In troduction of plastic

plastic products
Plastic products are a general term for life, industry and other articles processed by using plastic as the main raw material. Including plastics as raw materials for injection molding, blister and other processes. Plastic is a type of synthetic polymer material with plasticity.
It forms three indispensable synthetic materials in daily life with synthetic rubber and synthetic fiber. Specifically, plastics are natural or synthetic resins as the main components, and various additives are added, which can be molded into a certain shape under certain temperature and pressure conditions, and keep the shape unchanged at normal temperature.
Compared with metal, stone, and wood, plastic products have the advantages of low cost and strong plasticity. They are widely used in the national economy. The plastic industry occupies an extremely important position in the world today. Over the years, the production of plastic products has developed at high speed around the world .
Compared with other materials, plastics have the following performance characteristics:
 Light weight
Plastic is a lighter material with a relative density distribution between 0.90-2.2. Obviously, can the plastic float on the water? Especially foamed plastics, because of the micropores inside, the texture is lighter, and the relative density is only 0.01. This characteristic makes plastics useful in the production of products that require reduced weight.
Excellent chemical stability
Most plastics have good corrosion resistance to chemicals such as acids and alkalis. Especially the polytetrafluoroethylene (F4) commonly known as plastic king, its chemical stability is even better than gold, and it will not deteriorate after being cooked in "aqua" for more than ten hours. Because F4 has excellent chemical stability, it is an ideal corrosion-resistant material. For example, F4 can be used as a material for transporting corrosive and viscous liquid pipelines.
 Excellent electrical insulation properties
Ordinary plastics are poor conductors of electricity, and their surface resistance and volume resistance are very large, which can be expressed by numbers up to 109-1018 ohms. The breakdown voltage is large, and the dielectric loss tangent is very small. Therefore, plastics are widely used in the electronics industry and machinery industry. Such as plastic insulated control cables.
 Poor thermal conductor, with noise reduction and shock absorption
Generally speaking, the thermal conductivity of plastic is relatively low, which is equivalent to 1 / 75-1 / 225 of steel, and the micropores of foam plastic.
It contains gas, which has better heat insulation, sound insulation and shock resistance. For example, the thermal conductivity of polyvinyl chloride (PVC) is only 1/357 of steel and 1/1250 of aluminum. In terms of thermal insulation capacity, single glass plastic windows are 40% higher than single glass aluminum windows and 50% higher than double glass. After combining the plastic form with the hollow glass, it is used in residences, office buildings, wards, and hotels. It has obvious benefits in saving heating in winter and air-conditioning expenses in summer.
Wide distribution of mechanical strength and high specific strength
Some plastics are as hard as stone and steel, and some are soft as paper and leather. From the mechanical properties of plastics such as hardness, tensile strength, elongation and impact strength, they have a wide distribution range and have a lot of choices. Because plastic has a small specific gravity and high strength, it has a high specific strength. Compared with other materials, plastic also has obvious shortcomings, such as easy to burn, stiffness not as high as metal, poor aging resistance, heat resistance, etc.
Introduction of main plastics:
Polyethylene is a polymer of ethylene monomer. The raw material for production is petroleum, coke oven gas or alcohol. Industrially produced polyethylene is generally made by dehydration of ethanol, catalytic hydrogenation of acetylene or pyrolysis at high temperature. Its trade name is abbreviated as "Yisu"; its abbreviation is PE. Due to the different density of polyethylene, it is divided into low density polyethylene, medium density polyethylene, and high density polyethylene.
Polypropylene (Polypropylene) is made from propylene under the action of a methylene aluminum and titanium trichloride catalyst under the conditions of 20 atm and 50 ° C using gasoline as the solvent for polymerization. Its trade name is abbreviated as "Bingsu" and its English abbreviation is PP.
Polystyrene is a plastic with a linear structure made by polymerizing styrene monomer. Its trade name is abbreviated as "Benzene" and its English abbreviation is PS. The synthesis of polystyrene often uses block polymerization and emulsion polymerization.
Polyvinyl chloride plastic is polymerized by vinyl chloride monomer and is one of the commonly used thermoplastics. Its trade name is abbreviated as "chloroplastic" and its English abbreviation is PVC.
The commercial names of phenolic plastics are "bakelite" and "bakelite", which are represented by PF. It is made of phenol and aldehyde as raw materials, polycondensed into phenolic resin under the action of acid or alkaline catalyst, and can be made into plastic by adding wood powder filler.
Urea-formaldehyde resin is synthesized from urea and formaldehyde, and can be made into urea-formaldehyde plastic by adding pulp. Its commercial name is "electric jade", abbreviated English name UF.
Plexiglass is a common name for polymethyl methacrylate. It is a linear resin formed by the polymerization of methyl methacrylate monomer. Its English abbreviation is PMMA.
Nitrocellulose plastic is a plastic made of natural cellulose such as cotton linters or other grasses, wood, etc., which is converted into nitrocellulose by nitrate, and then added with 20-30% plasticizer camphor. Its commercial name is celluloid, and the English abbreviation is CN.
1. Most plastics have strong corrosion resistance and do not react with acids and alkalis.
2. Plastic manufacturing costs are low.
3. Durable, waterproof and lightweight.
4. It can be easily molded into different shapes.
5. It is a good insulator.
6. Plastics can be used to prepare fuel oil and fuel gas, which can reduce crude oil consumption.
1. When recycling waste plastics, sorting is very difficult and economically uneconomical.
2. Plastics are easy to burn and produce toxic gases when burned. For example, polystyrene produces toluene when it is burned. A small amount of this substance can cause blindness, vomiting and other symptoms. PVC burning can also produce hydrogen chloride toxic gases. In addition to burning, it is a high temperature environment that can cause plastics to decompose toxic components, such as benzene Wait.
3. Plastics are made from petroleum-refined products, and petroleum resources are limited.
4. Plastic cannot be broken down naturally.
5. The heat resistance of plastics is poor and easy to age.