Related technologies and properties of common plastics.
(a) storage of ABS (acrylonitrile butadiene styrene * * * polymer
(2) PC (polycarbonate)
(III) Nylon 66
(4) polystyrene
(5) PVC
What kinds of plastics are there?
Plastic is a widely used synthetic polymer material, and plastic products abound in our daily life. From the toiletries used after getting up, the tableware used for breakfast, to the stationery used for work and study, the cushion mattress used for rest, the casing of TV, washing machine and computer, and the lights of various shapes that bring us light at night. ...
With its excellent performance, plastics have gradually replaced many materials and utensils that have been used for decades and hundreds of years, and become 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, petrochemical, machinery manufacturing, national defense, construction and other industries.
I. Classification of plastics
There are many kinds of plastics, so far there are about 300 kinds of plastics put into production in the world. There are many ways to classify plastics, and there are two commonly used methods:
1, according to the different properties of plastics after heating, it can be divided into thermoplastic and thermosetting plastics.
The molecular structure of thermoplastics is linear, which softens or melts when heated, can be shaped into a certain shape, and then hardens after cooling. It becomes soft when heated to a certain extent, and becomes hard after cooling. This process can be repeated many times. Such as polyvinyl chloride, polyethylene, polystyrene, etc. Thermoplastic molding process is relatively simple, can be produced continuously, and has quite high mechanical strength, so it develops rapidly.
The molecular structure of thermosetting plastics is a kind of bulk structure, which can be softened by heating and shaped into a certain shape. However, after heating to a certain extent or adding a small amount of curing agent, it will harden and set, and will not soften and deform after reheating. Thermosetting plastics, such as phenolic plastics, amino plastics, epoxy resins, etc. Can't be recycled after processing and molding. Thermosetting plastics are complicated in molding process and difficult to produce continuously, but they are good in heat resistance, difficult to deform and relatively low in price.
2. According to the different uses of plastics, they can be divided into general plastics and engineering plastics.
General plastics refer to plastics with large output, low price and wide application range, mainly including polyolefin, polyvinyl chloride, polystyrene, phenolic plastics and aminoplastics. Many products used in people's daily life are made of these general plastics.
Engineering plastics can be used as engineering structural materials instead of metals to manufacture machine parts. Such as polyamide, polycarbonate, polyoxymethylene, ABS resin, polytetrafluoroethylene, polyester, polysulfone, polyimide and the like. Engineering plastics have the characteristics of low density, high chemical stability, good mechanical properties, excellent electrical insulation and easy processing and molding. , widely used in automobiles, electrical appliances, chemicals, machinery, instrumentation and other industries, as well as aerospace, rockets, missiles and so on.
Second, the composition of plastic
The plastic we usually use is not a pure substance, it is made of many materials. Polymer (or synthetic resin) is the main component of plastic. In addition, in order to improve the properties of plastics, various auxiliary materials, such as fillers, plasticizers, lubricants, stabilizers, colorants, etc. , must be added to the polymer to become a plastic with good performance.
1, synthetic resin
Synthetic resin is the most important component in plastics, and its content in plastics is generally 40% ~ 100%. Because of its large content and the nature of resin often determines the nature of plastic, people often regard resin as synonymous with plastic. For example, PVC resin and PVC plastic, phenolic resin and phenolic plastic are confused. In fact, resin and plastic are two different concepts. Resin is a kind of raw material polymer, which is not only used to make plastics, but also used as raw material for coatings, adhesives and synthetic fibers. Except a few plastics contain 100% resin, most plastics need to add other substances besides the main component resin.
Step 2 pack
Fillers, also called fillers, can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood flour to phenolic resin can greatly reduce the cost, make phenolic plastic one of the cheapest plastics, and significantly improve the mechanical strength. Fillers can be divided into two categories: organic fillers, such as wood flour, rags, paper and various fabric fibers; Inorganic fillers, such as glass fiber, diatomite, asbestos and carbon black.
3. Plasticizer
Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easy to process and shape. Plasticizer is usually miscible with resin, non-toxic, tasteless and light-sensitive. ......
How many kinds of plastics are there?
ABS: commonly known as engineering plastics, it can be used for connectors, chair backs and seat boards. It is the main raw material for plastic electroplating (water electroplating).
PP: common name polypropylene, used for five-star feet, handrails, foot pads and connectors with low strength requirements. Disadvantages: poor wear resistance and low surface hardness.
PVC: commonly known as polyvinyl chloride, mainly used for edge sealing and insertion conditions. It is suitable for extrusion molding. At the same time, PVC material belongs to non-combustible materials in plastic parts, and its processing and molding temperature stability is poor, especially its color stability is not good.
