DTA etc Thermal stability, degradation mechanism of organic systems in the presence of inorganic Muhammad 2013... 

A polymer is a complex mixture of molecules that is difficult to define and reproduce. The quality of the polymer is markedly affected by the conditions of preparation. Different degrees and types of branching, differences in the number and distribution of various irregular structures, along with the degree of purity of the finished product and conditions of further treatment all influence the thermal stability of the polymer and the course of its thermal degradation. This further complicates the study of this polymer and explains the differences be-... 

Braun [22] showed from ozonolysis that for fractions of bulk PVC the number of internal double bonds and the rate of thermal degradation, although dependent on each other, were independent of the molecular weight. This clearly demonstrated the role of internal unsaturation on the stability of the polymer. After careful chlorination of the double bonds, an increase in thermal stability was observed and the number of double bonds as determined by oxidation with potassium permanganate were reduced. It was also shown that one polyene sequence was formed from each isolated double bond. 

The effect of substitution of labile chlorines by acetoxy groups on the thermal stability of polymer taken in isolation appears to correspond to the thermal degradation behavior of VCA Ac copolymers over the whole composition range [136,137]. 

Some polymers have both polar and nonpolar groups in the polymer chain. Thermal stability behavior of blends of some such polymers with PVC have also been studied. McNeill and coworkers [149] have studied the degradation of blends of PVC with poly (tetramethyl-ene sebacate) (PTMS). The structure of PTMS is given in Eq. (40). 

Protection of polymers against thermal and photo-oxidative degradation is achieved with appropriate stabilizers that ensure the desirable polymer properties throughout the entire service life of the polymer. Compatible and polymeric stabilizers usually give the best protection. In order to avoid migration and evaporation, polymeric stabilizers are used. 

The effect of local activation accounts for such features of PCSs as catalytic and stabilizing properties, autocatalysis, specific properties of thermal degradation, structural modification, and a number of other phenomena typical of polymers with a system of conjugated bonds. 

Polymer Degradation and Stability 53,No.2, 1996,p.l89-97 THERMAL DEGRADATION OF MIXED PLASTIC WASTE TO AROMATICS AND GAS... 

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