Topic 3 Organic Synthetic Materials

Topic 3

organic synthetic material

1. Organic compounds

There are two main types of compounds: inorganic compounds and organic compounds (abbreviated as organics). Organic compounds contain carbon, such as methane, ethanol, and glucose. Sodium chloride, sulfuric acid, and sodium hydroxide do not contain carbon elements, and they are inorganic compounds. A few compounds containing carbon elements, such as carbon monoxide, carbon dioxide and calcium carbonate, have the characteristics of inorganic compounds, so they are regarded as inorganic compounds.

In addition to carbon, organic matter may also contain elements such as hydrogen, oxygen, nitrogen, chlorine and phosphorus. In organic matter, carbon atoms can not only be directly combined with hydrogen, oxygen, nitrogen and other atoms, but also can be connected with each other to form carbon chains or carbon rings. Due to the different arrangement of atoms, the properties displayed are also different. Therefore, the number of organic matter is extremely large. Among the tens of millions of substances that have been discovered, the vast majority are organic substances.

The relative molecular mass of some organic substances is relatively small, such as ethanol, glucose, etc., which belong to small organic molecular compounds. The relative molecular mass of some organic substances is relatively large, ranging from tens of thousands to hundreds of thousands, even as high as millions or higher, such as starch and protein. They are usually referred to as organic polymer compounds, or organic polymers for short .

2. Organic synthetic materials

Materials made of organic polymer compounds are organic polymer materials. Cotton, wool and natural rubber are all natural organic polymer materials, while plastics, synthetic fibers and synthetic rubber, which are most used in daily life, belong to synthetic organic polymer materials, referred to as synthetic materials.?

The emergence of organic synthetic materials is a major breakthrough in the history of material development. Since then, human beings have got rid of the history of relying heavily on natural materials, and have made great progress in the development process. Compared with natural materials, synthetic materials have better performance in many aspects. Moreover, people can synthesize materials with certain special properties according to needs. Synthetic materials are inseparable from our daily life to modern industry, agriculture, national defense and science and technology.

Since most organic polymer compounds are polymerized by organic small molecule compounds, they are often called polymers. For example, a polyethylene molecule is a polymer compound formed by the polymerization of thousands of ethylene molecules . When small molecules are connected to form polymers, some form very long chains, and some form a network from chains

Polymer materials with a chain structure (such as polyethylene plastic) melt when heated, become solid after cooling, and can melt again after heating, so they are thermoplastic. This polymer material can be processed repeatedly and used multiple times, and can be made into thin films, drawn into wires or pressed into various shapes required for use in industry, agriculture and daily life. Some polymer materials with a network structure (such as phenolic plastics, commonly known as bakelite; pulse aldehyde plastics, commonly known as electric jade) will no longer melt when heated, so they are thermosetting.

Plastic is the most common organic synthetic material, which has the advantages of low density, corrosion resistance, and easy processing. There are many kinds of plastics with different uses.

The clothes we wear are usually made of fibers. Cotton, wool, silk, etc. are natural fibers, while polyester, nylon (nylon) and luna are synthetic fibers. Synthetic fibers have high strength, good elasticity, abrasion resistance and chemical corrosion resistance, but they are poor in water absorption and air permeability. Therefore, people often mix synthetic fibers with cotton fibers or wool fibers to make clothes comfortable and wrinkle-resistant .

Rubber was originally obtained from plants such as rubber trees. According to the molecular composition and structure of natural rubber, people have made synthetic rubber by chemical method. Commonly used synthetic rubbers include styrene-butadiene rubber, butadiene rubber and neoprene. Compared with natural rubber, synthetic rubber has high elasticity, insulation, oil resistance, high temperature resistance and non-aging properties, so it is widely used in industry, agriculture, national defense, transportation and daily life.

The application and development of synthetic materials have greatly facilitated human life. However, the sharp increase in waste of synthetic materials has also brought environmental problems, especially the " white pollution " caused by waste plastics . This is because most plastics are difficult to degrade in the natural environment. Long-term accumulation will destroy the soil, pollute the groundwater, and endanger the survival of marine organisms; if the incineration of chlorine-containing plastics will produce gases such as hydrogen chloride with a pungent smell, which will cause air pollution. pollute. To solve the problem of "white pollution", we should start from the following aspects:

Reduce the use of unnecessary plastic products, such as replacing plastic bags with cloth bags;

Reuse certain plastic products, such as plastic bags, plastic boxes, etc.;

Use some new, degradable plastics, such as microbiologically degradable plastics and photodegradable plastics;

Recycling of various waste plastics

Recycling waste plastic is very important, because plastic recycling can not only reduce the amount of waste plastic, but also save resources. But the sorting of plastics is a major obstacle to recycling and reuse, because different types of plastics have different ways to reuse them. In order to solve this problem, some countries have begun to print or mold the logo of the type of material used on plastic products.

In recent years, in order to solve the environmental problems caused by the use of synthetic materials, new organic synthetic materials have gradually developed towards the direction of environmental friendliness. In addition, in order to meet the needs of computer, bioengineering, marine engineering and aerospace industry, and other cutting-edge technology development, people have also developed synthetic materials with special functions such as light, electricity, and magnetism. In order to combine the advantages of different materials, people also combine several materials to form composite materials, such as glass fiber reinforced plastics, carbon fiber composite materials, etc. These new materials have shown potential application prospects in the fields of aerospace, construction, robotics, bionics and medicine, and their development will have a profound impact on human life and social progress.

You should know after finishing this topic

1.All organic compounds contain carbon, but not all compounds containing carbon are organic compounds.

2.Organic macromolecular compounds are organic compounds with a relatively large molecular mass.

3.Plastics, synthetic fibers and synthetic rubber are important organic synthetic materials. The emergence of organic synthetic materials is a supplement to natural resources, and chemistry plays an important role in the development of organic synthetic materials. New organic synthetic materials will surely create a better future for mankind.

4.The use of organic synthetic materials will have an impact on the environment, such as "white pollution".