A Japanese company has created a lightweight plastic that has the strength of steel. Types and properties of plastics. Identifying the type of plastic The strongest and lightest plastic

Currently, engineers around the world are looking for ways to make our vehicles more fuel efficient. This can be achieved with many different ways including the development of more efficient engines. However, the weight that these engines have to move also plays a significant role. The lighter the car, the less fuel is required to move it. That is why Sekisui Chemical has concentrated its efforts and created a new resin that has the strength of steel - but is much lighter than it.

This resin consists of three layers: In it, polyolefin foam is enclosed between thermoplastic sheets, in the structure of which graphene-like carbon components are integrated. Together, this results in an incredibly strong and tough plastic that is easy to heat treat while retaining its specific properties.

Sekisui Chemical says the plastic, which can be stamped into sheets up to 10mm thick, is currently available in two forms. One of them has increased rigidity and weighs 3500 g/m2. The second has a reduced weight due to less rigidity, and weighs only 2200 g/m2. For comparison, a steel sheet of similar stiffness weighs 10,100 g/m2.

The combination of low weight, thermoplasticity and enormous strength makes the new plastic ideal material for the production of cars, trains, ships and even aircraft, and Sekisui Chemical intends to focus on these markets. The company also has plans to test new plastic in construction. And, of course, do not forget that plastic has another huge advantage over steel - it is completely resistant to corrosion and does not require careful protective treatment. This allows you to significantly save not only on production and weight, but also on its maintenance.

The first industrial samples of the new material will be available this summer. If plastic really turns out to be as good as reports say, it could revolutionize several industries at the same time.

There are many types of plastic available today. How not to get lost in the world of these endless names?

Let's figure it out😊

• ABS- durable plastic, easy to process (mechanical and chemical) - you can bring the model to an absolutely glossy state, resistant to alkalis and acids, impact-resistant, moisture-resistant, the operating temperature of finished products is from -40 ° C to + 90 ° C. However, it cracks when hit by direct sun rays(requires opening ready product special varnish to avoid cracking), conducts electricity, must be printed without blowing, as it also cracks when cooled, dissolves with acetone and has a large shrinkage during printing.

• ABS+– has less shrinkage than conventional ABS, cracks at lower blowing temperatures, has the best quality on supports and more durable.
• PLA- environmentally friendly (often made from cane and corn), models from it retain their shape well, have minimal shrinkage, are excellently printed on supports, also have a high viscosity, due to which it is suitable for printing bearings, working temperature up to 60 ° C, you can print on printers without a heated bed. This plastic has a huge number of colors, which you can see by clicking on the link. With fairly good characteristics, there are still disadvantages: biodegradable (the service life of products decreases), low softening point, dissolves in almost all solvents on the market today.

• PLA+- has almost the same characteristics as conventional PLA, but has much greater strength.
• PETG- very flexible and durable plastic, shrinkage is much less than that of ABS, does not crack, temperature from -40°C to +70°C, practically the most transparent plastic on the market. Of the minuses, solubility in benzene can be noted.
• CoPET- plastic without harmful impurities in the composition, temperature from -40°C to +70°C, non-conductive, impact-resistant, insoluble in most solvents, but not resistant to benzene.
• Features of flexible plastics:
• Elastan comes in two types: D70 and D100 and differ from each other in the degree of rigidity
• Plastan is also plastic, however, if it is bent, it will no longer take its original shape.
• Primalloy does not dissolve and is quite soft in texture.
• TPU resembles rubber in its characteristics and prints very “cleanly”
• Flex is an excellent flexible material, lends itself well to bending and returns to its original shape.

Plastic for 3D printer: types of filaments

• POM- ideal for bushings, has a very high slip coefficient, is considered the most durable plastic, but rather unstable, which makes it difficult to print and does not accurately convey the shape of the product.
• PET- a higher temperature plastic, but over time it begins to vitrify and thereby wear out the nozzle.
• Carbon fiber is a mixture PLA plastic and carbon powder (80%:20%). It is hard, matte and creates almost perfectly even models, on which layering is not visible. The disadvantages are the same as those of PLA plastic. When using the wrong temperature regime can clog the nozzle. To print this plastic, you need a 3D printer that can withstand very high temperatures.
• PC- quite hard plastic, but has a strong shrinkage.
• PA (Nylon)– able to withstand a wide range of temperatures and is resistant to most organic solvents.
• PEEK- the highest temperature plastic for FDM printing, excellent for medical applications, as it can be sterilized.
• PVA- water-soluble plastic, used for printing supports, however, it has non-permanent shrinkage and melts at a temperature of 180 ° C.
• HIPS- also water-soluble plastic, durable polystyrene, dissolves.
• Metal plastics - consist of 80% PLA plastic and 20% powdered metal (aluminum, copper, bronze or brass). Great for decoration, as they look almost identical to metal products. Due to their composition, the nozzle wears out quickly.
• Wooden plastics- Great for decoration. At low temperatures more light color, at high - darker. Also, with prolonged use, the nozzle of a 3D printer wears out.

