Organic glass

The material under the brand Plexiglas was created in 1928 , patented in 1933 by Otto Röhm ( German Otto Röhm ) ^[2] . Since 1933, it began its industrial production by the company Röhm and Haas ( Darmstadt ) ^[3] , the first sales of finished products belong to 1936 ^[2] .

The appearance of organic glass (at that time “plexiglass”) in the period between the two world wars was claimed by the rapid development of aviation, the continuous increase in the flight speeds of all types of aircraft and the appearance of vehicles with a closed cockpit (crew). A necessary element of such structures is the cockpit canopy. For use in aviation at the time, organic glass had a successful combination of the necessary properties: optical transparency, splinterless, that is, safety for the pilot, water resistance, insensitivity to the action of aviation gas and lubricating oils ^[4] .

During the Second World War, organic glass was widely used in the construction of a cockpit canopy, turrets of defensive armament of heavy aircraft, glazing elements of submarine periscopes. However, due to very easy flammability, at the first opportunity in aviation they switched to other transparent materials.

Nevertheless, polymers are only partially capable of replacing heat-resistant high-strength glasses - in modern aviation in many cases they are applicable only in the form of composites . The development of modern aviation involves flying in the upper atmosphere and hypersonic speeds, high temperatures and pressure, where organic glass is not applicable at all. Examples include aircraft that combine the qualities of spacecraft and airplanes: the Space Shuttle and Buran .

There are organic alternatives to acrylic glass - transparent polycarbonate , polyvinyl chloride and polystyrene .

History in the USSR

In the USSR, domestic plexiglass - plexiglas was synthesized in 1936 at the Research Institute of Plastics (Moscow). Nowadays, heat-resistant fluoroacrylate organic glasses are used as light and reliable parts for glazing of military and civil aircraft that are operable at operating temperatures from −60 to + 250 ° C. ^[five]

Plexiglas completely consists of thermoplastic resin. The chemical composition of standard plexiglass is the same for all manufacturers. It is another matter when it is necessary to obtain a material with different specific properties: shock-resistant (anti-vandal), light-scattering, light-transmitting, sound-proofing, UV- protective, heat-resistant and others, then in the process of producing sheet material its structure can be changed , providing a complex of necessary characteristics.

• Formula: [-CH2C (CH3) (COOCH3) -] n
• Melting point: 160 ° C
• Density: 1.19 g / cm³ ^[6]
• IUPAC name: Poly (methyl 2-methylpropenoate)

These organic materials are only formally referred to as glass and belong to a completely different class of substances, which is indicated by their very name and what basically defines the limitations of the properties and, as a result, the application possibilities that are incompatible with glass in many ways. Organic glasses are capable of approaching the properties to most types of inorganic glasses only in composite materials , but they cannot be refractory . Resistance to aggressive environments of organic glasses is also determined by a much narrower range.

However, this material, when its properties provide obvious advantages (excluding special types of glass), is used as an alternative to silicate glass. The differences in the properties of these two materials are as follows:

• PMMA is lighter: its density (1190 kg / m³) is approximately two times less than the density of ordinary glass;
• PMMA is softer than ordinary glass and is sensitive to scratches (this defect is corrected by applying scratch-resistant coatings );
• PMMA can be easily deformed at temperatures above +100 ° C; when cooled, the given shape is preserved;
• PMMA is easily machined by conventional metal-cutting tools;
• PMMA is better than non-specialized, designed for this purpose types of glass, transmits ultraviolet and X-rays, while reflecting the infrared; Plexiglass light transmission is slightly lower (92–93% versus 99% for the best silicate varieties);
• PMMA is not resistant to alcohol , acetone and benzene .

