Acrylic (loanword)

Mechanical properties

Poly(methyl methacrylate) has good overall mechanical properties, in the forefront of general-purpose plastics, tensile, bending, compression and other strengths are higher than polyolefins, but also higher than polystyrene, PVC, etc., the impact toughness of poorer, but also slightly better than polystyrene. Cast the body of the polymerization of polymerized polymethyl methacrylate sheet (such as aviation with plexiglass sheet) tensile, bending, compression and other mechanical properties of some higher, can reach the level of polyamide, polycarbonate and other engineering plastics.

In general, the tensile strength of polymethyl methacrylate can reach the level of 50-77MPa, 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 of the characteristics of the plastic is basically hard and brittle, and notch sensitivity, easy to crack under stress, but the fracture fracture is not like polystyrene and ordinary inorganic glass as sharp jagged. 40 ℃ is a secondary transition temperature, equivalent to the side of the temperature of the methyl group began to move, more than 40 ℃, the material's toughness, ductility has been improved. The surface hardness of polymethylmethacrylate is low and easily scratched.

The strength of polymethylmethacrylate is related to the time of stress application, and the strength decreases with increasing time of application. The mechanical properties of polymethylmethacrylate (oriented plexiglass) after tensile orientation are significantly improved, and notch sensitivity is also improved.

The heat resistance of poly(methyl methacrylate) is not high, although its glass transition temperature reaches 104℃, but the continuous use temperature changes with different working conditions between 65℃-95℃, the heat distortion temperature is about 96℃ (1.18MPa), and the Vicat softening point is about 113℃. Heat resistance can be improved by copolymerizing the monomer with propylene methacrylate or bis ester-based ethylene glycol acrylate. Poly(methyl methacrylate) is also less resistant to cold, with a brittleness temperature of about 9.2°C. Thermal stability of poly(methyl methacrylate) belongs to the medium, better than polyvinyl chloride and polyformaldehyde, but not as good as polyolefins and polystyrene, thermal decomposition temperature is slightly higher than 270 ° C, its flow temperature of about 160 ° C, so there is still a wide range of melt processing temperature.

Thermal conductivity and specific heat capacity of poly(methyl methacrylate) are medium level in plastics, respectively 0.19W/M.K and 1464J/Kg.K.