All of the above plastics for you can purchase in our store. Contact us, we will be happy to advise you!

What material is used in production plastic containers. How are plastics different from each other? Plastic

It is quite easy to determine the type of plastic if there is a marking - but what if there is no marking, but it is necessary to find out what the thing is made of ?! For quick and high-quality recognition of various types of plastics, a little desire and practical experience are enough. The technique is quite simple: the physical and mechanical properties of plastics are analyzed (hardness, smoothness, elasticity, etc.) and their behavior in the flame of a match (lighter). It may seem strange, but different types of plastics burn differently! For example, some flare up brightly and burn intensely (almost without soot), while others, on the contrary, smoke heavily. Plastic even makes different sounds when it burns! Therefore, it is so important to accurately identify the type of plastic, its brand by a set of indirect signs.

How to determine LDPE (polyethylene high pressure, low density). Burns with a bluish, luminous flame with melting and burning streaks of polymer. When burning, it becomes transparent, this property is preserved long time after extinguishing the flame. Burns without soot. Burning drops, when falling from a sufficient height (about one and a half meters), make a characteristic sound. When cooling, the polymer drops look like frozen paraffin, very soft, when rubbed between the fingers, they are greasy to the touch. Extinct polyethylene smoke has the smell of paraffin. Density of LDPE: 0.91-0.92 g/cm. cube

How to identify HDPE (polyethylene low pressure, high density) . More rigid and dense than LDPE, fragile. Combustion test - similar to LDPE. Density: 0.94-0.95 g/cm. cube

How to identify Polypropylene. When introduced into a flame, polypropylene burns with a brightly glowing flame. Burning is similar to burning LDPE, but the smell is more pungent and sweetish. During combustion, streaks of the polymer are formed. When molten, it is transparent; when cooled, it becomes cloudy. If you touch the melt with a match, you can pull out a long, fairly strong thread. Drops of the cooled melt are harder than those of LDPE, they crush with a crunch with a solid object. Smoke with a sharp smell of burnt rubber, sealing wax.

How to identify Polyethylene teraphthalate (PET). Durable, tough and light material. The density of PET is 1.36 g/cm3. It has good thermal stability (resistance to thermal degradation) in the temperature range from - 40° to + 200°. PET is resistant to dilute acids, oils, alcohols, mineral salts and most organic compounds, with the exception of strong alkalis and some solvents. When burning, a very smoky flame. When removed from the flame, it self-extinguishes.

Polystyrene. When bending a strip of polystyrene, it bends easily, then breaks sharply with a characteristic crack. A fine-grained structure is observed at the break. It burns with a bright, strongly smoky flame (flakes of soot soar up in thin cobwebs!). The smell is sweetish, floral. Polystyrene dissolves well in organic solvents (styrene, acetone, benzene).

How to identify polyvinyl chloride (PVC). Elastic. Slowly combustible (when removed from the flame, self-extinguishes). When burning, it smokes strongly, a bright bluish-green glow can be observed at the base of the flame. Very strong, pungent odor of smoke. During combustion, a black, carbon-like substance is formed (it is easily rubbed between the fingers into soot). Let's dissolve in carbon tetrachloride, dichloroethane. Density: 1.38-1.45 g/cm. cube

How to identify Polyacrylate (organic glass). Transparent, fragile material. It burns with a bluish-luminous flame with a slight crackle. The smoke has a sharp fruity smell (of ether). Easily soluble in dichloroethane.

How to identify Polyamide (PA). The material has excellent oil-petrol resistance and resistance to hydrocarbon products, which provide a wide application of PA in the automotive and oil industries (manufacturing of gears, artificial fibers ...). Polyamide has a relatively high moisture absorption, which limits its use in humid environments for the manufacture of critical products. Burns with a bluish flame. When burning, it swells, “puffs”, forms burning streaks. Smoke with the smell of burning hair. Solidified droplets are very hard and brittle. Polyamides are soluble in phenol solution, concentrated sulfuric acid. Density: 1.1-1.13 g/cm. cube Drowning in water.

