The most durable plastic. The most durable materials in the world. Examples of the most common types of plastic in the automotive industry

The world around us is still fraught with many mysteries, but even those that have long been known phenomena scientists and the substances never cease to amaze and delight. We admire bright colors, enjoy tastes and use the properties of all kinds of substances that make our lives more comfortable, safer and more enjoyable. In search of the most reliable and strong materials man has made many exciting discoveries, and here is a selection of just 25 such unique compounds!

25. Diamonds

If not everyone, then almost everyone knows this for sure. Diamonds are not only one of the most revered precious stones, but also one of the hardest minerals on Earth. On the Mohs scale (a scale of hardness that evaluates the reaction of a mineral to scratching), a diamond is listed at line 10. There are a total of 10 positions on the scale, and the 10th is the last and hardest degree. Diamonds are so hard that they can only be scratched by other diamonds.

24. Catching webs of the spider species Caerostris darwini


Photo: pixabay

It's hard to believe, but the web of the Caerostris darwini spider (or Darwin's spider) is stronger than steel and harder than Kevlar. This web has been recognized as the hardest biological material in the world, although now it already has a potential competitor, but the data has not yet been confirmed. The spider fiber was tested for such characteristics as breaking strain, impact strength, tensile strength and Young's modulus (the property of a material to resist stretching and compression during elastic deformation), and for all these indicators the spider web showed itself in the most amazing way. In addition, the Darwin spider's web is incredibly lightweight. For example, if we wrap our planet with Caerostris darwini fiber, the weight of such a long thread will be only 500 grams. Such long networks do not exist, but the theoretical calculations are simply amazing!

23. Aerographite


Photo: BrokenSphere

This synthetic foam is one of the lightest fibrous materials in the world, and it consists of a network of carbon tubes just a few microns in diameter. Aerographite is 75 times lighter than foam, but at the same time much stronger and more flexible. It can be compressed to 30 times its original size without any harm to its extremely elastic structure. Thanks to this property, airgraphite foam can withstand loads up to 40,000 times its own weight.

22. Palladium metal glass


Photo: pixabay

A team of scientists from the California Institute of Technology (Berkeley Lab) has developed the new kind metal glass, combining an almost ideal combination of strength and ductility. The reason for the uniqueness of the new material lies in the fact that its chemical structure successfully hides the fragility of existing glassy materials and at the same time maintains a high endurance threshold, which ultimately significantly increases the fatigue strength of this synthetic structure.

21. Tungsten carbide


Photo: pixabay

Tungsten carbide is an incredibly hard material that is highly wear resistant. Under certain conditions, this connection is considered very brittle, but under heavy load it shows unique plastic properties, manifested in the form of slip bands. Thanks to all these qualities, tungsten carbide is used in the manufacture of armor-piercing tips and various equipment, including all kinds of cutters, abrasive discs, drills, cutters, drill bits and other cutting tools.

20. Silicon carbide


Photo: Tiia Monto

Silicon carbide is one of the main materials used for the production of battle tanks. This compound is known for its low cost, outstanding refractoriness and high hardness, and is therefore often used in the manufacture of equipment or gear that needs to deflect bullets, cut or grind other durable materials. Silicon carbide makes excellent abrasives, semiconductors, and even jewelry inserts that imitate diamonds.

19. Cubic boron nitride


Photo: wikimedia commons

Cubic boron nitride is a super-hard material, similar in hardness to diamond, but also has a number of distinctive advantages - high temperature stability and chemical resistance. Cubic boron nitride does not dissolve in iron and nickel even when exposed to high temperatures, while diamond under the same conditions enters into chemical reactions quite quickly. This is actually beneficial for its use in industrial grinding tools.

18. Ultra high molecular weight polyethylene (UHMWPE), Dyneema fiber brand


Photo: Justsail

High modulus polyethylene has extremely high wear resistance, low friction coefficient and high fracture toughness (low temperature reliability). Today it is considered the strongest fibrous substance in the world. The most amazing thing about this polyethylene is that it is lighter than water and can stop bullets at the same time! Cables and ropes made from Dyneema fibers do not sink in water, do not require lubrication and do not change their properties when wet, which is very important for shipbuilding.