PU: commonly known as polyurethane. Mainly used for handrail (foam) fittings.
POM: The common name is Sai Gang. Mainly used for wear-resistant parts such as foot pads, casters, door hinges, hinges and so on. Wear resistance and pressure resistance, but poor dimensional stability.
PA: commonly known as nylon. Mainly used as foot pads, five-star claws, casters and other places with wear resistance and high life requirements. Features: Wear resistance, pressure resistance, high strength and long indoor service life. Some models, such as PA66, are resistant to high temperature of 2200, but the disadvantages are variability, easy breakage and poor sun and weather resistance.
PMMA: plexiglass (commonly known as sub-afterburner). There are five transparent materials in plastics, and PMMA is the most transparent one. The workpiece smells of acetic acid when it is cut, and it is easy to deform when it is processed. Soaking in boiling water can shape and bend. Disadvantages: the surface is easy to scratch, the hardness is low, the bending is easy to crack, and the price is more than 20% higher than ABS.
PC: commonly known as polycarbonate. This variety is also a transparent material with high surface hardness, scratch resistance, strong impact resistance, high strength and good weather resistance (that is, not afraid of sunlight). The screens, partitions and sun panels in furniture are all made of this material by hollow extrusion. Features: high cost, about 40% higher than PMMA.
What kinds of plastics are there?
Basic concept of plastics and performance characteristics of common engineering plastics
First, the definition of plastic
Plastic is a kind of material with synthetic or natural polymer compounds as the main component. Under certain temperature and pressure conditions, it can be molded into a certain shape and keep its shape unchanged after removing external force at room temperature.
Second, the composition and classification of plastics
The main component of plastic is resin, accounting for about 40% ~ 100% of the total plastic.
1. Thermoplastics: The resin has a linear or branched macromolecular chain structure.
Polyethylene (PE), polypropylene (PBTP), polystyrene (PS), polyvinyl chloride (PVC), polyoxymethylene (POM), polyamide (commonly known as nylon) (PA), polycarbonate (PC), acrylonitrile-butadiene-styrene * * * polymer (ABS), polymethylmethacrylate (commonly known as plexiglass) (PMMA
2. Thermosetting plastics
Phenolic resin (PF), epoxy resin (EP), amino resin, alkyd resin, allyl resin, urea-formaldehyde resin (UF), melamine resin, unsaturated polyester (UP), silicone resin and polyurethane (PUR).
3. General plastic
Polyvinyl chloride, polystyrene, polyethylene, polypropylene, phenolic resin, amino resin.
4. Engineering plastics
Broad sense: all plastics that can be used as engineering materials, that is, structural materials.
Narrow sense: plastics with certain metal properties can withstand certain external forces, have good mechanical properties, electrical properties and dimensional stability, and can still maintain their excellent properties at high and low temperatures.
General engineering plastics: polyamide, polycarbonate, polyoxymethylene, acrylonitrile butadiene styrene polymer, polyphenylene ether (PPO), polybutylene terephthalate (PBTP) and their modified products.
Special engineering plastics (high performance engineering plastics): high temperature resistant and structural materials. Polysulfone (PSU), polyimide (PI), polyphenylene sulfide (PPS), polyethersulfone (PES), polyarylate (PAR), polyamideimide (PAI), polyphenylene ester, polytetrafluoroethylene (PTFE), polyetherketone, ion exchange resin and heat-resistant epoxy resin.
5. Functional plastics (special plastics)
Plastics with special functions such as radiation resistance, superconductivity, magnetic permeability and light sensitivity. Fluoroplastics, silicone plastics
6. Crystalline plastics
Plastic whose molecules are arranged regularly and keep their shape. Polyethylene, polypropylene, polyamide
7.amorphous plastics
A plastic in which long-chain molecules are wound into a ball (for thermoplastics) or form a network (for thermosetting plastics) and its shape remains unchanged. PS、PC、ABS
Third, the performance of plastics.
Fourth, the use of plastics.
1, industry
2. Agriculture
Step 3 transport
4. Defense cutting-edge industries
5. Health care
6. Daily life
Verb (abbreviation of verb) Development of plastic industry
6. Commodity names and performance characteristics of commonly used engineering plastics at home and abroad
(1) ABS plastic
The main body of ABS plastic is a mixture or terpolymer of acrylonitrile, butadiene and styrene, which is a tough and rigid thermoplastic. Styrene makes ABS have good formability, luster and rigidity; Acrylonitrile makes ABS have good heat resistance, chemical corrosion resistance and surface hardness; Butadiene makes ABS have good impact strength and low temperature resilience. The properties of the three components change with different proportions.