Advantages and disadvantages

Main advantages

• low thermal conductivity (0.2–0.3 W / (m · K)) compared with inorganic glasses (0.7–13.5 W / (m · K));
• high light transmission - 92%, which does not change over time, retaining its original color;
• resistance to impact is 5 times greater than that of glass;
• at the same thickness, Plexiglas weighs almost 2.5 times less than glass, therefore the design does not require additional supports, which creates the illusion of open space;
• resistant to moisture, bacteria and microorganisms, so it can be used for glazing yachts, the production of aquariums;
• environmentally friendly, when burning does not emit any poisonous gases;
• the ability to give a variety of forms using thermoforming without disturbing the optical properties with excellent detailing;
• machining is carried out with almost the same ease as wood processing;
• stability in the environment, frost resistance;
• transmits 73% of UV rays, while UV rays do not cause yellowing and degradation of acrylic glass;
• chemical stability;
• electrical insulating properties;
• must be recycled.

disadvantages

• during pyrolysis, it releases a harmful monomer, methyl methacrylate ;
• propensity to superficial damage (hardness 180–190 N / mm²);
• technological difficulties during thermo- and vacuum molding of products - the appearance of internal stresses at the bend points during molding, which leads to the subsequent appearance of microcracks;
• flammable material (flash point +260 ° C).

Features of extrusion plexiglass compared to molded plexiglass

• the number of possible sheet thicknesses is smaller, which is determined by the extruder capability
• possible sheet length is longer
• the thickness variation of sheets in the batch is smaller (tolerance in thickness is 5% instead of 30% in cast acrylic),
• lower impact resistance
• lower chemical resistance
• high sensitivity to stress concentration
• better bonding ability
• smaller and lower temperature range during thermoforming (approximately from +150 to +170 ° C instead of from +150 to +190 ° C),
• less forming force,
• large shrinkage when heated (6% instead of 2% in cast acrylic).

Chemical resistance

Plexiglas is affected by dilute hydrofluoric and hydrocyanic acids, as well as concentrated sulfuric, nitric and chromic acids. Plexiglas solvents are chlorinated hydrocarbons (dichloroethane, chloroform, methylene chloride), aldehydes, ketones and esters. Plexiglas is also affected by alcohols: methyl, butyl, ethyl, propyl. With a brief exposure to 10% ethanol, there is no interaction with organic glass.

Plexiglas is produced in two ways: extrusion and casting. Therefore, there are two types of Plexiglas - extrusion and cast. The production method itself imposes a number of restrictions and determines certain properties of plastic.

Extrusion plexiglass ( eng. Exstrusion , German Extrudiert ) is produced by continuous extrusion (extrusion) of the molten mass of granulated PMMA through a slit head, followed by cooling and cutting to specified sizes.

Block ( English cast , the terms “casting” and “cast” were also established in Russian) are obtained by pouring MMA monomer between two flat glasses with its further polymerization to a solid state.

Processing Methods

Drilling, threading, screwing, milling and machining according to a given profile, turning on a lathe, machining, pumming, grinding, polishing, molding, vacuum forming, punching, drawing in, blowing, bending, heating, cooling, annealing, joining, bonding, welding, dyeing and metallization.

Due to the rapid development of laser technology in recent years, the laser processing method PMMA has gained wide popularity. CO2 lasers are ideal for this task, since the laser wavelength of this type of laser (9.4 - 10.6 μm) is at the peak of PMMA absorption. The cut obtained by the method of laser irradiation is smooth, without traces of combustion products. When laser cutting transparent PMMA there is no color change on the cut. Color PMMA may change shade on the cut in rare cases.

As already noted, airplanes and helicopters belonging to the previous generation are glazed with single-layer or multi-layer (composite) materials based on organic and silicate glasses.

Plexiglas products are produced by vacuum forming, blow molding and stamping. Also used the method of cold forming. Many applications of these polymers intersect with glass, but Plexiglas is much easier to process and mold, and also has less weight. This determines its advantage for the manufacture of various interior parts, signs, promotional items and aquariums . Usually for communication using time-consuming optical glass. In this fiber, the core is made of quartz-germanate glass. Although the material of glass fibers is cheaper than plastic, their cost is higher due to the special processing and technology of products. In some less important cases, plastic fiber has a wide use for communication.

Of the unusual applications of plexiglass should be noted:

• Manufacturing glue - solvent for oneself by obtaining monomer ( methyl methacrylate ) by distillation;
• In the plumbing (acrylic baths ), in the trade equipment .

