Excuse me: What is acrylic rubber?

Acrylic is a type of plastic, right? . . . . . . . .

Is it a copolymer of acrylonitrile and styrene?

Actually, I have a similar question as well: what is the difference between methacrylate polymers and plexiglass? Added filler?

This post was last edited by the Cultivator on 2011-12-1 05:42. Reply 1# kying127 Acrylic is also known as PMMA or Acryl. They are all the Chinese terms for the English word \"acrylic\", and when translated, it actually refers to plexiglass. Its chemical name is polymethyl methacrylate. **Also known as Agalite, it is an important thermoplastic that was developed quite early on. It boasts good transparency, chemical stability, and weather resistance, is easy to dye and process, and has an attractive appearance; as a result, it is widely used in the construction industry. Acrylic products can generally be divided into cast sheets, extruded sheets, and molded plastics. Introduction to acrylic: Acrylic glass is suitable for secondary processing, such as machining, thermoplastic molding, blow molding, vacuum forming, solvent bonding, thermal printing, screen printing, etc. The history of acrylic. Acrylic (ACRYLIC), commonly known as specially treated plexiglass. The research and development of Yakli date back over a hundred years. In 1872, the polymerizability of acrylic acid was first discovered ； In 1880, the polymerizability of methacrylic acid became known ； In 1901, research on the synthesis method of acrylonipropylate was completed ； In 1927, the aforementioned synthesis method was attempted for industrial-scale production ； In 1937, the industrial production and development of methyl esters were successful, marking the beginning of large-scale manufacturing. During World War II, due to its excellent strength, toughness, and light-transmitting properties, acrylic was first used for airplane windshields and the viewports in tank drivers’ cockpits. The creation of the world’s first acrylic bathtub in 1948 marked a new milestone in the use of acrylic. Uses of acrylic: PMMA has advantages such as light weight, low cost, and ease of molding. Its manufacturing methods include casting, injection molding, machining, thermoforming, etc. Especially injection molding allows for mass production, has a simple process, and low costs. Therefore, its applications are becoming increasingly widespread; it is currently used extensively in components for instruments and meters, automotive headlights, optical lenses, transparent pipes, and more. 　　 Acrylic is the best new material that can be used to manufacture sanitary ware after ceramics. Compared to traditional ceramic materials, acrylic offers the following advantages in addition to its unparalleled high brightness: it is tough and not prone to breaking ； It has strong repair capabilities; simply using soft foam dipped in a little toothpaste can restore the fixtures to their original condition ； It has a soft texture, and there is no icy chill in winter ； Vibrant colors that can meet the individual taste preferences of different people. Sinks, bathtubs, and toilets made of acrylic not only feature beautiful designs and are durable, but they are also environmentally friendly; their level of radiation is similar to that emitted by the human body’s own bones. Acrylic sanitary ware first appeared in the United States, and it now accounts for over 70% of the entire international market. 　　 Due to the difficulty and high cost of producing acrylic, there are many inexpensive substitutes available on the market. These substitutes are also known as “acrylic,” but they are actually ordinary organic boards or composite boards (also known as sandwich panels). Ordinary organic boards are made by casting ordinary plexiglass pyrolysis material with pigments; they have low surface hardness, tend to fade, and yield a poor polishing effect after being sanded with fine sand. The composite panel has only a thin layer of acrylic on the surface, with ABS plastic in the middle; it is prone to delamination due to thermal expansion and contraction during use. Genuine and fake acrylic can be distinguished by the slight color differences and polishing effects in their cross-sections. 1. Construction applications: display windows, soundproof doors and windows, lighting covers, phone booths, etc. 2. Advertising applications: light boxes, signs, indicator boards, exhibition stands, etc. 3. Transportation applications: doors and windows of trains, cars, and other vehicles. 4. Medical applications: infant incubators, various surgical instruments. Consumer goods: bathroom fixtures, handicrafts, cosmetics, brackets, aquariums, etc. 5. Industrial applications: surface panels and protective covers for instruments. 6. Lighting applications: fluorescent lamps, chandeliers, street lamp covers, etc. There are many different specifications and types of acrylic sheets. Common types of plates include: transparent plates, stained transparent plates, milky white plates, and colored plates ； Specialty panels include: bathroom panels, cloud-patterned panels, mirror panels, fabric-reinforced panels, hollow panels, impact-resistant panels, flame-retardant panels, ultra-wear-resistant panels, panels with surface patterns, matte panels, pearlescent panels, and panels with a metal finish. Different performances, as well as various colors and visual effects, to meet a wide range of requirements. Process characteristics: 1. Polymethyl methacrylate contains polar side methyl groups, which give it significant hygroscopicity; its water absorption rate is generally between 0.3% and 0.4%. It must be dried before molding, with drying being carried out at 80°C–85°C for 4–5 hours. 　　 