Coextrusion: Melt Strength

Modified on Sunday, 01 February 2015 10:32 PM by mpieler — Categorized as: Extrusion Hints

Coextrusion: Melt Strength
Vol.21 #1, June 1994

Melt strength effects in coextrusion of flat sheets can be a critical factor in the successful production of multilayer sheets. Some combinations of resins may be critically affected by the melt strength of skin and core resins. Indeed, slight modifications of skin melt strength can move a product suffering from non uniform draw down from a die to excellent quality.

A simple way to determine if melt strength effects are controlling your situation is to add a comparable higher melt strength component. In olefin polymers, the addition of LDPE will often raise melt strength. Once you have determined that this effect is in control, you can contact your resin supplier about possible resin changes, or if the LDPE does not adversely effect your product's performance, continue to use the blend.

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