Why biodegradable or degradable plastic carrier bags?
Conventional plastics do not break down unless they are recycled. Therefore biodegradable and degradable plastic carrier bags are developed to make your daily tasks of waste reduction easier, safer and better for the environment.
So, what’s the difference?
Degradation is a process where very large molecules are broken into smaller molecules. Oxygen is incorporated into these molecular fragments, typically, strong plastic films become weak and brittle as a result of oxidative degradation. This outcome is because the molecules of which the films consist become a lot smaller. Degradation is caused by heat, or exposure to UV light.
Degradable plastic is a plastic designed to undergo a significant change in its chemical structure under specific environmental conditions, this results in a loss of some properties that may vary as measured by standard test methods appropriate to the plastic and the application in a period of time that determines its classification.
Biodegradation is the process by which microorganisms (microbes such as bacteria, fungi or algae) convert materials into biomass, carbon dioxide and water. Biomass is a term used to refer to the cells of the microorganisms that are using the material as a carbon source to grow on.
Biodegradable Plastic is a degradable plastic in which the degradation results from the action of naturally occurring micro-organisms such as bacteria, fungi, and algae.
There are two primary differences between ‘degradable’ and ‘biodegradable’. Firstly, heat, moisture and/or UV exposure most often causes the degradation of a degradable product, whereas microorganisms degrade a biodegradable product. Secondly, degradable products take much longer to break down into carbon dioxide, biomass and water.
When degradable plastics break down into smaller molecules, eventually they will be small enough to be consumed by microorganisms and so biodegradation occurs. All degradable films will eventually biodegrade but at different speeds.
What are plastic carrier bags made of?
Biodegradable and degradable plastics can be made from many different sources and materials as listed below:
- Starch based polymers: Thermoplastic starch-based polymers made with at least 90% starch from renewable resources such as corn, potato, tapioca or wheat.
- Polyesters (Bacteria based polymers): Polyesters manufactured from hydrocarbons (oil or gas). All polyesters degrade eventually, with degradation rates ranging from weeks for aliphatic polyesters(e.g. polyhydroxyalkanoates). Bacteria are an additional treatment used to create a different type of biodegradable polymer.
- Starch or Polyester blends: Mixed with thermoplastic starch with polyesters made from hydrocarbons.
- Oxo-biodegradable polymers: These polymers undergo controlled degradation through the incorporation of ‘prodegradant’ additive (additive that can trigger and accelerate the degradation process). These polymer undergo accelerated oxidative define degradation initiated by natural daylight, heat and/or mechanical stress, and embrittle in the environment and erode under the influence of weathering.
- Photodegradable polymers: These polymers are those that break down through the action of ultraviolet(UV) light, which degrades the chemical bond or link in the polymer or chemical structure of the plastic. This process can be assisted by the presence of UV-sensitive additives in polymer.
- Water-soluble polymers: These polymers are those that dissolve in water within a designated temperature range and then biodegrade in contact with microorganisms.
What are my options for Polythene Film?
There are two main options for making normal polyethylene into a biodegradable film:
Starch based or Biobased (Hydrodegradable)
It is made from corn (maize), potatoes, wheat. This form of biodegradable films meets the ASTM standard (American Standard for Testing Materials) and European norm EN13432 for composting as it degrades at least 60% within 180 days or less.
Examples of polymers with which starch is commonly used:
- Polycaprolactone (PCL)
- Polyvinyl alcohol (PVA)
- Polylactic acid (PLA)
Pros & Cons of Starch based to Additive based film/bag
- Degradable & Compostable
- No fossil fuel or very little fossil fuel (if % mixed with traditional polymer)
- Faster degradation
- Poorer 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
- Can only be composted in a special composting facility.
Typical Application area
Industrial Compostable Facility, Please visit your local city government’s website to see if you have an industrial composting facility that accepts residential compost.
Additive based (Oxodegradable/Photodegradable)
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 5 years in a landfill site and/or standard composting system. In these films, biodegradation 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.
Pros & Cons of Additive based to Starch based film/bag
- Cheaper & Proven
- Controlled degradation
- Longer shelf life than most biodegradable films
- These films look, act and perform just like their non-degradable counterparts, except they break down after being discarded.
