In everyday life, we often use ready-made blocks of knowledge obtained in childhood, often at school. We practically do not analyze them, considering them a priori indisputable, requiring neither additional proofs nor analysis. And if you ask us, for example, whether the glass transmits ultraviolet light, the majority will confidently answer: "No, it does not, we remembered it at school!"

But one day our friend will appear and say: "You know, I spent the whole day behind the wheel yesterday, the sun was merciless, my entire forearm from the window side was sunburned!" And in response to a skeptical smile, he rolls up his shirt sleeve, showing reddened skin ... This is how stereotypes are destroyed, and a person remembers that by nature he is a researcher.

And yet - what about our question? After all, we know that it is ultraviolet light that causes sunburn of the skin in people. The answer is not as straightforward as it might seem at first. And it will sound like this: "It depends on what glass and what ultraviolet light!"

Properties of ultraviolet rays

Ultraviolet radiation has a wavelength of about 10 to 400 nm. This is a fairly large spread, and, accordingly, rays in different parts of this range will have different properties. Physicists divide the entire UV spectrum into three different types:

1. Type C or hard UV radiation ... It is characterized by a wavelength of 100 to 280 nm. This radiation got its name for a reason, it is extremely dangerous for humans, leading to skin cancer or rapid eye burns. Fortunately, the rays of the range are almost completely blocked by the Earth's atmosphere. A person can encounter them only very high in the mountains, but even here they are extremely weakened.
2. Type B or medium UV ... Its wavelength is from 280 to 315 nm. These rays cannot be called affectionate to a person either, they are similar in their properties to the previous type, but still act less destructively. Like type C, they are also lost in the atmosphere, but are less retained by it. Therefore, 20% of them still reach the surface of the planet. It is the rays of this type that lead to the appearance of sunburn on our skin. But this radiation is not able to penetrate through ordinary glass.
3. Type A or mild UV ... 315 to 400 nm. The atmosphere does not care for him, and it passes unhindered to the level of the ocean, sometimes even penetrating through light clothing. This radiation perfectly overcomes a layer of ordinary window glass, appearing in our apartments and offices, leading to fading of wallpaper, carpets and furniture surfaces. But "A rays" cannot lead to tanning of human skin in any way!

True, extreme ultraviolet light is also emitted with a wavelength below 100 nanometers, but it manifests itself only in conditions close to vacuum, and under conditions of the earth's surface it can be neglected.

And what should you say to your friend who is a motorist? Why did his forearm get tanned?

Different types of glass

And here we come to the second part of our answer: "It depends what kind of glass!" After all, glasses are different: both in composition and in thickness. For example, quartz crystal transmits all three types of UV radiation through itself. The same picture is observed when using plexiglass.
And silicate, used in window frames, and in cars, allows only "soft radiation" to pass through.

However, there is one important "BUT" here! If the glass is very thin or very transparent, high-quality polished (as in the case of a car), it will also allow a small fraction of the "B radiation" responsible for our tanning to pass through. This is not enough to get a tan after standing near the window for an hour. But if the driver has spent many hours behind the wheel, exposing his skin to the sun, then it will tan even through closed glass. Especially if the skin is delicate, and the case is high in relation to sea level.

And now, having heard the question whether ultraviolet light passes through the glass, we can answer in a very complex way - it does, but only in a limited part of the spectrum, and only if we talk about ordinary window glass.

Polymer plastic is characterized by strength, practicality, durability and ease of installation. In this case, the service life of the material depends on its technical characteristics. Today we will consider a topic that is so relevant for many builders and gardeners, such as whether polycarbonate transmits ultraviolet rays.

UV protection

Polycarbonate is considered one of the strongest and strongest polymers. However, this material degrades when exposed to sunlight. So, sheets of polymer plastic used for cladding greenhouse structures, garden greenhouses, gazebos, verandas, terraces and other open buildings quickly deteriorate. After 2–3 years from the moment the building was erected, the cladding completely loses its original physical properties and qualities.

Polycarbonate is UV-resistant, making it ideal for greenhouse sheathing

Polymer plastics manufacturers have found a way to improve the material's wear resistance. Polycarbonate began to be produced with a special ultraviolet coating. The protective layer was a kind of stabilizer-granules, which were added to the material during primary processing. Unfortunately, the use of this kind of technology requires a significant investment. Accordingly, the cost of the building material rises.

Currently, polymer plastic is manufactured with a thin ultraviolet coating, which is called UV protection.

