Polymers are active chemical substances, which in recent times gain wide popularity due to the mass consumption of plastic products. Every year, the volumes of world production of polymers are growing, and materials made using them are gaining new positions in the household and industrial sectors.

All product tests are carried out in laboratory conditions. Their main task is to determine the factors environment, which have a devastating effect on plastic products.

The main group of adverse factors that destroy polymers

The resistance of specific products to negative climatic conditions is determined taking into account two main criteria:

• the chemical composition of the polymer;
• type and strength of external factors.

In this case, the adverse effect on polymer products is determined by the time of their complete destruction and the type of impact: instant complete destruction or subtle cracks and defects.

Factors affecting the degradation of polymers include:

• microorganisms;
• thermal energy of varying degrees of intensity;
• industrial emissions containing harmful substances;
• high humidity;
• UV radiation;
• x-ray radiation;
• an increased percentage of oxygen and ozone compounds in the air.

The process of complete destruction of products is accelerated by the simultaneous action of several unfavorable factors.

One of the peculiarities of the climatic testing of polymers is the need for test expertise and study of the influence of each of the listed phenomena separately. However, such evaluation results cannot fully reflect the picture of the interaction of external factors with polymer products. This is due to the fact that under normal conditions, materials are most often subjected to combined effects. In this case, the destructive effect is markedly enhanced.

Effect of ultraviolet radiation on polymers

There is a misconception that plastic products the sun's rays are particularly damaging. In fact, only ultraviolet radiation has a destructive effect.

Bonds between atoms in polymers can be destroyed only under the influence of rays of this spectrum. The consequences of such adverse impact can be observed visually. They can be expressed:

• in the deterioration of the mechanical properties and strength of the plastic product;
• increased fragility;
• burnout.

In laboratories, xenon lamps are used for such tests.

They also conduct experiments to recreate the conditions of exposure to UV radiation, high humidity and temperature.

Such tests are needed in order to draw conclusions about the need for changes in chemical composition substances. So, in order for the polymer material to become resistant to UV radiation, special adsorbers are added to it. Due to the absorbing ability of the substance, the protective layer is activated.

The stability and strength of interatomic bonds can also be increased by introducing stabilizers.

The destructive action of microorganisms

Polymers are substances that are highly resistant to bacteria. However, this property is typical only for products made of high quality plastic.

In low-quality materials, low molecular weight substances are added that tend to accumulate on the surface. A large number of such components contribute to the spread of microorganisms.

The consequences of the destructive impact can be noticed quite quickly, since:

• aseptic qualities are lost;
• the degree of transparency of the product is reduced;
• brittleness appears.

Among the additional factors that can lead to a decrease in the performance of polymers, it should be noted elevated temperature and humidity. They create conditions favorable for the active development of microorganisms.

The ongoing research has made it possible to find the most effective method preventing the growth of bacteria. This is the addition of special substances - fungicides - to the composition of polymers. The development of bacteria is suspended due to the high toxicity of the component for the simplest microorganisms.

Is it possible to neutralize the impact of negative natural factors?

As a result of the research, it was possible to establish that most of the plastic products presented on modern market, does not interact with oxygen and its active compounds.

However, the mechanism of polymer destruction can be triggered by the combined action of oxygen and high temperature, humidity, or ultraviolet radiation.

Also, when conducting special studies, it was possible to study the features of the interaction of polymeric materials with water. Liquid affects polymers in three ways:

1. physical;
2. chemical (hydrolysis);
3. photochemical.

Additional simultaneous exposure elevated temperature can accelerate the process of destruction of polymer products.

Corrosion of plastics

In a broad sense, this concept implies the destruction of the material under the negative influence of external factors. Thus, the term “polymer corrosion” should be understood as a change in the composition or properties of a substance caused by adverse influence which leads to partial or complete destruction of the product.

Processes of targeted transformation of polymers to obtain new material properties do not fall under this definition.

We should talk about corrosion, for example, when polyvinyl chloride comes into contact and interacts with a chemically aggressive environment - chlorine.

