Types of daily plastic products
Plastics are widely used and have many types.
1. PET, polyethylene terephthalate
main application:
The most common use is for beverage bottles, screen protectors and other transparent protective films. PET can also be spun, which is what we often call polyester, so during the Olympics there is a saying that beverage bottles will be recycled to make clothes. Many sportswear pursuing breathability and lightness are made of polyester. The popular clothing material "Queenliang" was also this thing a long time ago. However, due to the backward spinning methods at that time, the clothing of Zhenliang was not as comfortable to wear as it is now. In addition, PET also has many engineering applications.
Use note:
Non-toxic, but the synthesis process may retain monomers, low molecular oligomers and side reaction products such as diethylene glycol. These are all toxic to a certain extent. The PET raw materials used in beverage bottles have strict national standards.
PET has a higher melting point in plastics. But general bottles are not recommended to be reused, especially for boiling water. Because PET bottles are generally thin and are manufactured by blow molding, when the bottle body is heated to about 90°C, due to the rearrangement of the PET molecular chain and internal stress, the bottle body will twist and shrink, and use at this time will easily cause burns. In addition, higher temperatures increase the risk of hazardous substances leaching out of 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 used in all aspects of daily life. More representative ones include plastic barrels, films, inner walls of paper cups, water pipes and cable sheaths.
Use note:
PE itself is non-toxic. However, some processing or modification additives, such as fillers, stabilizing additives or pigments, are used in production. Some additives are toxic. Since PE products will soften or even melt at higher temperatures, use at temperatures 100°C higher than the boiling water temperature should be avoided as much as possible.
3. PVC, polyvinyl chloride
main application:
PVC is now mostly used to make some cheap artificial leather, foot pads, sewer pipes, etc.; due to its good electrical properties and certain flame retardant properties, it is widely used in the manufacture of wire and cable sheaths. In addition, PVC is widely used in industrial fields, especially in places with high requirements for acid and alkali corrosion.
Use note:
A large number of plasticizers (plasticizers, such as DOP) and heat stabilizers containing heavy metals are used in the production of PVC, and it is difficult to eliminate the existence of free monomers during the synthesis process, which are considered to be toxic. Therefore, PVC is gradually being replaced by PP and PE in the application of human body contact, especially in medical and food applications.
PVC is a kind of plastic that is not resistant to high temperatures and cannot be used in places with higher temperatures.
4. PP, polypropylene
main application:
The scope of application of PP is also very wide, daily necessities such as packaging, toys, washbasins, buckets, hangers, water cups, bottles, etc.; engineering applications such as car bumpers. PP spun into silk is called polypropylene and is very common in textiles, non-woven fabrics, ropes, fishing nets and other products.
Use note:
PP and PE have similar processing methods and scope of use, and they are also non-toxic. The possible threat comes from the additives in processing and modification. Especially due to the poor weather resistance of PP, anti-aging agents containing heavy metals may be used in production. Compared with PE products, PP products have slightly better heat resistance, and the temperature of typical LOCK&LOCK water cups can reach
It reaches 110°C, but no matter how high the temperature is, there is a danger of softening and melting, and it should be avoided as much as possible.
5. PS, polystyrene
main application:
Cheap transparent products, foam plastics, CD boxes, water cups, fast food boxes, insulation linings, etc.
Use note:
The raw materials used to synthesize polystyrene are poisonous. Through a suitable synthesis process, the residual monomers of polystyrene are already very small, but this material is rarely used in water cups.
Polystyrene is flammable, especially PS after foaming. Burning will produce a lot of toxic gas. In some high-rise fire house accidents, because the widely used PS foam board is used as the insulation material, a large amount of smoke and toxic gas generated after the fire have become the main cause of a large number of casualties.
The following are combined into "other" items in the recycling mark:
6. ABS, acrylonitrile-butadiene-styrene copolymer
main application:
ABS is divided into many kinds according to the content of three components and molecular chain form. It is widely used in various electrical appliance shells, office supplies components, safety helmets, door and window pipes, etc. In industry, ABS is often used in the blending and modification of other plastics.
Use note:
ABS is non-toxic, but it is mostly used in structural materials, and it is rarely used in the packaging of daily utensils.
ABS has many advantages, but it still has the common characteristics of plastics: not heat resistant. Of course, the temperature requirements for the normal use of the electrical enclosure can still be reached.
7, PA, polyamide
main application:
Speaking of another name for polyamide: nylon, everyone must be familiar with it. The polyamide family is very powerful, whether it is PA6, PA66, PA11 or PA12, all have excellent physical and chemical properties. This is also the reason why PA is widely used in the electronics and automotive industries. In daily life, nylon ropes and nylon stockings are also common items. The spun PA fiber is called nylon and is used for fishing lines, fishing nets, ropes and conveyor belts.
Use note:
It has a large molecular weight and is non-toxic. However, it is often blended with other plastics (see "Blends" below) due to its easy moisture absorption and performance changes when used alone. Some additives are used when blending, and these additives may be toxic.
Nylon has good heat resistance, especially heat resistance and resistance to deformation, so it can even be used in the manufacture of engine parts. Although it cannot be compared with cermet materials that can work normally at hundreds of degrees Celsius, the operating temperature of 200 degrees Celsius is enough to surpass most plastics.
8. PC, polycarbonate
main application:
PC has excellent mechanical properties, toughness and rigidity, and good light transmission. It is often used in transparent water cups, baby bottles, drinking buckets, CD substrates, lenses and lampshades in daily life.
Use note:
Non-toxic. However, during the synthesis process of bisphenol A PC, some people worry that there will be residual or decomposed bisphenol A. Bisphenol A is a toxic substance. In addition, the widely used PC synthesis method uses highly toxic phosgene. For these reasons, PC plastics have been questioned a lot.
In fact, PC will be washed and precipitated in the final stage of synthesis to remove unreacted bisphenol A and salts. The PC processing process requires strict drying to avoid decomposition. Although PC products may be in contact with water for a long time during use, they will not decompose below the upper limit temperature of the container. Some studies have found that the thermal decomposition of PC with qualified initial phenol content must reach a high temperature of about 200°C to release phenolic substances, which far exceeds
The normal use temperature of water cups, etc.
9. Blend (XX-XX alloy)
Because it is difficult for a single plastic to meet complex use requirements, different plastics are often mixed together in the plastics industry to make plastic alloys, which can not only take advantage of 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, mobile phone shells are mostly PC-ABS alloy; some sewer pipes are made of two kinds of PE alloys in order to meet the needs of performance and processing, called bimodal polyethylene.
Use note:
Although combining the advantages of multiple plastics, the material is still plastic after all, and heat resistance is still a big pain. However, in actual applications, most products will not be exposed to high temperatures. As long as you pay attention to the application environment, plastic is definitely a good material for cheap and suitable.
There will be relevant national mandatory standards for plastics that come into contact with food and drugs, and the standards are still relatively high. As long as the use of plastics and related additives is regulated, the public's health risks will be minimized. Even if it is a matter of life and death, the FDA's access to drugs will weigh the pros and cons. Regardless of the formulation of ISO, national standards or other standards, it is similar, and you must not give up because of choking.