How to identify Polyurethane. The main area of ​​application is shoe soles. Very flexible and elastic material room temperature). In the cold - fragile. Burns with a smoky, glowing flame. At the base, the flame is blue. When burning, burning droplets-streaks are formed. After cooling, these drops are a sticky, greasy substance to the touch. Polyurethane is soluble in glacial acetic acid.

How to identify Plastic ABC. All combustion properties are similar to polystyrene. It is quite difficult to distinguish from polystyrene. ABS plastic is stronger, tougher and more viscous. Unlike polystyrene, it is more resistant to gasoline.

How to determine Fluoroplast-3. It is used in the form of suspensions for applying anti-corrosion coatings. Not flammable, charred when heated. When removed from the flame, it immediately extinguishes. Density: 2.09-2.16 g / cm3

How to determine Fluoroplast-4. Non-porous material white color, slightly translucent, with a smooth, slippery surface. One of the best dielectrics! Not combustible, melts when heated. It is insoluble in virtually all solvents. The most resistant of all known materials. Density: 2.12-2.28 g / cm3 (depending on the degree of crystallinity - 40-89%).

Physical and chemical properties of waste plastics in relation to acids

Physical and chemical properties of plastic waste plastic waste in relation to alkalis

ANY plastic releases chemicals into the contents of the bottle varying degrees danger.

application

For super thin gadgets

Since the discovery of graphene, it has been assumed that it will change electronic technology near future. This was confirmed huge amount patent applications for the right to use it filed by technology companies. However, in 2012, a similar but more promising material, silicene, was synthesized in Germany. Graphene is a layer as thick as a carbon atom. Silicene is the same layer of silicon atoms. Many of their properties are similar. Silicene also has excellent conductivity, which guarantees increased productivity with less heat input. However
silicene has a number of undeniable advantages. First, it surpasses graphene in structural flexibility, its atoms can stick out of the plane, which increases the range of its application. Secondly, it is fully compatible with already existing electronics based on silicon. This means that it will take much less time and money to implement it.

The leader in the production of construction, finishing and packaging materials from mushrooms is a young company Ecovative, whose founders found a gold mine in the mycelium - the vegetative body of the fungus. It turned out that he has excellent cementing qualities. The guys at Ecovative mix it with corn and oatmeal husks, shape the mixture into the right shape, and keep it in the dark for a few days. During this time, the mushroom nutrient organ processes the food and binds the mixture into a homogeneous mass, which is then fired in an oven for strength. As a result of these simple manipulations, a light, durable, fire- and moisture-resistant eco-friendly material is obtained that looks like foam. Based on this technology, Ecovative is now developing a material for bumpers, doors and dashboards of Ford vehicles. In addition, they launched the production of small houses Mushroom Tiny House, completely created on the basis of mycelium.

mushroom materials

application

For sustainable building
and furniture production

Airgel

application

For thermal insulation

An ordinary gel consists of a liquid, which is communicated by a three-dimensional polymer framework. mechanical properties solids: lack of fluidity, ability to retain shape, plasticity and elasticity. In the airgel, the liquid, after drying the material to a critical temperature, is replaced by a gas. It turns out a substance with amazing properties: a record low density and thermal conductivity. So, graphene-based airgel is the lightest material in the world. Despite the fact that 98.2% of its volume is air, the material has tremendous strength and can withstand a load of 2,000 times its own weight. Airgel is almost the best thermal insulator today, used both in NASA spacesuits and in jackets for climbers with a thickness of only 4 mm. Another of its amazing properties is the ability to absorb substances 900 times its own weight. Just 3.5 kg of airgel can absorb a ton of spilled oil. Due to its elasticity and thermal stability, the absorbed liquid can be squeezed out like a sponge, and the residue is simply burned or removed by evaporation.

Ferrofluid is liquid material capable of changing its shape under the influence of magnetic field. It owes this property to the fact that it contains microparticles of magnetite or other iron-containing minerals. When a magnet is brought near them, they are attracted to it and push the molecules of the liquid along with them. Ferrofluid is probably the most accessible of all the materials presented: you can buy it on the Internet or even make it yourself. Ferrofluids in terms of heat capacity and thermal conductivity surpass all lubricants and cooling materials. Now they are used as liquid seals around the rotating axles of hard disks and as a working fluid in hydraulic suspension pistons. In the near future, NASA plans to use them in telescope mirrors so that they can adjust to atmospheric turbulences. Plus magnetic fluids should come in handy in the treatment of cancer. They can be mixed with anticancer drugs and, using a magnet, accurately inject the drug into the affected area without harming the surrounding cells.

