“Biodegradable plastic” the eco-friendly alternatives

Since the birth of plastics, its excellent performance and low cost have been widely used in all aspects of production and life. From 1950 to 2015, humans have produced 8.3 billion tons of plastic products, of which 4.9 billion tons were directly landfilled or abandoned, 800 million tons were directly incinerated, and 2.6 billion tons still in use, of which 100 million tons were recycled plastics . The use of plastics will continue to grow in the future, and global plastic consumption is expected to grow at an annual rate of 8%. In 2030, the annual consumption of plastics will reach 700 million tons. In the natural environment, it generally takes 200-700 years to degrade. The existence of a large amount of waste plastic has greatly threatened the health of wild animals and humans. Therefore, in the face of huge amounts of white pollution, various countries have actively promoted the restriction of plastics, the prohibition of plastics, and the development and use of degradable plastics to reduce garbage pollution.

Global plastic production is about 359 million tons, of which bioplastics account for about 1%. In 2018, the global market for biodegradable plastics exceeded 1.1 billion U.S. dollars, with a total production capacity of about 912,000 tons. It is expected to achieve 1.7 billion U.S. dollars and 1.288 million in 2023. Ton. Europe is the main market for biodegradable plastics, accounting for 55% of the world, the Asia-Pacific region accounts for 25% of the world, and North America's demand for 19%. The application range of biodegradable plastics continues to expand, including packaging, textile fibers, and automobile transportation. The largest proportion of packaging is 58%. With the rapid development of express delivery, food delivery and other businesses, the demand for plastics continues to grow. For these fields, degradable plastics are particularly suitable. With technological progress, large-scale production, cost reduction, and improvement of environmental protection concepts, the future growth of degradable plastics is huge.

Degradable plastics are mainly divided into two categories: PLA and PBAT. PLA is a polymer material produced by polymerization of lactic acid as raw material. It has the characteristics of non-toxic, non-irritating, high strength, easy processing and molding and excellent biocompatibility. Polylactic acid is commercialized early and has the best mechanical properties. It can be injection molded, foamed, and blow molded. The disadvantage is that it has insufficient toughness. The melting point of PLA is 160-180 degrees, and the heat-resistant temperature can reach 150 degrees. PBAT is obtained by polycondensation of terephthalic acid, adipic acid and butanediol. It is a new type of biodegradable plastic. Because its structure contains both aliphatic and aromatic segments, it contains flexible The aliphatic chain ensures that it has good molecular chain flexibility, low melting point, poor heat resistance, and is not suitable for injection molding materials. It has good ductility and good application prospects for blown film. The melting point of 110-130 degrees is suitable for various film bag products, including shopping bags, express bags, plastic wrap, etc. The above two types account for 90% of all degradable plastics. PHA is a polyhydroxy fatty acid ester synthesized by microbial fermentation. It is a plastic synthesized from microbial plasmids. The processing performance is relatively simple. The heat resistance is 80 degrees Celsius and the cost is 35,000 yuan/ton. The advantage is that the gas barrier is relatively good. The disadvantage is that the molecular weight is relatively uniform. During the processing, the processing does not melt, and the temperature reaches a certain level and melts together and cannot be processed. Plastic products still require a certain difference in molecular weight. Suitable for tires and cigarette films. PBS polyglycol succinate, the strength is between PBAT and PLA, the heat resistance is better, and the performance is close to polypropylene, melting point 110 degrees. PPC carbon dioxide copolymer, a product invented in Japan and unique to China, features carbon dioxide consumption, but is relatively soft and has poor heat resistance and melts at 30-40 degrees Celsius. Blended biodegradable plastics, PBAT and PLA are blended, starch is thermally plasticized with PBAT and other materials, and PLA is blended with talc, calcium carbonate and other inorganic materials to prepare products. Currently, no more than 30% starch is added to degradable products. From the cost point of view, adding starch can improve the efficiency of oil use, and the price is more popular in the market than polyethylene.