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Polystyrene is from the styrene which is extracted from coal and oil. There are lots of ways of polymerization process, and the main ways are block polymerization,suspension polymerization and emulsion polymerization. If adapting the suspension polymerization , first put a certain content of foaming agent into the polystyrene, with help of the raising temperature the foaming agent will decompose and be foaming, after adding foaming agent the polystyrene then becoming EPS(expandable polystyrene). By heating and pressurizating the mould with the EPS in it,the EPS can be used to produce different foam product with different foaming ratio.

At present,manufacturers aways adapts the suspension polymerization processing to produce the EPS.According to the ways of adding the foaming agent,there are two suspension polymerization methods.

1 One-step suspension polymerization
Adding foaming agent at the beginning of or during the polymerization process, with the effect of the suspending agent, the styrene can suspend in the deionized water,the polymerization reaction will take place when there are the evocating agent and foaming agent.
2 Two-steps way,impregnation and polymerzation are divided into two independent stage
One Main ausiliary raw material for the EPS
1 Styrene monosomy
Its molecular is 104, it’s Colorless-transparent flammable. liquid with pungent-scented ,and it is a kind of dangerous goods at level A.
Its boiling point is 145.2℃,the density is 0.9048kg/m3,the explosion limit is 1.1%-6.1%,
the solubility in water is less than 0.1%;it is denderous for the body even if one breathe in 1% of the styrene monosomy;it will irritate one’s skin,if he being with it in a long time.
The sunshine or the nomal temperature will cause the polymerzation reaction of the styrene monosomy,so during the production process, the manufacturer store styrene monosomy at the temperature below 15℃ with the mathods of spraying temperature reduction and adding the polymerization inhibitor; the storage time is about three months
2, the de-ionized water(desalted water)
Its requirements are:PH=6~8; the conductivity is 0.2~0.5μs/cm, the organic matter content should less than 1PPm,the hardness should be less than PPm
Preparation for the de-ionized water: with the method of zwitterion exchanging resin
3 Emulsifying agent
It can disperse the styrene into the small oil drop suspengding in the water, and uniform the particle size;select different emulsifying agent according to the different disperse system, to make the beads be smooth and be non-caked.
4 Suspension agent(stabilizing agent)
Firstly,suspension agent is an important factor for keeping the suspension systm stable .It can prevent the granular styrene from seperating during its shaping process and prevent the polystyrene from caking.
Secondly, it can control and adjust the size and shape of the EPS beads.The uaual suspension agents are activity Calcium phosphate (TCP),t-butyl perbenzoate, Gelatin.
TCP,its formal name is hydroxy calcium phosphate(HAP),and its molecular formula is Ca2(PO4)6(OH)2,and it is water-insolubility inorganic power.For its activity ,suspension and dispersivity,usually ,it is used as the dispersing agent during the process of the resin suspending polymerization,it can play a effective part in improving the outlook of the product、the production efficiency and the reducing the cost.
Droxyethylce has lots of advantages, such as incesing the density of the suspension liquid、eulsifying、suspension、keeping moisture and erosion-resisting against the microorganisms.