Plastics are widely used and of various kinds, with only one "general plastic manual" of nearly one thousand pages. This paper hopes to help you understand plastics and understand plastics correctly.
1. Pet, polyethylene terephthalate
Main applications:
The most common are used as beverage bottles, screen protectors and other transparent protectors. Pet can also be spun, which is what we often call polyester. Therefore, during the Olympic Games, there was a saying that recycled beverage bottles were used to make clothes. Many sportswear that pursues breathability and portability are made of polyester. Dacron, a popular cloth material long ago, was also made of Dacron. However, due to the backward spinning methods at that time, dacron clothes were not as comfortable as they are now. In addition, pet has many engineering applications.
Note for use:
It is nontoxic, but monomers, oligomers and by-products such as diethylene glycol may remain in the synthesis process, which are toxic to some extent. There are strict national standards for PET raw materials used in beverage bottles.
Pet has a high melting point in plastics. However, the general bottle is not recommended to be reused, especially for boiling water. Because PET bottle is generally thin, it is made by blow molding. When the bottle body is heated to about 90 ℃, due to the rearrangement of PET molecular chain and the internal stress, the bottle will twist and contract, which is easy to cause scald. In addition, higher temperature will increase the risk of dissolution of harmful substances in materials.
2. PE, polyethylene (HDPE: HDPE; LDPE: LDPE)
Main applications:
At present, PE is the most widely used plastic. With the help of different modification methods, PE can be used in all aspects of daily life. Typical ones include plastic barrel, film, inner wall of paper cup, water pipe and cable sheath, etc.
Note for use:
PE itself is non-toxic. However, some processing or modification AIDS, such as fillers, stabilizers or pigments, will be used in the production. Some additives are toxic. PE products will soften or even melt at high temperature, so it should be avoided to use at 100 ℃ higher than boiling water temperature.
3. PVC
Main applications:
PVC is now mostly used to make some cheap leathers, foot mats, water pipes, etc.; because of its good electrical performance and its own flame retardant characteristics, it is widely used in the skin manufacturing of wires and cables. In addition, PVC is widely used in the industrial field, especially in places with high requirements for acid and alkali corrosion resistance.
Note for use:
A large number of plasticizers (plasticizers, such as DOP) and heat stabilizers containing heavy metals will be used in PVC production, and it is difficult to eliminate the existence of free monomers in the synthesis process, which are considered to be toxic. Therefore, PVC is gradually replaced by PP and PE in contact with human body, especially in the application of medicine and food.
PVC is a kind of heat-resistant plastic, which can not be used in places with high temperature.
4. PP, polypropylene
Main applications:
PP is also widely used, such as packaging, toys, washbasins, buckets, hangers, cups, bottles, etc.; engineering applications such as car bumpers, etc. PP spun into silk is called polypropylene fiber, which is very common in textiles, non-woven fabrics, ropes, fishing nets and other products.
Note for use:
PP is similar to PE in processing method and application scope, and is non-toxic. The possible threat comes from additives in processing and modification. In particular, due to the poor weather resistance of PP, aging agents containing heavy metals may be used in production. Compared with PE products, PP products have a slightly better heat resistance. The typical use temperature of the Teflon water cup can reach 110 ℃, but the higher the temperature, there is a danger of softening and melting, which should be avoided as much as possible.
5, PS, polystyrene
Main applications:
Cheap transparent products, foam plastics, CD boxes, water cups, snack boxes, thermal insulation liners and so on.
Note for use:
The raw materials used for the synthesis of polystyrene are toxic. Through the appropriate synthesis process, there are few residual monomers of polystyrene, but now there are few water cups and so on.
Polystyrene is flammable, especially PS after foaming. Combustion produces a lot of toxic gases. In some high-rise fire accidents, because the widely used PS foam board is used as the thermal insulation material, a large number of smoke and toxic gases produced after the fire become the main cause of a large number of casualties.
The following are combined as "other" items in the recycling ID:
6. ABS, acrylonitrile butadiene styrene copolymer
Main applications:
According to the content of three components and molecular chain shape, ABS can be divided into many kinds, which are widely used in various electrical enclosures, office supplies components, safety helmets, doors and windows pipes, etc. in industry, ABS is often used in blending modification of other plastics.
Note for use:
ABS is nontoxic, but it is mostly used in structural materials, and seldom used in daily utensils packaging.
ABS has many advantages, but it still has the common feature of Plastics: heat resistance. Of course, it can meet the temperature requirements of the normal use of the electrical shell.
7, PA, polyamide
Main applications:
Mention another name of polyamide: nylon, you must be familiar with it. The polyamide family is very powerful. No matter PA6, PA66, PA11 or PA12, all of them have excellent physical and chemical properties. This is also the reason why PA is widely used in the electronics and automobile industry. Life, nylon rope, nylon socks are also common items. The spinning PA fiber is called nylon, which is used for fishing line, fishing net, rope and conveyor belt.
