The manufacture of plastics requires the use of non-renewable materials such as petroleum and natural

gases. Many plastics are harmful to the environment as they take years to biodegrade and can leach chemicals.

An alternative must be found.

Plastic Alternatives

AlternativesCarrier Bags:-• An alternative to using plastic bags would be to use reusable bags

such as cloth bags which are durable, reusable and washable so they do not have to be thrown away and will not contribute to the build up of waste in land fill sites.

Plastic Bottles:-• An alternative to using plastic bottles would be to use glass bottles

as they do not contain BPA and are therefore better for us and babies as glass does not leach such chemical when heated like plastic does.

Biodegradable Plastics• These plastics break down when exposed to sunlight (UV), water, dampness,

bacteria, enzymes, wind abrasion and some instances rodent pest or insect attack are also included as forms of biodegradation or environmental degradation.

• This degradation in some cases only works if the conditions are right for it, i.e. at landfill and composting systems.

• Starch powder has been used. It has mixed with a plastic as a filler to help it degrade more easily but it does not completely breakdown the plastic so is not all that good for the environment as it fragments the plastic.

• Bacteria have been genetically engineered which synthesise a completely biodegradable plastic but they are very expensive at present.

Bags are Used, Reused and Recyclable.

2. The degradation process is triggered by heat, UV light and/or mechanical stress.

3. In approximately 2 years bags are fully degraded to carbon dioxide, water and biomass - photosynthesis begins, trees and green plants grow!

Biodegradable PlasticsEcoflex:-• A biodegradable polyester for food packaging has been

made by a German company who specialise in chemicals called BASF.

Oxo-biodegradable:-• It is a polyolefin plastic to has metal salts added to it that

act as a catalyst. • As long as the plastic has access to oxygen (as in a littered

state), these salts speed up degradation.• Once degraded to a small enough particle they can

interact with biological processes to produce to water, carbon dioxide and biomass.

• The process is shortened from hundreds of years to months for degradation and thereafter biodegradation depends on the micro-organisms in the environment.

Compostable Plastics Compostable Plastics are a new generation of plastics which

are biodegradable and compostable. They are derived generally from renewable raw materials like

starch (e.g. corn, potato, tapioca etc), cellulose, soy protein, lactic acid etc.

They are not hazardous/toxic in production and decompose back into carbon dioxide, water, biomass etc. when composted. 

Some compostable plastics may not be derived from renewable materials, but instead derived made from petroleum or made by bacteria through a process of microbial fermentation.

Degradation of compostable plastics…

Compostable Plastic Resins

Currently, there are a number of different compostable plastics resins available in the market and the number is growing every day.

The most commonly used raw material for making the compostable plastics is corn starch, which is converted into a polymer with similar properties as normal plastic products.

Other compostable resins are available made from potato starch, soybean protein, cellulose and as well from petroleum and petroleum by products.

Corn Starch Polymer

Compostible Plastic Resins Continued… It is counter intuitive to think that compostable resins could be

derived from petroleum, when all normal plastic products are derived from petroleum and are non compostable.

However, there are certified compostable resins available in the market, derived from petroleum and the field of compostable plastics is constantly evolving with new materials and technologies being worked on and being brought to market.

There is even research underway to make compostable plastics from carbon dioxide which would utilise the gas produced by burning fossil fuels.

However, we want to try and reduce our use of fossil fuels and move toward the use of

raw materials…

Biodegradability and Compostability Bioplastics can take different length of times to

totally compost, based on the material and are meant to be composted in a commercial composting facility, where higher composting temperatures can be reached and is between 90-180 days.

Most existing international standards  require biodegradation of 60% within 180 days along with certain other criteria for the resin or product to be called compostable.

It is important to make the distinction between degradable, biodegradable and compostable. These terms are often (incorrectly) used interchangeably.

Criteria for Compostible Plastics

Biodegrade - break down into carbon dioxide, water, biomass at the same rate as cellulose (paper).

Disintegrate - the material is indistinguishable in the compost, that it is not visible and needs to be screened out

Eco-toxicity - the biodegradation does not produce any toxic material and the compost can support plant growth.

Biodegradeable Plastics:

Biodegradable Plastic is plastic which will degrade from the action of naturally occurring microorganism, such as bacteria,  fungi etc. over a period of time. 

However, there is no requirement for leaving "no toxic residue", and as well as no requirement for the time it needs to take to biodegrade.

Degradeable Plastics:

Degradable Plastic is plastic which will undergo a significant change in its chemical structure under specific environmental conditions resulting in a loss of some properties. 

There is no requirement that the plastic has to be degrade from the action of "naturally occurring microorganism" or any of the other criteria required for compostable plastics.

Estimated Composting Times

Home Composting Home composting rates are slower and can

vary, depending on how frequently the pile is turned over, the moisture and material content and the temperature.

Commercial Composting

Commercial composting facilities grind the materials, turn over the piles and reach high temperatures, thus reducing the amount of time it takes to compost and, is thus, the recommended method for composting these products.

http://biobasics.gc.ca/english/View.asp?x=790