Development and Application of Degradable Plastics II

3. Use natural recyclable degradable materials as much as possible

According to the latest research report of the International Biodegradable Polymers Association (IBAW), between 2001 and 2003, the use of biodegradable plastics worldwide has doubled, and the total use has risen to 40,000 tons/year. IBAW states that although this figure also includes petroleum-based biodegradable materials, petroleum resources are now becoming increasingly scarce. As long as the technology permits, producers will use natural, recyclable materials as much as possible. Biodegradable plastics currently made from starch and vegetable oils have dominated the market. Recent surveys conducted in several countries show that consumers are very interested in this type of packaging material, and more interestingly, consumers are willing to pay more for this. Recently, a survey conducted by the American market research institution Grapentine Company found that 41% of American consumers and 59% of European consumers are very eager to buy foods made of natural biodegradable plastic packaging. About 77% of European consumers are willing to pay 5 cents more for this, and 74% of American consumers are willing to pay 10 cents more. IBAW predicts that the share of natural biodegradable plastics in the biodegradable plastics market will continue to rise, especially under the current high oil prices.

4. Thermoplastic starch resin is a kind of fully biodegradable plastic that is currently the most promising

The starch molecules are allosterically and disordered to form a thermoplastic starch resin, followed by a small amount of additives such as plasticizers, so-called full starch plastics. The starch content is above 90%, and the small amount of other substances added are also non-toxic and can be completely degraded, so the whole starch is truly a fully degradable plastic. Almost all plastic processing methods can be applied to the processing of whole starch plastics. All-starch plastic is currently the most promising biodegradable plastic at home and abroad. Sumitomo Corporation of Japan, Wanler lambert of the United States and Ferruzzi of Italy announced that they have successfully developed full-starch plastics with a starch content of 90% to 100%. The product can be completely biodegraded within 1 year without leaving any traces and no pollution. In the manufacture of various containers, films and garbage bags. The Battelle Research Institute in Germany developed a biodegradable plastic with modified green pea starch with a high linear content, which can be processed and formed by conventional methods. As a substitute for PVC, it can be completely degraded in a moist natural environment.

5. Carbon dioxide-based biodegradable plastics are currently research projects with broad development prospects

Japan's Inoue has found that carbon dioxide can undergo ring-opening polymerization with epoxides to form aliphatic polycarbonate (APC), which is the most promising CO2 copolymer to date. Takanashi et al. used a terpolymer of carbon dioxide, propylene oxide, and an ester-containing epoxide as a drug release agent. Masahiro et al. used the method of evaporating solvent to prepare PPC microspheres as the carrier of the drug sustained-release system, and studied the influencing factors of the release rate of the system, such as the molecular weight of PPC and the drug content. The results showed that with the decrease of the diameter of the microspheres or the increase of the drug concentration, the drug release rate increased, but the drug release rate and biodegradability were independent of the molecular weight of the copolymer. The morphology of the microspheres before and after drug release was observed by SEM, and the PPC was confirmed. Microspheres support long-acting, uniform release of drugs. U.S. experts adopted a new technology that uses special zinc catalysts to mix and copolymerize carbon dioxide and ethylene oxide (or propylene oxide) in a certain proportion to produce plastic packaging materials with new features. The carbon dioxide-based fully biodegradable plastics project implemented by China Jilin Group Corporation and the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, has been included in the National 863 Research Program. It is a new high-tech environmental protection material research and development project with broad development prospects.

6. Definition of degradable plastics and evaluation methods are the basis for the promotion of degradable plastics

However, the world’s developed countries, especially the United States, have also done a lot of research. At present, ASTM has announced the following test standards: Biodegradable plastics related evaluation test standards, ASTM D5209-92, ASTM D5210-92, ASTM D5247-92, ASTM D5271-92, ASTM D5338-92. Photodegradable plastics related evaluation test standards, ASTM D5071-91, ASTM D5208-91, ASTM D3826-92. Environmental safety related evaluation test standard, ASTM D5152-91. At present, China has published the relevant test standards are as follows: GB 18006.1-1999 "General technical conditions for disposable degradable tableware", GB/T 18006.2-1999 "Test method for degradation performance of disposable degradable tableware", HJBZ 12-2000 “Technical Requirements for Environmental Labeling Products of Packaging Products”, HBC 1-2001 “Technical Requirements for Environmental Labeling Products for Disposable Tableware”, QB/T 2461-1999 “Degradation polyethylene film for packaging”. In the future, reference will still be made to the relevant test standards of developed countries and China, combined with the market promotion of various types of degradable plastic products, and the research on the definition and evaluation methods of degradable plastics will be in-depth. The relevant test standards will be continuously improved and improved. This is the promotion of degradable plastic products. The foundation and industrialization of the premise.

Third, the Olympic Games, the World Expo, etc. for the use of biodegradable plastic enrich vitality

The Olympic Games will consume a large amount of plastic materials. The biodegradable plastics will be very important for highlighting the theme of "Green Olympics." The China Plastics Processing Association Degradable Plastics Subcommittee proposed to promote the use of biodegradable plastics in the 2008 Beijing Olympic Games to enhance the "Technology Olympics" and add luster to the "Green Olympics." The product summary for the use of fully biodegradable plastics is as follows: disposable food and beverage supplies - lunch boxes, knives, forks, spoons, drinking cups, straws; packaging materials - all kinds of product packaging bags: food, beverages, souvenirs; cheerleading supplies - Horns, whistles, ribbons, small flags, light sticks; stadium signage - signposts, division logos, stadium hallmarks, table cards, badges; stationery office supplies - stickers, signature pens, correction bottles, cutting paper Knife handles; hotel supplies - disposable shoes, toothbrushes, combs; sanitary supplies - garbage bags, disposable garbage baskets; other - umbrellas, fans, eyeglass frames, handbags. In 2010 Shanghai World Expo will also promote the use of biodegradable plastics. Its concept and meaning are the same as for the Beijing Olympic Games. It is also a highlight for the "Expo of Science and Technology" and a luster for the "Green Expo".

Huang Genlong, Researcher, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences

Shanghai Packaging