Science and Standards

摘要

It is now recognised that short-term mineralization is not a satisfactory test for the biodegradation of agricultural plastics or for packaging that requires a relatively long but controlled service life. A more relevant standard is required to assess the environmental impact of oxo-biodegradable polymers, irrespective of whether they are fossil-based or bio-based. The presently accepted international standards act more as a hindrance rather than a help in the development of ecologically suitable biodegradable materials in a range of environments and they are counterproductive at a time when the packaging industries are being exhorted by governments to improve their 'green' credentials. If standards for degradable polymers are to be convincing, they must be based upon a scientific understanding of how nature deals with its own waste. The research discussed in this paper suggests that this is much more complex process than has previously been assumed and that abiotic processes play a major synergistic role with biological processes during the bioassimilation of all polymers. Most polymers require a much longer time for composting if the product is to be acceptable for use in agriculture. Additional standards (based on Scheme 3) are currently under consideration to embrace man-made or man-modified polymers that, like lignocellulose, humus and rubbers, biodegrade by an oxidative mechanism.