Bacterial degradation aliphatic polyesters

Polymers with hydrolysable linkages in the backbone are very useful in a range of degradable materials. For disposable table-wares as cups or expendable packages many of them are still too expensive and do not exhibit the desirable combination of mechanical and chemical properties. Well-known synthetic hydrolysable polymers are polyesters [1], polycarbonates [2], polyanhydrides [2], polyamides [2] and poly(amino acids) [2]. Hydrolysable biopolymers may be cheaper than synthetically produced polymers (e.g. aliphatic polyesters such as polylactides) and many scientists today are looking for new possibilities using such traditional natural polymers as polysaccharides, proteins and lipids. Special interest is focused on poly(P-hydroxybutyrate) and its copolymers [3,4] (see Chapters 9 and 10). Well-known natural products such as Pullulan (a bacterial polysaccharide produced by Aerobasidium pullulans), cellulose acetate and starch, as well as synthetic polyvinyl alcohol are important degradable materials. 

The degradation of aromatic polyesters has been studied for many years and the principal problem was identified as hydrolysis under the high temperature conditions. However, free radical autoxidation process also occurs when aliphatic groups are present [1]. It can be expected that similar mechanisms will be active also in the case of bacterial polyesters. 

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