- Made using fossil fuel
- Degradation depends on conditions of heat, light, stress, air etc.
- Typical Applications
- Rubbish Bags, Compost Bags, Carrier bags, Agricultural Film, Mulch Film
What is my best environmental and commercial choice of film?
When choosing the biodegradable/degradable film that you are going to use, you must ask several questions in order to get the correct type of biodegradable film to suit your requirements:
- What is the cost of the film absolutely and relative to other film options?
- What is its function? – Is it a mailer, a can liner, box liner, a bag for a compost pile?
- What will happen to this product once discarded using the intended product? Consider Waste collection and landfill costs, Recycling and Waste-to Energy possibilities
- How is the plastic film going to be stored and for how long?
Biodegradable and degradable plastic carrier bags product specification
Common materials used for Biodegradable/degradable film:
- Low density polythene blended with degradable additive
- Medium density polythene blended with degradable additive
- High density polythene blended with degradable additive
- Recycled polythene blended with degradable additive
- Starch based plastics
80 Gauge(20microns) to 1000 Gauge(250microns)
Normally, Biodegradable film/bags in Great Britain should follow widely accepted industrial standards according to British Standard – see BS7344, 1990
- Width: Plus or minus 3mm (0.125″) or 2% whichever is greater
- Length: Plus or minus 6mm (0.25″) or 2% whichever is greater
- Gauge: Plus or minus 10%
Standards for ‘Biodegradable/degradable film or bag’ to use for food contact and medical application:
Food Contact – To use Degradable/Biodegradable film or bags inside European Union, in contact with food should comply with the relevant legislation on food contact including Great Britain.
- Great Britain: Statutory Instrument, 1998 No. 1376 and BPF-BIBRA (1995), Polymer Specification 4, Polyethylene
- EU: Commission Directive 90/128/EEC, 92/39/EEC, 93/9/EEC, 95/3/EEC and 96/11/EC, Section A.
- Example of a company comply with food contact: Polybags Limited
Medical use – Similarly, to use Degradable/Biodegradable film or bags inside European Union, to produce containers for preparations for medico-pharmaceutical purposes should comply with the following regulation:
- European Pharmacopoeia – Monograph 3.1.3 “Polyolefin’s” for medico-pharmaceutical purposes.
- The final responsibility for the decision of whether a material is fit for a particular application lies with the pharmaceutical firm.
- Example of a company comply with medical use: Polybags Limited
Special options available in biodegradable & degradable plastic carrier bags
Flat Biodegradable/Degradable bags: Standard Biodegradable/Degradable bags often called by flat bags. It is used for general purpose.
Gusseted Biodegradable/Degradable bags: Plastic bags with fitted bottom and expandable sides (gusset) form to the shape of your product.
Perforated Biodegradable/Degradable bags: Perforated bags have a perforation for a easy tear off from either a bunch of bags or roll.
Plain Mini grip/Self seal/Reclosable bags: Plain Self-seal biodegradable/degradable bags with interlocking closure that can be used over and over again. Ideal where you want to secure contents and avoid leakage or contamination, no need of heat sealing.
Plain Self seal biodegradable/degradable bags with write on panel: Plain self-seal biodegradable/degradable bags with write on panels is used for content identification, coding etc. Easy to label contents using a marker, ballpoint pen or pencil.
Biodegradable/Degradable Specimen bags: Biodegradable/Degradable Specimen bags comes with outer pouch for record cards. Ideal for use in hospitals, medical labs to safely transfer specimens and paperwork.
End weld (bottom) Biodegradable/Degradable bags: End weld bags are generally welded in the bottom. Bottom weld offers added strength for packing heavier items.
Side weld Biodegradable/Degradable bags: When bags welded on the sides of the bags is referred to Side weld bags. Side weld bags are ideal for packaging lighter materials such as greeting cards/envelopes.
Elliott Packaging – Plastic Carrier Bag Experts
Elliot Packaging are specialists in providing 100% eco-friendly biodegradable and degradable plastic carrier bags, with custom printing available on all our plastic carrier bag products. To get started on your orders, please contact Elliott Packaging by filling out our enquiry form or alternatively you can give us a call on 01606 350036.