17. Titanium alloys


Photo: Alchemist-hp (pse-mendelejew.de)

Titanium alloys are incredibly ductile and exhibit amazing strength when stretched. In addition, they have high heat resistance and corrosion resistance, which makes them extremely useful in areas such as aircraft manufacturing, rocketry, shipbuilding, chemical, food and transport engineering.

16. Liquidmetal alloy


Photo: pixabay

Developed in 2003 at the California Institute of Technology, this material is renowned for its strength and durability. The name of the compound is associated with something fragile and liquid, but when room temperature it is in fact unusually hard, wear-resistant, is not afraid of corrosion, and when heated, it transforms like thermoplastics. The main areas of application so far are the manufacture of watches, golf clubs and covers for mobile phones (Vertu, iPhone).

15. Nanocellulose


Photo: pixabay

Nanocellulose is isolated from wood fiber and is a new type of wooden material, which is stronger than even steel! In addition, nanocellulose is also cheaper. The innovation has great potential and in the future could seriously compete with glass and carbon fiber. The developers believe that this material will soon be in great demand in the production of military armor, super-flexible screens, filters, flexible batteries, absorbent aerogels and biofuels.

14. Teeth of limpet snails


Photo: pixabay

Previously, we already told you about the Darwin spider’s catching net, which was once recognized as the strongest biological material on the planet. However, a recent study has shown that the limpet is the most durable biological substance known to science. Yes, these teeth are stronger than the web of Caerostris darwini. And this is not surprising, because they are tiny sea ​​creatures They feed on algae growing on the surface of harsh rocks, and in order to separate food from the rock, these animals have to work hard. Scientists believe that in the future we will be able to use the example of the fibrous structure of the teeth of sea limpets in the engineering industry and begin to build cars, boats and even high-strength aircraft, inspired by the example of simple snails.

13. Maraging steel


Photo: pixabay

Maraging steel is a high-strength, high-alloy alloy with excellent ductility and toughness. The material is widely used in rocket science and is used to make all kinds of tools.

12. Osmium


Photo: Periodictableru / www.periodictable.ru

Osmium is an incredibly dense element, and due to its hardness and high melting point, it is difficult to machining. That is why osmium is used where durability and strength are valued most. Osmium alloys are found in electrical contacts, rocketry, military projectiles, surgical implants, and many other applications.

11. Kevlar


Photo: wikimedia commons

Kevlar is a high-strength fiber that can be found in car tires, brake pads, cables, prosthetic and orthopedic products, body armor, fabrics protective clothing, shipbuilding and in unmanned aerial parts aircraft. The material has become almost synonymous with strength and is a type of plastic with incredibly high strength and elasticity. The tensile strength of Kevlar is 8 times higher than that of steel wire, and it begins to melt at a temperature of 450℃.

10. Ultra-high molecular weight high-density polyethylene, Spectra fiber brand


Photo: Tomas Castelazo, www.tomascastelazo.com / Wikimedia Commons

UHMWPE is essentially a very durable plastic. Spectra, a UHMWPE brand, is, in turn, a lightweight fiber of the highest wear resistance, 10 times superior to steel in this indicator. Like Kevlar, Spectra is used in the manufacture of body armor and protective helmets. Along with UHMWPE, the Dynimo Spectrum brand is popular in the shipbuilding and transport industries.

9. Graphene


Photo: pixabay

Graphene is an allotropic modification of carbon, and its crystal cell Just one atom thick, it is so strong that it is 200 times harder than steel. Graphene looks like cling film, but breaking it is an almost impossible task. To pierce a graphene sheet, you will have to stick a pencil into it, on which you will have to balance a load that weighs an entire school bus. Good luck!

8. Carbon nanotube paper


Photo: pixabay

Thanks to nanotechnology, scientists have managed to make paper that is 50 thousand times thinner than a human hair. Sheets of carbon nanotubes are 10 times lighter than steel, but the most amazing thing is that they are as much as 500 times stronger than steel! Macroscopic nanotube plates are most promising for the manufacture of supercapacitor electrodes.

