Mechanical properties of acrylic glass

Acrylic glass has good comprehensive mechanical properties and ranks in the forefront of general-purpose plastics. The tensile, bending, and compression strengths are all higher than polyolefins, and higher than polystyrene, polyvinyl chloride, etc., and the impact toughness is poor, but slightly better In polystyrene. The cast bulk polymerized polymethyl methacrylate sheet (such as aerospace plexiglass sheet) has higher tensile, bending, and compression mechanical properties, and can reach the level of engineering plastics such as polyamide and polycarbonate. Generally speaking, the tensile strength of polymethyl methacrylate can reach the level of 50-77Mpa, and the bending strength can reach the level of 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, and have notch sensitivity, easy to crack under stress, but the fracture is not like polystyrene and ordinary glass. Sharp and jagged. 40°C is a secondary transition temperature, which is equivalent to the temperature at which the pendant methyl group starts to move. Above 40°C, the toughness and ductility of the material will be improved. Polymethyl methacrylate has low surface hardness and is easy to scratch. The heat resistance of polymethyl methacrylate is not high. Although its glass transition temperature reaches 104°C, the maximum continuous use temperature varies between 65°C and 95°C depending on the conditions of the workpiece, and the heat distortion temperature is about 96 ℃ (1.18MPa), the Vicat softening point is about 113℃. The heat resistance can be improved by copolymerization of monomers with methyl methacrylate or ethylene glycol diester acrylate. The cold resistance of polymethyl methacrylate is poor, and the embrittlement temperature is about 9.2°C. The thermal stability of polymethyl methacrylate is moderate, better than polyvinyl chloride and polyoxymethylene, but not as good as polyolefin and polystyrene. The thermal decomposition temperature is slightly higher than 270°C, and its flow temperature is about 160°C. There is a wide range of melt processing temperature. The thermal conductivity and specific heat capacity of polymethyl methacrylate are both at a medium level among plastics, which are 0.19W/CM.K and 1464J/Kg.K, respectively.