It is known that high molecular weight polyolefins like PE and PP are hydrophobic and not prone to attack by micro-organism. This high moleculare weight is the reason why many applications are unable to disintegrate rapidly. Distengration occur at a very slow place and may take upto 400 years to biodegrade. A lower value of molecular weight (<5000) polymer/fragment increases its intrinsic microbial accessibility and enables subsequent biodegestion.
Oxo-biodegradable additives when added in small percentage will degrade polyethylene and polypropylene under the certain environmental conditions consisting of oxygen, heat and sunlight. It contains certain pro-oxidants which can be added to plastic in requisite ratio to render it degradable in a realistic time frame. The initial chain scission of polymer causes change in physical properties such as tensile strength, elongation and reduction in molecular weight which leads to disintegration followed by consumption of bacteria which is very well known to convert plastic to carbon dioxide and water.
Degradation speed is mainly dependent on:
- Let down ratio of additive
- Thickness of film
- Presence of certain additives such as antioxidant, UV, minerals and pigments
- Presence of oxygen
- Temperature and moisture
- Type of exposure