Plexiglass is a popular name. From this name, you may not know what kind of substance it is or what elements it is made of. The chemical name of this polymer transparent material is polymethyl methacrylate, which is abbreviated as PMMA in English. It is made by polymerization of methyl methacrylate with chemical resistance and solvent resistance. Polymethacrylate can resist dilute inorganic acids, but strong inorganic acids can corrode it and alkali, but warm sodium hydroxide and potassium hydroxide can corrode it. It can resist salt and oil, aliphatic hydrocarbons, and is insoluble in water, methanol, glycerol and so on. , but it can absorb alcohol swelling. Its solubility parameter is about 18.8(J/CM3) 1/2. It can be dissolved in many chlorinated hydrocarbons and aromatic hydrocarbons, such as dichloroethane, trichloroethylene, chloroform, toluene and so on. , can also be dissolved with vinyl acetate and acetone. The chemical name of (1) material PMMA is polymethyl methacrylate, which is a polymer compound polymerized from methacrylate. (2) Plexiglass is widely used, not only in commerce, light industry, architecture, chemical industry and so on. In addition, the production of plexiglass is widely used in advertising decoration and sand table models, such as signs, billboards, light box panels and Chinese and English letter panels. The choice of materials depends on the design, what kind of shape, what kind of plexiglass, color and variety, and the best effect can be achieved by repeated experiments. With good modeling design, it needs careful processing to become exquisite handicrafts [1]. (3) The characteristic surface is smooth, colorful, small in specific gravity, high in strength, corrosion-resistant, moisture-resistant, sun-resistant, and good in insulation and sound insulation. (4) The shape can be divided into three types: tubular, rod and plate. (5) There are four types. Color transparent plexiglass: commonly known as color plate. The light transmission is soft, and the light boxes and handicrafts made of it make people feel comfortable and generous. Colored plexiglass can be divided into three types: transparent color, translucent color and opaque color. Magnetic plexiglass is not as bright and fragile as pearlescent plexiglass, and is suitable for making dials, boxes, medical devices and modeling materials for people and animals. Transparent plexiglass: high transparency, suitable for lamps. The chandelier made of it is exquisite and crystal clear. Translucent plexiglass is similar to frosted glass, with soft reflection. The handicrafts made with it make people feel comfortable and generous. Colorless transparent organic chandelier, exquisite workmanship, crystal clear. Pearlescent mobile phone glass: made by adding pearl powder or fluorescent powder to ordinary plexiglass. This kind of plexiglass has bright colors and high surface finish. After the external shape is hot-pressed by the mold, even after polishing, the molded pattern is still maintained, forming a unique artistic effect. It can be used to make figures, animal models, trademarks, decorations and publicity and exhibition materials. Embossed plexiglass: transparent, translucent and colorless, fragile and fragile, suitable for production. [Edit this paragraph] The birth and development of plexiglass 1927. Chemists from Germany's Roma-Haas company heated acrylate between two glass plates, and the acrylate polymerized to form a sticky rubber-like interlayer, which can be used as shatterproof safety glass. When they polymerized methyl methacrylate in the same way, PMMA with good transparency and other properties was obtained, which was polymethyl methacrylate. 193 1 year, Haas, Rome established a factory to produce polymethyl methacrylate, which was first used in the aircraft industry to replace celluloid plastics and used as aircraft canopy and windshield. If various dyes are added in the production of plexiglass, it can be polymerized into colored plexiglass; If a fluorescent agent (such as zinc sulfide) is added, it can be polymerized into fluorescent plexiglass; If artificial pearl powder (such as basic lead carbonate) is added, pearlescent plexiglass can be made. [Edit this paragraph] The characteristics of plexiglass ① High transparency. Plexiglass is the best polymer transparent material at present, and its light transmittance is as high as 92%, which is higher than that of glass. The lamp tube of solar lamp called artificial small sun is made in time, because it can completely transmit ultraviolet rays in time. Ordinary glass can only transmit 0.6% ultraviolet rays, while plexiglass can transmit 73%. ② High mechanical strength. The relative molecular weight of plexiglass is about 2 million, and it is a long-chain polymer compound with a soft molecular chain. Therefore, the strength of plexiglass is relatively high, and its tensile and impact resistance is 7- 18 times higher than that of ordinary glass. One kind of plexiglass is heated and stretched, and the molecular segments are arranged in a very orderly way, which greatly improves the toughness of the material. Nail into this plexiglass, even if the nail penetrates, there will be no cracks on the plexiglass. This plexiglass won't break into pieces after being punctured by bullets. Therefore, the stretched plexiglass can be used as bulletproof glass and also as the cockpit cover of military aircraft. ③ Light weight. The density of plexiglass is 1. 