Dual advantages of low cost and insulating properties make polystyrene a widely used material for food packaging. However, regulatory and consumer pressure to reduce the impact of packaging waste have been forcing processors to seek more environmental-friendly alternatives. Conventional polystyrene containers can take hundreds of years to break down, although the process can be accelerated considerably using chemicals and other methods. These, however, are costly both costly and cause further environmental damage.

Chinese scientists have developed a novel approach to make foam polystyrene biodegradable. Foam polystyrene is used as a protective packaging for all sorts of products, but it is not biodegradable. Previously manufacturers have tried making it more environmental friendly by incorporating cellulose and starch, which microbes can break down, or by adding light sensitive polymers that degrade in sunlight. However, all these methods have serious disadvantages. A team of scientists from the Polymer Science and Engineering College of Quingdao University of Science and Technology in China has now developed a new approach that involves embedding water-absorbing resin particles about 5 micromeres in diameter throughout a chemical like styrene before it is polymerized to form a polystyrene-like material. When the resulting solid comes into contact with water, the polymer particles expand, reducing the polymer structure to a powder that should then biodegrade. The team says that by altering the ratio of ingredients, it is also possible to control the rate of disintegration. A crucial factor is that the resulting foamed polystyrene is cheaper than conventional materials and should therefore be readily adopted by cost-conscious companies that also want to be environmentally responsible.

Additionally, a new polystyrene foam for food packaging offers accelerated degrading with no loss of performance while in use. Canadian firm Cascades claims its Bioxo oxo-degradable polystyrene foam containers break down within 3 years, with no loss of performance while used as a packaging material. Bioxo uses totally degradable plastic additives (TDPAC), developed by Canadian polymer additives supplier. The additive, mixed with the base resin acts as a catalyst to promote degradation, without compromising performance while the material is used as a package, the manufacturer claims. After use, the foam degrades through exposure to oxygen, heat and ultra-violet light or mechanical stress into a fine powder. Once broken down, bacteria and other micro-organisms can digest the powder. The breakdown process will release carbon dioxide into the atmosphere and so while the shortage of landfill space may be alleviated, the solution will inevitably add to the problems of greenhouse gas emissions. Bioxo has been approved for use as a food contact material by both Canadian and US regulators.