Acrylic processing manufacturers take you to understand the mechanical properties
As an acrylic processing manufacturer, the chemical name of the sheet we produce is polymethyl methacrylate. Let’s take a look at its mechanical properties.
Polymethyl methacrylate has outstanding comprehensive mechanical properties and ranks in the forefront of general-purpose plastics. Its tensile, bending, and shrinking strengths are higher than polyolefins, and higher than polystyrene, polyvinyl chloride, etc., and its impact toughness is poor. But it is also slightly better than polystyrene. The cast bulk polymerized polymethyl methacrylate sheet (for example, aerospace plexiglass sheet) has higher tensile, bending, and shrinking 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 the mechanical properties are basically attributed to hard and brittle plastics, which are notch-sensitive and easy to crack under stress, but the fracture is not like polystyrene and ordinary inorganic glass. That's 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. If it exceeds 40°C, the toughness and ductility of the material will be improved. Polymethyl methacrylate has low surface hardness and is easy to scratch.
The strength of polymethyl methacrylate is related to the time of the stress effect. When the effect is added, the strength decreases. The mechanical properties of polymethyl methacrylate (oriented plexiglass) after stretching and orientation are obviously improved, and the notch sensitivity is also improved.
The heat resistance of polymethyl methacrylate is not high. Although its glass transition temperature reaches 104°C, the maximum continuous operating temperature varies between 65°C and 95°C with different working conditions, and the heat distortion temperature is about 96°C. ℃ (1.18MPa), Vicat softening point is about 113℃. The heat resistance can be improved by copolymerization of monomers with propylene methacrylate or ethylene glycol diester acrylate. The cold resistance of polymethyl methacrylate is also poor, and the embrittlement temperature is about 9.2°C. The thermal stability of polymethyl methacrylate is classified as medium, 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 activity 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 the middle level in plastics, which are 0.19W/MK and 1464J/Kg.K, respectively.