How to understand the vast sea of ​​plastic? How do they differ from each other?
“Society of Plastic Industry” (abbreviated SPI), to facilitate the process of classification of different types of plastics coined SPI special codes. Did you see them – just look at the bottom of a plastic bottle. The number inside the triangle indicates the type of plastic to facilitate sorting and recycling. Also under the sign may be present letter plastic code. What do they mean?

PET (made pet). First produced in the 1940s, the PET is primarily intended for the production of fibers, but in the 1960s began to be used for the production of the film. In 1973 it was patented in the USA the PET bottle. Technology Development blowing of preforms, PET BOTTLE RECYCLING impact resistance, freedom in the choice of design and relatively low cost have led to the fact that the bottles – one of the most significant uses of PET plastics. PET is used for the production of bottles for carbonated drinks, mineral water, juices, beer, vegetable oil, mayonnaise, cosmetics, household cleaners, and other food and non-food containers.
Under the image is usually put alphabetic code PETE, PET and sometimes figure 1.

LDPE (low density polyethylene, high density).
Used since the Second World War, but has not lost relevance in our days. By the 60 th year completely replaced cellophane. Used for the manufacture of packaging, fasovoch-tion package (the so-called “shurshunchikov”). Used HDPE letter code and figure 2.

LDPE (low density polyethylene, low density).
The most common type of plastic. Used in the manufacture of bottles for detergents, toys, greenhouse films, pipes. From it also made and continue to make various cosmetic bottles, barrels, insulation of the cable, etc. – You name it.
LDPE is used, and the number 3 letter code.

Polyvinyl chloride (PVC).
It used since 1927. The basic material for the production of linoleum. Very toxic when burning! (Phosgene, chlorine stand in oxygen).
After a number of publications in 1973, its use in food dishes fell sharply.
To indicate the letter code used PVC and figure 4.

Polypropylene.
Enough tough and elastic material. Because it makes disposable syringes, dishes for hot dishes, packing tape, shrink film, bags of sugar, etc. Suffice it is widely used for the manufacture of bottles resealable foil lids.
All products are made of polypropylene can withstand boiling and steam sterilization.
Used PP letter code and figure 5.

Polystyrene. Disposable tableware, cups for yogurt, inner lining of refrigerators, the rear wall of the domestic TV, polystyrene insulating film. In the production of polystyrene used reactive substances that deplete the ozone layer. Use letter code PS and figure 6.

Other. Most often, it is a multi-layer packaging or packaging of several types of plastics.
For example liter juice box consists of cardboard, foil and polymer. Such packaging is virtually impossible to recycle, because it is technologically very difficult to separate the packaging material into components.
Literal code is absent, and inside the triangle – a dash or number 7.

Determine the type of plastic, if there is a marking, easily enough – but what if there are no markings, and learn from what made the thing – you need ?!
In most cases, it is quite difficult to do, particularly when the similarity of the physical properties of plastics. The most advanced is a special plastic recognition system. About 30 different polymers can be identified for one second using the so-called infrared spectroscopy. This system is used in Europe for recycling old cars. For Russia, this system will not soon be widely distributed, and it is necessary to recognize the plastic now.
For a quick and qualitative detection of various types of plastics is enough desire and a little practical experience (it took me about a month).
The technique is quite simple: analysis of physical and mechanical characteristics of plastic (hardness, smoothness, elasticity, etc…), And their behavior in a flame of a match (lighter).
It may seem strange, but the different types of plastic and lit in different ways! For example, some bright flash and burn intensely (almost no soot), while others, on the contrary, strongly smoked. Plastics even emit different sounds when it is burned! Therefore, it is important to recruit indirect signs accurately identify the type of plastic, its brand.
First, we consider the general characteristics for various plastics, and later they will be consolidated into a single table that will easily and quickly carry out the analysis.

LDPE (low density polyethylene, low density). Solid bluish, luminous flame to fusion and burning resin streaks. When burned, it becomes clear, this property is preserved for a long time after flame extinction. Burning without smoke. Last minute drop, a fall from a sufficient height (about one and a half meters), emit a distinctive sound. When cooling, the polymer droplets solidified wax like, very soft, when crushed between-finger oily to the touch. Smoke extinct polyethylene has the smell of paraffin. LDPE Density: 0,91-0,92 g / cm. cu.