7. Metal microgrid


Photo: pixabay

This is the lightest metal in the world! Metal microgrid is a synthetic porous material that is 100 times lighter than foam. But let him appearance Don't be fooled, these microgrids are also incredibly strong, giving them great potential for use in all sorts of engineering fields. They can be used to make excellent shock absorbers and thermal insulators, and amazing ability This metal shrinks and returns to its original state, allowing it to be used to store energy. Metal microlattices are also actively used in production various parts for aircraft of the American company Boeing.

6. Carbon nanotubes


Photo: User Mstroeck / en.wikipedia

We have already talked above about ultra-strong macroscopic plates made of carbon nanotubes. But what kind of material is this? Essentially these are graphene planes rolled into a tube (9th point). The result is an incredibly light, resilient and durable material with a wide range of applications.

5. Airbrush


Photo: wikimedia commons

Also known as graphene airgel, this material is extremely lightweight and strong at the same time. The new type of gel completely replaces the liquid phase with a gaseous phase and is characterized by sensational hardness, heat resistance, low density and low thermal conductivity. Incredibly, graphene airgel is 7 times lighter than air! The unique compound is able to restore its original shape even after 90% compression and can absorb an amount of oil that is 900 times the weight of the airgraphene used for absorption. Perhaps in the future this class of materials will help combat environmental disasters such as oil spills.

4. Untitled material, developed by the Massachusetts Institute of Technology (MIT)


Photo: pixabay

As you read this, a team of scientists from MIT is working to improve the properties of graphene. The researchers said they have already succeeded in converting the two-dimensional structure of this material into three-dimensional. The new graphene substance has not yet received its name, but it is already known that its density is 20 times less than that of steel, and its strength is 10 times higher than that of steel.

3. Carbin


Photo: Smokefoot

Even though it's just linear chains of carbon atoms, carbyne has 2 times the tensile strength of graphene and is 3 times harder than diamond!

2. Boron nitride wurtzite modification


Photo: pixabay

This newly discovered natural substance is formed during volcanic eruptions and is 18% harder than diamonds. However, it is superior to diamonds in a number of other parameters. Wurtzite boron nitride is one of only 2 natural substances found on Earth that is harder than diamond. The problem is that there are very few such nitrides in nature, and therefore they are not easy to study or apply in practice.

1. Lonsdaleite


Photo: pixabay

Also known as hexagonal diamond, lonsdaleite is made up of carbon atoms, but in this modification the atoms are arranged slightly differently. Like wurtzite boron nitride, lonsdaleite is a natural substance superior in hardness to diamond. Moreover, this amazing mineral is as much as 58% harder than diamond! Like wurtzite boron nitride, this compound is extremely rare. Sometimes lonsdaleite is formed during the collision of meteorites containing graphite with the Earth.

In modern cars, the proportion of plastic parts is constantly growing. The number of repairs on plastic surfaces is also growing, and 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 primarily due to the properties of plastics themselves: they are more elastic and have less adhesion to paintwork materials. And since the range of polymer materials used in the automotive industry is very diverse, if it weren’t for some universal repair materials capable of creating high-quality decorative coatings on many of their types, painters would probably have to get special education in chemistry.

Fortunately, everything will actually turn out to be much simpler and we won’t have to dive headlong into studying the molecular chemistry of polymers. But still, some information about the types of plastics and their properties, at least for the purpose of broadening one’s horizons, will clearly be useful.

Today you will find out

Plastics to the masses

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

The first plastic was invented in 1855 by British metallurgist and inventor Alexander Parkes. When he decided to find a cheap substitute for an expensive Ivory, from which billiard balls were made at that time, he could hardly imagine what significance 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 hardened at normal temperature. This is how parkesin was born - the progenitor of modern plastics.

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

From then on it all began... Almost every year there were reports from chemical laboratories about yet another synthetic material with new, unprecedented properties, and today the world annually produces millions of tons of all kinds of plastics, without which life modern man absolutely unthinkable.

