Structure and Degradation

Usually, peroxy radicals are formed at the beginning of polymer degradation in the presence of oxygen [35]  

The oxidative reaction forms new oxidative moieties due to the utilisation of a substantial amount of stabilisers, leading to a consequent decrease of long-term stability and deterioration of mechanical properties. For an effective recycling process, it is necessary to know the extent and effect that degradation has on the structure, mechanical properties and long-term stability of recyclates. Plastics face prolonged use before being discarded as waste [23]. 

PP is a semicrystalline polymer, the oxidation of which is confined to the amorphous phase. Photooxidation takes place on the surface, leading to extensive recrystallisation and the production of surface cracks which can propagate through the product [37]. Embrittlement occurs because of the preferential scission of the tie molecules linking the crystallites in the polymer which causes a disproportionate amount of applied stress [38]. 

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R. M. Brown, Jr., ed.. Cellulose and OtherlAaturalPolymer Systems Biogenesis, Structure, and Degradation, Plenum Press, New York, 1982. 

Roughley PJ et al (2006) The structure and degradation of aggrecan in human intervertebral disc. Eur Spine J 15(Suppl 3) S326-S332... 

Fig. 4.3. Biosynthesis, structure, and degradation of the pheromones 4 and 5 of Linyphia triangularis and Linyphia tenuipalpis. ACP, acyl carrier protein CoA, coenzyme A.

In general, there is a paucity of information on the relationship between polymer structure and degradation kinetics. This becomes especially critical in multiphase polymers like heterophasic copolymers, thermoplastic elastomers and blends. This review should stimulate research in this important area, which could ultimately lead to polymers with better photo-thermal and radiation resistance as well as more effective stabilizers. 

Brown RM Jr (ed) (1982) Cellulose and other natural polymer systems biogenesis, structure, and degradation. Plenum Press, New York... 

Fig. 17.3 Structures and degradation of GM2 and GA2 glycolipid. In normal cells, IV-acetylgalactosamine terminating GM2 ganglioside and its asialo-derivative GA2 are hydrolysed to GM3 and lactosylceramide respectively, by hexosaminidase. Deficiencies in hexosaminidase activity results in the accumulation of GM2 and GA2 GalNAc A-acetylgalactosamine Gal galactose Cer ceramide NeuAc sialic acid...

Structure and Degradation Process for Waterlogged Archaeological Wood... 

Hoffmann Jones Structure and Degradation of Waterlogged Wood 37... 

The structure and degradation of the cell membrane complex including the structure of the epicuticle. 

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