18kg/dm? The weight of the same size material is only half that of ordinary glass, and the weight of aluminum metal is 43% of that of light metal. ④ Easy to process. Plexiglass can be not only cut by lathe and drilled by drilling machine, but also glued into various shapes by acetone, chloroform and other instruments. It can also be processed into various products as large as aircraft cockpit covers, as small as dentures and braces by plastic molding methods such as blow molding, injection molding and extrusion. [Edit this paragraph] The use of plexiglass plexiglass has the above excellent properties, which makes it widely used. In addition to being used as the canopy, windshield and chord window of aircraft, it is also used as the windshield and window of jeep, the skylight of large building (which can prevent damage), the screen of TV and radar, the protective cover of instruments and equipment, the shell of telecommunication instruments, and the optical lens of telescopes and cameras. There are many kinds of articles for daily use made of plexiglass, such as buttons, toys and lamps made of pearlescent plexiglass, which are particularly beautiful because of the decorative effect of colored plexiglass. There is also a wonderful use of plexiglass in medicine, which is to make artificial cornea. If the transparent cornea of the human eye is covered with an opaque substance, light cannot enter the eye. This is blindness caused by leukoplakia of the whole cornea, which cannot be treated with drugs. Therefore, medical scientists imagine to replace the cornea covered with white spots with artificial cornea. The so-called artificial cornea is made of a transparent material with a diameter of only a few millimeters, and then a small hole is drilled in the cornea of the human eye to fix the lens column on the cornea, and the light enters the eye through the lens column, so that the human eye can see the light again. As early as 177 1 year, ophthalmologists made columns of optical glass and implanted them in the cornea, but they failed. Later, it took only half a year to replace the optical glass with crystal, which failed. In World War II, when some planes crashed, the cockpit cover made of plexiglass was blown off, and the pilot's eyes were embedded with plexiglass fragments. After many years, although these fragments were not taken out, they did not further cause inflammation or other adverse reactions in human eyes. This accident shows that plexiglass has good compatibility with human tissues. At the same time, it also inspires ophthalmologists to make artificial cornea with plexiglass, which has good light transmittance, stable chemical properties, no toxicity to human body, easy processing into the required shape and long-term compatibility with human eyes. At present, plexiglass artificial cornea has been widely used in clinic. [Edit this paragraph] The production method of plexiglass (1) The pasting method is to cut plexiglass into a certain shape and paste it on a flat surface. (2) After the plexiglass plate is heated by hot pressing, it is hot pressed in the mold. Handicrafts made by this modeling method have the characteristics of plump figure, smooth curve and strong three-dimensional sense, and have relief effect. Hot-pressing mold can be made of wood and sludge, then cast lead and gypsum are used as male and female molds, and plexiglass is heated and pressed to form. (3) The plexiglass blocks with different colors are cut into required geometric figures by mosaic method, and then the plexiglass blocks are spliced on the bottom plate. This method requires strict stitching and sharp edges, and can receive strong colors but seamless effects. (4) Stick-shaped plexiglass or thick plate-shaped plexiglass is bonded by vertical grinding method, and then directly grinded, polished and molded on a grinding wheel. Crafts made by this method are similar to sculptures, with unique artistic images and colorful surface shapes. And (5) overlapping and pasting the plate-shaped plexiglass together by a crushing method, and then directly grinding and molding. Crafts made by this method can achieve the effect of changeable colors and