Status and development of photodegradable plastic packaging materials
since more than half a century, the technology of plastic industry has developed rapidly, and its applications have penetrated into all fields of industry, agriculture and people's life, and become the four pillar materials of the national economy together with steel, wood and cement. However, the use of plastic will bring a lot of solid waste, especially the wide use of plastic products, such as food packaging bags, beverage bottles, agricultural films, which seriously pollute the living environment of human beings and become a worldwide public hazard. Data shows that the mass percentage of plastics in municipal solid waste has reached more than 10%, while the volume percentage is about 30%, and most of them are disposable plastic packaging and daily use. 3. Some dynamometers are installed with non-standard waste. Their pollution to the environment and damage to the ecological balance have aroused great concern in the society. Therefore, solving this problem has become a top priority for environmental protection
generally speaking, in addition to thermal degradation, the speed of photodegradation and biodegradation of plastics in the natural environment is relatively slow. The degradation of plastics in soil is tracked by CL4 isotopes. The results show that the degradation speed of plastics varies with environmental conditions (rainfall, permeability, temperature, etc.), but in general, the degradation speed is very slow, which is generally considered to take 200 ~ 400 years. In order to solve this problem, industrial developed countries have used burial, incineration and recycling methods to deal with waste plastics, but these methods have insurmountable defects. The landfilling treatment covers a lot of land and makes the landfilling unstable. When incineration is carried out, it is easy to damage the incinerator and discharge dioxins due to its large heat emission, and sometimes other harmful gases may be discharged. For recycling, it is often difficult to collect or even force collection for recycling, and the economic benefit is very poor or even no economic benefit. Therefore, more and more scholars advocate the development and application of degradable plastics, and regard it as an ideal way to solve this world problem. Before providing processed auto parts, developed countries in the world actively developed degradable plastics. The United States, Japan, Germany and other developed countries have successively formulated laws and regulations to restrict or prohibit the use of non degradable plastics
degradable plastics
degradable plastics refer to a kind of plastics whose properties can meet the use requirements, the performance remains unchanged during the storage period, and can degrade into environmentally friendly substances under natural environmental conditions after use. Degradable plastics can be divided into biodegradable plastics, photodegradable plastics and environmental degradable plastics according to their degradation mechanism. The 21st century is an era of protecting the earth's environment and an era of increasing tension in resources and energy. In order to deal with those large, scattered, dirty and difficult to collect, ensure that the power supply voltage meets the input voltage value specified by the tension machine, or force collection for recycling, the disposable plastic waste with poor or no economic benefits not only pollutes the ecological environment, but also a great waste of resources and energy. Degradable plastics can reduce white pollution and have significant economic and social benefits. Therefore, the research and development of efficient degradable plastics has become a key issue in the plastic industry, an important development strategy for the packaging industry and the environmental protection industry, and has become a global focus of research and development. At the same time, with the improvement of people's understanding of degradable materials and the continuous strengthening of environmental protection awareness, this kind of materials will have an extremely broad prospect
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