Liquid metal

application

For cancer treatment

Self-healing materials

application

For the long life of things

Self-healing materials are invented in various fields: construction, medicine, electronics. Among the most interesting developments is a computer protected from physical damage. Engineer Nancy Sottos came up with the idea of ​​supplying wires with microscopic liquid metal capsules. When broken, the capsule breaks and fills the crack in seconds. Microbiologist Hank Jonkers similarly prolongs the life of roads and buildings by mixing bacterial spores and nutrients for them. As soon as a crack appears in the cement and water enters it, the bacteria wake up from their sleep and begin to process food into durable calcium carbonate, which fills the cracks. The innovation also affected the textile industry. American scientist Marek Urban created durable material, which can independently repair the resulting damage. To do this, a concentrated ultraviolet beam must be directed to the fabric.

In the near future, matter will be able to change its shape, density, structure and other physical properties in a programmable way. This requires the creation of material, which is inherent in the ability to process information. In practice, it will look like this: a table from IKEA will assemble itself as soon as it is taken out of the box, and if necessary, the fork will easily turn into a spoon. Already, MIT is creating objects that can change shape. For this, superfine electronic boards are combined with shape-memory alloys - metals that change their configuration under the influence of heat or a magnetic field. The boards release heat at predetermined points, as a result of which the object is assembled into the structure conceived by scientists. Yes, from flat metal sheets managed to assemble a robot-insect. An important area of ​​programmable matter is Claytronics, which develops nanorobots that can come into contact with each other and create 3-D objects that the user can interact with. Claytronics will be able to offer a realistic sense of connectivity over long distances, referred to as "pario". Thanks to him, it will be possible to hear, see and touch something located on the other side of the world.

Claytronics

application

To produce things capable of
change shape on demand

bacterial cellulose

application

For sustainable clothing production

In modern cars, the proportion of plastic parts is constantly growing. The number of repairs on plastic surfaces is also growing, more and more often we are faced with the need to paint them.

In many ways, the coloring of plastics differs from the coloring metal surfaces, which is due, first of all, to the very properties of plastics: they are more elastic and have less adhesion to paintwork materials. And since the range of polymeric materials used in the automotive industry is very diverse, there are no universal repair materials capable of creating high-quality decorative coating on many of their types, painters would probably have had to get special education in chemistry.

Fortunately, everything will actually turn out to be much simpler and dive headlong into learning molecular chemistry We don't need polymers. But still, some information about the types of plastics and their properties, at least for the purpose of broadening one's horizons, will obviously be useful.

Today you will know

Plastics - to the masses

In the 20th century, humanity experienced a synthetic revolution, new materials entered its life - plastics. Plastic can be safely considered one of the main discoveries of mankind; without its invention, many other discoveries would have been obtained much later or they would not have existed at all.

The first plastic was invented in 1855 by the British metallurgist and inventor Alexander Parkes. When he decided to find a cheap substitute for the expensive ivory from which billiard balls were made at that time, he could hardly imagine what value the product he received would later acquire.

The ingredients of the future discovery were nitrocellulose, camphor and alcohol. The mixture of these components was heated to a fluid state, and then poured into a mold and solidified at normal temperature. Thus, parkesine was born - the progenitor of modern plastics.

From natural and chemically modified natural materials to fully synthetic molecules, the development of plastics came a little later - when German Staudinger, a professor at the University of Freiburg, discovered a macromolecule - that "brick" from which all synthetic (and natural) organic materials are built. This discovery brought the 72-year-old professor the Nobel Prize in 1953.

Since then, it all started ... Almost every year there were reports from chemical laboratories about the next synthetic material with new, unprecedented properties, and today millions of tons of all kinds of plastics are produced annually in the world, without which life modern man absolutely unthinkable.

Plastics are used wherever possible: in ensuring the comfortable life of people, agriculture, in all areas of industry. The automotive industry is no exception, where plastic is being used more and more, irresistibly displacing its main competitor, metal.

Compared to metals, plastics are very young materials. Their history is not even 200 years old, while tin, lead and iron have been known to mankind since ancient times- for 3000-4000 years BC. e. But despite this, polymer materials in a number of indicators, they are significantly superior to their main technological competitor.

