PS (polystyrene) performance and processing process characteristics

1 .PS performance

PS is an amorphous polymer, good fluidity, low water absorption (less than 00.2%), is a transparent plastic easy to mold and process. Its products light transmission rate of 88-92%, strong coloring power, high hardness. However, PS products are brittle, easy to produce internal stress cracking, heat resistance is poor (60-80 ℃), non-toxic, specific gravity of about 1.04g/cm3 (slightly greater than water).

Molding shrinkage (its value is generally 0.004-0.007), the name transparent PS only indicates the transparency of the resin, not crystallinity. (Chemical and physical properties: most commercial PS is a transparent, non-crystalline material. ps has very good geometric stability, thermal stability, optical transmission properties, electrical insulation properties, and a very slight tendency to absorb moisture. It is resistant to water, dilute inorganic acids, but can be corroded by strong oxidizing acids such as concentrated sulfuric acid, and can swell and deform in some organic solvents.)

2 .Process characteristics of PS

PS melting point of 166 ℃, processing temperature is generally appropriate at 185-215 ℃, melting temperature of 180 ~ 280 ℃, for the flame retardant material its upper limit of 250 ℃, decomposition temperature of about 290 ℃, so its processing temperature range is wide.

The mold temperature is 40~50℃, injection pressure: 200~600bar, injection speed is recommended to use fast injection speed, runners and gates can be used for all conventional types of gates. PS material usually does not need to be dried before processing unless it is stored improperly. If drying is required, the recommended drying conditions are 80C and 2 to 3 hours.

Because of the low specific heat of PS, its production of some mold heat dissipation that can be quickly cold condensation curing, its cooling rate than the general raw materials to be faster, open the mold time can be earlier. Its plasticization time and cooling time are shorter, molding cycle time will reduce some; PS products with the increase in mold temperature and the better the luster.

3. Typical application range

Packaging products (containers, hoods, bottles), disposable medical supplies, toys, cups, knives, tape shafts, storm windows, and many foam products - egg crates. Meat and poultry packaging trays, bottle labels and foamed PS cushioning materials, product packaging, household items (tableware, trays, etc.), electrical (transparent containers, light scatterers, insulating films, etc.).