Role of the interphase in the flow stability of reactive coextruded multilayer polymers

Abstract

Coextrusion technologies are commonly used to produce multilayered composite sheets or films for a large range of applications from food packaging to optics. The contrast of rheological properties between layers can lead to interfacial instabilities. Important theoretical and experimental advances regarding theses defects have, during the last decades, been made using a mechanical and numerical approach. This study deals with the influence of the physicochemical affinity between the neighboring layers on interfacial instabilities for functionalized incompatible polymers. It was experimentally confirmed, in this case, that weak disturbance can be predicted by considering an interface of nonzero thickness (corresponding to an interdiffusion/reaction zone interphase) instead of a purely geometrical interface between the two reactive layers. According to the rheological investigations, an experimental strategy was here formulated to investigate the parameters that controlled the stability of the reactive multilayer flows. The role of the viscosity ratio, elasticity ratio, and layer ratio of the stability of the interface was also investigated coupling to the reaction rate/compatibilization phenomenon. Hence, based on this analysis, guidelines for a stable coextrusion of reactive functionalized polymers can be provided coupling the classical parameters and the physicochemical affinity at the polymer/polymer interface. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Numerical modeling of multilayer film coextrusion with experimental validation

“…This implies that viscous effects dominate over elastic ones for the three polymers used in this study and therefore elastic effects are not considered. Both the primary (N 1 ) and secondary (N 2 ) normal stress difference values are also used to ascertain the elasticity of a fluid [16,59]. For the three PET polymers investigated in this study, Newtonian behavior is exhibited within the shear rates of interest ( Fig.…”

“…This is not always obtainable and certain coextrusion issues can have a negative impact on the final product performance [3]. Both viscous and elastic melt property differences can lead to an unwanted nonlinear interface, which would have deleterious effects upon the optical, physical, and mechanical film properties [15,16]. Such interfacial irregularity can be either spatial (caused by viscous effects) or temporal (elastic effects).…”

Fundamental studies of interfacial rheology at multilayered model polymers for coextrusion process

“…Indeed, in multiphase polymer systems (blend/multilayer), interfacial phenomena like interdiffusion, interfacial slippage and/or interfacial reactions taking place at the polymer-polymer interface are very important considering that an interphase (a non-zero physicochemical affinity as opposed to a plane interface) may appear therein, which impacts the adhesion and properties [1][2][3][4][5][6]. So far, rheology /properties associated with such interphase as well its contributions persist as a hot issue.…”

“…Owning the advantage of combining separate features of different individual polymers together in a facile way, coextrusion has been widely used to fabricate multilayered composite sheets or films for various applications ranging from food package to reflective optics [1][2][3]. This technology is realized by a combination of two or three extruders using a multimanifold die or a feedblock within which polymer melts are brought together.…”

“…To date, most important theoretical and experimental advances regarding such interfacial defects are limited to mechanical and numerical approaches [1,2]. Indeed, in multiphase polymer systems (blend/multilayer), interfacial phenomena like interdiffusion, interfacial slippage and/or interfacial reactions taking place at the polymer-polymer interface are very important considering that an interphase (a non-zero physicochemical affinity as opposed to a plane interface) may appear therein, which impacts the adhesion and properties [1][2][3][4][5][6].…”