wuyong（斜风细雨）

wuyong（斜风细雨） wuyong(斜风细雨) Polymer paper degradable plastic [2010/5/18 12:25:49] Polymer materials in life Biodegradable plastics Abstract: polymers are widely used in various fields of life, and plastics are widely used. Plastic plays a major role in life, but it also brings harm to the environment. How to solve the white pollution caused by plastic locks is a common problem facing all mankind. At present, in many solutions, the development of biodegradable plastics has become the focus of attention worldwide. The definition, classification, properties, application, development trend and development prospect of degradable plastics are described and expounded in this paper. [keyword]: polymer materials, biodegradable plastics, biodegradable plastics, biodegradable plastics, natural polymers, modified plastics [text]: Plastic is a synthetic polymer material, also known as polymer or giant molecules, is also commonly known as plastic or resin, can change the shape of the body. It is a kind of material which is synthesized by condensation or condensation of monomer material. It is composed of synthetic resin and filler, plasticizer, stabilizer, lubricant, pigment and so on. Its main component is synthetic resin. The plastic has the advantages of light weight, chemical stability, no corrosion, good impact resistance, good insulation, low thermal conductivity, good transparency and good abrasion resistance, etc.. On the other hand, plastics have serious pollution to the environment: 1, a wide range of pollution. 2, rapid growth of pollutants. As plastics are cheap, easy to aging, and shorter in life, as plastics increase, resulting in the rapid growth of waste, American experts estimate that every 10 years will double; 3, difficult to deal with. 4, recycling difficult. 5, the ecological environment is harmful, and waste plastics will lower the quality of cultivated land and affect the growth of crops. How to solve the white pollution caused by plastic locks is a common problem facing all mankind. At present, in many solutions, the development of biodegradable plastics has become the focus of attention worldwide. Definition and classification of degradable plastics Biodegradable plastics is adding some additives in the production process (such as starch, modified starch, cellulose or other photosensitizer, biological degradation agent), stability decreases, more easily in the natural environment of biodegradable plastic. Biodegradable plastics are generally divided into four broad categories: Light degradable plastics add photosensitizer to plastics and decompose plastics gradually under sunlight. It belongs to an earlier generation of degradable plastics. Its disadvantage is that the degradation time is difficult to predict because of the sunshine and climate change. Therefore, it is impossible to control the degradation time. Biodegradable plastics can be completely broken down into low molecular compound plastics under the action of microorganisms. The utility model has the advantages of convenient storage and transportation, as long as the utility model has the advantages of dry drying, no need of avoiding light and wide application range, and not only can be used for agricultural film and packaging bags, but also can be widely used in the medical field. A class of plastics that combines light / biodegradation, photodegradation, and microorganisms. It also has the characteristics of light and microbial degradation of plastics. Water degradation plastics add water absorbing substances in plastic. When they are used up, they can be dissolved in water. They are mainly used in medical and sanitary equipment (such as medical gloves), so they are easy to destroy and disinfect. With the development of modern biological technology, biodegradable plastics have been paid more and more attention and become a new hot spot of research and development. Plastic products of every hue has greatly enriched people's life, but the waste plastic in nature decomposed slowly, completely decomposed to several decades, or even centuries, so the plastic degradation and reuse problems placed in front of all of today's environmental chemist. Interestingly, however, biodegradable plastics are not the original intention of scientists to develop plastics. At present, scientists are developing or already developed biodegradable plastic, the scope of application is still relatively narrow, still can not replace popular plastics. Two. Properties and applications of degradable plastics 1. Biodegradable plastics and light biodegradable plastics Biodegradable plastics are plastics that are decomposed by photochemical reactions that absorb sunlight. There are two kinds of general light degradable plastics preparation methods: one is to add a light sensitive agent in polymer materials, can produce a sensitive agent to absorb the light after radical to polymer materials oxidation to cracking; two is the use of the copolymerization method will be suitable for the light sensitive agent into material characteristics to light degradation polymer structure. Commonly used in light degradation and are: metal salts, two ferrocene derivatives, carboxylic salts, alkyl dithiocarbamate, iron and so on. The plastic film made of this kind of plastics has three characteristics: (1) after use, it can be decomposed by sunlight in its own light, and the small residual body after decomposition can be further decomposed by microorganisms in the soil. (2) the service life can be controlled. (3) the cost of recycling mulch film is saved, and the pollution of soil and environment by residual film is solved. The degradation rate of the degradable plastics depends on the time and intensity of sunlight, and the debris is easy to form two pollution after degradation. With the combination of photo degradation technology and biological degradation technology, it is possible to realize the artificial control of the degradation time by using the matching proportion and dosage of the photosensitive system. Therefore, there are more double degradable starch plastics combined with photo degradation technology and biodegradation technology. There are 35 light biodegradable plastics production lines in our country. The main reason for restricting the application of this technology is that the production cost is greater than that of ordinary plastics, so it is difficult to popularize. 