Plastics are used wherever possible: in providing comfortable life of people, agriculture, in all areas of industry. The automotive industry is no exception, where plastic is used more and more widely, uncontrollably displacing its main competitor - metal.

Compared to metals, plastics are very young materials. Their history does not even go back 200 years, while tin, lead and iron were familiar to humanity in ancient times - 3000-4000 BC. e. But despite this, polymer materials are significantly superior to their main technological competitor in a number of indicators.

Advantages of plastics

The advantages of plastics over metals are obvious.

Firstly, plastic is significantly lighter. This allows you to reduce the overall weight of the car and air resistance when driving, and thereby reduce fuel consumption and, as a result, exhaust emissions.

A total reduction in vehicle weight of 100 kg due to the use of plastic parts allows saving 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 shapes.

The advantages of plastics also include their high corrosion resistance, resistance to atmospheric influences, acids, alkalis and other aggressive chemical products, excellent electrical and thermal insulation properties, high noise reduction coefficient... In short, it is not surprising why polymer materials are so widely used in the automotive industry.

Has there been any attempt to create an all-plastic car? But of course! Just remember the well-known Trabant, produced in Germany more than 40 years ago at the Zwickkau plant - its body was made entirely of laminated plastic.

To obtain this plastic, 65 layers of very thin cotton fabric (arrived at 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 temperature 160 °C for 10 minutes.

Until now, the bodies of the GDR “Trabants”, about which songs were sung, legends were told (but more often jokes were written), lie in many landfills across the country. They lie... but they don’t rust!

Trabant. The world's most popular plastic car

Jokes aside, there are promising developments of all-plastic bodies for production cars even now; many sports car bodies are made entirely of plastic. Traditionally, metal parts (hoods, fenders) on many cars are now also being replaced with plastic ones, for example, in Citroën, Renault, Peugeot and others.

But unlike the body panels of the popular “Trabi”, plastic parts modern cars no longer evoke 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 make you feel deep respect for this material.

Concluding the conversation about the advantages of plastics, one cannot fail to note the fact that, although with some reservations, most of them are still perfectly paintable. If the gray polymer mass had not had such an opportunity, it is unlikely that it would have gained such popularity.

Why paint plastic?

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

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

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

What is plastic?

In accordance with the domestic state standard:

Plastics are materials whose main constituents are high-molecular organic compounds that are formed as a result of the synthesis or transformation of natural products. When processed under certain conditions, they tend to exhibit plasticity and the ability to be molded or
deformation.

If you remove the first word “plastics” from such a difficult description, even to read, and not just to understand, perhaps, hardly anyone will guess what we are talking about. Well, let's try to figure it out a little.

“Plastics” or “plastic masses” were so called because these materials are capable of softening when heated, becoming plastic, and then under pressure they can be molded a certain form, which is retained upon further cooling and hardening.

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

The word polymer comes from the Greek words poly (many) and meros (parts or units). This is a substance whose molecules consist of large number identical, interconnected links. These links are called monomers(“mono” - one).

This is, for example, what a monomer of polypropylene, the type of plastic most used in the automotive industry, looks like:

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

Chains of polypropylene molecules

Based on their 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 are found industrial application, most plastics are synthetic.

Synthetic polymers are obtained through a chemical synthesis process from the corresponding monomers.

The feedstock is usually oil, natural gas or coal. As a result chemical reaction polymerization (or polycondensation), many “small” monomers of the starting material are connected together, like beads on a string, into “huge” polymer molecules, which are then molded, cast, pressed or spun into the finished product.

So, for example, polypropylene plastic is obtained from the flammable gas propylene, 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 of their chemical names. For example, polyvinyl chloride is designated as PVC(Polyvinyl chloride), polyethylene - P.E.(Polyethylene), polypropylene - PP(Polypropylene).

In addition to the polymer (also called a binder), plastics may contain various fillers, plasticizers, stabilizers, dyes and other substances that provide the plastic with certain technological and consumer properties, such as fluidity, ductility, 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;
• thermosets;
• elastomers.