1, performance characteristics
ABS has good impact strength and surface hardness, good dimensional stability, certain chemical resistance and good electrical insulation in a certain temperature range. Opaque, generally light ivory color, can be made into other high-gloss products after coloring. Electroplating appearance can be decorated by electroplating, vacuum coating, etc. Universal ABS is impervious to water, and burns slowly, becoming soft when burning, and the flame turns yellow and smokes. Finally, it burns with a special smell, but there is no molten drop. It can be processed by injection, extrusion and vacuum.
2. Level and purpose
According to different uses, ABS can be divided into general grade (including various impact grades), flame retardant grade, heat resistant grade, electroplating grade, transparent grade, structural foaming grade and modified ABS. Ordinary grade is used to manufacture gears, bearings, handles, machine shells and parts, various instruments, computers, tape recorders, televisions, telephones and other shells and toys; Flame retardant grade is used to manufacture electronic components, such as computer terminals, machine casings and various household appliances; The structural foaming stage is used to manufacture the shell of electronic equipment. heatproof ......
What are the plastic products?
1. Household appliances and communication equipment: shell, inner container and structural parts. Food category: 1. Plastic box for microwave oven. 2. Ice box in freezer. 3. Plastic wrap. 3. Building materials industry: water supply and drainage soft and hard pipes, calcium-plastic corrugated cardboard. 4. Packaging industry category: turnover boxes, packaging barrels, packaging films, packaging bags and bottle caps. Agriculture: plastic film, greenhouse film. 6. Medical care: needles and artificial organs.
7. Aviation and aerospace: coating for the shell of aviation and aerospace equipment.
Wait a minute.
What are the plastic products?
Plastic products are widely used, and the huge industry provides strong support for the development of China's plastic products industry. With the promulgation of "Detailed Planning Rules for Revitalizing Petrochemical Industry", the plastic products industry in China has ushered in new development opportunities. The market demand of plastic products in China is mainly concentrated in agricultural plastic products, packaging plastic products, building plastic products, industrial transportation and engineering plastic products.
Plastic products are made of different materials and have different uses. The numbers on the bottom of plastic bottles represent different materials.
The number "1" stands for polyethylene terephthalate, that is, PET. Mainly used in mineral water bottles, carbonic acid, fruit juice beverage bottles and soy sauce vinegar bottles. The heat-resistant temperature of PET bottles is 70 degrees Celsius, which is only suitable for warm or frozen drinks. After being filled with boiling water or heated, it is easy to deform, and substances harmful to human body will also be dissolved out.
The number "2" stands for high density polyethylene, namely HDPE. Composite membranes made of HDPE and other plastics are also used in aquatic products.
The number "3" stands for polyvinyl chloride (PVC). Because of its low price, it is also used to make intravenous infusion bags and disposable sterile infusion sets. However, if it is used for a long time, it will lead to the accumulation of harmful substance DEHP. Therefore, from the perspective of safety, it is the future trend for pharmaceutical industry to choose non-PVC materials.
The number "4" is low density polyethylene, namely LDPE. No.4 plastic is widely used in packaging. LDPE is mainly used to produce food preservative film and food plastic bag.
The number "5" is polypropylene, or PP. One is to make containers. PP is the only one that can be put in the microwave oven.
Plastic containers, or reusable plastic containers, can be used as storage containers to store food, oil and condiments. The second is packaging film, which has unstretched and biaxial stretching. Untretched polypropylene (CPP) is commonly used for
Packaging of snacks, bread, fruits, etc. ; Biaxially oriented polypropylene (BOPP) is a flexible packaging material comparable to cellophane.
The number "6" is polystyrene, or PS PS is mainly processed into film and foam in packaging. Film is used to package fruits and vegetables; Foamed plastics are mostly used in the bowls of instant noodle boxes and fast food boxes, but they are not resistant to high temperature and cannot be directly put into microwave ovens for heating, so as to avoid releasing toxic chemicals when the temperature is too high.
The number "7" is polycarbonate, that is, PC or other plastics. The plastic container made of PC may release toxic bisphenol A. The higher the temperature, the more it will be released and the faster it will be. So don't heat or directly expose to the sun when using.
What are the injection molding products?
All products molded by injection molding machine are injection molded products. Including thermoplastics and some thermosetting injection products now.
The most remarkable feature of thermoplastic products is that raw materials can be injected repeatedly, but some physical and chemical properties of raw materials will be reduced.
The prospect of injection molding products is still relatively good. Injection molding products are used in various industries, such as automobiles, medical care and so on. Injection molding products have basically penetrated into various industries.