Acrylic in architecture

The most beautiful architectural structures are created from acrylic glass - transparent roofs, facades, road barriers, awnings, canopies, gazebos. All these structures are used in outdoors under constant exposure to sunlight. A reasonable question arises: can acrylic structures withstand the "onslaught" of the rays of the scorching sun, while maintaining excellent performance, brilliance, and transparency? We hasten to please you: there is no reason for concern. Acrylic structures can be safely used outdoors under constant impact. ultraviolet radiation even in hot countries.

Comparison of acrylic with other plastics in terms of UV resistance

Let's try to compare acrylic with other plastics. Today, for the manufacture of facade, roof glazing and protective structures, a large number of different transparent plastics are used. At first glance, they are no different from acrylic. But synthetic materials, similar to acrylic in their visual characteristics, lose their visual appeal after a few years of operation in direct sunlight. No additional coatings and films are able to protect low-quality plastic from ultraviolet radiation on long term. The material remains sensitive to UV rays, and, alas, there is no need to talk about the reliability of all kinds of surface coatings. Protection in the form of films and varnishes cracks and peels off over time. It is not surprising that the warranty against yellowing of such materials does not exceed several years. Acrylic glass from the Plexiglas brand behaves quite differently. The material has natural protective properties, therefore it does not lose its excellent characteristics for at least three decades.

How does acrylic sun protection technology work?

UV resistance of Plexiglas is ensured unique technology complex protection Naturally UV Stable. Protection is formed not only on the surface, but throughout the entire structure of the material at the molecular level. The plexiglass manufacturer Plexiglas provides a 30-year warranty against yellowing and clouding of the surface during continuous outdoor use. This warranty applies to transparent colorless sheets, pipes, blocks, rods, corrugated and ribbed plates made of Plexiglas brand acrylic glass. canopies, roof coverings, transparent acrylic facades, arbors, fences and other plexiglass products do not acquire an unpleasant yellow tint.

The diagram shows changes in the light transmission index of acrylic during the warranty period in various climatic zones. We see that the light transmission of the material is slightly reduced, but these are minimal changes, imperceptible to the naked eye. A decrease in the light transmission index by a few percent can only be determined using special equipment. Visually, acrylic remains pristinely transparent and shiny.

On the graph, you can trace the dynamics of changes in the light transmission of acrylic in comparison with ordinary glass and other plastics. First, the light transmission of acrylic in its original state is higher. It is the most transparent plastic material known today. Over time, the difference becomes more noticeable: low-quality materials begin to darken, fade, and the light transmission of acrylic remains at the same level. None of the known plastics, except acrylic, can transmit 90% of the light after thirty years of operation under the sun. That is why modern designers and architects prefer acrylic when creating their best projects.

When we talk about light transmission, we are talking about the safe spectrum of ultraviolet rays. Dangerous part of the solar radiation spectrum acrylic glass delays. For example, in a house under an acrylic roof or in an airplane with acrylic windows, people are under reliable protection of the glazing. To clarify, let's look at the nature of ultraviolet radiation. The spectrum is divided into short-wave, medium-wave and long-wave radiation. Each type of radiation has a different effect on the surrounding world. The most high-energy radiation with a short wavelength, absorbed by the ozone layer of the planet, can damage DNA molecules. Medium-wave - with prolonged exposure causes skin burns and inhibits the main functions of the body. The safest and even most useful is long-wave radiation. Only a part of the dangerous medium-wave radiation and the entire long-wave spectrum reaches our planet. Acrylic allows the useful spectrum of UV radiation to pass through, while blocking dangerous rays. This is a very important advantage of the material. Glazing at home allows you to keep maximum light in the room, protecting people from the negative effects of ultraviolet radiation.

IN AND. Tretyakov, L.K. Bogomolova, O.A. Krupinin

One of the most aggressive types of operational impacts on polymer Construction Materials is UV exposure.

To assess the resistance of polymeric building materials, both full-scale and accelerated laboratory tests are used.

The disadvantage of the former is the long duration of the test, the impossibility of isolating the influence of a single factor, as well as the difficulty of taking into account annual fluctuations in atmospheric effects.

