The Necessity and Countermeasures of Synthetic Polymer Waste Recycling

(1 Department of Chemical Engineering, School of Textiles and Clothing, Qingdao University, Qingdao 266033, China; 2. Qingdao Textile Technical Supervision Bureau, Qingdao 266071). It also introduces countermeasures that developed countries can learn from and solve difficult problems in the recycling process.

1 Advantages and Necessity of Synthetic Polymer Waste Recycling and Recycling With the progress of human society, people have profoundly realized that protecting the habitat of human beings that thrives on the habitat of the earth's natural environment is the top priority for human survival and development. Uncontrolled exploitation and utilization of natural resources is a serious hazard to the natural environment. It is also considered natural that landfills are incompatible with beautifying the natural environment. Therefore, human beings will inevitably pay more attention to the contradiction between economic development and the ecological environment. They will invest more human, material, and financial resources to conduct research. It is human ideals and efforts to minimize the impact of economic development on the natural environment.

Synthetic polymer materials have been widely used in many fields of national economy for their superior performance. At the same time, it also caused the destruction of petroleum as a raw material for polymer materials (petroleum is non-renewable). The post-consumer polymer discarded poplar, due to its non-biodegradability, will have a longer lifespan in the natural world and will have a long-term impact on the environment.

Humanity is trying to find a more suitable alternative to oil to solve resource and ecological problems. However, this is a goal that will be achieved gradually in the medium to long term. It is imperative to seek an effective solution to the contradiction between the polymer industry and the ecological environment. The necessity and advantages of synthetic polymer waste recycling and regeneration can be summarized as follows: Organic polymer materials, composite materials, with their outstanding performance, are recognized as two major categories of modern four major materials, they all use A large number of synthetic polymers. Petroleum, a raw material for synthetic polymers, is a natural resource with a wide range of uses and limited stocks. Its reserves will be depleted within the 21st century. Taking all measures to use this precious natural resource most effectively should be a subject of serious human research.

It is one of the important measures to maximize the use of waste synthetic polymers. It is also economical.

With increasing human environmental awareness, landfills will be severely restricted. Some waste is forbidden to landfill. For example, many states in the United States prohibit the landfilling and incineration of lead-acid batteries. The ecological requirements for landfills will be more stringent, leading to increased landfill charges. Synthetic polymer waste, due to its light weight, occupies more space under the same density conditions. In view of the above reasons, it is required to reduce the amount of landfills as much as possible. Recycling of wastes with reuse value will inevitably be mentioned on the agenda. Some waste plastics are properly processed and their compressive strength can reach 3 times that of concrete, which may be more suitable for railways.

With the advancement of science and technology, people are becoming more and more interested in energy conservation and harmless production. The reprocessing of recycled plastics precisely meets this requirement, while allowing manufacturers to obtain lower-cost raw materials.

This is an important measure to improve the company's operating conditions and improve economic efficiency. 'Disposal synthetic polymers can be obtained through depolymerization and other methods to obtain monomers, oligomers, chemicals and fuels. They can be used as raw materials for the production of high-quality plastic products and qualified fuels for various motor vehicles. De-agglomeration of some mixed plastics is also under development, which will eliminate the thorny process of separating plastics. In short, if the depolymerization process technology with high production efficiency, low cost, and harmless process can be obtained, the synthesis of polymer materials-processing-manufacturing-consumption-recycling-disintegration will form a cyclic chain and maximize the use of natural resources. Reducing human dependence on limited natural resources, greatly extending the useful life of petroleum, and maximizing the natural appearance of the natural ecological environment will be the most ideal ecological solutions for mankind's handling of synthetic polymer waste.

2 Difficulties in recycling and development strategies that can be used by developed countries 2.1 Foreign recycling methods Synthetic polymer packaging accounts for about 43.3% of U.S. municipal solid waste. The most difficult task for recycling materials is the collection of materials. . In particular, it is collected in a manner that is free from pollution and convenient for regeneration. For the packaging, post-consumer materials are very scattered. It is estimated that American consumers produce an average of only 16kg of plastic bottle waste per year. In addition, there is little economic incentive for consumers to send post-consumer waste to the recycling station. Therefore, in order to achieve a successful recycling of packaging, a complete system of grassroots collection agencies must be established. The way and quantity of waste should be made economically feasible when it is processed. The United States has developed a variety of systems for collecting reusable waste, the most effective of which is the bottle deposit recycling net, which is mainly used for beverage bottles. Nine states in the United States have enacted certain types of legislation for depositing beverage bottles. When consumers buy drinks, they need to pay a deposit, usually 5 cents. When the bottle is returned to the designated collection point, the deposit is refunded. The retailer who sells the beverage must commit (mandatory) to the work of recovering and repaying the deposit. Retailers can get a fee from the wholesaler or deposit sponsor. The recycling rate of bottles exceeds 90%, which is 35% higher than that of states without a deposit system. This legislation makes PET the plastic with the highest recovery rate. At the same time, it promoted the development of this bottle's effective reprocessing system and recycled polymer market. The biggest disadvantage of this collection system is that the pre-packaged material costs more than the above recycling system.

