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Polyethylene or polythene film is usually stable and resistant to degradation. Methods are available to make it more degradable under certain conditions of sunlight, moisture, oxygen, and composting.

If traditional polyethylene film is littered it can be unsightly and be a hazard to wildlife. Plastic recycling improves usage of resources. If disposed of in a sanitary landfill, most traditional plastics do not readily decompose. Typical plastic films can be incinerated and the heat can be used. Some believe that making plastic shopping bags biodegradable is one way to try to reduce harmful litter.

Contents 1 Types of biodegradable polythene film 1.1 Starch based or biobased (hydrodegradable) film 1.1.1 Examples of polymers with which starch is commonly used: 1.1.2 Pros & cons of starch based film/bag 1.1.2.1 Pros 1.1.2.2 Cons 1.1.2.3 Typical application area 1.2 Additive based (oxodegradable/photodegradable) 1.2.1 Pros & cons of additive based film/bag 1.2.1.1 Pros 1.2.1.2 Cons 1.2.1.3 Typical applications 2 References 3 See also

Polythene or Polyethylene film cannot biodegrade naturally. However, there are two methods two resolve this problem : One is to modify the carbon chain of polyethylene to improve its degradability and at some point its biodegradability, the other is to make a film similar to polyethylene with renewable ressources (starch).

This is made from corn (maize), potatoes or wheat. This form of biodegradable film meets the ASTM standard (American Standard for Testing Materials) and European norm EN13432 for compostability as it degrades at least 90% within 180 days or less under specified conditions.

• Polycaprolactone (PCL)
• Polyvinyl alcohol (PVA)
• Polylactic acid (PLA)

The heat, moisture and aeration one gets in a compost pile are required for this type of biodegradable film to biodegrade.

• Litter is biodegradable and compostable. Biodegradable means that, under certain conditions, the material will be degraded into small pieces that can be absorbed by microorganisms and transformed into CO2, H2O, energy and neutral residue.
• Reduced fossil fuel content (depending on loading of filler)
• Faster degradation of litter
• No net increase of carbon dioxide in global ecosystem^{[citation needed]}

• Source of starch can be problematic (competition against food use, rainforests being cleared to grow crops for bioplastics)
• Poorer mechanical strength than additive based example – filling a starch bag with wet leaves and placing it curbside can result in the bottom falling out when a hauler picks it up. However, some biodegradable and compostable films are now very close to polyethylene or polypropylene, depending on the starch used.
• Degradation in a sealed landfill takes at least 6 months.
• Limited Shelf life. Some conditions must be respected for stockage.
• Some need to be composted in industrial facilities because the temperature of the compost needs to be at 58°C. Others ( OK-compost) are home composting (temperature 20°C).
• If mixed with other plastics for recycling, the value of recycling is reduced.
• For plastic recycling, resin identification code 7 is applicable.

Carrier bag, refusal sacks, vegetable bags, food films, agricultural films, mailing films. The list of application cannot be exhaustive as new developments appear each month following the evolution of bio polymers. However, these applications are still very limited compare to those of petroleum based plastic films.

These films are made by blending an additive to provide a UV / oxidative and/or biological mechanism to degrade them. This typically takes 6 months to 2 years in a landfill site. According to people who develop this process, degradation is a two stage process; first the plastic is converted by reaction with oxygen (light, heat and/or stress) to molecular fragments that water can wet, and then these smaller oxidized molecules are biodegraded, i.e. converted into carbon dioxide, water and biomass by microorganisms. But complete biodegradation, i.e. transformation by micro-organisms in energy, CO2 and H2O, has never been established. Indeed, at the end of degradation, the small particles are still too big to be absorbed and transformed by micro-organisms. If put in a compost, the oxo degradables are only another source of pollution (cf International Biodegradable Polymers Association and Working groups).

• Much cheaper than starch-based plastics
• Materials are well known
• Does not compete against food use
• These films look, act and perform just like their non-degradable counterparts, except that they are weaker and break down after being discarded.

• Made using fossil fuel (contributes to global warming through the release of carbon dioxide)
• Degradation in a sealed landfill is very slow.
• Degradation depends on conditions of heat, light, stress, air etc
• No biodegradability established, which means cannot be absorb by micro-organisms. Pollution is not visible but exists.
• They do not comply with European Norms on compostable products
• If mixed with other plastics for recycling, the value of recycling is reduced.
• For plastic recycling, resin identification code 7 is applicable.

Trash Bags, Garbage Bags, Compost Bags, Carrier bag, Agricultural Film, Mulch Film

BBC News: "All Tesco bags 'to be degradable dt. 10th May’06" http://news.bbc.co.uk/1/hi/uk/4758419.stm

BBC News: "Degradable carrier bags launched dt. 2nd Sep’02" http://news.bbc.co.uk/1/hi/uk/2229698.stm

• Biodegradable plastic
• Bioplastic
• Plastic bag
• Plastic recycling
• Packaging
• Photodegradation