What kinds of plastic products are there?

1, PET, polyethylene terephthalate

main application:

The most common are used as beverage bottles, screen protectors and other transparent protective films. PET can also be spun, which is what we often call polyester. Therefore, there is a saying that recycled beverage bottles are made during the Olympics. Many sportswear that pursues breathability and lightness is made of polyester. The clothing that was popular a long time ago is "this is good", but it is limited to the backwardness of the spinning method at the time, and it is true that the clothes are not as comfortable as the current ones. In addition, PET has many engineering applications.

Note:

Non-toxic, but the synthesis process may contain monomer, low molecular oligomers and side reaction products such as diethylene glycol, which are all toxic, and the PET raw materials used in beverage bottles have strict standards.

PET has a higher melting point in plastics. However, general bottles are not recommended for reuse, especially for boiling water. Because the PET bottle is generally thin, it is manufactured by blow molding. When the bottle is heated to about 90 °C, the bottle body will be twisted and contracted due to the rearrangement and internal stress of the PET molecular chain. At this time, the use is easy to cause burns. In addition, higher temperatures increase the risk of the release of harmful substances in the material.

2, PE, polyethylene (high density polyethylene: HDPE; low density polyethylene: LDPE)

main application:

At present, PE is the most widely used plastic. With different modification methods, PE can be applied in all aspects of daily life. More representative ones include plastic drums, films, paper cup inner walls, water pipes and cable sheaths.

Note:

PE itself is non-toxic. However, some processing or modifying auxiliaries such as fillers, stabilizing auxiliaries or pigments are used in the production. Some auxiliaries are toxic. PE products should be used at temperatures higher than 100 ° C above the boiling water temperature because they will soften or even melt at higher temperatures.

3, PVC, PVC

main application:

PVC is now used to make some cheap artificial leather, foot mats, sewer pipes, etc.; due to its good electrical properties and certain self-flame retardant properties, it is widely used in the manufacture of wire and cable sheaths. In addition, PVC is widely used in the industrial field, especially where high acid and alkali corrosion resistance is required.

Note:

PVC is a kind of plastic that is not resistant to high temperatures and cannot be used at higher temperatures. A large number of plasticizers (plasticizers such as DOP) and heat stabilizers containing heavy metals are used in the production of PVC, and the synthesis process is difficult to prevent the presence of free monomers, which are considered to be toxic. Therefore, PVC is gradually being replaced by PP and PE in contact with human body, especially for medical and food applications.

4, PP, polypropylene

main application:

PP is also widely used, such as packaging, toys, washbasins, buckets, hangers, cups, bottles, etc.; engineering applications such as car bumpers. The spun silk PP is called polypropylene and is very common in textiles, nonwovens, ropes and other products.

Note:

The processing method and use range of PP and PE are similar, and they are also non-toxic. Possible threats come from additives in processing and modification. In particular, due to the poor weatherability of PP, ageing agents containing heavy metals may be used in production. Compared with PE products, the heat resistance of PP products is slightly better. The temperature of typical locks and buckles can reach 110 °C, but there is a danger of softening and melting at higher temperatures, which should be avoided.

5, PS, polystyrene

main application:

Cheap transparent products, foam plastics, CD boxes, water cups, snack boxes, insulation linings, etc.

Note:

The raw materials used to synthesize polystyrene are toxic, and the residual monomers of polystyrene have been few through suitable synthetic processes, but this material has rarely been used in water cups and the like.

Polystyrene is flammable, especially PS after foaming. Combustion produces a large amount of toxic gases. In some high-rise fire accidents, because the insulation layer material uses the widely used PS foam board, a large amount of smoke and toxic gas generated after the fire has become the main cause of a large number of casualties.

6, ABS, acrylonitrile-butadiene-styrene copolymer

main application:

ABS is divided into various types according to the content of three components and molecular chain shape, and is widely used in various electrical enclosures, office supplies components, helmets, door and window pipes, etc. In industry, ABS is often used for blending modification of other plastics.

Note:

ABS is non-toxic, but it is mostly used for structural materials. Applications on daily ware packaging are rare. ABS has many advantages, but it still has the general characteristics of plastic: it is not heat resistant. Of course, it is still possible to meet the temperature requirements for the normal use of the electrical enclosure.

7, PA, polyamide

main application:

Another name for polyamide: nylon, everyone must be familiar. The polyamide family is very powerful, whether it is PA6, PA66, PA11 or PA12, all of which have excellent physicochemical properties. This is why PA is widely used in the electronics, electrical and automotive industries. In life, nylon rope and nylon socks are also common items. The spun PA fibers are called nylon and are used for fishing lines, fishing nets, ropes and conveyor belts.

Note:

Large molecular weight, non-toxic. However, the use alone is often blended with other plastics due to its ability to absorb moisture (see "Blends" below). Some additives are used in the blending, and these additives may be toxic. Nylon has good heat resistance, especially heat resistance and is not easily deformed, so it can be used even for the manufacture of engine parts. Although it is not comparable to cermet materials that work properly at a few hundred degrees Celsius, the temperature at 200 ° C is sufficient to exceed most plastics.

8, PC, polycarbonate

main application:

PC has excellent mechanical properties, is tough and rigid, and has good light transmission. It is often used in transparent cups, bottles, drinking buckets, CD substrates, lenses and lampshades.

Note:

Non-toxic. However, during the synthesis of bisphenol A type PC, there is concern about the presence or absence of residual bisphenol A. Bisphenol A is a toxic substance. In addition, the widely used PC synthesis method uses highly toxic phosgene. For these reasons, PC plastic has suffered a lot of questions.

In fact, PC will be washed and precipitated in the final stage of the synthesis to remove unreacted bisphenol A and salts. The processing of the PC requires strict drying to avoid decomposition. Although the PC product may be in contact with water for a long period of time in use, it does not decompose below the specified upper limit temperature of the container. Some studies have found that PC heat fractions with acceptable initial phenol content liberate phenolic materials to temperatures of around 200 °C, which far exceeds the normal operating temperatures of water cups and the like.

9, blend (XX-XX alloy)

Since a single plastic is difficult to meet complex use requirements, the plastics industry often mixes different plastics together to form a plastic alloy, which can not only exploit the advantages of different materials, but also save the cost of developing new materials.

main application:

Plastic alloys are widely used in various structural materials. For example, the outer casing of the mobile phone is mostly PC-ABS alloy; some sewer pipes are made of two kinds of PE alloys, called ** polyethylene, in order to meet the performance and processing requirements.

Note:

Although combined with the advantages of a variety of plastics, but the material is still plastic, heat resistance is still a major pain. However, most products in actual application will not be exposed to high temperatures. As long as attention is paid to the application environment, plastic is definitely a good material for cheap use.

Plastics that come into contact with food and medicines have relevant national mandatory standards, and their standards are still high. As long as plastics and related additives are used, public health risks will be minimized. Even the FDA's access to drugs for life and death will have a trade-off between pros and cons, regardless of the ISO, national standard or other standards, and must not be squandered.