BIODEGRADABLE POLYMERS

DEGRADABLE POLYMERS...

Key Terms:

--> Degradation: the deterioration of polymers

-Oxo-degradable polymers have additives that promote short degradation times, e.g less than five years. These additives will help the polymer break down into fine power from the effects of heat, oxygen, moisture and even mechanical stress, making it more readily digestible by micro-organisms.
- Photo-degradable polymers will break down when exposed to UV light making them more readily biodegradable.

BIODEGRADABLE POLYMERS...

Key Terms:

--> Biodegradable: a term given to materials that break down with the aid of natural processes such as sunlight and rain.

--> Renewable: materials that are extracted from managed sources, such as Scandinavian pine taken from forests where trees are replaced by saplings as they are felled.

 

- Conventional oil-based plastics do not break down easily and, since the main bulk of domestic waste is made up of plastics, they have a significant effect on the environment. Biodegradable plastics however are designed to be degradable under the right conditions, i.e in a biologically rich environment.

• Applications:

Applications for biodegradable polymers vary widely: packaging - shopping bags, food trays and some soft drink bottles; catering - disposable pots, bowls and cutlery; gardening; and medical and sanitary products such as disposable gloves.

The majority of biodegradable plastics are derived entirely from renewable raw materials. For example, starch-based polymers are produced from wheat, corn and potatoes and are used in the manufacture of capsules for medicines.

 

Corn starch based polymers - Polylactides (PLA) is another type of polymer that is derived from natural resources. This polymer is transparent and has similar properties to polyethylene and polypropylene and, as such, can be processed in similar ways to these conventional thermoplastics. Applications include packaging in the form of bottles and films for carrier bags and gardening products such as plant pots. They are also used in the manufacture of disposable nappies.

 

Cellulose based polymers - Biodegradable plastics can also be produced naturally by using bacteria to aid in fermenting plant sugars. There polymers are called Polyhydroxyalkanoates (PHA) also known as BIOPOL.- a polymer made from natural cellulose, which can be used to make biodegradable packaging.

 

Water-soluble polymers - One of the areas of biodegradation that is coming increasingly to the fore is water-soluble polymers. Products such as liquid detergent pouches make use of water-soluble properties of these materials to dispense the detergent only when in contact with warm water. Other applications include laundry bags where the dirty laundry is held by the material until it is placed in a large washing machine thereby protecting, for example, hospital staff.

 

The cost of producing biodegradable polymers remains more expensive than conventional polymers and this is reflected in the cost of products made from these materials. However, with increasing interest in these materials, scales of production are likely to increase, thus bringing costs down.