What are the characteristics of PMMA materials for cosmetic containers PMMA bottles

The cosmetic container PMMA bottle is made of PMMA material. What are the characteristics of this material?
PMMA plastic, called polymethylmethacrylate (PMMA, English Acrylic), also known as acrylic or plexiglass, is often called agaric in Hong Kong, with high transparency, low price, and easy machining And other advantages, it is a commonly used glass substitute material. The monomer of polymethyl methacrylate is methyl methacrylate (MMA, acrylic monomer). It has excellent transparency and outstanding aging resistance; its specific gravity is less than half of ordinary glass, but its resistance to fragmentation is several times higher; it has good insulation and mechanical strength; it has strong resistance to acids, alkalis and salts Corrosion resistance; and easy to process; it can be used for bonding, sawing, planing, drilling, engraving, grinding, screen printing, sandblasting and other manual and mechanical processing. After heating, it can be bent and molded into various acrylic products. Such as cosmetic packaging bottles.
PMMA is lighter in weight and has a lower density than glass: PMMA has a density of about 1150-1190 kg/m3, which is half of glass (2400-2800 kg/m3). The weight of a material of the same size is only half that of ordinary glass, and 43% of aluminum (belonging to light metal).
PMMA has high mechanical strength. The relative molecular weight of plexiglass is about 2 million. It is a long-chain polymer compound, and the molecular chains are very soft. Therefore, plexiglass has relatively high strength, tensile and impact resistance. The capacity is 7-18 times higher than ordinary glass. The tensile strength is 6-7 kgf/mm2, and the compressive strength is 12-14 kgf/mm2. The impact resistance is better than that of polystyrene; it also has the characteristics of not being easily broken. There is a kind of plexiglass that has been heated and stretched, in which the molecular chains are arranged in a very orderly manner, which significantly improves the toughness of the material. Use nails to penetrate the plexiglass, even if the nail penetrates, the plexiglass No cracks are produced, and the plexiglass will not break into fragments after being broken down by bullets. Therefore, the stretched plexiglass can be used as bulletproof glass, and also as a cockpit cover on military aircraft.
PMMA in the molten state has a higher melt viscosity and poor fluidity, and the melt viscosity is more sensitive to temperature changes. The change of injection temperature has a more significant effect on the melt flow length than the injection pressure, and is more significant than the injection rate, and more significant than the mold temperature. Therefore, changing the fluidity of PMMA molding mainly starts from the injection temperature.
PMMA has a certain degree of hydrophilicity. The water absorption of the particles reaches 0.3% to 0.4%, and the presence of moisture causes bubbles to appear in the melt, and the obtained product has silver wires and the transparency is also reduced. Therefore, cosmetic packaging bottle manufacturers are required to dry the resin before injection.