What Are The Specific Classifications Of Plastics?

Plastics are macromolecular compounds (macromolecules) made by polymerizing monomers as raw materials through polymerization or condensation reactions, with medium resistance to deformation, between fibers and rubbers, and consisting of synthetic resins and additives such as fillers, plasticizers, stabilizers, lubricants, and colorants.

The main component of plastic is resin. Resin is a polymer compound that has not yet been mixed with various additives. The term resin was originally named after the lipids secreted by plants and animals, such as rosin and wormwood. Resin accounts for about 40% to 100% of the total weight of plastic. The basic properties of plastics are mainly determined by the nature of the resin, but additives also play an important role. Some plastics are basically composed of synthetic resins and contain no or few additives, such as plexiglass.

Plastics are polymers whose main component is a synthetic resin. In addition, there are additives that are added as needed for specific purposes, such as plasticizers to improve plasticity and antioxidants to prevent aging of the plastic. Although the relative molecular mass of polymers is very large, their composition is not complicated and their structure has a certain pattern. They are produced by the polymerization of small molecules, for example, polyethylene plastics are produced by the polymerization of ethylene molecules.

Classification according to usage characteristics

General Purpose Plastics: Generally, these are plastics that are produced in large quantities, have a wide range of uses, are well molded, and are inexpensive. General-purpose plastics have five major varieties, namely, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS) and acrylic-butadiene-styrene co-polymer (ABS). They are all thermoplastics.

Engineering plastics: generally refers to the ability to withstand certain external forces, has good mechanical properties and high and low temperature resistance, good dimensional stability, can be used as an engineering structure of plastics, such as polyamide, polysulfone and so on.

Specialty plastics: generally refers to plastics with special features that can be used in aviation, aerospace and other special applications. Such as fluorine plastic and silicone with outstanding high temperature resistance, self-lubricating and other special features, reinforced plastics and foam with high strength, high cushioning and other special properties, these plastics belong to the category of special plastics.

Reinforced plastics: reinforced plastic raw materials in shape can be divided into granular (such as calcium plastic reinforced plastic), fibrous (such as glass fiber or glass cloth reinforced plastic), flaky (such as mica reinforced plastic) three. According to the material can be divided into cloth-based reinforced plastics (such as rag reinforced or asbestos reinforced plastics), inorganic mineral-filled plastics (such as quartz or mica-filled plastics), fiber reinforced plastics (such as carbon fiber reinforced plastics) three.

Foam: Foam can be divided into rigid, semi-rigid and flexible foam three. Rigid foam has no flexibility, compression hardness is very large, only to reach a certain stress value to produce deformation, stress relief can not be restored to its original state; soft foam flexibility, compression hardness is very small, it is easy to deformation, stress relief can be restored to its original state, the residual deformation of a small; semi-rigid foam flexibility and other properties between the rigid and soft foam.

Classification by Processing Method

According to the different molding methods of various plastics, they can be divided into various types such as film pressing, lamination, injection, extrusion, blow molding, casting plastics and reaction injection plastics.

Blister: Vacuum forming is called blister, is a plastic processing technology, the main principle is to spread the hard plastic sheet heating soften, using vacuum adsorption on the surface of the mold, after cooling molding. Mainly divided into two categories of thick sheet blister thin sheet blister. Widely used in automotive accessories, lighting, advertising, decoration, large machinery shell, display, aerial class, large appliances, sanitary ware and other industries.

Injection molding: that is, thermoplastic plastic injection molding, this method that is the plastic material is melted, and then injected into the film cavity. Once the molten plastic enters the mold, it is cold and molded into a certain shape according to the mold cavity. Common products are: computer chassis shell, connectors, cell phone shells, keyboards, mice, stereos and so on.

Blow molding: also known as hollow blow molding, a rapid development of plastic processing methods. Thermoplastic resin by extrusion or injection molding of tubular plastic parison, while hot (or heated to a soft state), placed in a folio mold, closed mold immediately after the parison into the compressed air, so that the plastic parison blown and tightly adhering to the inner wall of the mold, after cooling demolding, that is, to obtain a variety of hollow products. Common life bottles, barrels, cans, boxes and all the packaging of food, beverages, cosmetics, pharmaceuticals and daily necessities containers with the plastic processing technology are blow molding.

Extrusion: Extrusion molding in plastic processing is also known as extrusion, in rubber processing is also known as pressing out. It refers to the material through the extruder barrel and the role of the screw between the side of the heat plasticization, while being pushed forward by the screw, continuous through the head and made into a variety of cross-section products or semi-products of a processing method. Extruded products are continuous profiles, such as tubes, rods, wires, plates, films, wire and cable coverings. The most commonly used products are PS, PE, PP, TPE, TPE, TPU, etc. The most common products are PS, PE, PP, TPE, TPE, TPU, etc. After the processing is completed in our life there are like what LED lampshade, drainpipe, supermarket price tags and so on.