There are two ways to apply the UV layer:

1. Spraying. The surface of the polymer plastic panel is covered with a thin layer of a special solution, which looks like an industrial paint. This method has significant drawbacks. During transportation, installation and operation of the web, the protective layer is erased, as a result of which the polymer becomes unusable. Applied in the form of spraying, UV protection is not resistant to atmospheric precipitation and external mechanical influences.
2. Extrusion protection from direct sunlight. A special layer that prevents the destruction of the polymer is implanted into the surface of the polycarbonate panel. The canvas is resistant to physical and chemical damage, as well as to various weather conditions. The service life of polycarbonate with extrusion sun protection is 20-25 years.

Video "Protection of polycarbonate from ultraviolet radiation"

From this video you will learn what kind of UV protection is in cellular polycarbonate.

Selection rules

Many people wonder how to determine the presence of UV coating on the surface of a polymer plastic sheet.

Responsible manufacturers apply a protective film to polycarbonate sheets. Transparent colorless polyethylene means that there is no sun protection on this side of the panel. Transparent color film is the first landmark of the presence of a protective ultraviolet layer.

• name and type of building material;
• technical characteristics of polycarbonate;
• recommendations on the peculiarities of loading, unloading, transportation, installation and maintenance of the polymer;
• information about the manufacturer.

Some types of polycarbonate sheets have enhanced protection against
ultraviolet radiation, it is worth picking them up depending on the purpose

Often, the marking is applied to colored polyethylene, which helps to avoid scratches, dents, chips and cracks on the outside of the polycarbonate.

If there is no film, turn the polymer towards the sun. The UV coated side reflects the characteristic violet reflections in the sun.

When choosing a building material, including polymer plastic, you need to focus on the technical properties and quality of the material.

UV-protected polycarbonate is a guarantee of the durability and strength of the building's cladding.

The steel structure is protected against corrosion by priming followed by painting. But aluminum does not need protection. For greater reliability, experts recommend an anodized aluminum profile reinforced with a steel rod.

Wood is also used. Compared to metal, wooden elements are much more massive. In addition, they need a number of protective measures: painting, treatment with antiseptics and fire retardants.

The plastic profile offered on the market is more suitable for temporary structures. In our climatic conditions, it quickly deteriorates. So that it does not bend from a strong gust of wind, it is better to choose a profile reinforced with a metal rod.

The main surface of the walls and roof is formed by translucent structures fixed to the frame. They use glass, film and plastic.
Glass transmits 90% of sunlight and retains heat well: even in frosty weather in a glazed greenhouse, the temperature will be 4 ° C higher than outside. Its main disadvantages are fragility and significant weight. For greenhouses, glass with a thickness of 3 mm is used. The glazing of the metal frame is sealed with a rubber seal, and the wooden one - with wooden glazing beads.
Acrylic (plexiglass)- a light, colorless material that can withstand significant mechanical loads (which is important in heavy snowfalls), transmits ultraviolet rays and is not inferior in transparency to glass.
Polycarbonate- polymer material, which is 250 times stronger and 6 times lighter than glass. It has high strength, heat and fire resistance, as well as low thermal conductivity. It does not transmit much less light than clear glass. Can be sewn up polycarbonate the whole frame and do not dismantle the coating for the winter for many years. This material is monolithic and cellular. Elements of both flat and curved shapes are made from the first. Such products are quite rigid and do not require a supporting frame. However, they are relatively expensive, so flat roofs are covered with cellular polycarbonate. Due to its structure, it has high thermal insulation characteristics. And its low weight allows for the installation of lightweight supporting structures. As a roofing material, sheets with a thickness of at least 8 mm are used. For walls, you can choose thinner sheets. The surface of the polycarbonate is sensitive to mechanical stress.
Polyvinyl chloride (PVC) produced in the form of corrugated sheets. It is distinguished by high mechanical and impact resistance, resistance to ultraviolet radiation, durability, flexibility at temperatures from -40 to +65 ° C. Transparent colorless PVC sheets transmit 82% of the light, but do not transmit ultraviolet light, therefore, specially treated PVC materials are used for greenhouses that transmit the UV radiation necessary for photosynthesis.
Polymer film elastic, transparent and easy to install. It can withstand frosts down to -20 ° C, but does not tolerate sudden changes in temperature. Polyethylene film transmits 80% of visible and ultraviolet rays, is resistant to alkalis and acids, does not transmit water and steam. Its disadvantage is high thermal permeability, up to 90%. Under the influence of ultraviolet radiation and air, the film ages, its translucency decreases, and by the end of the season the material is destroyed. The film strip is glued with phenol, formaldehyde, formic acid, welded with a soldering iron or iron. When docking it is laid so that the edge of one sheet overlaps the edge of the other by 10-15 mm. A strip of cellophane is applied to the seam.
PVC film transmits 90% of visible and up to 80% of UV rays, but almost does not transmit infrared rays, due to which greenhouses are slightly cooled at night. The service life of this material is two to three seasons.
Copolymer ethylene vinyl acetate film it is characterized by increased strength, elasticity and lightfastness. It is wind and puncture resistant. Serves up to three years.
Roll fiberglass made on the basis of glass fiber reinforced polyester resins. It is characterized by high strength, reliability and poor thermal radiation transmission. Supplied in rolls 90 cm wide. The pieces are joined with ether resins. The service life of rolled fiberglass is four years.