simplicity. (6) The plexiglass is processed into a certain shape by a hot stewing method, the plexiglass is heated, and the plexiglass is directly and quickly nested and kneaded by hands. Some laws require that the composition be well prepared in advance, agile and accomplished in one go. Crafts made in this way have rough lines and simple images. The above methods can be used alternately, and the best method can be determined according to the artistic requirements of modeling design. [Edit this paragraph] Polymethyl methacrylate, a thermoplastic, is usually called plexiglass, abbreviated as PMMA. It has the advantages of high transparency, low price and easy processing, and is a commonly used glass substitute material. Plexiglass is an important thermoplastic with an early development, which has transparency, stability and weatherability, easy dyeing, easy processing and beautiful appearance, and is widely used in the construction industry. In architecture, plexiglass is mainly used for lighting bodies, roofs, shed roofs, stairs and indoor wallboard. In recent years, the application of plexiglass in lighting lampshades and car lights of expressways and high-grade roads is also quite rapid. With the construction of hotels, guesthouses and high-grade houses in big cities, daylighting bodies have developed rapidly. The plexiglass extruded board lighting body has the characteristics of high overall structural strength, light weight, high light transmittance and good safety performance, and has great advantages compared with inorganic glass lighting devices. In sanitary ware, plexiglass can be used to make bathtubs, washbasins, dressing tables and other products. Plexiglass bathtub has been widely used in recent years because of its luxurious appearance, deep texture, easy cleaning, high strength, light weight and comfortable use. At present, the United States and Japan have made it compulsory to use plexiglass in primary and secondary schools and kindergartens. With the continuous improvement of China's laws, it is expected that corresponding regulations will be made in the near future. At the same time, all parts of our country have accelerated the pace of urban construction, and road signs, advertising light boxes and telephone booths made of plexiglass will also appear in large numbers, so plexiglass has great development space and broad market prospects! [Edit this paragraph] Why is plexiglass different from ordinary glass? Plexiglass and ordinary glass look like a family, but in fact they are completely different. The "father" of ordinary glass is silicate, but the "parents" of plexiglass are acetone, methanol, sulfuric acid and hydrogen cyanide. The real name of plexiglass is polymethyl methacrylate. This name is awkward, because it is a synthetic polymer, so people generally call it plexiglass. Plexiglass is generally more stubborn than ordinary glass. Although its density is half that of ordinary glass, it is not as easily broken as glass. It is very transparent, crystal clear and has good thermoplasticity. After heating, it can be shaped into glass rod, glass tube or glass plate at will. Because of its attractive appearance and personality, it has a wide range of uses. When jet planes fly at high speed in the clouds, they often encounter severe vibration and sudden changes in air temperature and pressure, which is a severe test for the window glass of the cockpit of the aircraft. Who can stand this test? Plexiglass. If it is a fighter plane, when chasing the enemy, plexiglass will not be broken into pieces, but will only wear a small hole, so that accidents like glass fragments will not happen again. When the thickness of ordinary glass exceeds 15 cm, it will turn green and cannot be seen clearly through the glass. Plexiglass 1 m thick, you can clearly see the opposite thing. Because its light transmission performance is quite good and ultraviolet rays can penetrate, it is often used to manufacture optical instruments. Plexiglass has another amazing performance. As long as the curvature of the bent plexiglass rod is less than 48 degrees, light can be projected along it like water passing through a water pipe. How interesting it is that light can make a detour! Using this stunt, it has become a treasure to make surgical transparent glass instruments. Therefore, when a doctor performs an operation in the operating room, there is no need to worry about not seeing clearly. Plexiglass is light in weight, good in toughness, stable in chemical properties and plastic when heated, so it is widely used. If some dyes are properly added to the raw materials of plexiglass, it can be made into colorful plexiglass with red, green and purple colors according to people's needs. [Edit this paragraph] The property of plexiglass is 1. Mechanical Properties Polymethyl