Vliv zpracovatelských aditiv na stabilitu koextruzního toku

Abstract

Byla použita metoda konečných prvků využívající viskoelastické konstituční rovnice pro analýzu vícevrstevného toku tavenin LDPE v plochých koextruzních hlavách. Bylo zjištěno, že elongační viskozita polymerních tavenin je kritickým parametrem pro nástup meziplošných nestabilit.

Interfacial instabilities developed during two-layer flows of LDPE melts were investigated theoretically through viscoelastic FEM analysis as well as experimentally on a flat multi-manifold coextrusion die. During continuous reduction of the minor layer, wave type appears in the film first whereas the zig-zag type is only visible later, at much thinner minor layer, which is an opposite order compared to film blowing coextrusion. Moreover, extensional viscosity of the minor layer was found to play a significant role from the interfacial instability point of view