Polyhydroxyalkanoate is an intracellular polyester synthesized by many bacteria. It mainly exists as a carbon source and energy storage substance in the organism. It has physical and chemical properties similar to synthetic plastics and does not have synthetic plastics. It has many excellent properties such as biodegradability, biocompatibility, optical activity, piezoelectricity, and gas barrier properties. Polyhydroxy fatty acid esters have broad application prospects in biodegradable packaging materials, tissue engineering materials, sustained-release materials, electrical materials and medical materials, but they can be applied on a large scale only after reducing the production cost of PHA.
Polyhydroxyalkanoates (PHA), which has been rapidly developed in the past 20 years, is an intracellular polyester synthesized by many microorganisms and a natural polymer biomaterial. Because PHA has good biocompatibility, biodegradability and thermal processing properties of plastics, it can be used as biomedical materials and biodegradable packaging materials at the same time, so it has become the most active research in the field of biomaterials in recent years Hot spot. PHA also has nonlinear optics, piezoelectricity, gas separation and many high value-added properties.
Natural or synthetic biodegradable polymer materials often have high water vapor permeability, which is disadvantageous in food preservation. The PHA has good gas barrier properties, which makes it possible to be used in fresh-keeping packaging for a long time. Because the penetration of water vapor is an important indicator in fresh-keeping packaging, the performance of PHA at this point is completely comparable to products such as PET and PP. On the other hand, PHA also has good hydrolytic stability. The cup made of PHA is washed in an automatic dishwasher at 75°C for 20 cycles. Its shape and molecular weight have not changed, indicating that PHA can perform well. Used in appliance production. In addition, compared with other polyolefins and polyaromatic polymers, PHA also has good UV stability. PHA can also be used as a source of biodegradable environmentally friendly solvents. For example, ethyl hydroxy-acid EHB (ethyl3-hydroxy-butyrate) is water-soluble, has low volatility, and can be used in cleaners, glues, adhesives, dyes, and so on. Ink solvent. It is precisely because PHA brings together these excellent properties that it can be used in packaging materials, adhesive materials, spray materials and clothing materials, appliance materials, electronic products, durable consumer goods, agricultural products, automation products, chemical media, and solvents. application.
Compared with PLA and other biological materials, the structure of PHA is diversified. The composition of PHA can be easily changed by changing the strain, feeding and fermentation process, and the diversified performance brought about by the diversity of composition structure makes it obvious in application. The advantages. According to its composition, PHA is divided into two categories: one is short-chain PHA (monomers are C3-C5), and the other is medium-long-chain PHA (monomers are C6-C14). In recent years, there have been reports that strains can synthesize short-chain and Medium and long chain copolyhydroxy fatty acid esters. The production of PHA has experienced the first generation of PHA-polyhydroxybutyrate (PHB), the second generation of PHA-hydroxybutyric acid copolyester (PHBV) and the third generation of PHA-hydroxybutyric acid copolyester (PGBHHx), the third-generation PHBHHx of PHA was produced by Tsinghua University and its cooperative enterprises for the first time, and the fourth-generation product P34HB (poly-3-hydroxybutyrate/4-hydroxybutyrate copolymer) , The domestic production companies are mainly Tianjin Guoyun Biomaterials Co., Ltd. (10,000 tons/year) and Shenzhen Ekman Biotechnology Co., Ltd. (5,000 tons/year). [3] Compared with the production process of traditional chemical plastic products, the production of PHA is a kind of production with low energy consumption and low carbon dioxide emissions. Therefore, the production process and the products are very beneficial to environmental protection.
PHA is not only an environmentally friendly bioplastic with excellent performance, but also has many adjustable material properties. With the further reduction in cost and the development of high value-added applications, PHA will become a biomaterial with a cost acceptable to the market for multiple applications. . Since it is a widely composed family, its properties from rigidity to high elasticity make it suitable for different application needs. PHA's structure diversification and performance variability make it an important member of biomaterials. Compared with PLA, the development history of PHA is very short, the development potential is greater, and the space for its application is also greater.
