Several common plastic wastes

  • Detail

Several common plastic wastes

※ polyethylene waste

polyethylene is a thermoplastic with the largest output and wide applications in plastics. It is polymerized from ethylene and is part of the crystalline material, which can be processed by the molding method of general thermoplastic. Polyethylene can be divided into high-density polyethylene, low-density polyethylene and linear low-density polyethylene

the density of high-density polyethylene is generally higher than 0.94g/, while the density of low-density polyethylene and linear low-density polyethylene is between 0.91~0.94g/cm. There are two main sources of waste polyethylene film:

1 Leftover materials and defective products produced in film production. These wastes are clean, with clear varieties. They can be crushed and compressed and directly sent to the extruder for granulation. The recovery process is relatively simple

2. Waste films from chemical industry, electrical industry, food and consumer goods industry, etc. These waste films have been polluted, some have been colored and printed with trademarks, and some also contain impurities such as sand, sawdust or shredded paper

polyethylene has a wide range of applications due to its low price, easy availability and convenient molding, but it is packaging products that are most used, which is estimated to be more than 60%. High density polyethylene is mainly used in packaging films, bottles and hollow containers; The main uses of LDPE are packaging film and agricultural film; Linear low-density polyethylene is mainly used in film, film plastic parts, pipes, wires and cables

※ PVC waste

PVC used to be the most used plastic in history. Now it is replaced by polyethylene and pet in some fields, but it is still used in large quantities, and its consumption is second only to polyethylene and polypropylene. PVC products are very rich in forms, which can be divided into three categories: hard PVC, soft PVC and PVC paste. UPVC is mainly used for extruded products such as pipes, door and window profiles and sheets, as well as injection molded parts such as pipe joints and electrical parts and extruded bottle products, which account for more than 65% of the consumption of PVC. Soft PVC is mainly used for calendering sheets, automotive interior accessories, handbags, films, labels, wires and cables, and medical blades; (3) Load bar, but the position of the adjusting block on the bar at the beginning of the experiment is not appropriate. PVC paste accounts for about 10% of PVC products, and the main products are plastic lined products

※ the experimental machine adopts a neuron based adaptive control system. Polymethylmethacrylate waste

polymethylmethacrylate (PMMA) is commonly known as plexiglass. PMMA has unique properties that other plastics do not have: excellent transparency (close to glass); Good toughness, chemical resistance and weather resistance. Therefore, it has been widely used in automobiles, medical devices, indoor swimming pools and other places. With the development of automobile and other related industries, the consumption of PMMA is also increasing. PMMA products mainly fall into three categories: sheets obtained by casting or extrusion; Specific products that contain modifiers, pigments and other additives; Paint and coating

※ polystyrene waste

polystyrene is a homopolymer of styrene, a thermoplastic general-purpose plastic, and its output is second only to polyethylene, polypropylene and polyvinyl chloride. Polystyrene has a wide range of applications. It can be roughly divided into the following four aspects:

general purpose polystyrene: products on a large number of daily-use products and transparent products such as household appliances, computers, medical treatment, etc

high impact polystyrene: its impact strength and elongation at break are greatly improved. The products are widely used in electrical accessories, home appliance shells, food containers, etc

extruded expanded polystyrene sheets and their thermoformed products: thick plates are mainly used as heat insulation, sound insulation and shock proof materials. Thermoformed products are widely used in food packaging and fast food containers

expandable polystyrene foam products: products are used for shockproof packaging of electrical appliances, thermal insulation materials in construction, refrigeration and other industries

the first two types of polystyrene products have a long service life, and the waste thickness can be recycled by conventional recycling methods, so the pressure on the environment is also small. The second kind of polystyrene products are mostly disposable packaging, with large volume and large consumption. If they are directly discarded without treatment, it will cause great pressure on the environment. Because we have 10 feet of confidence and determination in China's composite material market. A large part of what people often call "white pollution" is foam polystyrene

※ polyethylene terephthalate waste

polyethylene terephthalate (PET) is a condensation polymer of terephthalic acid or dimethyl terephthalic acid and ethylene glycol, which is a linear thermoplastic. Pet is usually a crystalline plastic, but in bottle and film products, in order to be highly transparent, special process conditions can be used to make it an amorphous plastic

pet is widely used because of its excellent performance and low cost. According to its product form, it can be divided into four categories: polyester fiber, film, engineering injection molded parts, and bottles. PET bottles have been widely used in food, beverage, cosmetics and other fields, especially in beverage bottles, because of their light weight and low energy consumption. Beverage bottles are disposable, so the waste is huge

The recovery technology of PET bottles has reached a high level abroad, and the recovery rate in the United States, Germany and other countries has reached more than 80%. Moreover, in order to facilitate recycling, these countries have also formulated some local regulations, which have mandatory provisions on the waste, collection, use, design and manufacture of PET bottles

Copyright © 2011 JIN SHI