With petroleum-derived plastics becoming ubiquitous, the world is facing a huge problem with both the source and the disposal of these materials. A real alternative is emerging in the form of plastics derived from soybeans, as they are renewable and can also be made to be biodegradable.
The real drive for soy as a petroleum alternative started in America in the ‘30s and ‘40s due to shortages caused by World War II. This led to research into fuels derived from other, more abundant sources, such as soy. Along with incorporating soybean products in phenolic resins as filler, there was Henry Ford’s “Plastic Car” concept, which was a project to replace steel (another rationed resource) in automobiles. Although both of these programs succeeded, the end of WWII meant that gasoline and steel was no longer rationed, and the development of soy plastics was effectively ended.
In the case of soy, there are a couple of derivatives that can be used. Once processed, 60 lbs. of soy yields 11 lbs. oil, 48 lbs. meal, or 38 lbs. defatted soy flour; 20 lbs. protein concentrate; and 12 lbs. soy protein isolate. In this article we will focus on using protein isolate. The meal undergoes a series of refinements and at each turn the amount of material reduces as the protein content increases. Dehulled soybean, after defatting and meal grinding, becomes soy flour, which can be toasted to various degrees of protein solubility. This soy flour has the water/alcohol-soluble sugars leached out and is termed soy protein concentrate. Finally, the soy protein concentrate is dissolved in caustic 12 solution at pH 9 and reprecipitated by acidification at pH 4.5, becomes the purest commercially available soy protein at 90% protein. Bioplastics are long chain of monomers joined with each other by ester bond which considered as polyesters