The difference between polyurethane foam and polystyrene foam

Polyurethane rigid foam is a kind of polymer made of isocyanate and polyether as the main raw materials, adding foaming agent, catalyst and other additives, mixed by special equipment and foamed by high-pressure injection. Polystyrene foam is made of polystyrene resin as the main body, adding foaming agent and other additives. It is a widely used buffer material. Polystyrene foam is similar to polyurethane foam in insulation, strength, stability and many other aspects. But its disadvantage is a narrow range of temperature resistance, exposure to open fire easy to emit toxic gas, water absorption is easy to lose the thermal insulation effect, is a gradually phased out of the product.

Hard foam polyurethane and polystyrene plastic foam difference 1: different foaming mechanism

Rigid polyurethane foam is a kind of obturator rate can amount to 90% of light foam, foam is a kind of thermosetting, two-component liquid (commonly known as black, white material) after fully mixing, rapid chemical reaction and curing (a few seconds to a few minutes), such as foaming agent, catalyst, foam stabilizer additives under the action of foam into a mesh structure.

Polystyrene foam (EPS, XPS) is a kind of thermoplastic foam with granular structure. It is heated and expanded by granular or powdery material and expanded by vaporization of foaming agent. It has the potential of secondary foaming.

The difference between hard foam polyurethane and polystyrene plastic foam 2: different physical and chemical properties of foam

Heat insulation performance

Compared with hard foam polyurethane, polystyrene foam insulation performance is better, but its value is relatively large, such as EPS board ≈ 0.04W/K ·m, XPS board ≈ 0.031W/K ·m, PUR board ≈ 0.022W/K ·m. On the premise of the same energy saving index, the thickness of insulation board can be reduced to improve the quality stability of insulation system.

② Thermal stability

The thermal stability of rigid foam polyurethane can be as high as 120℃, while the thermal stability of benzene plate is only 70℃. In summer, the external surface temperature of exterior wall in China is generally above 70℃, which is easy to lead to secondary foaming and cracking of benzene board.

3) Surface binding energy

Polyurethane molecular chain has certain - OH key, namely the hydrophilic gene, easy to bond and cement slurry, but not for polystyrene - OH keys, is a kind of hydrophobic material, its surface is hard to and inorganic material such as cement slurry blending, the benzene board exterior insulation system is one of the main reasons for cracking, fall off.

④ Combustion principle

Hard foam polyurethane is a kind of thermosetting material, which forms a carbonization layer after heating and combustion, hindering the further penetration of heat and oxygen, hindering the further combustion of foam, and is not easy to cause fire spread accidents. Polystyrene foam is a thermoplastic material that shrinks and melts when heated, and then drops and burns. It does not produce a carbonization barrier layer, which is prone to flame spread accidents.

⑤ Corrosion resistance

Polyurethane is waterproof, oil resistant and solvent resistant. Polystyrene water resistance but not solvent resistance, benzene, ester solvents are very sensitive, easy to produce rapid corrosion.

Hard foam polyurethane and polystyrene plastic foam difference 3: application range is different

Polystyrene foams can only be extruded into a mill in a factory state, while rigid polyurethane foams can be sprayed, poured and factory foamed. Therefore, the application of polyurethane foam is more convenient and diversified than that of polystyrene foam.