1. Polymethyl methacrylate contains a polar side methyl group, has a relatively obvious hygroscopicity, the water absorption rate is generally 0.3% - 0.4%, must be dried before molding, drying conditions are 80 °C -85 °C drying 4-5h .
2. Polymethyl methacrylate has significant non-Newtonian fluid properties within the molding processing temperature range, the melt viscosity decreases significantly with increasing shear rate, and the melt viscosity is also sensitive to temperature changes. Therefore, for the polymethyl methacrylate molding process, increasing the molding pressure and temperature can significantly reduce the melt viscosity and achieve better fluidity.
3. The temperature at which polymethyl methacrylate starts to flow is about 160°C, the temperature at which decomposition starts is higher than 270°C, and it has a wider processing temperature range.
4, poly methyl methacrylate melt viscosity, cooling rate and faster, the product is prone to internal stress, so the molding process of strict control of the conditions, after the formation of products also need post-processing.
5, polymethyl methacrylate is an amorphous polymer, shrinkage and its range of changes are small, generally about 0.5% -0.8%, is conducive to the molding of a high dimensional accuracy of plastic parts.
6. The polymethyl methacrylate has a very good cutting performance, and its profiles can be easily machined to various required sizes.
Polymethyl methacrylate can be used for casting, injection molding, extrusion, thermoforming and other processes.