1. Acrylic contains polar side methyl groups, which has obvious hygroscopicity. The water absorption rate is generally 0.3%-0.4%. Before molding, the acrylic sheet must be
It must be dried, and the drying conditions are 4-5h at 80℃-85℃.
2. Acrylic has effective and obvious non-Newtonian fluid characteristics in the temperature range of forming and processing. The melt viscosity will decrease significantly with the increase of shear rate, and the melt viscosity is also very sensitive to temperature changes. Therefore, for the molding of polymethyl methacrylate, increasing the molding pressure and temperature can significantly reduce the melt viscosity and achieve better fluidity.
3. The temperature at which acrylic begins to flow is about 160°C, and the temperature at which it begins to decompose is higher than 270°C, with a wide processing temperature range.
4. Acrylic has a high melt viscosity and a fast cooling rate, and the product is prone to internal stress. Therefore, the process conditions are strictly controlled during molding, and post-processing is also required after the product is formed.
5. Acrylic is an amorphous polymer, the shrinkage rate and its variation range are small, generally about 0.5%-0.8%, which is conducive to molding plastic parts with high dimensional accuracy. 6. Acrylic has very good cutting performance, and its profiles can be easily machined into various required sizes.
Acrylic can be cast, injection molded, extrusion, thermoforming, laser engraving, laser cutting and other processes.
Casting is used to form plexiglass sheets, bars and other profiles, that is, the profiles are formed by bulk polymerization. The products after casting need to be post-treated. The post-treatment conditions are 2 hours at 60°C and 2 hours at 120°C.
Contact Person: Mr. Jason