methacrylate (PMMA) has good comprehensive mechanical properties, and ranks in the forefront of general plastics. Its tensile, bending and compressive strength is higher than that of polyolefin, polystyrene and polyvinyl chloride, and its impact toughness is poor, but it is also slightly better than that of polystyrene. The mechanical properties such as tensile strength, bending strength and compressive strength of the cast bulk polymerized polymethylmethacrylate sheet (such as plexiglass for aviation) are high, which can reach the level of engineering plastics such as polyamide and polycarbonate. Generally speaking, the tensile strength of PMMA can reach 50-77MPa, and the bending strength can reach 90- 130MPa. The upper limit of these performance data has reached or even exceeded some engineering plastics. Its elongation at break is only 2%-3%, so its mechanical properties are basically hard, brittle and plastic, and it is notch sensitive and easy to crack under stress, but its fracture surface is not as sharp and uneven as polystyrene and ordinary inorganic glass. 40℃ is the second-order transition temperature, which is equivalent to the temperature at which the side methyl group begins to move. When the temperature exceeds 40℃, the toughness and ductility of the material are improved. Polymethyl methacrylate has low surface hardness and is easy to scratch. The strength of polymethyl methacrylate is related to the stress action time, and the strength decreases with the increase of action time. After tensile orientation, the mechanical properties of PMMA (oriented PMMA) are obviously improved, and the notch sensitivity is also improved. The heat resistance of polymethyl methacrylate is not high. Although its glass transition temperature reaches 104℃, the maximum continuous use temperature varies between 65℃ and 95℃ according to different working conditions. The thermal deformation temperature is about 96℃( 1. 18MPa), and the Vicat softening temperature is about 1 13℃. Heat resistance can be improved by polymerization of monomers with propylene methacrylate or ethylene glycol acrylate. The cold resistance of PMMA is also poor, and the brittle temperature is about 9.2℃. The thermal stability of polymethyl methacrylate is moderate, which is better than PVC and polyoxymethylene, but not as good as polyolefin and polystyrene. The thermal decomposition temperature is slightly higher than 270℃, and the flow temperature is about 65438 060℃, which still has a wide melting processing temperature range. The thermal conductivity and specific heat capacity of polymethyl methacrylate are at a medium level in plastics, which are 0. 19W/CM respectively. K and 1464J/Kg. K 2, respectively The electrical properties of PMMA are not as good as those of nonpolar plastics such as polyolefin and polystyrene, because there are polar methyl ester groups on the main chain side. The polarity of methyl ester group is not too great, and polymethyl methacrylate still has good dielectric and electrical insulation properties. It is worth pointing out that polymethyl methacrylate and even the whole acrylic plastic have excellent arc resistance, and under the action of arc, there will be no carbonized conductive path and arc trajectory on the surface. 20℃ is the second-order transition temperature, which corresponds to the temperature at which the pendant methyl ester groups begin to move. Below 20℃, the side methyl ester group is frozen, and above 20℃, the electrical properties of the material will be improved. 3. Chemical-resistant and solvent-resistant PMMA can resist dilute inorganic acids, but concentrated inorganic acids can corrode it, and it can resist alkali, but warm sodium hydroxide and potassium hydroxide can corrode it, and it can resist salt and oil, aliphatic hydrocarbons, and is insoluble in water, methanol, glycerol, etc. However, it can absorb stress cracking caused by alcohol expansion and is intolerant to ketones, chlorinated hydrocarbons and aromatic hydrocarbons. Its solubility parameter is about 18.8(J/CM3) 1/2. It can be dissolved in many chlorinated hydrocarbons and aromatic hydrocarbons, such as dichloroethane, trichloroethylene, chloroform, toluene and so on. , can also be dissolved with vinyl acetate and acetone. Polymethyl methacrylate has good resistance to gases such as ozone and sulfur dioxide. 4. Weather-resistant PMMA has excellent atmospheric aging resistance. After four years of natural aging test, the weight of the sample changed, the tensile strength and light transmittance decreased slightly, the color turned yellow slightly, the crack resistance decreased obviously, the impact strength increased slightly, and other physical properties remained almost unchanged. 5. Combustible PMMA is easy to burn, and its limiting oxygen index is only 17.3.