PMMA | Polymethyl methacrylate
Thermoplastics > Acrylates
| PMMA Polymethylmethacrylate | |||||
What is polymethylmethacrylate? Polymethyl methacrylate is a plastic (thermoplastic) hard, tough, transparent, excellent optical properties with high refractive index, good resistance to aging and weathering. Polymethylmethacrylate, [-CH2 -C (CH3) (COOCH3) -] n, is an amorphous material whose property foremost is its excellent transparency; hence its main applications are as a substitute for glass.Its breaking strength is seven times higher than that of equal thickness glass, making it more resistant to shocks. In horticulture it means cost reduction breakage and lower maintenance costs in greenhouses. It is a lightweight material having a density of 1.19 kg / m3. It presents good mechanical strength and stability. Despite its light weight it can withstand a load of 70 kg / m2, which is important for those areas at risk of snowfall. The transparency of this plastic is between 85 and 92%, so let almost all UV and diffusion power is almost zero. It has a high opacity to night soil radiation. Its duration is greater than that of polyester, as for drawbacks the main one is its high cost. | |||||
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| Propriedades PMMA | |||||
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| What kind of material is methacrylate? | |||||
Poly (methyl methacrylate) characterized by an average mechanical strength and high rigidity. However, it has low impact strength, yet is six times higher than the normal glass. Has a high hardness, and polishable surface by a special treatment, the surface acquires an excellent scratch resistance.Su resistencia a la rotura es siete veces superior a la del cristal a igualdad de espesores, por lo que resulta más resistente a los golpes. En horticultura esto significa reducción de gastos por rotura y menores costes de mantenimiento en invernaderos. Sus propiedades mecánicas son considerables, y tiene un comportamiento rígido a temperatura ambiente. En cambio, tiene una baja resistencia al impacto y es sensible al calor. Es un material higroscópico, razón por la cual es necesario secarlo antes de procesarlo. La absorción de agua es próxima al 0.3%, por lo que tiene tendencia a la fisura por tensión. Debido a la poca resistencia al impacto y a la tensofisuración del PMMA, han surgido los copolímeros de injerto de MMA con caucho de estireno-butadieno (MBS), de ABS (MABS) o con caucho acrílico (acrilato de butilo, PBA). El MBS y MABS pueden incluirse en el grupo del poliestireno transparente y resistente al impacto, con las siglas MMA/BA, el cual se conoce como PMMA resin resistente al impacto. Se conocen también copolímeros de acrilonitrilo con MMA (A/MMA), que poseen una excelente resistencia al impacto y a la tensofisuración, aparte de una resistencia mecánica elevada. Granules are for injection or extrusion process and the sheets for thermoforming or machining. Competes in terms of applications with other plastics such as polycarbonate (PC), polystyrene (PS), but the acrylic stands out against other transparent plastics in terms of weather resistance, transparency and scratch resistance. | |||||
| Modified PMMA | |||||
Due to the poor impact resistance and stress cracking of PMMA, they have emerged the graft copolymers of MMA with styrene-butadiene rubber (MBS), ABS (MABS) or acrylic rubber (butyl acrylate, PBA). The MBS MABS can be included in the group of transparent and impact - resistant polystyrene, with acronyms MMA / BA, which is known as impact resistant PMMA. Also known are copolymers of acrylonitrile with MMA (A / MMA) having excellent impact resistance and stress cracking, besides a high mechanical strength. The polymerization "in situ" of these copolymers is more difficult to perform homopolymerization methacrylatepure methyl, carrying higher production costs. Other modifications are achieved by way of adding large amounts of fillers filler (ground quartz or aluminum oxide / Aluminia), which is a material simile marble. The solid sheets of large thickness marketed colored, streaked or matte silkily, which can be machined by removing chips are used as platforms table (counters) and in the health sector. | |||||
| PMMA Products range | |||||
There are different kinds of PMMA resin, many of these contain added to improve the original properties of polycarbonate for a particular application, such as high impact, UV absorbers, additives anti-flame (have compliance with UL94, V0, 5VA) and other specifications and includes products that can be used in applications that must meet the requirements of parts without halógenos.desmoldantes, antioxidants, etc. All these materials can be marketed in transparent "color" (other than materials with some anti-flame) or translucent colors (ditto) and opacas.Tenemos a broad design versatility through its wide range of viscosities and product options, such as environmental friendliness by its scratch resistance, hardness, heat-resistance, weatherability. | |||||
| PMMA Thermal properties | |||||
The low molecular weight PMMA behaves like a thermoplastic when heated, whereas if the molecular weight is high does as a thermoelastic. The strip continuous use temperatures extends from -40 to +75 ° C, with peaks of 100 ° C for a short time. Between 120 and 180C acquires elastic consistency and molded. From 180 C becomes Vicoso liquid (injectable, moldable). Dilation temperature is high. Excellent thermal and acoustic insulation. The coefficient of thermal conductivity of polymethylmethacrylate is 0.16 KCal / mh ° C while the glass is 0.64 KCal / mh ° C, preventing in the case of the night cooling greenhouses. PMMA against direct fire burns with a yellow and blue flame at the base, produces bubbling and crackles. The detached fumes are toxic and acidic. PMMA decomposes forming primarily carbon dioxide and carbon monoxide, water, low molecular weight compounds and even monomer. The generated monomer can react with oxygen to form acetone, methyl pyruvate and formaldehído.El flame behavior may vary depending on their composition (additives used in its formulation). The flame retardant additives significantly modify their behavior to the fire. In general, the burning drips extrusion methacrylate (burning drops) while one casting no.Rango working temperature -40 + 85 ° C. | |||||
