In the field of modern materials science, polymers occupy a vital position. Polymers, that is, high molecular compounds, can be classified in many ways according to their composition, structure and properties.
According to the source classification, polymers can be divided into natural polymers and synthetic polymers. Natural polymers are widely present in nature. For example, cellulose, which is the main component of plant cell walls, provides many important materials for humans. Paper, cloth, etc. are made on the basis of cellulose. There is also protein, which is the main bearer of life activities and plays a variety of key functions in organisms, from structural support to catalytic reactions.
Synthetic polymers are artificially synthesized polymers. There are many types of polymers that meet the needs of different fields. Taking plastics as an example, polyethylene is a common synthetic polymer. It has good flexibility and corrosion resistance. It is widely used in the packaging industry, such as food packaging bags. Polypropylene is also a widely used synthetic polymer. It has a relatively high hardness and performs well in the manufacture of automotive parts and home appliance housings.
According to the thermal properties of polymers, they can be divided into thermoplastic polymers and thermosetting polymers. Thermoplastic polymers soften or melt when heated and can be processed and formed many times, such as polyvinyl chloride, which can be used to make plastic pipes, doors and windows, etc. Thermosetting polymers can no longer be processed repeatedly after being heated and cured. Once formed, they will only decompose when heated again, such as phenolic resin, which is often used to make electrical insulation materials, automotive brake pads, etc.
According to the structure of the molecular chain, polymers can also be divided into linear polymers, branched polymers and cross-linked polymers. Linear polymer molecular chains are straight chains, branched polymer molecular chains have branched structures, and cross-linked polymer molecular chains are connected by chemical bonds to form a network structure.
Understanding the classification of polymers will help us better understand and use these magical polymer materials and promote the development and progress of various industries.