There is also a buy-return system. Recycling centers, which are renewable materials, are paid at a price per pound to consumers who send materials to the center. There is also a reverse vending machine to recycle beverage bottles. Separated from the system, including the buckets in supermarkets where people are required to put their waste packaging supplies, once a month to a mobile multi-materials collection center at a fixed location, at a permanent multi-materials collection center in a community gathering place, this collection method is generally absent. Remunerated. It is worth mentioning that Germany is the country with the most stringent requirements for packaging methods in the world. Industrial groups that bring packages into commercial circulation must be responsible for the recycling and reuse of these packages. The state has stipulated strict indicators, the collection rate has reached 80%, and the reuse rate of collected materials has reached 80% to 90%. Many companies choose to pre-sign with Duales System Deutschland (DSD) to solve consumer packaging problems. DSC is a professional recycling group. Members of the DSC paid a fee to require DSC to collect their packaging, allow the company's retail business to be approved, and ensure that the material recycling rate meets legal requirements. In addition, developed countries also use electronic media to facilitate the convenience of the recycling of recycled materials market. Fine, efficient, and low-cost sorting technology is a prerequisite for obtaining high-use value materials and ensuring that the processing process is economically viable.

Macro classification technology generally refers to the classification technology of complete packages. To make it easier for consumers or processors to determine the type of plastics used for packaging, it is definitely a good method to mark specific codes on plastic packages. InternationalStandardsOrgani-Zat1n(ISO) developed a fairly complex plastic identification code recommended ISO code. Undoubtedly, the use of logo codes will greatly facilitate the macro classification of materials. There are manual methods for its classification, but due to high labor costs and low work efficiency, the United States is replacing manual methods with various automated macro-classification systems it has developed. There are already many commercially available automatic sorting devices of this kind.

The new generation of automatic macro classification system uses a UPC code (Unirersal Product Code) on-line scanner, so long as the UPC code is read out, the computer can determine the plastic variety and color.

Microscopic classification technology generally refers to the classification technology of granulated plastics. It can be classified based on the difference in density of various polymers, and the media used are various. The classification can be based on the difference in surface energy, electro-affinity, particle size, and softening point between polymers. Light classification techniques can also be used.

Molecular classification Even microscopic classification techniques cannot separate blended polymers, such as multilayered packaging. The only effective way to classify this type of material is to dissolve the polymer after it has been dissolved.

2.2.2 Methods to avoid classification All measures to avoid classification can not only significantly reduce the cost of reprocessing, but also obtain high-quality, high-value-added recycled products. Therefore, research in this field should be given high priority.

Use a single variety of polymer as much as possible. For example, PVC (polyvinyl chloride) film labels are used only for PVC packaging.

The label adhesive requirements are water dispersible. Thoroughly remove the aluminum barrier on the inside of the plastic bottle and eliminate the aluminum cap used in the plastic bottle. Change the design structure and eliminate HDPE (high-density polyethylene) mats in PET soft drink bottle caps. European PET beverage bottles and caps are all PET. Will, (3 out of the bottle packaging area, all with PET instead, and so on.

When designing all plastic multilayer packages, consider the compatibility of various polymers. After the post-consumer packaging is reprocessed, it can be used to manufacture high-value-added products. HDPE bottle caps and seals must be compatible with HDPE resins. Recycling eliminates the need for classification and provides high-value end-use films and bottles.

According to the introduction, the mixed polymer waste can be obtained through mild hydrocracking, including gaseous fuels, olefins and aromatics, and further distillation can provide high quality crude gasoline with a recovery rate of 45%.

3.3 Development and Market Issues of Relevant Recycling Processing Equipment PET is only taken as an example. The recycling of PET soft drink bottles requires washing, shredding, granulation, separation, and other equipment as the case requires.

The depolymerization of the polymer into the monomer recovery form also requires related equipment, as well as the addition of a layer of material to the recycled material, and the production of equipment for contact with food packaging is indispensable for recycling.

Table 1 Regenerative DET usage Recycled material types 10,000 tons strapping Extrusion strips andcompounds Alloy and composite sheet Extruded panels 5 million pounds, its market conditions are shown in Table 1. Currently, the market demand for recycled PET in the United States exceeds the supply, it is estimated that In 2000, the amount of recycled materials used was 143% in 1994. 3 Suggestions for China's Synthetic Polymer Wastes China's entry into the WTO is imminent. To facilitate the development of international trade and to make useful contributions to global resources and the environment, it should be as soon as possible. Mandatory use of international ISO plastic identification code.

The use of covers, labels, adhesives, etc. by manufacturers must meet the principle of easy recycling.

As soon as possible, formulate scientific evaluation methods for judging the environmental impact of industrial products and further optimize the relationship between industrial production and the environment and resources.

Using rich labor resources and drawing on the experience of developed countries, especially Germany, we have established a collection, recycling and processing green enterprise group. In addition to adopting traditional means, it uses electronic commerce to cultivate the trading market.