2. Polymethyl methacrylate exhibits significant non-Newtonian fluid properties within the temperature range of its molding process; its melt viscosity decreases markedly as the shear rate increases, and it is also highly sensitive to changes in temperature. Therefore, for the molding of polymethyl methacrylate, increasing both the molding pressure and temperature can significantly reduce the melt viscosity and achieve better flowability. 　　 3. Polymethyl methacrylate begins to flow at around 160°C, and its decomposition starts at temperatures above 270°C, resulting in a wide processing temperature range. 　　 4. Polymethyl methacrylate has a high melt viscosity and a rapid cooling rate, which causes internal stresses to develop in the products. Therefore, strict control over the processing conditions is required during molding, and post-treatment is also necessary after the products are formed. 　　 5. Polymethyl methacrylate is an amorphous polymer with a low shrinkage rate and a narrow range of variation, typically around 0.5%-0.8%, which facilitates the production of plastic parts with high dimensional accuracy. 　　 6. Polymethyl methacrylate has excellent machinability, and its profiles can be easily processed into various sizes as required. Processing techniques: Polymethyl methacrylate can be processed using methods such as casting, injection molding, extrusion, and thermoforming. 1. Casting molding Casting molding is used to shape acrylic sheets, rods, and other profiles, that is, to form these profiles through bulk polymerization. The products obtained after casting require post-treatment, with the conditions being 2 hours at 60°C followed by 2 hours at 120°C. Injection molding: This process uses granules produced through suspension polymerization, and the molding is carried out using ordinary plunger-type or screw-type injection molding machines. Table 1 shows the typical process conditions for the injection molding of polymethyl methacrylate. 　　Process parameters: Screw-type injection molding machine, Plunger-type injection molding machine
Cylinder temperature (°C): Rear part – 180-200, 180-200; Middle part – 190-230; Front part – 180-210, 210-240
Nozzle temperature (°C): 180-210, 210-240
Mold temperature (°C): 40-80, 40-80
Injection pressure (MPa): 80-120, 80-130
Holding pressure (MPa): 40-60, 40-60
Screw speed (rpm): 20-30
The injection-molded products also require post-treatment to eliminate internal stresses; this treatment is carried out in a hot air circulation drying oven at 70-80°C. The treatment time depends on the thickness of the product, but generally it takes around 4 hours. 3. Extrusion molding: Polymethyl methacrylate can also be processed by extrusion molding; granules produced through suspension polymerization are used to manufacture acrylic sheets, rods, tubes, and sheets. However, the profiles obtained in this way, especially sheets, have lower mechanical properties, heat resistance, and solvent resistance due to the low molecular weight of the polymer. The advantage of this method is its high production efficiency, particularly for tubes and other products for which molds are required in the casting process. Profiles that are difficult to manufacture. Extrusion molding can be carried out using single-stage or two-stage vented extruders, with the screw length-to-diameter ratio generally ranging from 20 to 25. Table 2 shows the typical process conditions for extrusion molding. 　　Process Parameters Sheet Material Rod Material Screw Compression Ratio 2 2 Barrel Temperature (°C) Rear section: 150–180, 150–180 Middle section: 170–200, 170–200 Front section: 170–230, 170–200 Extrusion Pressure (MPa): 2.8–12.4, 0.7–3.4 Feed Port Temperature (°C): 50–80, 50–80 Die Temperature (°C): 180–200, 170–190 4. Thermoforming Thermoforming is the process of transforming acrylic sheets or plates into products of various sizes and shapes. The materials are cut to the desired dimensions and clamped in a mold frame; they are then heated to soften, and pressure is applied to force them to conform to the shape of the mold. After cooling to set the shape, the edges are trimmed to complete the product. Pressurization can be achieved by vacuum drawing or by applying direct pressure to a punch with a shaped surface. The thermoforming temperature can refer to the temperature range recommended in Table 3. When using rapid vacuum low-drawing to form products, it is advisable to use a temperature close to the lower limit; for products with complex shapes formed by deep drawing, a temperature close to the upper limit is appropriate. Under normal circumstances, a standard temperature is used. Features of acrylic: 1. Hardness: Hardness is one of the parameters that best reflect the production process and technology involved in manufacturing cast acrylic sheets, and it is an important aspect in quality control. The quality of rigid acrylic lamp shades reflects factors such as the purity of the PMMA raw material, the weather resistance of the sheet, and its heat resistance. Hardness directly affects whether the sheet will shrink, bend, or deform, as well as whether cracks will appear on its surface during processing. Hardness is one of the key indicators for assessing the quality of acrylic sheets, with an average Duro hardness value of around 89 degrees. 　　2. Thickness tolerance: The control of sheet thickness tolerance is an important aspect of quality management and production technology. There is an international standard ISO7823 for the production of acrylic sheets. The tolerance requirements for cast sheets are: tolerance = ± (0.4 + 0.1 x thickness). For extruded sheets, the tolerance requirement is: tolerance < 3 mm; for thicknesses greater than 3 mm, the tolerance is ± 10%. 3. Transparency/whiteness: Strict selection of raw materials, advanced formulation techniques, and modern production processes ensure that the sheets have excellent transparency and high whiteness. It becomes crystal clear after flame polishing.

