Save Planet-Use Less Plastic

As plastic is made from materials which do not decompose, it has resulted in severe environmental degradation. We can start using less plastic to save the planet or use recycled plastic. We can also use biodegradable plastics manufactured from soybean that can help in reducing the adverse impact on the environment.

Until now, application of protein was restricted to nutrition studies. But with a lot of research on non-food usage of agricultural raw material and with more emphasis on proteins, new tools and concepts have been developed in the field of polymer science and technology.

Proteins are defined as natural polymers that can form amorphous three-dimensional structures which stabilize mainly by non-covalent interactions. The functional properties of these materials are vastly dependent on structural heterogeneity, hydrophilic behavior and thermal stability of proteins. A number of proteins of plant origin have received attention for manufacturing biodegradable polymers. These proteins are cornzein, soy protein, wheat gluten, and peanut protein.

Soybeans have come into limelight due to their use in value-added products such as biodegradable plastics. A breakthrough achieved in using soybeans in biodegradable plastic film has its use in applications like lawn and leaf bags, trash bags, carry bags and agricultural mulch film. The plastic film can be developed by using soybean protein and oil.

At present, products which are designed lack consideration of their ultimate disposability. By making plastics with biodegradable material we can make sure that they end at an appropriate disposal system which is environmentally and ecologically sound. For example, by composting paper waste and biodegradable plastic along "organic' materials like agricultural waste and food, we can generate much-needed carbon-rich composite.

Bioplastics which are made out of cornstarch-polyester blends are already used commercially in Japan and US. But soy proteins offer property and functionality enhancement which can be even more beneficial than starch. Proteins have reactive nitrogen functional groups, like carboxyl and amino groups which react with polyesters.

In addition, nitrogen is also an important nutrient for microbial activity and plants -an added value for protein film. Soy protein polymers also have the functional ability to blend well with polyesters which enhances biodegradability.

A great deal of research on soybean plastics has been conducted and soybean products are used in phenolic resins especially as extender or filler to decrease the cost of the plastics.

Early soy proteins films could not meet the expectation on the performance front compared with typical non-degradable low-density polyethylene (LDPE) film used in trash bags. As soy protein is hard and brittle, it is difficult to make plastic films. To be flexible, it requires a good plasticizer. These types of films are normally weak and brittle with best elongation to breaks reportedly around 40-60%. Typically 200-300% is required for many films applications.

Researchers had lot of success in creating extrusion-blended hydrophilic soy protein with selected aliphatic polyesters at 30-40% levels to produce fully biodegradable thermoplastic compositions which can be blown into films. These blends elongate to 500% with tensile strength around 2000 per square inch.

This plant-based plastic which is biodegradable has opened new avenues which help in keeping the environment cleaner and greener.