December 16, 2024 – Plastics, an indispensable material in modern industry, come in a wide variety with diverse properties. But what exactly are plastics, and what are the common types and their characteristics?
Essentially, plastics are materials primarily composed of polymer compounds, which can be either synthetic or natural. Under specific temperature and pressure conditions, plastics can be molded into various shapes and retain those shapes at room temperature once the external force is removed. This unique property makes plastics widely applicable in packaging, construction, transportation, electronics, and many other fields.
The main component of plastics is resin, accounting for 40% to 100% of the total plastic material. Based on the molecular structure and properties of the resin, plastics can be categorized into different types. Thermoplastics, with linear or branched macromolecular chains, such as polyethylene and polypropylene, are notable for their ability to be reheated and reshaped multiple times. In contrast, thermosets, like phenol formaldehyde resin and epoxy resin, cannot be reshaped once they have been heated and cured.
Within the vast family of plastics, engineering plastics stand out due to their exceptional performance. Broadly defined, engineering plastics refer to plastics that can be used as engineering materials. More narrowly, they are plastics with metallic properties, capable of withstanding external forces, and possessing good mechanical, electrical, and dimensional stability. They maintain their excellent properties at both high and low temperatures, making them widely used in automobiles, electronics, aerospace, and other high-end applications.
Engineering plastics can be further divided into general-purpose engineering plastics and special engineering plastics. General-purpose engineering plastics, such as polyamide and polycarbonate, offer good overall performance at relatively affordable prices. Special engineering plastics, like polysulfone and polyimide, are even more high-end, featuring high-temperature resistance and use as structural materials, making them indispensable in advanced technological fields.
Additionally, plastics can be classified based on other characteristics. Functional plastics possess special properties such as radiation resistance and superconductivity. Crystalline plastics have orderly arranged molecules to maintain their shape, while amorphous plastics have long-chain molecules tangled or networked to retain their form.
In summary, the variety of plastics is vast, with each type having unique properties and applications. When selecting and using plastics, it is crucial to choose the appropriate type based on specific application scenarios and requirements to ensure product quality and performance.