Polystyrene photodegradation

Durene n (durol, 1,2,4,5-tetramethylbenzene) CgH2(CH3)4. A substance occurring in coal tar, but usually prepared from xylene and methyl chloride in the presence of AICI3. It has been patented (U.S. 4,000,120) as an additive to make packaging films of polyolefins and polystyrene photodegradable under direct action of sunlight. 

PL can be used as a sensitive probe of oxidative photodegradation in polymers. After exposure to UV irradiation, materials such as polystyrene, polyethylene, polypropylene, and PTFE exhibit PL emission characteristic of oxidation products in these hosts. The effectiveness of stabilizer additives can be monitored by their effect on PL efficiency. 

Consider the photodegradation of polystyrene in sunlight (Scheme 9.5). Polymer photodegradation can be slowed down by adding photostabilisers, which may be ... 

Quinones are effective compounds for the photodegradation of polystyrene (105-10 )pPolyisoprene (108.109).polypropylene (110),polyamides (111),polyurethanes (97) and oellulose (112). 

In this report we examine the effects of several vinyl ketone monomers on the photodegradation of polystyrene in the solid phase. Previous work Sj has indicated that copolymers containing vinyl ketones undergo photolysis by the Norrish type I and type n primary reactions. Studies by Golemba and Gulllet and by Kato and Yone-shiga 0 have shown that these processes also occur in copolymers of styrene with meUiyl vinyl ketone and widi phenyl vinyl ketone. 

It is well known that individually, photoinitiators and certain metallic organic compounds cause hydrocarbon polymers, such as polyethylene or polystyrene, to photodegrade faster than the original polymer not containing such an additive. We have discovered that by combining both types of additives in a plastic a striking synergistic effect occurs. 

Weir has reviewed specific mechanisms phenomena and unsolved problems in the photodegradation of polystyrenes. ... 

Since 1971 our department is Involved in study of photodegradation, sensitized photooxidation and photostabilization of polymers. A big effort is made in the study of singlet oxygen oxidation of several important polymers, such as polydienes, poly(vinyl chloride), polystyrene and polyesters, reactions of atomic oxygen and ozone with polydienes and photostabilization of these polymers. 

Rabek [500, 502] found that benzoyl peroxide, butyl peroxide and cumyl peroxide sensitize the photodegradation of c/s-l,4-polyisoprene in benzene. Similarly, anthracene peroxide added to a benzene solution of polystyrene shows a strong photosensitizing effect only when oxygen is present [504]. 

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