Acrylic mechanical properties

Acrylic has good comprehensive mechanical properties and ranks in the forefront of general-purpose plastics. The tensile, bending, and compressive strengths are higher than those of polyolefins, and also higher than those of polystyrene and polyvinyl chloride. The impact toughness is poor, but it is also slightly better. polystyrene. The cast bulk polymerized polymethyl methacrylate sheet (such as plexiglass sheet for aviation) has higher mechanical properties such as tensile, bending and compression, and can reach the level of engineering plastics such as polyamide and polycarbonate.

Generally speaking, the tensile strength of acrylic 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 the mechanical properties are basically hard and brittle plastics, and have notch sensitivity, 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 starts to move. Above 40℃, the toughness and ductility of the material are improved. Acrylic has low surface hardness and is easy to scratch.

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 being stretched and oriented are significantly improved, and the notch sensitivity is also improved.

The heat resistance of acrylic is not high. Although its glass transition temperature reaches 104 °C, the maximum continuous use temperature varies between 65 °C and 95 °C with different working conditions, and the heat distortion temperature is about 96 °C (1.18MPa). , the Vicat softening point is about 113 ℃. The heat resistance can be improved by copolymerizing the monomer with propylene methacrylate or ethylene glycol diester acrylate. The cold resistance of acrylic is also poor, and the embrittlement temperature is about 9.2 °C. The thermal stability of acrylic is moderate, better than that of polyvinyl chloride and polyoxymethylene, but not as good as polyolefin and polystyrene. Processing temperature range.

The thermal conductivity and specific heat capacity of acrylic belong to the medium level in plastics, which are 0.19W/M.K and 1464J/Kg.K respectively.

Acrylic electrical properties

Because acrylic contains polar methyl ester groups on the side of the main chain, its electrical properties are not as good as those of non-polar plastics such as polyolefin and polystyrene. 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 pointing out that acrylic and even the entire acrylic plastic have excellent arc resistance. Under the action of the arc, the surface will not produce carbonized conductive paths and arc tracks. 20°C is a second-order transition temperature, which corresponds to the temperature at which the side carboxyl group starts to move. Below 20°C, the side carboxyl group is in a frozen state, and the electrical properties of the material will be improved when it is above 20°C.

Acrylic solvent resistance

Acrylic is resistant to relatively dilute inorganic acids, but concentrated inorganic acids can make it eroded, and it can resist alkalis, but warm sodium hydroxide and potassium hydroxide can make it eroded, resistant to salts and oils, and resistant to Aliphatic hydrocarbons, insoluble in water, methanol, glycerin, etc., but can absorb alcohol swelling, and produce stress cracking, not resistant to ketones, chlorinated hydrocarbons and aromatic hydrocarbons. Its solubility parameter is about 18.8(J/CM3)1/2, it is soluble in many chlorinated hydrocarbons and aromatic hydrocarbons, such as dichloroethane, trichloroethylene, chloroform, toluene, etc. Vinyl acetate and acetone can also make it dissolve.

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

Acrylic weather resistance

Acrylic 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 slightly turns yellow, the craze resistance decreases significantly, and the impact strength is still high. Slightly improved, other physical properties are almost unchanged.

Acrylic flammability

Acrylic is easy to burn, and the limit oxygen index is only 17.3.
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