2 biodegradable plastics The main raw material used for photodegradation and photo degradation plastics is synthetic polymer monomer, which does not have environmental solubility, but still can cause two pollution to the environment. Therefore, more and more attention has been paid to the study of complete biodegradable plastics in the world. Fully biodegradable plastics can be divided into three categories: microbial synthesis, polymer degradation plastics, chemical synthesis, high polymer degradation plastics and natural polymer modified plastics. L microbial synthesis of high polymer degradable plastics Microbial synthesis of high molecular degradable plastics is the synthesis of microorganisms or genes, in which gene synthesis is the most viable and promising synthetic method. Among a large number of microbial synthetic biodegradable materials, poly (PHAs) produced by microbial fermentation has become the focus of research. As an optically active polyester, PHAs has good biocompatibility as well as the basic properties of polymers. Studies have shown that making use of PHAs shampoo bottle, in the natural environment, nine months after basically was completely degraded, And the same synthetic plastic products, complete degradation time takes about 100 years. At present, more than 40 PHAs have been identified, among which poly (beta hydroxy ester) (PHB) and 3- hydroxybutyrate and 3- hydroxy acid ester copolymer (PHBV) are typical representatives of PHAs. It exists in many microorganisms and has a wide range of applications. Disposable plastic products made from PHB, whose wastes are easily decomposed into carbon dioxide and water in the ecological environment, without polluting the environment. In addition, because PHB has good biocompatibility, strong repulsion of organism of PHB not with that of other materials, in the body can easily be hydrolyzed into monomer hydroxybutyric acid, finally through ketone metabolism into carbon dioxide and water, can be used as carrier delivery system control surgical suture in medicine and drugs. L chemical synthesis of high polymer biodegradable plastics Chemical synthetic polymer biodegradable plastics are based on chemical polymers related technology, the use of molecular design methods to produce a degradable plastic. Polylactic acid (PLA), polycaprolactone (PCL) and polyvinyl alcohol resin (PVA) can be synthesized by this method. In 1930, polylactic acid was used as an aliphatic polymer. L natural macromolecule modified degradable plastics Most natural polymers can be biodegraded, but their thermal and mechanical properties are poor, which can not meet the performance requirements of Engineering materials. Natural polymer degradable plastics include starch, avant-garde, lignin, polysaccharides, and protein based composites. At present, the most important is the starch based system, which takes modified starch as the main component and adds a small amount of hydrophilic biodegradable polymers (such as PVA) as the technical route. Because of the low price of starch based plastics, the processing equipment is simple and the degradability is excellent, and many kinds of products have been sold at home and abroad. The main factors affecting the use of starch based biodegradable plastics are: consuming large amounts of grain; poor mechanical properties; higher cost than ordinary plastic 10%-20%. According to the latest reports, China's Fudan University, after 10 years of efforts to develop a straw, wood chips as raw materials, liquefaction and isocyanate reaction, synthesis of microbial decomposition of polyurethane. The material not only has excellent properties of ordinary polyurethane, but also can be completely decomposed in a specified time. 3, degradable plastics development trends and development prospects Development trend of degradable plastics: (1) the positive development of efficient photosensitizer, oxidizing agent, biological agent, accelerator and stabilizer induced degradation, further improve the degradable plastics on time with controllable, rapid degradation and complete degradation. (2) in order to avoid the two pollution, and ensure that there are rich raw materials, the synthesis of high polymer biodegradable plastics with natural macromolecule microorganisms will be paid more and more attention. (3) because of its special functions and applications, hydrolytic plastics and edible materials have attracted much attention, and become the hot spot of the adaptation materials of Huang Jing (two). (4) make full use of genetic engineering technology to cultivate biological plants that can produce polyester, so as to reduce the cost of biodegradable plastics. [References]: [1] Zhai Yu Yan. Petrochemical [M]. Beijing: Petroleum Industry Press, 1996. [2] Song Zhaozhen. Production technology of degradable plastics [J]. progress of fine petrochemical industry, 2005, (3): 13-20. [3] Zhou Peng. Research progress of degradable plastics [J]. Shanxi chemical engineering, 2005, (2): 23-27. [4] Zhang Liping. Development and application of degradable plastics abroad. [J]. foreign petroleum, 2002, (3): 37-41. He had [5]. Group status and development trend of degradable plastics [J]. chemical production and technology, 2004, (1): 26-30. [6], Yang Dongzhi. Preparation and characterization of starch based biodegradable plastics [J]. plastics, 2005,34 (3): 51-55. [7] money Bozhang. The application status and development trend of degradable plastics [J]. Shanghai chemical industry, 2004, (2): 43-46