Where there is white pollution

White pollution is a unique environmental pollution in China's cities, a large number of discarded plastic products can be seen everywhere in various public places, they come from nature, made by human beings, and are not easy to be absorbed by nature when they are ultimately attributed to nature, thus affecting the ecological environment of nature. From the perspective of resource conservation, because plastic products are mainly facing depleted petroleum resources, they should be as much as possible, but because the production cost of re-production at this stage is much higher than the direct production cost, it is difficult to do so under the current market economy conditions. In the face of the increasingly serious problem of white pollution, people hope to find a plastic substitute that can replace the current plastic performance, and does not cause white pollution, degradable plastic came into being, this new functional plastic, which is characterized by a certain service life after being discarded, under specific environmental conditions, due to its chemical structure changes significantly, causing some performance loss and appearance changes and degradation, harmless or less harmful to the natural environment.

For example, starch filled plastic, first of all, the starch contained in it is quickly decomposed by the amylase secreted by the microorganisms in the soil in a short period of time and forms a cavity, resulting in the decline of the mechanical properties of the film, and at the same time, the self-oxidizer added in the formula reacts with the metal salts in the soil to form peroxide, so that the chain of polyethylene is broken and degraded into small fragments that are easily swallowed by microorganisms, which are absorbed by the natural environment and play a role in improving the soil.

Basically, there is white pollution in modern places, white pollution mainly refers to waste plastic products, these plastic products are difficult to be naturally degraded, although these products have brought convenience to human beings, but also caused serious environmental pollution, because of its convenience so large area of use, pollution to the soil.

In the place of a large number of discarded plastic products.

Refers to the pollution caused by plastic products, such as plastic bags...

1. It is difficult to dispose of waste plastic packaging mixed with domestic garbage: landfill treatment will occupy land for a long time, and it is not suitable for composting treatment, and waste plastic packaging is mixed in the soil, which affects the absorption of nutrients and water by crops, which will lead to a reduction in crop yield.

2. The sorted waste plastic is also difficult to use because the quality cannot be guaranteed, if incinerate, because the plastic bag is often mixed with soil and water, it is difficult to burn through, and even cause secondary pollution of the environment.

3. Waste plastic packaging discarded on land or water bodies is swallowed by animals as food, resulting in the death of animals.

4. Almost all white garbage is combustible, and methane and other combustible gas will be produced in the natural stacking process, and fire accidents caused by open flames or spontaneous combustion continue to occur, often causing heavy losses.

5. White garbage can become a nest for pests, they can provide food, habitat and breeding places for rats, birds, mosquitoes and flies, and the residue in it is often the source of infectious diseases.

The so-called "white pollution" is an image of people polluting the environment with plastic waste. It refers to the phenomenon that all kinds of plastic products made of polystyrene, polypropylene, polyvinyl chloride and other polymer compounds are discarded as solid waste after use, and are littered at will and difficult to degrade, resulting in environmental pollution.

Agricultural plastic mulch film has played a great role in moisture preservation, heat preservation and crop yield, but with the increase in the use of agricultural film year by year, "white pollution" is becoming more and more serious, causing great damage to the farmland environment. At present, most of the plastic film is made of polyethylene, which is not easy to decompose in the natural environment, and it is not easy to remove the accumulation in the farmland, and the residual film remains in the soil even after decades. If excessive residual film accumulates in the soil, it will reduce the water conduction, storage and capillary function of the soil, thereby affecting the growth and development of plant roots, water and fertilizer absorption, and leading to soil pollution.

The types of white pollution are:

1. Polyethylene.

Polyethylene is a thermoplastic resin prepared by addition polymerization of ethylene. Depending on the polymerization conditions, polyethylene with relative molecular weights ranging from 10,000 to millions can be obtained. Polyethylene is a slightly white granule or powder, translucent, non-toxic and odorless, with good chemical stability and acid and alkali corrosion resistance.

Polyethylene is commercially divided into low, medium and high densities. The main thing used for packaging is low density (g cm3) without plasticizers.

2. Polypropylene.

The relative molecular weight is between 90,000 and 200,000. The polypropylene backbone has a methyl side chain. If the methyl group is all distributed on one side, it is called isometric polypropylene; If the methyl group is regularly distributed on both sides of the main chain, it is called inter-regular polypropylene; If the methyl group is irregularly distributed on the main chain, it is called random polypropylene.

Polypropylene is usually a translucent solid, odorless and non-toxic, with density (0 90g cm3-0 91g cm3), higher mechanical strength than polyethylene, and good heat resistance. Among the three types of polypropylene, isometric polypropylene has the largest output. Using titanium trichloride-chlorodiethyl aluminum as a catalyst, propylene was polymerized in hydrogenated gasoline to obtain isometric polypropylene.

3. Polyvinyl chloride.

The relative molecular weight is 50,000 to 120,000, and polyvinyl chloride is formed into a polymer through free radical addition polymerization, which is a thermoplastic resin. Amorphous white powder, no fixed melting point, density of (1 35g cm3-1 45g cm3), with good chemical stability. Melted in cycloethyl ketone, chlorobenzene, dimethylformamide, toluene-acetone mixed solvent, etc.

Fourth, polystyrene.

The average relative molecular mass is about 200,000. Colorless and odorless transparent resin, good light transmittance. The surface is shiny, flammable, and has excellent waterproofness, corrosion resistance, and electrical insulation

Production method: bulk polymerization method, suspension polymerization method, emulsion polymerization method Here is an introduction to the bulk polymerization method. Initiator and a small amount of additives are added to the styrene monomer, low-temperature polymerization is carried out in the prepolymerization kettle, the prepolymer is prepared, and then transferred to the polymerization tower for high-temperature heating, and the temperature is maintained in stages.

Among these pollutants are plasticizers, blowing agents, heat stabilizers, antioxidants, etc.