It’s a bit long, so take a long look. . A brief history of plexiglass acrylic (acrylic) As early as the 1920s, Rohm and Haxin Company first invented the method of polymerizing MMA into acrylic sheets. This sheet was later called "Oroglas/Plexiglas". Features:
Good weather resistance, acid and alkali resistance, no yellowing or hydrolysis caused by years of exposure to the sun and rain
Long life, unlike other materials Compared with other products, the service life is more than three years longer
The light transmittance is good, up to 92 or more, the required light intensity is smaller, saving electric energy
It has strong impact resistance and is an ordinary Sixteen times that of glass, suitable for installation in areas that require special safety
Excellent insulation performance, suitable for various electrical equipment
Light in weight, half lighter than ordinary glass, buildings and supports It bears a small load
It has bright colors and high brightness, which cannot be compared with other materials
It has strong plasticity, large shape changes, and easy processing and molding
Recyclability rate High, recognized by the increasingly strengthened environmental awareness
Easy to maintain and clean, it can be cleaned naturally with rainwater, or wiped with soap and soft cloth
Classification, composition and Performance plastic is a synthetic polymer material with a wide range of uses. Plastic products abound in our daily lives. From the toiletries we use after getting up, the tableware we use for breakfast, to the stationery we use when working and studying, the seat cushions and mattresses we use when resting, as well as the casings of TVs, washing machines, computers, and what the night brings to us Bright lamps of various shapes... With its excellent performance, plastic has gradually replaced many materials and utensils that have been used for decades or centuries, becoming an indispensable assistant in people's lives. Plastic combines the hardness of metal, the lightness of wood, the transparency of glass, the corrosion resistance of ceramics, and the elasticity and toughness of rubber. Therefore, in addition to daily necessities, plastics are more widely used in aerospace, medical equipment, petroleum Chemical industry, machinery manufacturing, national defense, construction and other industries. 1. Classification of plastics
There are many types of plastics. So far, there are about 300 kinds of plastics put into production in the world. There are many classification methods for plastics, and there are two commonly used ones:
1. According to the different properties of plastics after heating, they are divided into thermoplastic plastics and thermosetting plastics.
The molecular structure of thermoplastic plastics is linear. Type structure, softens or melts when heated, can be molded into a certain shape, and hardens again after cooling. It softens again after being heated to a certain extent, and hardens again after cooling. This process can be repeated many times. Such as polyvinyl chloride, polyethylene, polystyrene, etc. The thermoplastic molding process is relatively simple, can be produced continuously, and has very high mechanical strength, so it is developing rapidly.
The molecular structure of thermosetting plastics is a body structure. It also softens when heated and can be molded into a certain shape. However, when heated to a certain extent or a small amount of curing agent is added, it hardens and sets and is heated again. It won't soften or change shape. After thermosetting plastics are processed and formed, they no longer soften when heated, so they cannot be recycled and reused. Such plastics include phenolic plastics, amino plastics, and epoxy resins. The molding process of thermosetting plastics is relatively complex, so continuous production has certain difficulties, but it has good heat resistance, is not easy to deform, and is relatively cheap.
2. According to the different uses of plastics, they are divided into general plastics and engineering plastics
General plastics refer to plastics with large output, low price and wide application range, mainly including polyolefin, polyethylene Five major varieties: vinyl chloride, polystyrene, phenolic plastics and amino plastics. Many of the products people use in our daily lives are made from these common plastics.
Engineering plastics are plastics that can be used as engineering structural materials and as replacements for metal in manufacturing machine parts. For example, polyamide, polycarbonate, polyoxymethylene, ABS resin, polytetrafluoroethylene, polyester, polysulfone, polyimide, etc.
Engineering plastics have the characteristics of low density, high chemical stability, good mechanical properties, excellent electrical insulation, and easy processing and molding. They are widely used in automobiles, electrical appliances, chemicals, machinery, instruments, meters and other industries, as well as in aerospace, rockets , missiles, etc.
2. Composition of plastic
The plastic we usually use is not a pure substance. It is made of many materials. Among them, high molecular polymers (or synthetic resins) are the main components of plastics. In addition, in order to improve the performance of plastics, various auxiliary materials are added to the polymers, such as fillers, plasticizers, lubricants, stabilizers, Colorants, etc., can become plastics with good performance.
