Compared with other materials, plastic products have the following performance characteristics:
1. Lightweight
Plastic is a light material with a relative density of 0.90-2.2. Obviously, can plastic float to the surface? Foam plastics, in particular, are relatively light because of their micropores, and their relative density is only 0.0 1. This feature enables plastics to be used to produce products that require weight reduction.
2. Excellent chemical stability
Most plastics have good corrosion resistance to chemicals such as acid and alkali. In particular, polytetrafluoroethylene (F4), commonly known as the king of plastics, is even more chemically stable than gold, and will not deteriorate after boiling in aqua regia for more than ten hours. F4 has good chemical stability and is an ideal corrosion-resistant material. For example, F4 can be used as a pipeline material for transporting corrosive and viscous liquids.
3. Excellent electrical insulation performance
Ordinary plastics are poor conductors,
Its surface resistance and volume resistance are very large, which can reach 109- 10 18 ohms in digital terms. The breakdown voltage is large and the dielectric loss tangent is small. Therefore, plastics are widely used in electronic industry and mechanical industry. Such as plastic insulated control cables. 4. Thermal poor conductor has the function of noise elimination and shock absorption.
Generally speaking, the thermal conductivity of plastics is relatively low, which is equivalent to the micropores of steel 1/75- 1/225 and foam plastics.
It contains gas and has good heat insulation, sound insulation and seismic performance. For example, the thermal conductivity of polyvinyl chloride (PVC) is only 1/357 for steel and11250 for aluminum. In terms of thermal insulation capacity, single glass plastic window is 40% higher than single glass aluminum window, and double glass is 50% higher. After the plastic form is combined with insulating glass, it can be used in houses, office buildings, wards and hotels, saving the cost of heating in winter and air conditioning in summer, with obvious benefits.
5. The mechanical strength is widely distributed and the specific strength is high.
Some plastics are as hard as stone and steel, while others are as soft as paper and leather. From the mechanical properties of plastics such as hardness, tensile strength, elongation and impact strength,
It has a wide distribution range and many uses. Because of its low specific gravity and high strength, plastics have high specific strength. Compared with other materials, plastics also have obvious disadvantages, such as easy combustion, lower rigidity than metals, poor aging resistance and heat resistance. The above are the characteristics of plastic products, but "ten fingers have length", and each one has its two sides. What are the advantages and disadvantages of plastic products? Let's see:
superiority
1. Most plastics have strong corrosion resistance and do not react with acid and alkali.
2. The plastic manufacturing cost is low.
3. Durable, waterproof and light.
4. It is easy to be molded into different shapes.
5. It is a good insulator.
6. Plastics can be used to prepare fuel oil and gas, which can reduce the consumption of crude oil.
disadvantaged
1. When recycling waste plastics, sorting is very difficult and uneconomical.
2. Plastic is easy to burn, which will produce toxic gas.
For example, when polystyrene burns, it will produce toluene, a small amount will lead to blindness, and inhalation will vomit. When PVC burns, it will also produce toxic gas of hydrogen chloride. In addition to combustion, it is a high temperature environment, which will lead to the decomposition of toxic components such as benzene rings in plastics. 3. Plastics are products refined from petroleum, and the petroleum resources are limited.
4. Plastics can't decompose naturally.
5. Plastic has poor heat resistance and is easy to age.
Many animal tragedies have been caused by the unnatural degradation of plastics. For example, monkeys, pelicans, dolphins and other animals in the zoo will accidentally swallow the 1 plastic bottle thrown by tourists, and finally die of indigestion; Looking at the beautiful and pure sea, I took a closer look. In fact, it is full of all kinds of plastic garbage that the ocean can't accommodate. In the intestines of many dead seabirds, I found all kinds of indigestible plastics.
The most dangerous plastic products are phthalates, which is the main reason for the decline in the number of men. At present, the EU has banned the use of phthalates in cosmetics, teething rings and children's toys. However, pregnant women are still exposed to phthalates, because this chemical is often used to soften household items, such as plastic furniture, shoes, PVC floors and shower curtains.
Phthalates will enter the human body through food and water packaged in plastic containers, such as canned food, recyclable milk and the inner coating of mineral water bottles. Studies have shown that the higher the fat content in canned foods, the easier it is to be polluted, such as pork, anchovies and sardines. Fetuses, infants and adolescent children are the most sensitive to it, and their health is also the most fragile.
In order to reduce the harm of phthalate esters to human body,
Usually, we should pay attention to it. It is best not to soak instant noodles in foamed plastic containers, nor to heat imported food in the microwave oven with plastic containers filled with PVC. The correct way is to heat food with heat-resistant glassware or ceramic ware. The above is an introduction to the characteristics, advantages and disadvantages of plastic products, and friends who like it can collect it.