Plastic

Plastics can be classified according to their chemical structure, namely the molecular units that make up the backbone and backbone of the polymer. Some important groups in these classifications are acrylics, polyesters, silicones, polyurethanes, and halogen resins. Plastics may also be classified according to the chemical process used in their synthesis; for example, like condensation, polyaddition, cross-linking, etc. Other classification based on quality is relevant to the manufacture or design of the product. Plastics can also be ranked by various physical properties such as density, tensile strength, glass transition temperature, resistance to various chemical products, etc.

Due to its relatively low cost, ease of manufacture, flexibility and water repellency, plastics are used in a wide range of products, from tapes to spacecraft. They relocated many traditional materials, such as wood; Rock; horns and bones; skin; paper; metal; glass; and ceramic, in most applications before. The use of plastics is largely limited by their organic chemistry, which severely reduces hardness, density and resistance to heat, organic solvents, oxidation and ionizing radiation.

In particular, most plastics will melt or decompose when heated to a few hundred degrees celsius. While plastics can be conductive to some extent, they are still not suitable for metals such as copper or aluminum. Dyeing is still too expensive to replace wood, concrete and ceramic in bulky objects such as ordinary buildings, bridges, dams, pavements, railways, etc.