Benefits of plastics

The advantages of plastics over metals are obvious.

First, plastic is significantly lighter. This reduces the overall weight of the vehicle and the air resistance when driving, and thereby reduces fuel consumption and, as a result, exhaust emissions.

The overall reduction in vehicle weight by 100 kg due to the use of plastic parts saves up to one liter of fuel per 100 km.

Secondly, the use of plastics gives almost unlimited possibilities for shaping, allowing you to translate any design ideas into reality and obtain details of the most complex and ingenious forms.

The advantages of plastics can also be attributed to their high corrosion resistance, resistance to weathering, acids, alkalis and other aggressive chemicals, excellent electrical and thermal insulation properties, high noise reduction coefficient ... In a word, it is not surprising why polymer materials are so widely used in the automotive industry.

Have any attempts been made to create an all-plastic car? But how! Recall at least the notorious Trabant, which was produced in Germany more than 40 years ago at the Zwickkau plant - its body was entirely made of laminated plastic.

To obtain this plastic, 65 layers of very thin cotton fabric (which came to the plant from textile factories), alternating with layers of ground cresol-formaldehyde resin, were pressed into a very strong material 4 mm thick at a pressure of 40 atm. and a temperature of 160 °C for 10 minutes.

Until now, the bodies of the GDR Trabants, about which they sang songs, told legends (but more often composed jokes), lie in many landfills of the country. They lie ... but they do not rust!

Trabant. The most popular plastic car in the world

Jokes are jokes, and there are promising developments of all-plastic bodies for serial cars even now, many sports car bodies are entirely made of plastic. Traditionally metal parts(hoods, fenders) on many cars are now also being changed to plastic ones, for example, on Citroën, Renault, Peugeot and others.

But unlike the body panels of the popular "Trabi", the plastic parts of modern cars no longer cause an ironic smile. On the contrary, their resistance to impact loads, the ability of deformed areas to self-heal, the highest anti-corrosion resistance and low specific gravity compel to imbue this material with deep respect.

Concluding the conversation about the merits of plastics, one cannot fail to note the fact that, although with some reservations, most of them lend themselves well to coloring. If the gray polymer mass did not have such an opportunity, it would hardly have gained such popularity.

Why paint plastic?

The need to color plastics is due, on the one hand, to aesthetic considerations, and on the other, to the need to protect plastics. After all, nothing is eternal. Although plastics do not rot, they are still subject to aging and destruction processes during operation and exposure to atmospheric influences. And the applied paint layer protects the plastic surface from various aggressive influences and, therefore, prolongs its service life.

If in production conditions the painting of plastic surfaces is very simple - in this case we are talking about a large number of new identical parts from the same plastic (and there are their own technologies), then a painter in an auto repair shop is faced with problems of heterogeneity of materials of various parts.

This is where you have to answer the question: “What is plastic in general? What is it made of, what are its properties and main types?

What is plastic?

According to the domestic state standard:

Plastics are called materials, the main component of which are such high-molecular organic compounds that are formed as a result of synthesis or transformations. natural products. When processed into certain conditions they tend to exhibit plasticity and the ability to be molded or
deformations.

If the first word “plastics” is removed from such a difficult even for reading, and not only for understanding, description, perhaps no one will guess what it is all about. Well, let's try to understand a little.

"Plastics" or "plastic masses" were named so because these materials are capable of softening when heated, becoming plastic, and then under pressure they can be given certain form, which is retained upon further cooling and curing.

The basis of any plastic is (the same "high molecular organic compound from the definition above).

The word "polymer" comes from Greek words"poly" ("many") and "meros" ("parts" or "links"). It is a substance whose molecules are composed of a large number identical links connected to each other. These links are called monomers("mono" - one).

So, for example, the monomer of polypropylene, the type of plastic most used in the automotive industry, looks like:

The molecular chains of a polymer are made up of an almost countless number of such pieces connected into a single whole.

Chains of polypropylene molecules

By origin, all polymers are divided into synthetic and natural. Natural polymers form the basis of all animal and plant organisms. These include polysaccharides (cellulose, starch), proteins, nucleic acids, natural rubber and other substances.

Although modified natural polymers have industrial uses, most plastics are synthetic.

Synthetic polymers are obtained in the process of chemical synthesis from the corresponding monomers.

