Photostabilisation of Polymers

A number of reviews on polymer photostabilisation have appeared as well as the stabilisation of ceramic paints clearcoats, wood finishes and car body paints . Hindered piperidine stabilisers (HALS) have also been reviewed in depth and the surface stabilisation of polystyrene covered .  

The dielectric strength of polyethylene has been measured as a function of additive concentration while in stabilised polymers the depth of degradation was found to be uniform . HALS have been found to be effective stabilisers for UV cured coatings and do not influence the cure rate . Bleached wood pulps can be effectively stabilised by ascorbic acid and wool by hydroxy-benzotriazoles and HALS . Hydroxybenzotriazole stabilisers also protect wood pulp and polyurethanes by co-reaction . The spectroscopic properties of monomeric and polymeric benzotriazoles have also been compared . UV absorbers are effective in clear coats and when grafted to wood . Dihydroxybenzophenone stabilisers inhibit the chain scission in the photodegradation of poly(methoxyacrylophenone) while tin stabilisers have also been found to photostabilise PVC . 

Several modified phthalocyanine compounds have been found to effectively stabilise rubber/ Other unusual stabilisers include piperylene-methyl-styrene in poly(ethylene), dioxynaphthylpropane in polyfethylene), ketones and anilines for poly(3-butylthiophene), thioglycerol for wood pulp and dibutylphthalate for PMMA/ N-Arylphthalimides are self stabilising due to their donor-acceptor energy transfer properties/  

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The photostabilisation of polymers still maintains a high level of activity with the mechanistic action and performance of hindered piperidine compounds continuing to attract interest. Some interesting reviews have appeared with one very extensive and highly recommended paper on the mode of action of hindered piperidine light stabilisers while another has dealt with their manufacturing properties. The kinetic reactions and photophysics of light stabilisers have been covered in another review as has the stabilisation of polyacetals. ... 

Lu et al. have reported that the fluorescence intensities of Eu3+ and Tb3+ are markedly enhanced when they are bound on to a poly(acrylamide-acrylic acid copolymer). Dhake et al. have observed interesting differential effects of pressure on the fluorescence of a polymer and the corresponding monomer. Sterically hindered piperidines have for long been of interest as efficient photostabilisers of polymers. Gugumus has now reported that these stabilisers form charge-transfer complexes with molecular oxygen, thereby preventing the formation of such complexes with the polymer. 

B Ranby and J. F. Rabek, Photodegradation, Photo-oxidation and Photostabilisation of Polymers, Wiley, London, 1975. 

B. Ranby, F. J. Rabek Photodegradation, Photooxidation and Photostabilisation of Polymers. J. Wiley Sons, London 1975. 

Rabek, J.F. Photostabilisation of Polymers, Principles and Applications-, Elsevier London, 1990. 

J.F. Rabek (1990) Photostabilisation of Polymers, Chapman and Hall, London. 

Scott G (1993) Photodegradation and photostabilisation of polymers in Scott G, ed.. Atmospheric Oxidation and Antioxidants, Vol. II, Elsevier, Chapter 8. 

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