1. Foaming agent can play its role only at higher temperature.
When heating produced by the decomposition of foaming agent in the process of melt processing, which will make the viscosity and strength of the melt unstable and fluctuate, means the foaming process is difficult to control. So normally the performance of foaming products has different degrees of instability, which makes the application of the foaming material very limited.
Therefore, add foaming directly into feeding zone of extruder that is not good idea. No matter with which extruder as conical or parallel twin screw extrusion line.
2. Foaming and Rigid best solution at two different mixer.
In one mixer, for example, today u mixed 12 hours foaming skirting boards to storage in one 20M3 silo; then clean inside of hot mixer (cleaning is a complex process, waste labor time), although u clean very well, which must have some foaming agent that stick at body of barrel; When u are producing rigid skirting board, will have microcellular to affect the rigid quality. For sure, some buyers can accept this microcellular, we manufacture can agree also.