Definition of biodegradable polymer materials
Biodegradable bag supplier to share with you: According to the US ASTM standard, biodegradable polymer materials are defined as: under certain conditions, within a certain period of time, can be microorganisms (bacteria, fungi, mold, algae, etc. ) Or its secreted polymer materials that can degrade under the action of enzymes or chemical decomposition, also known as green ecological polymer materials.
Biophysical degradation: After the microorganisms erode the polymer, the polymer material is mechanically damaged due to the enlargement of the cells;
Biochemical degradation: Under the direct action of biological enzymes, microorganisms attack macromolecular chains and cause polymer cleavage. In general, biochemical degradation requires two processes: first, the microorganism secretes hydrolyzing enzymes to the surface of the material in vitro, cuts the polymer chain by hydrolysis, and generates small molecular compounds (organic acids, esters, etc.) with a molecular weight of less than 500; Degradation products are taken into the body by microorganisms, undergo various metabolic routes, and are synthesized into microbial organisms or energy converted into microbial activities, which are eventually converted into H2O and CO2;
Microbes interact with polymers to form new substances.
Polymer biodegradation is not a single mechanism, but a complex physical and chemical process that is synergistic and interacts with each other.
Microbial synthetic polymer materials
In an environment where life nutrients such as nitrogen, oxygen, phosphorus, and mineral ions are controlled, some bacteria produce a large amount of biodegradable aliphatic polyesters during fermentation. Such as: Algae anaerobicus can use fructose as a carbon source to produce PHB (poly-3-carboxybutyrate). In the 1970s, the British company ICI first developed the hydroxybutyrate-hydroxyvalerate copolymer (PHB-HV) Biopol product. This material can be made into biodegradable packaging bags (paper) Film, or foam molding is used for food packaging and containers.
Biodegradable Packaging Bags
Chemical synthesis of biodegradable polymer materials
Showa Polymer Co., Ltd. in Japan produced polybutylene succinate (PBS) and polybutylene succinate-adipate (PBSA) by dehydration polymerization of diol and diacid; Union Carbide Company in the United States used polycaprolactone (PCL ) Developed a product called "Tone" for raw materials; Showa Polymer Corporation of Japan also developed a similar product, named Bionolle, which has been used to produce packaging bottles, films, etc
In recent years, the world's most actively researched and developed degradable polymer material is polylactic acid (PLA). Currently, there are only five types of PLA resins on the international market: CPLA, a product of Dainippon Ink and Chemicals; LACEA, a product of Mitsui Chemicals. LACTY from Shimadzu, Japan; Ecopla from Cargill Dow; Heplon from Chronopol, USA.
Natural polymer synthetic materials
Natural polymers such as cellulose, starch, chitin, and protein are abundant in nature. Such naturally grown and naturally decomposed products are completely non-toxic, but most of them are not thermoplastic, difficult to form and process, and poor in water resistance, and cannot be used alone. It is generally blended with chemically synthesized biodegradable polymer materials to make polymer alloys, or modified to make it processable.
At present, the United States mainly uses the American Material Testing Standard (ASTM) as the standard method. China does not yet have a unified national standard, ministry standard, and line standard. Some scientific research institutions mainly use some biochemical and microbiological experimental methods to evaluate the biodegradability of biodegradable polymer materials. Such as: field environment test, environmental microbial test, specific microbial erosion test, in vitro test of specific separately isolated enzymes, in vitro degradation test of biodegradable polymer human built-in materials, etc.
Biodegradable polymer materials are still in the continuous development stage and have a bright future. Its application is of great significance to alleviate environmental pressure and ease the crisis of oil resources. However, its high cost has limited its development. The main challenges in the future are to reduce costs and refine materials and refine them.