Oil is usually used as feedstock natural gas or coal. As a result of a chemical polymerization (or polycondensation) reaction, many "small" monomers of the original substance are interconnected, like beads on a string, into "huge" polymer molecules, which are then molded, cast, pressed or spun into a finished product.

So, for example, polypropylene plastic is obtained from propylene combustible gas, from which bumpers are made:

Now you probably guessed where the names of plastics come from. The prefix "poly-" ("many") is added to the name of the monomer: ethylene → polyethylene, propylene → polypropylene, vinyl chloride → polyvinyl chloride etc.

International abbreviations for plastics are abbreviations for their chemical names. For example, polyvinyl chloride is referred to as PVC(Polyvinyl chloride), polyethylene - PE(Polyethylene), polypropylene - PP(Polypropylene).

In addition to the polymer (it is also called a binder), plastics may include various fillers, plasticizers, stabilizers, dyes and other substances that provide plastic with certain technological and consumer properties e.g. fluidity, plasticity, density, strength, durability, etc.

Types of plastics

Plastics are classified according to different criteria: chemical composition, fat content, hardness. But the main criterion that explains the nature of the polymer is the behavior of the plastic when heated. On this basis, all plastics are divided into three main groups:

• thermoplastics;
• thermoplastics;
• elastomers.

Belonging to a particular group is determined by the shape, size and arrangement of macromolecules, along with the chemical composition.

Thermoplastics (thermoplastic polymers, plastomers)

Thermoplastics are plastics that melt when heated and return to their original state when cooled.

These plastics are composed of linear or slightly branched molecular chains. At low temperatures, the molecules are located tightly next to each other and hardly move, therefore, under these conditions, the plastic is hard and brittle. With a slight increase in temperature, the molecules begin to move, the bond between them weakens and the plastic becomes plastic. If the plastic is heated even more, the intermolecular bonds become even weaker and the molecules begin to slide relative to each other - the material passes into an elastic, viscous state. When the temperature is lowered and cooled, the whole process goes in the reverse order.

If you do not allow overheating, at which the chains of molecules break up and the material decomposes, the process of heating and cooling can be repeated as many times as you like.

This feature of thermoplastics repeatedly softens allows you to repeatedly process these plastics into certain products. That is, theoretically, one wing can be made from several thousand yogurt cups. From an environmental point of view, this is very important, since the subsequent processing or disposal is a big problem for polymers. Once in the soil, plastic products decompose within 100-400 years!

In addition, due to these properties, thermoplastics lend themselves well to welding and soldering. Cracks, breaks and deformations can be easily eliminated by thermal action.

Most of the polymers used in the automotive industry are thermoplastics. They are used for the production of various parts of the interior and exterior of the car: panels, frames, bumpers, radiator grilles, lamp housings and exterior mirrors, wheel covers, etc.

Thermoplastics include polypropylene (PP), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymers (ABS), polystyrene (PS), polyvinyl acetate (PVA), polyethylene (PE), polymethyl methacrylate (plexiglass) (PMMA), polyamide (PA) , polycarbonate (PC), polyoxymethylene (ROM) and others.

Thermoplastics (thermosetting plastics, duroplasts)

If for thermoplastics the process of softening and curing can be repeated many times, then thermoplastics after a single heating (during molding of the product) pass into an insoluble solid state, and upon repeated heating they no longer soften. Irreversible curing occurs.

In the initial state, thermoplastics have a linear structure of macromolecules, but when heated during the production of a molded product, the macromolecules "crosslink", creating a networked spatial structure. It is thanks to this structure of closely linked, "cross-linked" molecules that the material turns out to be hard and inelastic, and loses the ability to re-transition into a viscous state.

Because of this feature, thermosetting plastics cannot be recycled. Also, they cannot be welded and formed in a heated state - when overheated, the molecular chains break up and the material is destroyed.

These materials are quite heat-resistant, so they are used, for example, for the production of crankcase parts in the engine compartment. From reinforced (for example, fiberglass) thermosets, large-sized external body parts (hoods, fenders, trunk lids) are produced.

The group of thermoplastics includes materials based on phenol-formaldehyde (PF), urea-formaldehyde (UF), epoxy (EP) and polyester resins.

Elastomers are plastics with highly elastic properties. When subjected to force, they show flexibility, and after the stress is removed, they return to their original shape. Elastomers differ from other elastic plastics in their ability to retain their elasticity over a wide temperature range. So, for example, silicone rubber remains elastic in the temperature range from -60 to +250 °C.

