Corn plastic is a biomass plastic made from corn. It is a new type of environmentally friendly material. It was developed and launched in 2018 by Ningbo Keen Biomaterials Co., Ltd. and a foreign biomass material research center.

Corn plastic is a colorless and transparent liquid produced by modern biotechnology from corn full of starch, lactic acid, and then a granular polymer material, polylactic acid, is generated through a special polymerization process. Corn plastic can replace chemical plastic particles and be made into building wall panels, textile fabrics, medical materials, and automotive interiors.

The properties of corn plastic are similar to those of ordinary plastics. The products made from it can be 100% biodegraded within half a year when buried in the soil. Packaging bags and agricultural mulch made of polylactic acid can reduce white pollution through effective recycling.

Concept

Corn full of starch can produce a colorless and transparent liquid, lactic acid, through modern biotechnology, and then a granular polymer material, polylactic acid, is generated through a special polymerization process. Polylactic acid particles extracted from corn are called "corn plastics". They can replace chemical plastic particles and be made into building wall panels, packaging materials, textile fabrics, daily utensils, agricultural mulch, carpets, medical materials, car interiors and home decorations according to different needs. Items made of this biopolymer material can be composted and landfilled after being discarded. They are completely decomposed into water and carbon dioxide under the action of natural microorganisms, and can be used as organic fertilizers to be applied to farmland as plant nutrients.

Experimental process

After 8 years of research and development and 1 year of industrialization, "corn plastics" with the scientific name of "polylactic acid" have finally walked out of the Tongji University laboratory and are currently in the industrial trial production stage. This fully degradable biological and environmentally friendly material can completely replace chemical plastics and is regarded as the "fourth type of new material" after metal materials, inorganic materials, and polymer materials. It has important strategic significance in social and economic development.

Liquid lactic acid extracted from corn and its generated polylactic acid particles, as well as cups, bowls, and disposable tableware made of "corn plastic", all have warm colors and feel softer than traditional plastic products. Professor Ren Jie, a leader of the project and a professor at Tongji University who specializes in polymer materials, told reporters that in order to transform this high-tech achievement of biology and materials into an industry, it is necessary to reduce production costs so that the market can generally accept it. After 8 years of concentrated research, researchers finally obtained the ideal production cost by producing polylactic acid through the "one-step method". At present, only one company in the United States can produce polylactic acid in the world. Because the production process adopts the "two-step method", its production cost is high and the price per ton is about US$3,000, which makes it difficult to replace traditional chemical plastics. However, through the organic combination of bioengineering technology and polymer synthesis technology, the "one-step method" synthesizes lactic acid into polylactic acid particles, greatly reducing production costs. The ex-factory price is about RMB 10,000 per ton, which is close to the price of chemical plastic particles. Therefore, "corn plastic" has the conditions for promotion and industrialization.

"Corn plastic" can be widely used in engineering materials, packaging materials, daily utensils, agricultural mulch films, furniture panels, and is also very useful in the field of medicine and medical treatment. Bone nails and surgical sutures made of "corn plastic" have been used in clinical practice. Because of its complete degradation in the body, it is no longer necessary to perform medical procedures such as extraction and suture removal. "Corn plastic" can also be used to make tissue engineering scaffolds for artificial bones and artificial skin, on which bone cells or skin cells are cultivated. When the scaffold material degrades, artificial bones and artificial skin are also grown. Using the non-toxic, harmless and degradable characteristics of "corn plastic", it can also be made into sustained-release capsules, thereby changing people's medication habits. Since this sustained-release capsule is gradually digested and degraded in the human body, people can take a drug wrapped in a sustained-release capsule and continue to get the required amount of medicine within a few days or a week.

Production process

There are two main production processes for lactic acid to polylactic acid: (1) One-step method: L-lactic acid obtained by corn fermentation is directly polycondensed into polylactic acid in one step. This method is simple, but the molecular weight of the obtained polymer is small, generally less than 5000; (2) Two-step method: also called non-solvent method, the obtained L-lactic acid is first made into the intermediate lactide, and then ring-opening polymerization into polylactic acid, which can obtain PLA with a higher molecular weight, but the process is complicated. The specific process is shown in Figure 1.

Practical significance

(1) Green and environmentally friendly, no pollution to the environment

Compared with traditional chemical plastics, corn plastics are environmentally friendly in production, use and disposal. Traditional chemical plastics come from petrochemical products. The petroleum refining process will produce a large amount of greenhouse gases and other pollutants; on the contrary, corn can absorb diols during its growth process. It oxidizes carbon and releases oxygen. After being discarded, it can be completely degraded and converted into carbon dioxide and water before participating in photosynthesis again. Its entire life process can realize the circulation of materials and purification of the air. It is a green and environmentally friendly renewable resource.

(2) Relieve the pressure of oil consumption

Chemical plastics are downstream products of the oil industry. A large amount of oil resources are consumed every year in the production of chemical plastics. Corn plastics have opened up sources of chemical raw materials other than oil. According to statistics, corn plastics can save nearly 70% of fossil fuels in the production of the same plastic products.

(3) Solve the pressure of food inventory and increase the added value of crops

Corn and other cereal crops may deteriorate and mold after being stored for 1-2 years and can no longer be eaten. At this time, deep chemical processing is a good way out. If the annual inventory of corn is In the processing and production of corn plastics, in addition to the products that can benefit mankind, the added value of corn can be increased and the cost of corn inventory can be reduced.

(4) Possible adverse effects of corn plastics

Although corn plastics have the above advantages, they have not yet been produced and applied on a large scale, which shows that they still have certain problems. First, the efficiency of producing polylactic acid by biological methods is not high, and it is difficult to produce on a large scale industrially; second, using corn as the main raw material for plastic production will inevitably consume a large amount of corn and raise food prices, which will have a more serious impact on those areas of the world that have not yet solved the problem of food and clothing; third, with the rapid development of industrialization and urbanization, the area of arable land has been decreasing year by year. If we want to meet the increasing demand for corn, it will inevitably lead to deforestation and land reclamation, which will cause damage to the ecological environment.

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