Conference proceedings
Formation of foam structures and influence of processing procedure in foam injection moulding of thermoplastic materials 

Publication Details
Heim, H.; Bledzki, A.; Rohleder, M.; Tromm, M.
Cellular Materials ( CELLMAT 2012)
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Due to the trend of lightweight construction, material and energy efficiency, foaming of plastics is becoming increasingly important. Due to the trends of lightweight construction, material and energy efficiency, foamed plastics are becoming increasingly important. The processing procedure and the processing parameters create the structure of the foam, which is essential for the component properties. However, the relationship between the structures and properties is very complex and depends on the materials. Foam injection moulding of thermoplastic materials leads to an integral structure with a low density in the core of the component, and a high density in the outer layers. This is due to the filling behaviour in the mould. This typical structure is caused by the viscose-elastic behaviour and the resulting laminar flow of the polymer melt. The polymer melt swells into the mould the front of the melt is heads towards the core. The wall adhesion of the outer layers leads to faster freezing in these areas. As a result of this, the formation of foam structures is inhibited. Chemical or physical blowing agents are used in the process. With the help of high pressure, they are incorporated in the melt in form of gas. During compounding, a singlephase flow is created, which can expand due to the pressure drop during injection. The type of blowing agent, as well as the processing parameters, the additives, and the local flow conditions determine the pore size, pore distribution and the thickness of the outer layer.

Last updated on 2019-05-12 at 16:02