| Optical properties | |||||
With regard to the optical properties, it has excellent transparency. It is bright and absolutely colorless and can be dyed easily and colors in tranlúcidos opaque. It is a tough, hard and with a transparent plastic optical properties and very good, so is used in those applications requiring a plastic transparent.Competes in terms of applications with other plastics such as polycarbonate (PC), polystyrene (PS), but the acrylic stands out against other transparent plastics in terms of weather resistance and transparency. It presents stability both in color and brightness. The advantages of this material are many but which differentiate it from the glass are: low weight, greater transparency, less fragility. Of other plastics especially for its improved transparency, easy molding and possible repair in case of any stripe surface difference. Resistant to the weather and ultraviolet rays.Most commercial acrylic polymers are stabilized UV for good resistance to prolonged exposure to sunlight, as their optical and mechanical properties vary greatly in these conditions. Therefore, the PMMA pellets is suitable for outdoor applications intended for outdoor exposure over time. No appreciable aging in ten years of outdoor exposure does not affect its optical properties. | |||||
| Electrical properties | |||||
Es un buen aislante eléctrico, con cargas electrostáticas altas, por lo que tiene tendencia a acumular polvo. | |||||
| PMMA Chemical properties | |||||
Methacrylate has high resistance to attack by many compounds but is attacked by others, Resists acids and alkalis low or medium concentration. It is also resistant to non - polar solvents (aliphatic hydrocarbons, oils). Conversely, it is not resistant to polar solvents (esters, ketones, chlorinated hydrocarbons and the like), to cetato acetate, acetone, glacial acetic acid, bichromatic sulfuric acid, amyl alcohol, benzene, butanol, dichloromethane, trichloromethane (chloroform), toluene. Water absorption is close to 0.3%. It has a tendency to stress cracking. It has excellent weather resistance and ultraviolet and heat aging.No appreciable aging in ten years of outdoor exposure. L os poly (methyl methacrylate) have good resistance to aging under normal conditions nor are subject to biological attack. Only if it is made with dyes they may suffer discolouration in bright light, because their presence. Also, in extreme cases, photooxidation of PMMA granules causes the appearance of hydrolysates as alcoholic groups. | |||||
| PMMA Processability | |||||
PMMA are for injection or extrusion process and the sheets for thermoforming or machining. Film, sheet, rods, rings and tubes (plasticized or unplasticized) also can be produced using extrusion. Also powdered PMMA polymer are used as protective coatings, such as thermally fusible powders or as solutions in adhesives, sealing etc. Semifinished parts, sheets, rods and rings are very easy toprocess mechanically. Other special processes, such as mono- and biaxial orientation by stretching plates are made to improve the mechanical caracteríticas, such as mechanical strength.Methacrylate is easier to grate with any instrument, so that this aspect should be considered as a factor negativo.Se can esterilzar with gamma radiation or formalin. Not recommended sterilization in an autoclave PMMA polymer. It is a hygroscopic polymer, the molecular chains contain within them (in the ester group) the carbonyl group, which, as described in section, can form hydrogen bonds with water molecules. Indeed, PMMA, if kept in the air at 23 ° C and a relative humidity of 50% to saturation, absorbs 0.6% of moisture and 23 ° C and 100% relative humidity to saturation, absorbs up to 1.6% moisture, according to ISO 62. For this reason, need dehumidification before transforming, if exposed to ambient air or if the pellets are not stored in moisture resistant bags. To produce clear products with excellent optical, mechanical and aesthetic properties, a moisture content of less than 0.06% (600 parts per million or ppm) in the starting granules for most applications is required. | |||||
| PMMA welding | |||||
The gluing gives good results and is possible with pure solvents, monomers or in the presence of chloroform or using PMMA dissolved in solvents. | |||||
| PMMA Polimerization | |||||
PMMA is a vinyl polymer formed by free radical vinyl polymerization from methyl methacrylate monomer. Methyl methacrylate, also known as acid methyl ester methacrylic acrylic (C5H5O2), is a colorless liquid with strong fruity odor, with a boiling point of 100 ° C and stored with polymerization inhibitors. The polymer is formed from the opening of the C = C double bond when placed in contact with initiators. Thermoplastic PMMA is not toxic if it is fully cured. Its component MMA (methyl methacrylate monomer) yes it is in liquid phase. Mass polymerization Mass polymerization of methyl methacrylate, also known as polymerization "in situ", allows the manufacture of blocks and thick plates. Pure monomer or a prepolymer of higher viscosity (polymerization state of incipient) was added the initiators and comonomers needed. Once this is done, it is poured between methacrylic perfect polished