The advantage of accelerated laboratory tests is that they can be carried out in a short time. At the same time, in some cases, it is possible to describe the obtained dependences of changes in properties over time by known mathematical models and predict their durability for longer periods of operation.

The purpose of this work was to assess the resistance to UV radiation in the conditions of the Krasnodar Territory of samples of white laminated polypropylene fabric with special additives in the shortest possible time.

Laminated polypropylene fabric is used for temporary protection of erected and reconstructed building structures, as well as individual elements from atmospheric influences.

The resistance of the material to UV irradiation was evaluated by changing the tensile strength according to GOST 26782002 on samples - strips, dimensions (50x200) ± 2 mm and changing appearance(visually).

For the limiting value of the aging of the material is taken to reduce its strength to 40% of the original value.

Tensile strength tests were carried out on a ZWICK Z005 universal testing machine (Germany). The initial tensile strength of the tested samples was

115 N/cm. ""

" Picture 1.

Ultraviolet irradiation of the image

material samples were carried out in an irradiation apparatus

artificial weather (AIP) type "Xenotest" with a xenon emitter DKSTV-6000 according to GOST 23750-79 with a water cooling system and a quartz glass jacket. The radiation intensity in the wavelength range of 280-400 nm was 100 W/m2. The hourly dose of UV irradiation (O) is 360 kJ/m2 for this spectral regime.

During exposure to AIP, the intensity of tissue irradiation was controlled by an intensimeter - a dosimeter manufactured by OBkDM (Germany).

The samples were irradiated continuously for 144 h (6 days). Removal of samples to assess the change in tensile strength was carried out at certain intervals. The dependence of the residual tensile strength (in%) on the initial value of the laminated polypropylene fabric on the exposure time in the AIP is shown in Figure 1.

After mathematical processing of the obtained data using the least squares method, the obtained experimental results are generalized by the linear dependence shown in Figure 2.

20 40 60 80 100 120 140 160 Dependence of residual tensile strength (in %) on the value of laminated polypropylene fabric on time in AIP

building materials and structures

Theoretical Observatory of Moscow State University is 120,000 kJ/m2 year (O f M)

At the same time, there are no data on the annual dose of the UV part of solar radiation in the Krasnodar Territory (Ouf c c) in the literature. The above values ​​of Osum for Moscow and the Krasnodar Territory make it possible to approximately calculate the total annual UV dose for the Krasnodar Territory using the following formula:

O f -O c / O

uv M sums K.k "

Figure 2. Linear dependence of the residual tensile strength of a laminated polypropylene fabric on the logarithm of the irradiation time in the AIP

1 - experimental values; 2 - values ​​calculated using equation (1)

hence,

Of k \u003d 1200001.33 \u003d

160320 kJ/m2 year

P% \u003d P0 - 22.64-1dt,

where P% ost - residual value of tensile strength (in%) after UV irradiation; P0 - initial value of tensile strength (in%), equal to 100; 22.64 - a value numerically equal to the tangent of the slope of the straight line in the coordinates: residual tensile strength (in %) - the logarithm of the irradiation time in the AIP; T is the exposure time in the AIP, in hours.

The results of mathematical processing (see equation (1) and figure 2) allow extrapolating the obtained data for a longer test period.

An analysis of the obtained results shows that a decrease in the residual strength of the laminated polypropylene fabric up to 40% will occur after 437 hours of irradiation. In this case, the total dose of UV radiation will be 157320 kJ/m2.

A visual assessment of the appearance of the irradiated material shows that already after 36 hours of irradiation, the tissue has a denser structure, becomes less loose and less shiny. With further irradiation, the stiffness and density of the tissue increase.

According to GOST 16350-80, the total dose of solar radiation (Osumm) for moderate warm weather mild winter climate of the Krasnodar Territory (GOST, table 17) is 4910 MJ / m2 (Osum Kk), and for the temperate climate of Moscow - 3674 MJ / m2 (Osum M). The annual dose of the UV part of solar radiation according to the Moscow

Comparison of the annual dose of UV irradiation for the Krasnodar Territory (160320 kJ/m2) with the dose of UV irradiation in laboratory conditions (157320 kJ/m2) allows us to conclude that under natural conditions the strength of the material will decrease to 40% of the initial value under the action of UV radiation. exposure for approximately one year.