Summer residents who have decided to use polycarbonate to build a greenhouse or greenhouse in their suburban area for growing vegetables, are interested in the question: "Does polycarbonate transmit ultraviolet rays?" The emergence of such a question is not groundless, because the harm that ultraviolet light has on plants is known. To be able to answer the question that has arisen, and make a final decision on the use of the polymer, you will need to have information about the positive and negative aspects of the material.

Material advantages

Regardless of whether polycarbonate transmits ultraviolet rays or not, it has a huge number of undoubted advantages. These include the following material properties:

1. Low price for the material. Polycarbonate does not require constant and large financial investments in personal care during its operation.
2. The structure of the thermoplastic is such that even the assembled material can be easily disassembled for storage or reassembled.
3. Aesthetic qualities that are present thanks to the production of polymer in a wide color palette.
4. High strength index. Thermoplastic is able to withstand a high mechanical load (shock or under pressure of a high mass of something).
5. The ability to carry out independent assembly work with polymer. The material lends itself well to machining (drilling, cutting), so working with it does not require extra effort or special skills.
6. The speed of implementation of installation work with the material.
7. Excellent flexibility of thermoplastic panels, allowing them to be used even in complex structures.
8. Low weight. Polycarbonate is about fifteen times lighter than glass, and this makes it possible, during the use of material for greenhouses or greenhouses, not to install a foundation for the structure.
9. The transparency of colored sheets of material reaches fifty percent, and for transparent plates this figure reaches eighty-five percent. The duration of operation does not affect the decrease in the coefficient of permeability of light rays.
10. Good light diffusion is present due to the presence of a protective film on the surface of the panels, which helps to scatter the sun's rays and protect against the penetration of ultraviolet radiation from the sun into the interior of the room from contact with polycarbonate. This property allows you to evenly distribute the rays of the Sun between plants if the polymer is used in greenhouses or greenhouses.
11. Thermal conductivity. This property varies with the thickness of the slabs. The thicker the panel, the lower the thermal conductivity and vice versa.
12. Fire safety. The material is non-flammable and self-extinguishing. The polymer begins to melt only under the influence of a temperature of 570 degrees Celsius, while it does not release gases into the air that contain poison for living organisms.
13. If the material has nevertheless been subjected to significant impact and received mechanical damage, then it will not crumble into small particles, as if the glass and its edges will not be so sharp as to have the ability to cut a human body from careless contact.

disadvantages

Polycarbonate with and without UV protection, in addition to its advantages, also has a small number of disadvantages. These include the following material properties:

• a decrease in the ability to transmit light - this is possible if the cells of the edges of the panels are pasted over with ordinary tape or not at all, or were washed with solutions containing solvents, chlorine, abrasive particles;
• deformation of the material can occur if the profile and sheets are made by different manufacturers and do not adhere tightly to each other, or the linear expansion of the plates has not been taken into account;
• sags under the weight of snow or from strong influence of gusts of wind - this is possible if the material used is of poor quality or its thickness does not correspond to the climatic conditions of the given region, or the installation work was performed with errors.

Features of polycarbonate with and without UV protection

Knowing the answer to the question: "Does polycarbonate transmit ultraviolet rays?" it is possible to make the final decision on whether to use thermoplastic panels in the construction of the greenhouse.

Good to know: After all, it is known that ultraviolet light, which has penetrated into the greenhouse and is in the range of 390 nanometers, is capable of harming plants.

Polycarbonate is capable of not allowing ultraviolet light to pass through if its outer surface is covered with a special film with a thickness of 20-70 microns. Without a protective film, ultraviolet light will penetrate the polymer boards. The material with a protective film does not turn yellow and can be used without transmitting ultraviolet light for ten years.

Video about UV protection of polycarbonate