PMMA has found widespread use in ophthalmology : rigid gas-tight contact lenses and rigid intraocular lenses (IOL) have been manufactured from it for several decades, and they are now being implanted in the world to several million pieces per year. Intraocular (that is, intraocular) lenses are known as an artificial lens , and they replace a capsule that has clouded as a result of age-related changes and other causes leading to a cataract .

Organic glasses as biomaterials, precisely because of such qualities as plasticity, made it possible to replace inorganic glasses (for example, contact lenses ). The work of scientists for more than 20 years led to the creation in the late 1990s of silicone-hydrogel lenses , which, thanks to a combination of hydrophilic properties and high oxygen permeability, can be continuously used for 30 days around the clock. ^[7] However, it is not glass, but an optical material with its own characteristics.

Scopes: lighting equipment (plafonds, partitions, front screens, diffusers), outdoor advertising (front glass for boxes, light letters, molded three-dimensional products), commercial equipment (stands, showcases, price tags), plumbing equipment (bathroom equipment), construction and architecture (glazing of openings, partitions, domes, dance floor, volumetric molded products, aquariums), transportation (glazing of airplanes, boats, fairings), instrument-making (dials, observation windows, hulls, dielectric parts, capacities).

PMMA is widely used in micro and nanoelectronics . In particular, PMMA has found application as a positive electron resist in electron beam lithography . The PMMA solution is applied on a silicon wafer or other substrate using a centrifuge , resulting in a thin film, after which a focused electron beam , for example, in a scanning electron microscope (SEM), creates the desired pattern. In those places of the PMMA film, where electrons have fallen, there is a rupture of intermolecular bonds, as a result of which a latent image is formed in the film. Using the developing solvent, the highlights are removed. In addition to the electron beam, the pattern can be formed by irradiating PMMA with ultraviolet and X-rays . The advantage of PMMA in comparison with other resists is that it can be used to obtain pictures with lines of nanometer width. The smooth surface of PMMA can be easily nanostructured by treatment in oxygen high-frequency plasma, and the nanostructured surface of PMMA can be easily smoothed by irradiation with vacuum ultraviolet ( VUV ). ^{[8] [9] [10]}

Used as a material for making imitations of Baltic amber ^[2] .

Sports Tourism

The long and narrow trimming of plexiglass (30–50 × 5–9 cm) does not dampen, is easily set on fire and gives a bright, wind-stable flame, thanks to which cut plexiglas is often used in sports tourism , in hiking tours for making campfires and, in the dark days for local lighting.

Musical Instruments

Plexiglas (acrylic) is used in the manufacture of drums (DW Design Acryl ShellSet, Tama Mirage). Plexiglass drum sets look very impressive on stage during a show. Nevertheless, acrylic drums lose by the sound of wood (due to resonant qualities) and in studio work, as a rule, they are not used.

Sound insulation and sound reflection

Organic glass (Plexiglas) reflects sound in noise insulation screens, in noise insulation barriers on highways, bridges, pedestrian crossings, railroad crossings, in cottage villages, for sound insulation of buildings, etc.

For example, the installed amount of sound insulation PLEXIGLAS SOUNDSTOP 12 mm thick - 32 dB; 15 mm thick - 34 dB; 20 mm thick - 36 dB; 25 mm thick - 38 dB

Clear Plexiglas

A colorless crystal clear sheet with a light transmission of 92–93% (with a thickness of 3 mm), with a perfectly smooth surface, distinguished by a strong gloss on both sides. Maximum transparency, no image distortion. Application: glazing of buildings and structures (external and internal), shop windows, transparent protection of devices and mechanisms.

Clear color plexiglass

Plexiglas uniformly colored in mass. The most popular tinted sheets of gray (smoky), blue and brown (bronze) shades. In general, sheets can be painted in absolutely any color, have many variations of shades of different degrees of saturation, while remaining transparent, not distorting the image. Maximum transparency, no image distortion.

Application: transport glazing, medical equipment, partitions, enclosing structures, domes, sheds, atriums, lanterns, greenhouses, greenhouses, solariums, furniture items, worktops, shelves, trade and exhibition equipment, stands, holders, pockets of information stands, demonstration designs, models, products of outdoor and interior advertising, POSM, souvenir products, tags, tags, various thermoformed products, protective glazing of photos, paintings and stands, aquariums, interior details, transparent floors, tupeni stairs, handrails and so on. Registration of exhibitions, shows, concerts, television studios.

