Oxo-biodegradable plastics

Oxo-biodegradable Plastics Who They Are and to What They Serve—Present Status and Future Perspectives... 

Finally, regarding the future perspectives for the increasing production and consumption of oxo-biodegradable plastics based on full-aliphatic-carbon backbone... 

Roediger Agencies cc. Polymer Science Building Analytical Laboratory De Beer Street, Stellenbosch 7600 6th March 2012 Recycling Report on d2w oxo-biodegradable Plastics ... 

A second approach uses transition metal pro-oxidant catalysts as an additive (Pablos et al., 2010 Roy et al., 2009). Several photodegradable and oxo-biodegradable plastic products rely on this approach. Transition metals can act as redox catalysts to accelerate degradation via catalyzed peroxide decomposition into radicals. 

It is not possible to provide a specific timescale in a general standard for oxo-biodegradable polymers, (as distinct from a standard for industrial composting) because the conditions found in industrial composting are specific and the conditions foimd in the open environment are variable. Also, the time taken for oxo-biodegradable plastic to commence and complete the processes of degradation and biodegradation can be varied. 

There are also some polymer products on the market called oxo-biodegradable plastics. These so-called biodegradable ... 

BSi PKW/4 2002/701329 Draft Standard, Packaging - Determination of the biodegradability andeco-toxicity of packaging materials based on oxo-biodegradable plastics. 

Contaminated mixed plastics wastes from domestic sources present a difficult challenge to traditional recycling techniques. On the other hand, the hydrocarbon portion of mixed domestic wastes can be made oxo-biodegradable by the incorporation of transition metal ions that accelerate both perooxidation and biodegradation. Oxo-biodegradable plastics thus make a realistic contribution to the recovery of value from waste packaging as fertilisers and soil-improvers for agriculture and horticulture. 

Regarding requirement (3) above, concern has been expressed by environmentalists about the effect of transition metal compounds (often inappropriately called heavy metals ) present in oxo-biodegradable plastics when spread on land. Extensive research has been carried out on... 

The commonly used transition metal compounds in commercial oxo-biodegradable plastics are manganese, iron, cobalt and nickel. None of these have been shown to be toxic and until recently have not been in national lists of dangerous substances. All the above transition metal ions, which are required in human nutrition, are absorbed from foodstuffs and water. They are therefore considered to be essential minerals [70] required in oxygen transport systems. The non-toxicities of iron, which is present in haemoglobin, catalase and peroxidases and of manganese, required for manganese peroxidase, have not been questioned. 

Development of new, biodegradable, polymeric materials. The precise formulation of the LDH with catalytically active metal cations might permit their role as biocatalysts to favour degradation of the polymeric component. Polymer-nanoclay composites are currently very actively studied as potential candidates for oxo-biodegradable plastics [166]. 

Most scientists, even some polymer chemists, will not be familiar with this type of thermoplastic, so a description is called for. The term oxo-biodegradable plastic is commonly restricted to those plastics that, owing to particular compositional features or by means of additive chemistry, undergo oxidative degradation much more rapidly than would otherwise occur in a variety of environments. Although the plastic initially is bioinert, the oxidation products are biodegradable. 

A new standard test method is clearly required that will accommodate 0x0-biodegradable plastics and satisfy environmentalists that these materials are fully biocompatible. The British Standards Institution (BSi PKW/0 Packaging and the Environment ) and ASTM (D 20.96) are currently developing alternative mineralisation proeesses for oxo-biodegradable plastics that incorporate controlled pre-ageing processes before the mineralisation test. The protocol shown in Fig. 12.5 outlines the BSi twin-track route to mineralisation. Key features of the test method are as follows. 

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