Elastomers, as well as thermoplastics, consist of spatially networked macromolecules. Only unlike thermoplastics, elastomer macromolecules are located more widely. It is this arrangement that determines their elastic properties.

Due to their network structure, elastomers are infusible and insoluble, like thermoplastics, but they swell (thermoplastics do not swell).

The group of elastomers includes various rubbers, polyurethane and silicones. In the automotive industry, they are mainly used for the manufacture of tires, seals, spoilers, etc.

All three types of plastics are used in the automotive industry. Mixtures of all three types of polymers are also produced - the so-called "blends" (blends), the properties of which depend on the ratio of the mixture and the type of components.

Determining the type of plastic. Marking

Any repair to a plastic part must begin by identifying the type of plastic the part is made from. If in the past it was not always easy, now it is easy to “identify” plastic - all parts are usually marked.

Manufacturers usually stamp the plastic type designation with inside details, be it a bumper or a cover mobile phone. The type of plastic is usually enclosed in characteristic brackets and may look like this: >PP/EPDM<, >PUR<, .

Control task: remove the cover of your mobile phone and see what type of plastic it is made of. Most often it is > PC<.

There can be many variants of such abbreviations. We will not be able to consider everything (and there is no need for that), so we will focus on several types of plastics most common in the automotive industry.

Examples of the most common types of plastic in the automotive industry

Polypropylene - PP, modified polypropylene - PP/EPDM

The most common type of plastic in the automotive industry. In most cases, when repairing damaged or painting new parts, we will have to deal with various modifications of polypropylene.

Polypropylene has, perhaps, the combination of all the advantages that plastics can have: low density (0.90 g / cm³ - the lowest value for all plastics), high mechanical strength, chemical resistance (resistant to dilute acids and most alkalis, detergents, oils, solvents), heat resistance (begins to soften at 140°C, melting point 175°C). It is almost not subject to corrosion cracking, has a good ability to recover. In addition, polypropylene is an environmentally friendly material.

The characteristics of polypropylene make it an ideal material for the automotive industry. For such valuable properties, he even received the title of "king of plastics."

Almost all bumpers are made on the basis of polypropylene, this material is also used in the manufacture of spoilers, interior parts, dashboards, expansion tanks, radiator grilles, air ducts, battery cases and covers, etc. In everyday life, even suitcases are made of polypropylene.

When casting most of the above parts, not pure polypropylene is used, but its various modifications.

"Pure" unmodified polypropylene is very sensitive to ultraviolet radiation and oxygen, it quickly loses its properties and becomes brittle during operation. For the same reason, paint coatings applied to it cannot have durable adhesion.

The additives introduced into polypropylene - more often in the form of rubber and talc - significantly improve its properties and make it possible to color it.

Only modified polypropylene can be dyed. On "pure" polypropylene, adhesion will be very weak! Made of pure polypropylene >PP< изготавливают бачки омывателей, расширительные емкости, одноразовую посуду, стаканчики и т.д.

Any modifications of polypropylene, no matter how long the abbreviation of its marking is, are designated by the first two letters anyway, as > PP ...<. Наиболее распространенный продукт этих модификаций — >PP/EPDM< (сополимер полипропилена и этиленпропиленового каучука).

ABS (acrylonitrile-butadiene-styrene copolymer)

ABS is flexible, but at the same time impact-resistant plastic. The component of rubber (butadiene) is responsible for elasticity, and acrylonitrile is responsible for strength. This plastic is sensitive to ultraviolet radiation - under its influence, the plastic quickly ages. Therefore, ABS products cannot be kept in the light for a long time and must be painted.

Most often used for the production of lamp housings and exterior mirrors, radiator grilles, cladding dashboard, door upholstery, wheel covers, rear spoilers, etc.

Polycarbonate - PC

One of the most impact resistant thermoplastics. To understand how durable polycarbonate is, it is enough that this material is used in the manufacture of bulletproof bank counters.

In addition to strength, polycarbonates are characterized by lightness, resistance to light aging and temperature extremes, fire safety (it is difficult to ignite, self-extinguishing material).

Unfortunately, polycarbonates are quite sensitive to solvents and tend to crack under the influence of internal stresses.

Unsuitable aggressive solvents can seriously impair the strength characteristics of plastic, so when painting parts where strength is of paramount importance (for example, a motorcycle helmet made of polycarbonate), you need to be especially careful and strictly follow the manufacturer's recommendations, and sometimes even fundamentally refuse to paint. But spoilers, radiator grilles and polycarbonate bumper panels can be painted without problems.