Belonging to a particular group is determined by the shape, size and location 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, so 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 you heat the plastic 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 drops and cools, the whole process goes in reverse.

If overheating is avoided, at which point the chains of molecules break apart and the material decomposes, the process of heating and cooling can be repeated as many times as desired.

This feature of thermoplastics being repeatedly softened allows these plastics to be repeatedly processed into various 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 subsequent recycling or disposal is a big problem 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, kinks and deformations can be easily eliminated using heat.

Most polymers used in the automotive industry are thermoplastics. They are used for the production of various parts of the interior and exterior of a 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 (POM) and others.

Thermosetting plastics (thermoset plastics, duroplasts)

If for thermoplastics the process of softening and hardening can be repeated many times, then thermosets after a single heating (when molding the product) become insoluble solid state, and when reheated they no longer soften. Irreversible hardening occurs.

In the initial state, thermosets have a linear structure of macromolecules, but when heated during the production of a molded product, the macromolecules are “cross-linked”, creating a mesh 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-flow state.

Because of this feature, thermoset plastics cannot be recycled. Also, they cannot be welded and molded in a heated state - when overheated, the molecular chains disintegrate 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. Large-sized external body parts (hoods, fenders, trunk lids) are produced from thermosets reinforced (for example, glass fiber).

The group of thermosets 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 exhibit flexibility, and after the stress is removed, they return to their original shape. Elastomers differ from other elastic plastics in their ability to maintain their elasticity over a long period of time. temperature range. For example, silicone rubber remains elastic in the temperature range from -60 to +250 °C.

Elastomers, like thermosets, consist of spatially networked macromolecules. Only, unlike thermosets, the macromolecules of elastomers are located more widely. It is this placement that determines their elastic properties.

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

The group of elastomers includes various rubbers, polyurethane and silicones. In the automotive industry, they are used primarily 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 - so-called “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 with identifying the type of plastic the part is made from. If in the past this was not always easy, now it is easy to “identify” plastic - all parts, as a rule, are marked.

Manufacturers usually stamp the plastic type designation with inside parts, 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<, .

Test task: Take off the cover of your mobile phone and see what type of plastic it is made of. Most often this is >PC<.

There can be many variations of such abbreviations. We won’t be able to consider everything (and there’s no need to), so we’ll focus on several of the most common types of plastics 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 parts or painting new parts, we will have to deal with various modifications of polypropylene.

Polypropylene has, perhaps, a 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 and has good recovery ability. In addition, polypropylene is an environmentally friendly material.

The characteristics of polypropylene give reason to consider it an ideal material for the automotive industry. For its valuable properties, it even received the title of “king of plastics.”

Almost all bumpers are made from polypropylene; this material is also used in the manufacture of spoilers, interior parts, instrument panels, expansion tanks, radiator grilles, air ducts, battery housings 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.

Additives introduced into polypropylene - 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 from 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 designated by the first two letters as >PP...<. Наиболее распространенный продукт этих модификаций — >PP/EPDM< (сополимер полипропилена и этиленпропиленового каучука).

ABS (acrylonitrile butadiene styrene copolymer)

ABS is an elastic, but at the same time impact-resistant plastic. The rubber component (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 exposed to light for a long time and must be painted.

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

Polycarbonate - PC

One of the most impact-resistant thermoplastics. To understand how durable polycarbonate is, it is enough to know 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 changes, and fire safety (it is a low-flammable, self-extinguishing material).

Unfortunately, polycarbonates are quite sensitive to solvents and are prone to cracking under internal stress.

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

Polyamides - PA

Polyamides are rigid, durable and at the same time elastic materials. Parts made of polyamide can withstand loads close to the loads permissible for non-ferrous metals and alloys. Polyamide is highly resistant to wear and chemical resistance. It is almost impervious to most organic solvents.

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

Polyurethane - PU, PUR

Before the widespread introduction of polypropylene into production, polyurethane was the most popular material for the manufacture of various elastic car parts: steering wheels, mud covers, pedal covers, soft door handles, spoilers, etc.

