Acrylic has good comprehensive mechanical properties and is in the forefront of general-purpose plastics. The tensile strength, tensile strength, compression and other strengths are higher than that of polyolefins, and higher than that of polystyrene and polyvinyl chloride. The impact toughness is poor, but it is slightly better. Polystyrene. The cast bulk acrylic sheet (such as aerospace plexiglass sheet) has higher mechanical properties such as stretching, bending and compression, and can reach the level of engineering plastics such as polyamide and polycarbonate.
In general, acrylic tensile strength can reach 50-77MPa level, 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 the mechanical properties are basically hard and brittle plastics, and it has the sensitivity of notch. It is easy to crack under stress, but the fracture is not like polystyrene and ordinary inorganic glass. It’s sharp and uneven. 40 ° C is a secondary transition temperature, which is equivalent to the temperature at which the side methyl group starts to move. When the temperature exceeds 40 ° C, the toughness and ductility of the material are improved. Acrylic surface has low hardness and is easily scratched.
The strength of acrylic is related to the stress action time, and the strength decreases as the action time increases. The mechanical properties of the acrylic (oriented plexiglass) after stretching and orientation are significantly improved, and the notch sensitivity is also improved.
Acrylic heat resistance is not high, although its glass transition temperature reaches 104 ° C, but the maximum continuous use temperature varies from 65 ° C to 95 ° C depending on the working conditions, the heat distortion temperature is about 96 ° C (1.18 MPa) The Vicat softening point is about 113 °C. The heat resistance can be improved by a method in which a monomer is copolymerized with propylene methacrylate or ethylene glycol diacrylate. Acrylic also has poor cold resistance, and the embrittlement temperature is about 9.2 °C. Acrylic thermal stability is medium, better than polyvinyl chloride and polyoxymethylene, but less than polyolefin and polystyrene, the thermal decomposition temperature is slightly higher than 270 ° C, the flow temperature is about 160 ° C, so there is still a wide melting Processing temperature range.
Acrylic thermal conductivity and specific heat capacity are moderate in plastics, 0.19W/CM.K and 1464J/Kg.K, respectively.
2. Electrical properties
Acrylic has less electrical properties than non-polar plastics such as polyolefins and polystyrene due to the polar methyl ester group at the side of the main chain. The polarity of the methyl ester group is not too large, and the acrylic still has good dielectric and electrical insulation properties. It is worth noting that acrylic and even the entire acrylic plastic have excellent arc resistance. Under the action of arc, the surface does not produce carbonized conductive paths and arc track phenomena. 20 ° C is a secondary transition temperature, corresponding to the temperature at which the side methyl ester group begins to move, below 20 ° C, the side methyl ester group is in a frozen state, and the electrical properties of the material are increased above 20 ° C.
3. Chemical resistance and solvent resistance
Acrylic is resistant to relatively rare inorganic acids, but concentrated inorganic acids can erode it. It can be alkali-resistant, but warm sodium hydroxide and potassium hydroxide can etch it. It can withstand salt and oil. Aliphatic hydrocarbons, insoluble in water, methanol, glycerin, etc., but can absorb alcohol to swell, and produce stress cracking, not resistant to ketones, chlorinated hydrocarbons and aromatic hydrocarbons. Its solubility parameter is about 18.8 (J / CM3) 1/2, soluble in many chlorinated hydrocarbons and aromatic hydrocarbons, such as dichloroethane, trichloroethylene, chloroform, toluene, etc., vinyl acetate and acetone can also make it Dissolved.
Acrylic has good resistance to gases such as ozone and sulfur dioxide.
4. Weather resistance
Acrylic has excellent resistance to atmospheric aging. Its sample has been subjected to natural aging test for 4 years. The weight change, tensile strength and light transmittance are slightly decreased, the color is slightly yellowish, the anti-silverness is decreased, and the impact strength is also improved. Slightly improved, other physical properties are almost unchanged.
Acrylic is very easy to burn, with a limited oxygen index of only 17.3.
Post time: Apr-08-2019