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Material properties, uses, advantages and disadvantages of PS plastic

February 19, 2024

PS is commonly known as hard glue, ordinary hard glue, scientific name is polystyrene, monomer styrene---a colorless liquid synthesized from petroleum, polystyrene is a transparent glass-like material in nature, with a specific gravity of 1.05. It is basically the same as water. It is hard and brittle. When it is knocked, it makes a metallic "ding-dang" sound. The sound is crisp and clear. It is commonly known as "ringing glue". Non-toxic and odorless. Products made of pure PS will shatter immediately after making a crisp sound when dropped on the ground. Because PS has good fluidity, high decomposition temperature, and stable melting specific gravity, it has become an indicator parameter for measuring plasticizing efficiency of injection molding machines. Injection molding machines all over the world use PS to calibrate the capacity of injection molding machines.


Combustion characteristics: it's flammable and can continue to burn after being removed from the fire. The upper end of the flame is golden yellow. It will soften and foam when burning. No liquid will drip. It will emit thick black columns of smoke. At the same time, it will emit the sweet aroma of styrene monomer.


Advantages: 1. Polystyrene is resistant to acids, alkalis and low-energy alcohols, is corroded and softened by many hydrocarbons, ketones, high- grade fatty esters, etc., and is soluble in aromatic hydrocarbons.
                      2. It has excellent electrical insulation and is a good high-frequency insulating material with excellent arc resistance.
                      3. Polystyrene is a material with extremely high transparency and high surface gloss. Easy to print.
                      4. Polystyrene can be colored freely, is odorless, tasteless and non-toxic, and does not cause the growth of fungi.


Disadvantages: poor mechanical properties, hard and brittle, susceptible to solvent erosion and stress cracking, low surface hardness, easy to scratch, poor heat resistance, low heat distortion temperature.


Usages: 1. Used in the production of transparent lenses, imitation crystal tableware and other transparent products.
               2. Used for injection molding of low-end daily necessities and toy shells, lampshades.
               3. Used for extrusion blow molding containers, hollow products, bottles.


Injection molding performance: the general melting point of PS is 173°C, the decomposition temperature is 330°C, and the injection molding temperature has a large adjustable range. When injection molding, the general operating temperature is 180℃-240℃, because it is an olefin plastic, it does not absorb water and does not need to be dried during production. However, for the sake of product quality, it can be dried at 60℃ for 1 hour to drain away floating water. The melt viscosity of styrene is small and the flow length ratio is large. It generally does not require large gates and runners to fill the product. However, PS is hard and brittle. When designing products, sharp corners should be avoided and attention should be paid to the demoulding slope, otherwise, product cracking will occur. Products are easily charged with static electricity and the surface easily attracts dust. The shrinkage rate is 5‰ and the overflow value is 0.03mm.