Clear Corrugated Plexiglas

Transparent colorless and colored plexiglass with a convex pattern on one side of the sheet, the other side is smooth. Effects of light scattering due to light refraction with significant transmission of visible light. Behind such glasses objects and images get blurred outlines. Classical types of riffling: “crushed ice”, small and large corrugation “prismatic”, “honeycomb”, “small waves”, “drop”. Exclusive types of corrugation: “stream”, “pin prick”, “squares”, “pyramids”, “corduroy”, “skin”. Transparency, light refraction, partial hiding of the image behind the sheet, a special decorative effect.

Application: glazing of shower cabins, bath curtains, glazing of interior doors, filling of partitions, furniture, design elements, diffusers of lamps, suspended ceilings with internal illumination, decorative designs of the interior.

Frosted White Plexiglas

White light-diffusing sheet with light transmission from 20 (externally opaque) to 70% (translucent) with a smooth, high-gloss surface on both sides. Uniform light scattering, completely hiding the image behind the sheet (when illuminated, a light screen is formed).

Color Matte Plexiglas

Light-scattering sheet of a certain color (indicating the color according to RAL , Pantone or the manufacturer's catalog) with varying degrees of light transmission, a perfectly glossy surface. Uniform light scattering, completely hiding the image behind the sheet (when illuminated, a light screen is formed).

Application: diffusers of luminaires, luminous suspended ceilings, podiums, floors with internal illumination, commercial and advertising illuminated signs (light boxes) with application of self-adhesive films, photo caching, silk- screen printing, road light boxes , pylons, signs of public institutions, parking lots and so Further. Volumetric letters, layouts of the advertised products with internal illumination, miniature light boxes showing streets (house numbers), the use of printing technology for plastics, medical equipment, devices and so on.

Corrugated frosted white and colored plexiglas.

White (or colored) plexiglass with varying degrees of light transmission, corrugation applied on one side of the sheet, the other side is smooth. Uneven scattering, completely hiding the image behind the glass. It has the most limited areas of use: diffusers for fluorescent lamps, decorative interior elements with internal illumination.

• Organic glass is transported by road and rail in covered vehicles in accordance with the Rules for the Transport of Goods in force for this type of transport.
• It is allowed to transport plexiglas in open vehicles covered with waterproof material ^[11] .
• Plexiglass should be stored in closed warehouses at a temperature of +5 to +35 ° C with a relative humidity of 65% or less ^[11] .
• Transportation and storage of organic extrusion glass with chemical products is not allowed ^[11] .
• When storing and transporting plexiglass sheets that are folded together, it is better to shift them with sheets of paper to prevent mechanical damage.

• Matushevskaya A. Natural and artificial resins - some aspects of the structure and properties: [ eng ] = Natural and artificial resins - [trans. with rus. ] // Amber and his imitation : [ eng ] = Amber and its imitations: [trans. with rus. ]: collection / otv. ed. Z. V. Kostyashova, editorial board: Z. V. Kostyashova, T. Yu. Suvorova, A. R. Manukyan. - Kaliningrad: Ministry of Culture of the Kaliningrad Region , Kaliningrad Regional Amber Museum , 2013. - 113 p. - Proceedings of the international scientific-practical conference on June 27, 2013. - ISBN 978-5-903920-26-6 .
• Wagner-Vysetskaya E. Imitation of amber through the eyes of a chemist: [ eng ] = Amber imitations through the eyes of a chemist: [trans. with rus. ] // Amber and his imitation : [ eng ] = Amber and its imitations: [trans. with rus. ]: collection / otv. ed. Z. V. Kostyashova, editorial board: Z. V. Kostyashova, T. Yu. Suvorova, A. R. Manukyan. - Kaliningrad: Ministry of Culture of the Kaliningrad Region , Kaliningrad Regional Amber Museum , 2013. - 113 p. - Proceedings of the international scientific-practical conference on June 27, 2013. - ISBN 978-5-903920-26-6 .