plates, where it is allowed to polymerize. The heat of reaction is evacuated by cooling water or air. If you want to get polymers without internal tensions, careful evacuation of heat is necessary reaction, so the polymerization can last days or weeks.Poly (methyl methacrylate) thus obtained have molecular weights of several million, so can not melt without decomposition. This poly ( methylmethacrylate), acrylic glass known as casting, belongs to the thermoelastic. It is also possible to obtain high molecular weights by partial crosslinking is carried out by the addition of polyunsaturated esters. In the latter case we are talking poly (methyl methacrylate) crosslinked. To produce molding compositions capable of melting, polymerization is used in mass with appropriate primers. The reaction is quenched with a weight regulators relatively low molecular, the maximum of 150,000. Suspension Polymerization The suspension polymerization is usually done with bead polymerization, size of very uniform particle located between 0.1 and 0.5 mm. A great advantage of this process is the rapid evacuation of the reaction heat, which is transferred to water. Thermoplastic obtained with molecular weight less than 150,000, they are also susceptible to melt. | |||||
| PMMA vs PC | |||||
Acrylic, polycarbonate and glass are all transparent materials and, as mentioned above, the PC and PMMA are suitable alternatives and resistant glass. PMMA is often used as a light alternative to glass and a reasonable substitute polycarbonate (PC) with its profitability and when extreme resistance is not essential. Moreover, it is less likely that the PMMA scratch and do not get yellow over a period of time. Other benefits include PMMA PC provides a very high transmissivity and better optical clarity that can also be restored by polishing. PMMA is an excellent choice for optical devices because less tissue damages when fractured. | |||||
| PMMA Aplicaciones | |||||
Depending on the compositions, sizes, Tg and molecular weights, PMMA spheres thermoplastics can be used in different applications aplicaciones.Compite as with other plastics such as polycarbonate (PC) or polystyrene (PS), but the acrylic stands out from other plastics transparent about weather resistance, transparency and resistance to rayado.Por these qualities is used in the automotive industry as car headlight, lighting, cosmetics, spectacles, construction and optics, among many others. In the medical world polymethylmethacrylate resin for making bone and dental prostheses and as powder additive in the formulation of many pills that can be taken orally is used. Signage, displays, guards in machinery, decorative and protective separating partitions, aquariums and pools, artwork, etc. The possibility of continuous fibers of great length using a relatively inexpensive manufacturing process make with their high transparency that is a used for producing optical fiber material. Lately there are many designs, colors and finishes on the plates that open a world of possibilities for use in architecture and decoration sectors which is increasingly frequently used. | |||||
| Applications | |||||
Interior and Exterior trim PMMA is used to create inner and outer panels, trim, bumpers, fenders and other molded parts. Key qualities include: excellent surface hardness, UV and abrasion resistance. Polymethyl Methacrylate offers a myriad of coloring options from transparant to deep color, be it hgh gloss or matt. LCD screens and monitors All major brands of electronic products use screens made of PMMA. Durability and light transmission of polymethylmethacrylate make it the best choice, from small screens to ultra large screens. Medical and health PMMA is a material of high purity and easy to clean and, therefore, is used to make incubators, drug testing devices, storage cabinets in hospitals and research laboratories. Furthermore, due to its high biocompatibility, PMMA is also applied as fillers dental cavities and bone cement. furniture PMMA has exceptional properties such as transparency, toughness and aesthetics to produce chairs, tables, kitchen cabinets, bowls, rugs, etc. in any form, color or finish. illumination PMMA sheets are used to design LED lights which helps maximize the potential of light emission. It is also used for the construction of lamps due to its transparency and optical properties. Competes in terms of applications with other plastics such as polycarbonate (PC) or polystyrene (PS), but the acrylic stands against other plastics transparent regarding weather resistance, transparency and scratch resistance. other aplicaiones What is methacrylate and what is it? Methacrylate is a multiple application material because of its great advantages. Generally it is used in products requiring high durability, color stability or must withstand weathering. PMMA is widely used for the manufacture of electronic equipment. The surface hardness and scratch resistance are important performance where high repeated use is a factor. Thanks to its excellent impact resistance and UV, PMMA is widely used in profiles windows and doors, awnings, panels, facade design, urns, lids, trophies, displays, decorations and objects, boxes for power, signaling, exhibitors and many more products, screens, transparent roofs, skylights, skylights, windows,tables, lamps, wall lamps and furniture in general. Sharpshooters, gifts, glass windows, a light nuncios, traffic signs, light columns etc. i ncubadoras, operating tables, special containers etc. g AFAS, lenses, solar and photographic filters. etc. It also facilitates the transmission of light and provides good thermal insulation, therefore, is an appropriate option for the construction of greenhouses. PMMA is also used to build aquariums and marine centers. | |||||