Findings. Based on the presented material, the following conclusions can be drawn.

1. The resistance of samples of laminated polypropylene fabric for construction purposes to the action of UV irradiation in laboratory conditions was studied.

2. By calculation, the annual dose of UV radiation for the Krasnodar Territory was determined, which is 160320 kJ/m2.

3. According to the results of laboratory tests for 144 hours (6 days), it was found that the change in tensile strength under the influence of UV irradiation is described by a linear logarithmic dependence, which made it possible to use it to predict the light fastness of a polymer fabric.

4. Based on the dependence obtained, it was determined that the decrease in the strength of the laminated polypropylene fabric for construction purposes to a critical level under the influence of UV irradiation under natural conditions in the Krasnodar Territory will occur in approximately one year.

Literature

1. GOST 2678-94. Materials are rolled roofing and waterproofing. Test methods.

building materials and structures

2. GOST 23750-79. Devices of artificial weather on xenon emitters. General technical requirements.

3. GOST 16350-80. Climate of the USSR. Zoning and statistical parameters of climatic factors for technical purposes.

4. Collection of observations of the meteorological observatory of Moscow State University. M.: Publishing House of Moscow State University, 1986.

Accelerated method for evaluating UV resistance of laminated polypropylene fabric for construction purposes

To assess the light resistance of samples of laminated polypropylene fabric for construction purposes to UV irradiation in laboratory conditions by reducing the tensile strength of the test material to limit value 40%, a linear dependence of the residual strength on the exposure time in the artificial weather apparatus was obtained in logarithmic coordinates.

Based on the dependence obtained, it was determined that the decrease in the strength of the laminated polypropylene fabric for construction purposes to a critical level under the influence of UV irradiation in natural conditions of the Krasnodar Territory will occur in approximately one year.

The accelerated method of an estimation of resistance of the laminated polypropylene fabrics for building appointment to the ultraviolet-irradiation

by V.G. Tretyakov, L.K. Bogomolova, O.A. Krupinina

For an estimation of light resistance of laminated polypropylene fabric samples for building appointment to ultraviolet-irradiation influence in vitro on durability decrease at a stretching of a tested material to limiting value of 40% the linear dependence of residual durability on irradiation time in the device of artificial weather in logarithmic coordinates is received.

On the basis of the received dependence it has been defined that decrease in durability laminated polypropylene fabrics for building to a critical level under the influence of the ultraviolet-irradiation in natural conditions of Krasnodar territory would be occur approximately in one year.

Keywords: lightfastness, ultraviolet irradiation, prediction, critical strength level, climate, laminated polypropylene fabric.

Key words: light resistance, ultraviolet-irradiation, prognostication, critical level of durability, climate, laminated polypropylene fabric.

What it is?

Why is UV printing so good?

Why pay more?

The principle of UV printing

Ultraviolet printing (UV printing) is a type of printing using UV-curable ink by inkjet printing directly on the material. When exposed to UV radiation of a certain wave, such ink instantly polymerizes and turns into a solid state. Since the ink does not absorb into the material and does not spread over the surface, this allows you to create bright and saturated images.

UV ink has a matte finish after curing, so additional lacquer treatment is required to make it glossy. But if you use printing on glass on the reverse side, the images are juicy and glossy. Thus, the image can be applied to any surface. Glossy surfaces are treated with a special solution before application, which helps the ink to adhere to the surface of the material. Even without varnish, after polymerization, the ink stops evaporating harmful solvents and becomes harmless to humans.

When printing on transparent materials (glass, plexiglass) with white color, we get several layers: base (glass) + primer (for adhesion to the surface) + colored UV inks + white UV ink + white protective film security.

What are the advantages of printing with UV inks?

