Testing Readily Biodegradable Plastics

Andrady (2000) has reviewed the four common approaches available for studying biodegradation of polymers. These involve experiments where one of the reactants or a product is closely monitored. These are as follows  

Monitoring the accumulation of biomass (Seal, 1994). ASTM (1996) G22-76, ASTM (2009) G21-96. 

Monitoring the depletion of substrates either by simple weight loss (Tsuji and Suzuyoshi, 2002). ASTM D6003-96 or D5247-92). Alternatively, in 

FIGURE 6.13 Respirometry experiment for measuring evolved CO in biodegradation studies. Source Reproduced with permission from CaUl et al. (2006). 

Monitoring the changes in substrate properties. Changes in mechanical or other properties of degrading plastics substrate (as in D5247-92), which is an indirect measure of the degradation of the substrate. 

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Polyolefins are generally understood to be relatively bioinert. Indeed, polyethylene is specified as a negative control in the ASTM Standard Test Method (D5338) for Determining Aerobic Biodegradation of Plastic Materials. It is now well established, however, that the oxidation products of polyethylene are readily biodegradable (see section 3.5). In order to achieve rates of oxo-biodegradation for polyolefins that are compatible with established practices of plastics use and disposal, it is necessary to add one or more of an assortment of... 

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