Polymer photostabilization

Figure 6.15 Chemical structures of some polymer photostabilizers (a) 2-hydroxybenzophenone, (b) hydroxybenzotriazole, (c) oxanilide...

Ghiggino K P, Scully A D and Bigger S W (1988) Photophysics of hydroxyphenylbenzotriazole polymer photostabilizers, In The effects of radiation on high-technology polymers, Reichmanis E and O Connor J H (Eds), ACS Symp Ser 381 57-79. 

The action mechanism of polymer photostabilizers based on hindered amines attracted great attention after numerous reports on their high effectiveness had appeared. The main conclusions from the scientific literature on the mechanisms of hindered amine action are offered below. More detailed information can be found in numerous reviews, the ones compiled by the authors of the present article including (38,51-56). 

The photooxidation of polymers on the other hand continues to remain at a low profile. Bio- and photodegradable plastics continue to be useful for agricultural usage, although interest here is again minimal. The same applies to polymer photostabilization, where commercial applications dominate very much, with emphasis on the practical use of stabilizers. For dyes and pigments stability continues to be a major issue in so far as this section is concerned. 

J. Sedlar, J. Petruy, J. Pak, and M. Navratil, Polymer photostabilization by HALS derivatives the role of piperidine-hydroperoxide associates, Polymer 1980, 21, 5-7. 

D.W. Grattan, A.H. Reddoch, D.J. Carlsson, and D.M. Wiles, Polymer photostabilization by piperidine derivatives the role of nitroxide-hydroperoxide complexing, J. Polym. Sci. Polym. Lett. Ed. 1978, 16, 143-148. 

Metal acetylacetonates and thio-organic complexes show a strong interaction during processing as they yield dark colored samples. These materials are not acceptable as UV stabilizers. Hindered amine light stabilizers (HALS)s are commonly used polymer photostabilizers. HALSs are ineffective in imparting photostability to the polymer. Successful photostabilization of PPS can be achieved by using UV absorbers rather than quencher-type additives. 

Kikkawa K. New developments in polymer photostabilization. Poly Deg Stab 1995 49 135 3. 

Studies of polymer photostabilization directly throws light on overall phenomenological aspects under conditions relevant to practice. However, it is extremely difficult to draw unambiguous mechanistic conclusions from this kind of investigation. 

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