Commen Characteristics of EPS Raw Material
There are many varieties of eps raw material and various properties. But above all , eps raw material has the following three characteristics.
1. Ability to absorb shock loads
When the eps raw material is subjected to an impact load, the gas in the foam passes through the stagnation and compression, so that the externally acting energy is consumed and dissipated. The bubble gradually terminates the impact load with a small negative acceleration.
2, good thermal insulation performance
The thermal conductivity of eps raw material is much lower than that of pure plastics because the thermal conductivity of gases is nearly an order of magnitude lower than the thermal conductivity of plastics. The gases in the foam are isolated from each other, thus reducing convective heat transfer in the gas and helping to increase the thermal insulation capacity of the foam. The radiant heat is transmitted through the gas layer in the bubble. The radiant heat transfer capability of the foam is mainly determined by the absorption coefficient of the plastic to the infrared ray, the size of the cell, the shape of the cell, and the gas and volume ratio. The heat transfer capacity of the foam should be a combination of the above two heat transfer results (gas radiation and bubble heat conduction), and their relationship with the bubble density is simplified as shown in Fig. 3. At very low bubble densities, the amount of radiant heat transfer plays a major role in the overall heat transfer process. However, under high density conditions, the heat transfer performance of the foam depends mainly on the thermal conductivity of the foam. EPS foam has a very low thermal conductivity, and the national standard is ≤0.041w/m·k.
3, fire performance
EPS is an organic hydrocarbon and contains residual petroleum gas. Therefore, the general EPS product is a kind of flammable material, which can be ignited by fire, emits light when burned, and continues to burn even if it leaves the flame. It has thick smoke and molten dripping. . The temperatures for self-ignition and external ignition are 490 degrees Celsius and 296 degrees Celsius, respectively. Ordinary EPS foams that are not modified with flame retardants are classified as "flammable" and burn in case of fire, and the flame spreads rapidly over the entire surface. When EPS products are used in construction, shipbuilding, and refrigerated vehicles, certain flame retardant requirements must be proposed. To this end, all countries in the world produce a flame retardant EPS raw material which has been specially formulated and processed. These flame retardant EPS raw materials have greatly changed their combustion properties due to the addition of flame retardants such as organic halides. Expanded the use of EPS.