1. Synthetic resin
Synthetic resin is the main component of plastics, and its content in plastics is generally 40% to 100%. Due to its large content and the properties of the resin often determine the properties of plastic, people often regard resin as a synonym for plastic. For example, polyvinyl chloride resin and polyvinyl chloride plastic, phenolic resin and phenolic plastic are confused. In fact, resin and plastic are two different concepts. Resin is a raw, raw polymer used not only to make plastics, but also as a raw material for coatings, adhesives and synthetic fibers. Except for a very small part of plastics that contain 100% resin, most plastics need to add other substances in addition to the main component resin.
2. Filling
Filling is also called filler, which can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood powder to phenolic resin can greatly reduce the cost, making phenolic plastic one of the cheapest plastics, and it can also significantly improve the mechanical strength. Fillers can be divided into organic fillers and inorganic fillers, the former such as wood powder, rags, paper and various fabric fibers, etc., and the latter such as glass fiber, diatomaceous earth, asbestos, carbon black, etc.
3. Plasticizers
Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easier to process and shape. Plasticizers are generally high-boiling organic compounds that are miscible with resin, are non-toxic, odorless, and stable to light and heat. The most commonly used plasticizers are phthalates. For example, when producing polyvinyl chloride plastic, if you add more plasticizer, you can get soft polyvinyl chloride plastic; if you add no or less plasticizer (the amount is <10%), you can get hard polyvinyl chloride. plastic.
4. Stabilizer
In order to prevent synthetic resin from being decomposed and damaged by light and heat during processing and use, and to extend its service life, stabilizers should be added to plastics. Commonly used ones include stearate, epoxy resin, etc.
5. Colorants
Colorants can make plastics have various bright and beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.
6. Lubricant
The function of lubricant is to prevent the plastic from sticking to the metal mold during molding, and at the same time, it can make the surface of the plastic smooth and beautiful. Commonly used lubricants include stearic acid and its calcium and magnesium salts.
In addition to the above-mentioned additives, flame retardants, foaming agents, antistatic agents, etc. can also be added to plastics to meet different usage requirements.
3. Characteristics of plastics
1. Plastics have plasticity
As the name suggests, plastics are materials that can be molded. The so-called plasticity of plastic means that solid plastic can be softened by heating, and then the softened plastic can be placed in a mold and allowed to cool and solidify again into a solid shape of a certain shape. This property of plastic also has certain drawbacks, that is, it is easy to soften and deform when exposed to heat. Some plastics will even deform when scalded with high-temperature water. Therefore, plastic products are generally not suitable for contact with boiling water.
2. Plastics are elastic
Some plastics, like synthetic fibers, have a certain degree of elasticity. When it is stretched by an external force, the curled molecules are straightened due to flexibility, but once the pulling force is removed, it will return to its original curled state, which makes the plastic elastic, such as polyethylene and polyvinyl chloride. Film products. But some plastics are inelastic.
3. Plastic has high strength
Although plastic is not as hard as metal, it still has relatively high strength and wear resistance compared with glass, ceramics, wood, etc. . Plastics make strong gears and bearings in machines.
4. Plastic is corrosion-resistant
Plastic does not rust in humid air like metal, nor does it rot or be damaged in humid environment like wood. Microbial erosion, and plastics are resistant to acid and alkali corrosion. Therefore, plastics are often used as water and fluid pipes in chemical plants, doors and windows in buildings, etc.
5. Plastics are insulating
The molecular chains of plastics are atoms bound together by *** valence bonds. The molecules can neither be ionized nor transfer electrons in the structure, so Plastic is insulating. Plastics can be used to make wire sheaths, electrical sockets, electrical appliance casings, etc. Attachment: Commonly used types of plastics include:
①Polyvinyl chloride (PVC)
It is the largest plastic used in construction. The density of rigid polyvinyl chloride is 1.38~1.43g/cm3. It has high mechanical strength and good chemical stability. Its operating temperature range is generally between -15~55℃. It is suitable for manufacturing plastic doors and windows, sewer pipes, wire ducts, etc.
②Polyethylene (PE)
Polyethylene plastic is mainly used in water supply and drainage pipes and sanitary ware in construction.
③Polypropylene (PP)
The density of polypropylene is the smallest among all plastics, about 0.90. Polypropylene is commonly used to produce construction products such as pipes and sanitary ware.
④Polystyrene (PS)
Polystyrene is a colorless, transparent, glass-like plastic. Polystyrene is mainly used in construction to produce foam insulation materials, light-transmitting materials and other products.
⑤ABS plastic
ABS plastic is a modified polystyrene plastic, based on three groups of acrylonitrile (A), butadiene (B) and styrene (S) Branch office composition. ABS plastic can be used to make plastic decorative panels with patterns embossed on them