the science

Owing to the ever increasing usage of non-degradable plastic products in daily life and to the corresponding environmental/pollution hazards of their non-degradable characteristics, this bio-technological research was undertaken to make polyethylene totally bio-degradable. The end result encourages polyethylene products to undergo a change in their chemical composition when exposed to environmental conditions. The loss of chemical properties in polyethylene, whilst in contact with soils and water, can be measured in comparison to a standard list, appropriate to plastic, during the same time interval. Our bio-degradable product enables polyethylene (HDPE and LLDPE) to decompose both in atmospheric conditions and under soil or compost, thereby releasing CO2.

Bio-degradable polymers are generally recognised as those, which are designed to degrade through the action of living organisms. The bio-chemical agents, employed to produce the bio-degradable materials, comprise mainly of enzymes, sodium salts and oxidation agents, which react with polyethylene types HDPE and LLDPE. It is a highly cost-effective, eco-friendly and non-hazardous technology with applications primarily for making carrier bags, polyethylene liners and films.

difference between disintegration and bio-degradation of plastic

Disintegration of plastic products occurs where the intrinsic chemical structure of plastic residues remains unaltered in the soil, even after being exposed to UV radiation, photo-degradation and high-energy radiation. However, bio-degradation or, alternatively, chain-end degradation, is achieved within plastic when enzymatic characteristics aid the unzipping mechanism of the polyethylene molecular chain ends.

This results in a successive release of monomeric units composting with a successive liberation of CO2 gases. Thermal degradation also follows this unzipping procedure. The oxidation/reduction systems in connection with bacterial metabolism, inhibited in polyethylene through enzyme composition, have augmented the bio-degradable process. This idea of oxidation naturally involves the exhortation of oxygen to the compound, a typical example being the combustion of carbon to yield CO2. Bio-degradation of plastic products is achieved through an enzymatic composition, which contains various AMIDS. Our patented compound acts as an active centre of high energy on a cell surface caused by the interplay of inter-molecular forces between neighbouring polyethylene molecules. The treatment we use produces a specific power of absorption, of the inhibited bacterial culture, within the polyethylene lattice. The electron shells are distorted thus producing instability within the polyethylene molecules. The latter are now capable of undergoing a chemical and thermal change. The treatment compound, an inhibited culture of bifido bacterial metabolism, contains macro-molecules, which exert a living bio-chemical mode of action when the compound is exposed to normal micro-climatic conditions found outdoors. The myth, that the bacterial metabolism becomes inactive or dead at enhanced high temperatures, is subsequently proved to be wrong as the bacteria simply remain in a state of suspended animation only. Hence these bacteria once again become active and viable after coming into contact with outdoor soils, atmospheric conditions and normal temperatures.

bacterial sources

The plastic treatment, used in this technology, becomes a source for the growth of the bacterial culture. The latter have been observed for numbers and growth rates under laboratory conditions and testing. The total fungal and bacterial counts, for bio-degradable polyethylene bags, have been expressed in units of CFU/gm*. A definite bacterial group, found alive and active in these bags treated with our enzymes, proves that both soil and bag bacteria jointly eat away at the polyethylene film leading to total degradation of the latter. Bacterial and fungal counts were enumerated and classified by Vimta Labs. The total fungal count is < 10 CFU/g and total bacterial count is 25 CFU/g.

*CFU means Colony Forming Unit. Since bacteria have been enumerated as CFU, further multiplication of bacteria cannot be ruled out.

enzymes with polyethylene

Enzymes used with this product are regarded as catalysts, helping to promote the chemical reactions within the polyethylene and thus accelerating the process of degradation. Auto-trophic bacteria, present in mineral salt media, containing some form of nitrogenous material, are also employed in this technology. Carbon is formed from the added oxidation agents within this product. The pH value of this embedded polyethylene composition is 9.5 thus confirming its alkaline characteristics. All the ingredients of our plastic products are food-grade and non-toxic in nature.

composting of polyethylene

It is known that soil comprises at least 58% Carbon. The greater part of the nitrogenous fraction of soil is closely linked to organic matter. As the organic soil matter gradually decomposes, the nitrogen component gradually gives way to water or available forms of ammonia and nitrates. A moist soil environment reacts with the bio-degradable polyethylene film rendering it susceptible to composting and the release of carbon dioxide Process of Manufacturing Bio-Degradable Bags

The polyethylene product is preheated through a palletising process. The compounded polyethylene is then kept at normal temperatures for a period of 12-24 hours before subjecting it to an extrusion process. Subsequently to manufacture, the following test procedures have been adopted to evaluate any loss in tensile strength: -

1. Ultra-Violet Radiation
2. Water-Ageing
3. Soil Burial
4. Thermo-Gravimetric and Differential Analysis

The results were as per ASTM – D – 882 standard

conclusion

The enzymatic treatment is used at 4% - 10% dosage for Polyethylene (90% HDPE, 10% LLDE) and mechanically coated. The use of this product makes Polyethylene (HDPE LLDE) 100% bio-degradable and compostable. Costs for this process are very cheap compared to any other method currently prevailing in the world.