Characteristics and properties of acrylic

Characteristics and properties of acrylic

We are professional manufacturer of LED PANEL in China, which can be customized in size and shape with engraved acrylic. Here we'd like to introduce the characteristics and properties of acrylic.

Features

1. It has crystal like transparency, with a light transmittance of more than 92%, soft light and clear vision. The acrylic colored with dyes has a good color development effect.

2. Acrylic plate has excellent weather resistance, high surface hardness and gloss, and good high temperature performance.

3. Acrylic plate has good processing performance. It can be hot formed or machined.

4. Transparent acrylic plate has light transmittance comparable to glass, but its density is only half that of glass. In addition, it is not as fragile as glass. Even if it is damaged, it will not form sharp fragments like glass.

5. The wear resistance of acrylic plate is close to that of aluminum, with good stability and corrosion resistance to a variety of chemicals.

6. Acrylic board has good printability and spraying performance. Adopting appropriate printing and spraying process can give acrylic products ideal surface decoration effect.

7. Flame resistance: it is not spontaneous combustion, but it is flammable and does not have self extinguishing property.

Characteristics

1. Hardness

Hardness is one of the parameters that can best reflect the production process and technology of cast acrylic plate, and it is an important link in quality control. Hardness can reflect the purity of raw material PMMA, weather resistance and high temperature resistance of plate. Hardness directly affects whether the plate will shrink, bend and deform, and whether the surface will be chapped during processing. Hardness is one of the hardness indexes to judge the quality of acrylic board.

2. Thickness (acrylic tolerance)

Acrylic tolerance exists in the thickness of acrylic plate, so the control of acrylic tolerance is an important embodiment of quality management and production technology. Acrylic production has an international standard iso7823

Tolerance requirements for pouring plate: tolerance = ± (0.4 + 0.1 x thickness)

Tolerance requirements for extruded plate: tolerance = < 3 mm thickness: ± 10% > 3 mm thickness: ± 5%

3. Transparency / whiteness

Strict raw material selection, advanced formula follow-up and modern production technology ensure the excellent transparency and pure whiteness of the plate. It is crystal clear after flame polishing.

Properties

Mechanical property

Polymethylmethacrylate has good comprehensive mechanical properties and ranks in the forefront of general plastics. Its tensile, bending and compression strength are higher than polyolefin, polystyrene and polyvinyl chloride. Its impact toughness is poor, but it is also slightly better than polystyrene. The cast bulk polymerized polymethylmethacrylate plate (such as aviation plexiglass plate) has higher mechanical properties such as tensile, bending and compression, which can reach the level of engineering plastics such as polyamide and polycarbonate.

Generally speaking, the tensile strength of polymethylmethacrylate can reach the level of 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 and brittle plastics, with notch sensitivity and easy to crack under stress, but the fracture is not as sharp and uneven as polystyrene and ordinary inorganic glass. 40 ℃ is a secondary transition temperature, which is equivalent to the temperature at which the side methyl group begins to move. If it exceeds 40 ℃, the toughness and ductility of the material are improved. Polymethylmethacrylate has low surface hardness and is easy to scratch.

The strength of polymethylmethacrylate is related to the stress action time. With the increase of action time, the strength decreases. After stretching, the mechanical properties of polymethylmethacrylate (oriented plexiglass) are significantly improved, and the notch sensitivity is also improved.

The heat resistance of polymethylmethacrylate is not high. Although its glass transition temperature reaches 104 ℃, the maximum continuous service temperature changes between 65 ℃ - 95 ℃ with different working conditions. The thermal deformation temperature is about 96 ℃ (1.18mpa), and the Vicat softening point is about 113 ℃. The heat resistance can be improved by copolymerization of monomer with propylene methacrylate or ethylene glycol diester acrylate. The cold resistance of polymethylmethacrylate is also poor, and the embrittlement temperature is about 9.2 ℃. The thermal stability of polymethylmethacrylate is medium, better than polyvinyl chloride and polyformaldehyde, but less than polyolefin and polystyrene. The thermal decomposition temperature is slightly higher than 270 ℃, and its flow temperature is about 160 ℃, so it still has a wide melting processing temperature range.

The thermal conductivity and specific heat capacity of polymethylmethacrylate belong to the medium level in plastics, which are 0.19w / m.k and 1464j / kg. K respectively

Electrical properties

Polymethylmethacrylate has less electrical properties than non-polar plastics such as polyolefin and polystyrene because of its polar methyl ester group on the side of the main chain. The polarity of methyl ester group is not too large, and polymethylmethacrylate still has good dielectric and electrical insulation properties. It is worth noting that polymethylmethacrylate and even the whole acrylic plastics have excellent arc resistance. Under the action of arc, there will be no carbonized conductive path and arc track on the surface. 20 ℃ is a secondary transition temperature, corresponding to the temperature at which the side methyl ester group begins to move. If it is lower than 20 ℃, the side methyl ester group is frozen, and the electrical properties of the material will be improved when it is above 20 ℃.

Solvent resistance

Polymethylmethacrylate can resist dilute inorganic acids, but concentrated inorganic acids can make it erode and alkali resistant, but warm sodium hydroxide and potassium hydroxide can make it erode, salt and grease resistant, fatty hydrocarbons resistant, insoluble in water, methanol, glycerol, etc., but it can absorb alcohol swelling and produce stress cracking, and is not resistant to ketones, chlorinated hydrocarbons and aromatics. Its solubility parameter is about 18.8 (J / cm3) 1 / 2. It can be dissolved in many chlorinated hydrocarbons and aromatics, such as dichloroethane, trichloroethylene, chloroform, toluene, etc. it can also be dissolved by vinyl acetate and acetone.

Polymethylmethacrylate has good resistance to gases such as ozone and sulfur dioxide.

Weather resistance

Polymethylmethacrylate has excellent atmospheric aging resistance. After 4 years of natural aging test, the weight of the sample changes, the tensile strength and light transmittance decrease slightly, the color is slightly yellowing, the crazing resistance decreases significantly, the impact strength is slightly improved, and other physical properties are almost unchanged.

Flammability

Polymethylmethacrylate is easy to burn, and the limiting oxygen index is only 17.3.