• Fortitude
  UV ink is very resistant to environmental influences. In addition, they are more durable - they do not fade in the sun and do not dissolve in water and solvents.
• Environmental friendliness
  ​The components that make up UV inks, unlike solvent inks, do not contain resin-based solvents. In the process of working with ink, it is practically eliminated bad influence on the atmosphere and man. This allows you to use UV printing in places with high sanitary requirements (schools, kindergartens, hospitals) and in the interior.
• Big choice material and surfaces
  UV ink is not absorbed into the material, but remains on the surface. That is why you can print on any materials: flexible or hard, with smooth or uneven surfaces.
• Bright and vibrant colors
  Because UV ink is not absorbed and does not spread, the colors do not lose juiciness, and the lack of spreading allows you to print clear images as in the original file. That is why you can print on any surface without loss of juiciness and clarity.
• Durability
  In indoor advertising, the service life of UV printing is 10-15 years, and in outdoor advertising it is limited to 4-5 years. This is due to the fact that outdoor advertising materials are still exposed to ultraviolet radiation and significant temperature fluctuations.
• Printing in white
  ​Currently, very few printers can boast the ability to print in white. Wherein White color can be underlay, opaque, and just as a 5th spot color when printed on dark surfaces

So why pay for UV printing?

The UV printing technology itself is much more expensive than simple interior printing with solvent plotters. But when using printing on a solvent plotter, there are a number of significant drawbacks, including those that are harmful to health, since even after a few days the solvent ink continues to evaporate from the surface of the film. And it is better not to pronounce the list of diseases that it causes in a decent place. For example, let's look at the most common case - the manufacture of skinali (kitchen apron) So, skinali is installed in the kitchen between the lower and upper drawers, in close proximity from cooking. It is natural in this case to use more environmentally friendly products. Strained glass behind gas stove located in an area with temperature fluctuations, and the film in such places can "float", with the appearance of bubbles and drying of the film to the center of the glass, which in turn leads to the appearance of transparent stripes along the edges of the skinal. This is especially critical at the junctions of individual glasses. UV printing is deprived of all this, because. it is applied directly to the glass and is not afraid high temperatures. An added bonus will be high quality pictures and printing to the edge of the glass, even bevels are sealed. The difference in the cost of one square meter of photo printing on film and UV printing is 600-800 rubles. With an apron length of 4 p.m. additional expenses will amount to 1.5 - 2 thousand rubles. But for this money you will get bright colors, without dust and debris under the film, without transparent edges, with a guarantee for 10-15 years. You deserve a good product for the money spent!

Enamel resistance to fading

Conditional lightfastness was determined on samples of dark gray RAL 7016 enamel on REHAU BLITZ PVC profile.

The conditional light fastness of the paintwork was determined in tests in accordance with the standards:

GOST 30973-2002 "Polyvinyl chloride profiles for window and door blocks. Method for determining resistance to climatic influences and assessing durability". p. 7.2, tab. 1, approx. 3.

Determining the conditional light fastness at a radiation intensity of 80±5 W/m 2 was controlled by changing the gloss of the coatings and color characteristics. The color characteristics of the coatings were determined on a Spectroton device after wiping the samples with a dry cloth to remove the formed plaque.

The change in the color of the samples during the test was judged by the change in color coordinates in the CIE Lab system, calculating ΔE. The results are shown in table 1.

Table 1 - Change in gloss and color characteristics of coatings

Samples 1 to 4 are considered to have passed the test.

The data are given for sample No. 4 - 144 hours of UV irradiation, which corresponds to GOST 30973-2002 (40 conditional years):

L = 4.25 norm 5.5; a = 0.48 norm 0.80; b = 1.54 norm 3.5.

Conclusion:

The power of the luminous flux up to 80±5 W/m 2 leads to a sharp drop in the gloss of the coatings by 98% after 36 hours of testing as a result of plaque formation. With continued testing, no further loss of gloss occurs. Light fastness can be characterized in accordance with GOST 30973-2002 - 40 conditional years.

The color characteristics of the coating are within acceptable limits and comply with GOST 30973-2002 on samples No. 1, No. 2, No. 3, No. 4.