Polyamides - PA

Polyamides are rigid, strong and at the same time elastic materials. Polyamide parts can withstand loads close to those allowed for non-ferrous metals and alloys. Polyamide has high wear resistance, chemical resistance. It is nearly immune to most organic solvents.

Most often, polyamides are used for the production of removable car caps, various bushings and liners, tube clamps, door lock tongues and latches.

Polyurethane - PU, PUR

Prior to its widespread use in the production of polypropylene, polyurethane was the most popular material for the manufacture of various elastic car parts: steering wheels, mudguards, pedal covers, soft door handles, spoilers, etc.

For many, this type of plastic is associated with the Mercedes brand. Bumpers, side door linings, sills on almost all models were made from polyurethane until recently.

The production of parts from this type of plastic requires less sophisticated equipment than for polypropylene. At present, many private companies, both abroad and in countries former Union prefer to work with this type of plastic for the manufacture of all kinds of parts for car tuning.

Fiberglass - SMC, BMC, UP-GF

Fiberglass is one of the most important representatives of the so-called " reinforced plastics". They are made on the basis of epoxy or polyester resins (these are thermoplastics) with fiberglass as a filler.

High physical and mechanical properties, as well as resistance to various aggressive media, have determined the wide use of these materials in many areas of industry. A well-known product used in the production of American minivan bodies.

In the manufacture of fiberglass products, it is possible to use the "sandwich" technology, when the parts consist of several layers of different materials, each of which meets certain requirements (strength, chemical resistance, abrasion resistance).

Legend of unknown plastic

Here we are holding plastic part, which does not have any identification marks, no markings. But we desperately need to find out chemical composition or at least the type - it is a thermoplastic or a thermoset.

Because, if we are talking, for example, about welding, then it is possible only with thermoplastics (adhesive compositions are used to repair thermosetting plastics). In addition, only materials of the same name can be welded, dissimilar ones simply do not interact. In this regard, it becomes necessary to identify the “no name” plastic in order to correctly select the same welding filler.

Identifying the type of plastic is not an easy task. The analysis of plastics is carried out in laboratories according to various indicators: according to the combustion spectrogram, reactions to various reagents, smell, melting point, and so on.

However, there are several simple tests that allow you to determine the approximate chemical composition of the plastic and assign it to one or another group of polymers. One of these is the analysis of the behavior of a plastic sample in an open source of fire.

For the test, we need a ventilated room and a lighter (or matches), with which you need to carefully set fire to a piece of the material being tested. If the material melts, then we are dealing with a thermoplastic, if it does not melt, we have a thermoset.

Now remove the flame. If the plastic continues to burn, it could be ABS, polyethylene, polypropylene, polystyrene, plexiglass, or polyurethane. If it goes out, it is most likely polyvinyl chloride, polycarbonate or polyamide.

Next, we analyze the color of the flame and the smell formed during combustion. For example, polypropylene burns with a bright bluish flame, and its smoke has a sharp and sweet smell, similar to the smell of sealing wax or burnt rubber. Polyethylene burns with a weak bluish flame, and when the flame dies out, the smell of a burning candle is felt. Polystyrene burns brightly, and at the same time smokes a lot, and it smells quite pleasant - it has a sweetish floral smell. Polyvinyl chloride, on the contrary, smells unpleasant - chlorine or hydrochloric acid, and polyamide - burnt wool.

Something about the type of plastic can also tell him appearance. For example, if there are obvious traces of welding on the part, then it is probably made of thermoplastic, and if there are traces of burrs removed by emery, then it is thermosetting plastic.

You can also do a hardness test: try cutting off a small piece of plastic with a knife or blade. Chips will be removed from the thermoplastic (it is softer), but the thermoplastic will crumble.

Or another way: immersion of plastic in water. This method makes it quite easy to determine the plastics included in the group of polyolefins (polyethylene, polypropylene, etc.). These plastics will float on the surface of the water since their density is almost always less than one. Other polymers have a density greater than one, so they will sink.

These and other signs by which the type of plastic can be determined are presented in the form of a table below.

P.S. In we will pay attention to the preparation and painting of plastic parts.

Bonuses

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Deciphering the designation of plastics

Designations of the most common plastics

Classification of plastics depending on hardness

The main modifications of polypropylene and their areas of application in the car

Methods for determining the type of plastic