Prooxidant transition metal compounds

Typical prooxidant transition metal compounds (e.g. iron, cobalt or manganese stearates) are used commercially to induce peroxidation in degradable plastics. However, such prooxidants alone have no practical utility in commercial products unless the prooxidants are deactivated during polymer fabrication, since oxidative degradation begins during... 

Generally [17], starch is added at fairly low concentrations (6-15%) the overall disintegration of these materials is achieved by the use of transition metal compounds, soluble in the thermoplastic matrix, as prooxidant additives which catalyse the photo-and thermooxidative process [18-21]. 

Starch can be used as a natural filler in traditional plastics [11,22-32] and particularly in polyolefins. When blended with starch beads, polyethylene films [33] biodeteriorate on exposure to a soil environment. The microbial consumption of the starch component, in fact, leads to increased porosity, void formation, and the loss of integrity of the plastic matrix. Generally [31,34-37], starch is added at fairly low concentrations (6-15%) the overall disintegration of these materials is achieved by the use of transition metal compounds, soluble in the thermoplastic matrix, as prooxidant additives which catalyse the photo- and thermooxidative process [38-41]. An example of the contribution of starch in promoting the disintegration of photodegradable low density polyethylene (LDPE) is shown in Figs. 6.1 and 6.2 [42,43]. 

Many organic and inorganic compounds, fibers, and particles are capable of damaging nucleic acids by generating reactive oxygen species via the reduction of dioxygen. These stimuli include different classes of organic compounds, classic prooxidants (anticancer antibiotics, various quinones, asbestos fibers, and so on), and even antioxidants, which can be oxidized in the presence of transition metal ions. 

Information about single phenolic antioxidants content doesn t consider synergistic influences between phenolic compounds in wine, we ware limiting only on components, which ware analysed individually. Information about content of antioxidant components also doesn t consider prooxidative influence of transition metals content. Those effects... 

Polyunsaturated compounds readily hydroperoxidize and the hydroperoxides so formed act as initiators for both thermal oxidation and photooxidation. The incorporation of unsaturated fats into polyethylene has been used [31] to induce the oxidation of polyethylene in starch-filled polyethylene. The potential limitation of the use of prooxidants is that oxidation commences during processing and could lead to the formation of low molecular weight aldehydes and carboxylic acids (food taints) particularly in the presence of transition metal ions. 

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