Biodegradable polythene film

Introduction

Conventionally, it is taken for granted that plastics are made of fossil fuel. These conventional types of plastics are widely used everywhere in the world – mainly in packaging and household applicatons. Whilst the benefits of economic production costs, light weight, strength, relative imperviousness to gas and water, clarity, and printability are highly regarded, it is the final disposal of used flexible plastics that causes problems. Ever increasing use of plastics particularly in packaging has become a significant source of environmental pollution (litter) and created problems in waste management. If disposed of by landfill, the plastics worsen the shortage of landfill sites. If the plastics are incinerated, they can emit posionous gases such as dioxins. Thus, it is the latest and loudest signal of a new mood among the general public to take more care of the environment. Compobag makes your daily task of waste reduction easier, safer and better for the environment.

What are my options for Polythene Film?

There are mainly two options available to make normal Polythene into Biodegradable film and these are as detailed below:

(1) Starch based or Biobased (Hydrodegrable)

It is made from corn (maize), potatoes, wheat This form of biodegradable films meets the ASTM standard (American Standard for Testing mateials) and European norm EN13432 for compostability as it degrades at least 60% within 180 days or less.

Examples of commonly modified starch used as or with polymer are named below:

• Polycarpolactone (PCL)
• Polyvinyl alcohol (PVA)
• Polyactic acid (PLA)

These materials predominatly require an active microbial environment such as muncipal compost before they will degrade. The heat, moisture and aeration one gets in a compost pile are vital to this type of biodegradble film working well.

Pros & Cons of Starch based to Additive based film/bag

Pros: Degradable & Compostable No fossil fuel or very little fossil fuel (if % mixed with traditional polymer) Faster degradation Cons: Poor mechanical strength than additive based example – filling a starch bag with wet leaves and placing curbside can result in the bottom falling out when a hauler picks it up. Limited Shelf life

Typical Application area

Muncipal/Local authority compost system

(2)Additive based (Oxodegradable/Photodegradable)

Films made out of blending an additive to provide UV / Oxidative and/or Biological mechanism to degrade plastics film typically in 6 months to 2 years in a landfill site and/or standard composting system. In this, biodegradation is a two stage process in which, first the plastic is converted by reaction with oxygen (light, heat and/or stress) to molecular fragments that are water wettable and second, these smaller oxidized molecules are biodegraded. (converted into carbon dioxide, water and biomass by microorganisms)

Pros & Cons of Additive based to Starch based film/bag

Pros: Cheaper & Proven Controlled degradation Film made out using this look, act and perform just like their non-degradable counterparts, except they break down after being discraded. Cons: Made out using fossil fuel Degrdation depends on conditions of heat, light, stress, air etc

Typical Application area

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

News

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