The mechanical properties of acrylic
Poly methyl methacrylate has a good comprehensive mechanical properties, in the forefront of general plastics, tensile, bending, compression strength are higher than the polyolefin, but also higher than polystyrene, polyvinyl chloride, impact toughness is poor, But also slightly better than polystyrene. Casting bulk polymerization polymethyl methacrylate sheet (such as aviation plexiglass,acrylic sheet) tensile, bending, compression and other mechanical properties are higher, can reach the level of polyamide, polycarbonate and other engineering plastics.
In general, the tensile strength of polymethyl methacrylate can reach 50-77MPa level, bending strength can reach 90-130MPa, these performance data has reached or exceeded the upper limit of some engineering plastics. Its elongation at break only
2% -3%, so the mechanical properties of the characteristics are basically hard and brittle plastic, and has a notch sensitivity, easy to crack under stress, but the fracture does not like polystyrene and ordinary inorganic glass as sharp uneven. 40 ℃ is a secondary transition temperature, which is equivalent to the side of the beginning of the temperature of methyl, more than 40 ℃, the toughness of the material, ductility has improved. Poly methyl methacrylate surface hardness is low, easy to scratch.
The strength of polymethyl methacrylate was related to the time of stress, and the intensity decreased with the increase of reaction time. The mechanical properties of PMMA (oriented PMMA) after tensile orientation were improved obviously, and the notch sensitivity was also improved.
Poly methyl methacrylate heat resistance is not high, although its glass transition temperature reached 104 ℃, but the maximum continuous use temperature is different with the working conditions change between 65 ℃ -95 ℃, heat distortion temperature is about 96 (1.18MPa), Vicat softening point of about 113 ℃. The heat resistance can be improved by copolymerizing the monomer with propylene glycol methacrylate or diester ethylene glycol. Poly methyl methacrylate cold resistance is also poor, brittle temperature of about 9.2 ℃. The thermal stability of polymethyl methacrylate is medium, better than that of polyvinyl chloride and polyformaldehyde, but less than polyolefin and polystyrene. The thermal decomposition temperature is slightly higher than 270 ℃, and its flowing temperature is about 160 ℃. Has a wider melt processing temperature range.
The thermal conductivity and specific heat capacity of polymethyl methacrylate were all in the medium level of 0.19W / mK and 1464J / Kg.K
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