LDPE (low density polyethylene, high density). Tougher than LDPE and dense, brittle. Sample combustion – similar to LDPE. Density: 0,94-0,95 g / cm. cu.

PESD (medium density polyethylene). The toughest of polyethylene.
Density: 0,96-0,97 g / cm. cu.
All types of polyethylene are softened by placing in boiling water. At room temperature, it is not soluble in organic solvents. At a temperature of 100 degrees Celsius or higher, is completely soluble in benzene. Swim in the water.

Polyethylene foam. The spongy mass of white. Properties in combustion, see. LDPE.

Polypropylene. When entering into the flame, polypropylene burns brightly glowing flames. Burning burning LDPE is similar, but the smell more pungent and sweet. When burning polymer drips formed. The molten form – transparent during cooling – cloudy. If you touch the match melt, it is possible to draw a long, fairly strong thread. Drops of cooled molten stiffer than LDPE, hard object choke with a crunch. Smoke from the pungent smell of burnt rubber, sealing wax.
Polypropylene Density: 0,9-0,91 g / cc. ie it is lighter than LDPE and also floats in water.

Made pet (PET). Durable, tough and lightweight material. PET density is 1, 36 g / cc. It has good heat resistance (resistance to thermal degradation) in the temperature range from – 40 ° to + 200 °. PET is resistant to the action of dilute acids, oils, alcohols, mineral salts and most of organic compounds, with the exception of strong alkalis and some solvents. When burning strongly smoky flame. When removing from the flame self-extinguishes.

Polystyrene. When bending strips of polystyrene, easy to bend, then abruptly breaks with a characteristic bang. At the turn there is a fine-grained structure.
Burning bright, heavily smoky flame (soot flakes thin gossamer shoots up!). The smell of sweet, floral.
Polystyrene is soluble in organic solvents (styrene, acetone, benzene).
polystyrene density from 1.05 to 1.08 g / cc. cu. (Sink in water!).

Expanded polystyrene (foam). Light, porous material of white color. One of the best and affordable heat-sound-proof materials.
Volume weight: 0.01-0.1 g / cm. cu.
The sample combustion is similar to polystyrene. Readily soluble in acetone.

Polyvinyl chloride (PVC). Elastic. Slow-burning (when removed from the flame self-extinguishes). When burning smokes heavily, at the base of the flame can be observed a bright blue-green glow. Very sharp, pungent smell of smoke. On combustion, forms black uglepodobnoe substance (easily pounded between fingers in black).
Soluble in carbon tetrachloride, dichloroethane. Density: 1.38-1.45 g / cm. cu.

Polyacrylate (organic glass). The clear, brittle material.
Solid blue-glowing flame with a slight crackle. In sharp fruity odor of smoke (ether). Easily dissolved in dichloroethane.

Polyamide (PA). The material has excellent oil-petrol-resistant and resistant to hydrocarbon products, which provide a wide application of the PA in the automotive and oil industry (production of gears, artificial fibers …). Polyamide has a relatively high moisture absorption, which limits its use for the manufacture of critical parts in wet environments.
Solid bluish flame. When burning swells, “pshikat” forms burning drips. Smoke with a smell of burning hair. Frozen drops very hard and brittle. Polyamides soluble in phenol solution of concentrated sulfuric acid. Density: 1,1-1,13 g / cm. cu. It sinks in water.

Polyurethane. Main application – shoe soles.
Highly flexible and elastic material (at room temperature). In the cold – is fragile.
Lights smoky, luminous flame. At the base of the flame is blue. When burning form burning drops-drips. After cooling, the drops – a sticky, greasy to the touch material.
Polyurethane soluble in glacial acetic acid.

ABC plastic. All properties on combustion similar to polystyrene. From polystyrene it is quite difficult to distinguish. ABC plastic more durable, hard and tough. In contrast to polystyrene is more resistant to gasoline.

Teflon-3. It is used in the form of suspensions for the application of anti-corrosion coatings.
Not flammable, with strong heating char. When removing from the flame immediately fades.
Density: 2.09-2.16 g / cc.

Teflon-4. Bezporisty material is white, slightly translucent, smooth, slippery surface. One of the best insulators!
Not flammable under high heat melts. Practically does not dissolve in any solvent. The most durable of all known materials. Density: 2.12-2.28 g / cc. (Depending on the degree of crystallinity – 40-89%).