Many people associate this type of plastic with the Mercedes brand. Until recently, bumpers, side door trims, and sills on almost all models were made of polyurethane.

The production of parts from this type of plastic requires less complex equipment than for polypropylene. Currently, many private companies, both abroad and in the countries of the former Soviet Union, prefer to work with this type of plastic to produce 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 thermosets) with fiberglass as a filler.

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

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

The Legend of the Unknown Plastic

Here we are holding in our hands a plastic part that does not have any identification marks or markings on it. But we desperately need to find out its chemical composition or at least its type - is it thermoplastic or thermoset.

Because, if we are talking, for example, about welding, then it is only possible 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 additive.

Identifying the type of plastic is not an easy task. Plastics are analyzed in laboratories for various indicators: combustion spectrogram, reaction to various reagents, odor, melting point, and so on.

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

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

Now we remove the flame. If the plastic continues to burn, it could be ABS plastic, 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 produced during combustion. For example, polypropylene burns with a bright bluish flame, and its smoke has a pungent and sweetish odor, similar to the smell of sealing wax or burnt rubber. Polyethylene burns with a weak bluish flame, and when the flame dies out, you can smell the smell of a burning candle. Polystyrene burns brightly, and at the same time smokes heavily, and it smells quite pleasant - it has a sweetish floral smell. Polyvinyl chloride, on the contrary, smells unpleasant - like chlorine or hydrochloric acid, and polyamide - like burnt wool.

Its appearance can tell something about the type of plastic. For example, if there are obvious traces of welding on a part, then it is probably made of thermoplastic, and if there are traces of burrs removed by sanding, then it is a thermosetting plastic.

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

Or another way: immersing the plastic in water. This method makes it quite easy to identify plastics that are part of the polyolefin group (polyethylene, polypropylene, etc.). These plastics will float on the surface of the water because 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 below in table form.

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

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Decoding the designation of plastics

Designations of the most common plastics

Classification of plastics depending on hardness

Main modifications of polypropylene and their areas of application in automobiles

Methods for determining the type of plastic

28.03.2018

The concept of plastic strength from the point of view of a layman and an engineer is very different. If we talk about household durability, we mean a simple understanding based on the principle “it breaks or does not break.” The same characteristic for production, construction, design has many aspects, upon study of which it turns out that all materials have a number of characteristics by which their purpose and ability to be used for certain purposes can be determined.

Unfortunately, it is impossible to indicate the most durable polymer for objective reasons. This is explained by the fact that physical and strength characteristics are classified according to a wide range of characteristics, the totality of which defines the concept of strength. This depends on the properties of the plastic itself, its structure and reaction to changes in external conditions. For example, it is considered “strong” for creating concrete monoliths, but exhibits extremely weak resistance to bending and breaks. For a non-specialist, similar contradictions can be found in the properties of any polymer and the material based on it - plastic.

Characteristics of strength, hardness, elasticity of plastic

The concept of strength (the nature of the response to physical loads) usually includes the results of testing a material according to several criteria. Depending on how much force was applied to the sample, you can find out the characteristics of the polymer and its ability to resist a certain profile load:

compressive strength - preservation of the physical structure and shape of the sample when compressed;

tensile strength characterizes the ability of a sample to resist tensile force;

deformation strength - a criterion indicating the ability to withstand deformation and return to its original position;

plastic limit - the minimum force at which the material will “flow”, stretch, without returning to its original shape;

impact strength - the ability to absorb impact energy without destroying the structure;

hardness is the reciprocal of plasticity, the limit of shape retention under force.

Depending on what type of load the product will bear during production, processing and operation, a material with certain properties is selected. Therefore, it is useless to talk about the most durable polymer. ? - this is a question that requires a complex answer, consideration of a set of characteristics.

Strength of different types of plastics

Practical examples of assessing the strength characteristics of different plastics and plastics show how difficult it is for their properties to intersect with in-depth professional consideration.

