1. Cast molding Cast molding is used to form profiles o […]
1. Cast molding
Cast molding is used to form profiles of plexiglass sheets, rods, etc., that is, forming profiles by bulk polymerization. The cast product needs to be post-treated, and the post-treatment conditions are 2 h at 60 ° C and 2 h at 120 ° C.
2. injection molding
Injection molding uses pellets obtained by suspension polymerization and is formed on a conventional plunger or screw injection molding machine. Injection molding products also need post-treatment to eliminate internal stress. The treatment is carried out in a 70-80 °C hot air circulation drying oven. The treatment time depends on the thickness of the product, and generally takes about 4 hours.
3. extrusion molding
Polymethyl methacrylate can also be formed by extrusion molding, using granules produced by suspension polymerization to prepare plexiglass sheets, rods, tubes, sheets, etc., but the profiles thus prepared, especially the sheets, due to the small molecular weight of the polymer, The mechanical properties, heat resistance and solvent resistance are not as good as cast molding profiles, and the advantages are high production efficiency, especially for pipes and other casting molds. Profiles that are difficult to manufacture. Extrusion can be carried out with a single or double-stage vented extruder with a screw length to diameter ratio of 20-25. Table 2 is a typical process condition for extrusion molding.