This post was last edited by rocky on 2011-12-1 09:05. Well, the original poster is asking about rubber, which is an elastomer; it shouldn’t be PMMA. The following information was found online: Acrylic rubber waterproofing material: It is a liquid-based coating waterproofing material made primarily from acrylate rubber latex, with fillers, stabilizers, and colorants added as ingredients ； After being applied as a coating, this waterproof material forms a film by allowing water to evaporate through air drying; therefore, its drying time varies depending on temperature and humidity levels. Source: http://www.fixy.com.tw/node/452. Further searches for “acrylate rubber” yielded the following results: A synthetic rubber produced by copolymerizing acrylates as the main monomers; it possesses special properties such as heat resistance, oil resistance, ozone resistance, and resistance to ultraviolet radiation, making it a special type of rubber suitable for use in high-temperature and oily environments. It is mainly used as various heat- and oil-resistant seals, gaskets, and oil seals for automobiles and locomotives. 【History】 In 1912, the German O. Lehme first studied the vulcanization of polyacrylates. In 1944, C.H. Fisher and others in the United States developed a copolymer rubber of ethyl acrylate and 2-chloroethyl vinyl ether, and in 1948, Goodyear Chemical Company brought this product into industrial production. In 1952, American single-company manufacturers began producing acrylate rubber copolymerized from butyl acrylate and acrylonitrile. In 1955, the Japanese company East Asia Synthetic Chemical Industry also produced butyl acrylate-acrylonitrile copolymer rubber. To overcome the shortcomings of this rubber, such as its low strength and poor performance at low temperatures, DuPont in the United States developed acrylate-olefin copolymer rubber in 1975 – http://www.chinabaike.com/article/UploadPic/2007-6/20076714428129.jpg. The typical representatives of this type of rubber are ethyl acrylate-ethylene random copolymers, as well as the subsequent ethyl acrylate-ethylene alternating copolymer rubbers. It is reported that they can be used for a long time in fuel oil environments ranging from –40 to 175°C. With the rapid development of the automotive industry, the production of acrylate rubber has increased sharply. The world production was 1,300–1,500 tons in 1963, and it increased to 7–8 thousand tons by 1984. 【Classification】 It can be divided into two categories based on the synthesis route. One category is emulsion-polymerized rubbers. The main types include butyl acrylate-acrylonitrile copolymers, and ethyl acrylate-butyl acrylate-third monomer (such as vinyl chloride acetate) tercopolymers; these include high-temperature and low-temperature adhesives. They possess good heat and oil resistance, but have low strength (tensile strength of about 15 MPa) and poor performance at low temperatures (glass transition temperature: http://www.chinabaike.com/article/UploadPic/2007-6/20076714432529.jpg http://www.chinabaike.com/article/UploadPic/2007-6/20076714432619.bmp, ranging from -15 to -28°C) ； Another category is the solution-polymerized rubbers made from acrylates and olefins; these products have high strength and good performance at low temperatures (http://www.chinabaike.com/article/UploadPic/2007-6/20076714432529.jpg http://www.chinabaike.com/article/UploadPic/2007-6/20076714432619.bmp, at 38°C). 【Production Method】 There are two methods: ① Emulsion method. Anionic and non-ionic mixed emulsifiers (such as sodium dodecyl sulfate and alkoxypolyethylene oxide) are used to emulsify acrylates (including ethyl and butyl esters) or acrylonitrile in an aqueous medium, and water-soluble initiators are employed to initiate polymerization. Dry rubber is obtained from latex through processes such as coagulation, washing, and drying. The intrinsic viscosity number of raw rubber is 4–6. [http://www.chinabaike.com/article/UploadPic/2007-6/20076714433776.jpg] ②Solution method. Using a halohydrocarbon such as dichloromethane as a solvent, an azo compound as an initiator, and a Lewis acid as a complexing agent, acrylates and alkenes such as ethylene are copolymerized alternately at about 1 MPa. After the resin slurry is condensed and the solvent is recovered, the alternating copolymer rubber is obtained. If peroxides such as tert-butyl trimethyl acetoacetate are used as initiators to copolymerize ethyl acrylate with ethylene at about 180 MPa, the resulting rubber is a random copolymer. Both alternating copolymerized rubber and random copolymerized rubber are produced in bulk. The production cost of the solution method is high and the process is complex; therefore, most acrylate rubbers are produced using the emulsion method. Source: http://www.chinabaike.com/article/316/477/2007/20070607126280.html

It should be a product of the copolymerization of methyl methacrylate and acrylates (with other esters present in small amounts); since it is a rubber, the copolymer must contain sulfurizable groups.

PMMA is a plastic, but polymethyl methacrylate PBA, polybutyl acrylate PBA, polyisooctyl acrylate PEHA, and so on are elastomers; the glass transition temperature of PBA is -45 degrees Celsius, while that of PEHA is -70 degrees Celsius. Undoubtedly, acrylic rubber refers to polyacrylate elastomers. I have been working on synthesizing core-shell type AIM emulsions recently, so I am quite familiar with acrylate elastomers.

In fact, cross-linking occurs already during polymerization; the cross-linking agents include BDDA, DAP, TAIC, and so on.