Stabilizer dialkyltin heat

A number of recent studies have been concerned with the effects of commercial heat stabilizers on the photodegradation of PVC. During irradiation at room temperature under air with 253.7-nm light, several dialkyltin dicarboxylates were found to increase the rates of the photooxidation and cross-linking of the polymer (62). However, at 0°C under air in a sunshine weatherometer, photooxidation was shown to be retarded by certain dibutyltin dicarboxylates (63). The latter result was also obtained in experiments involving the use of dibutyltin maleate with irradiation in the (280-400)-nm wavelength region at 38°C under air (50,51,64, 5,66). 

Certain dioctyltin compounds are used for clear PVC materials. Dialkyltin carboxylate and dialkyltin mercaptide heat stabilizers are used in the PVC industry in many application34. 

The formation of dialkyltin dichloride may thus be considered, as a first approximation, to be a measure of the total stabilizer conversion. Accordingly the diagram in Figure 3.3.6 shows the correlation between the stabilizer conversion and the time of heat treatment at 180 °C. 

PVC is imstable imder exposure to light and heat resulting in discoloration and embrittlement. In the early 1940s it was found that this degradation could be prevented by addition of certain organotin derivatives. Presently, about 70% of the commercial organotin compounds are employed as PVC stabilizers in the form of mono and dialkyltin derivatives. Today, many of these stabilizers are based on organotin polymers made by Carraher and coworkers. [63]... 

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