Deformation strength

Polystyrene, polycarbonate, polymethyl methacrylate are characterized as mechanically strong materials at various stresses, but deformation load quickly causes their destruction. With a significant impact, the strength will be low, but a significant deforming force will be required to destroy hard plastic. So, the hardness of a plastic indicates its strength, limited impact strength and brittleness when deformed. It’s easy for a non-specialist to get confused about this.

Flexibility and plasticity

Polyethylene and polypropylene belong to the group of plastic materials - they slightly resist deformation, but at the same time do not break for a long time under such a load. This ability is characterized by an initial modulus of elasticity - the initial resistance to deforming force is quite large, but after overcoming a certain limit, deformation begins. Flexible plastics can be characterized as less durable, but with high impact resistance. They absorb energy well from the outside, upon impact and load, change shape for a long time, and do not “break.” That is why it is used where high flexibility of the material is needed, the ability to withstand significant force while maintaining its shape.

Strong plastic fibers

Materials such as Kevlar, nylon and carbon fiber have high strength comparable to hard plastics, they have limited shock load resistance, and can resist deformation for a long time. Their main advantage is the ability to resist breaking force for a long time. This is why fibers are used where tensile loads are likely to occur. An example of this is Kevlar, which is capable of not breaking under forces that tear steel.

Durable materials have a wide range of uses. There is not only the hardest metal, but also the hardest and most durable wood, as well as the most durable artificially created materials.

Where are the most durable materials used?

The tensile strength of this electrically conductive fiber is three times higher than that of the web of an orb-weaving spider. The resulting material is used to make ultra-light body armor and sports equipment. The name of another durable material is ONNEX, created by order of the US Department of Defense. In addition to its use in the production of body armor, the new material can also be used in flight control systems, sensors, and engines.

There is a technology developed by scientists, thanks to which strong, hard, transparent and lightweight materials are obtained through the transformation of aerogels. Based on them, it is possible to produce lightweight body armor, armor for tanks and durable building materials.

Novosibirsk scientists have invented a plasma reactor of a new principle, thanks to which it is possible to produce nanotubulene, a super-strong artificial material. This material was discovered twenty years ago. It is a mass of elastic consistency. It consists of plexuses that cannot be seen with the naked eye. The thickness of the walls of these plexuses is one atom.

The fact that the atoms seem to be nested into each other according to the “Russian doll” principle makes nanotubulene the most durable material of all known. When this material is added to concrete, metal, and plastic, their strength and electrical conductivity are significantly enhanced. Nanotubulene will help make cars and planes more durable. If the new material comes into widespread production, then roads, houses, and equipment can become very durable. It will be very difficult to destroy them. Nanotubulene has not yet been introduced into widespread production due to its very high cost. However, Novosibirsk scientists managed to significantly reduce the cost of this material. Now nanotubulene can be produced not in kilograms, but in tons.

The hardest metal

This metal is used in industry, smelting chromium steel, nichrome, and so on. It is used for anti-corrosion and decorative coatings. Stone meteorites falling to Earth are very rich in chromium.

The most durable tree

Wood is one and a half times stronger than cast iron, and its bending strength is approximately equal to that of iron. Because of these properties, iron birch could sometimes replace metal, because this wood is not subject to corrosion and rotting. The hull of a ship made of Iron Birch does not even need to be painted; the ship will not be destroyed by corrosion, and it is also not afraid of acids.

A Schmidt birch cannot be pierced by a bullet; you cannot cut it down with an axe. Of all the birches on our planet, the Iron Birch is the longest-living one - it lives for four hundred years. Its habitat is the Kedrovaya Pad Nature Reserve. This is a rare protected species that is listed in the Red Book. If it were not for such rarity, the ultra-strong wood of this tree could be used everywhere.

But the tallest trees in the world, redwoods, are not very durable material.

The strongest material in the Universe

Graphene will soon leave scientific laboratories. All scientists in the world today talk about its unique properties. So, a few grams of material will be enough to cover an entire football field. Graphene is very flexible and can be folded, bent, or rolled.

Possible areas of its use: solar panels, cell phones, touch screens, super-fast computer chips.
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