Imaging and analysis of wave type interfacial instability in the coextrusion of low-density polyethylene melts

Martyn, M. T.; Spares, R.; Coates, Phil; Zatloukal, Martin

doi:10.1016/j.jnnfm.2008.08.001

Cited by 33 publications

(28 citation statements)

References 37 publications

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“…For further information on elastic effects in polymer coextrusion (not described in this study), the reader is directed toward Refs. [1,3,13,14,21,23], and [32][33][34][35][36][37]. It is stated in Ref.…”

Section: Introductionmentioning

confidence: 98%

“…Multilayer polymer film coextrusion is defined as two or more separately extruded polymer melt streams coming together to form a single stratified structure with multiple layers [1][2][3][4]. In the coextrusion process, the different melt layers must remain distinct but well bonded (or compatible) when in contact [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…In the coextrusion process, the different melt layers must remain distinct but well bonded (or compatible) when in contact [5,6]. Assuming that a desirable final coextrusion structure is obtained, coextrusion can combine the properties of different polymers into a single structure with improved features [1][2][3][4]7]. There are many aspects that one must consider to obtain a successful coextruded product.…”

Section: Introductionmentioning

confidence: 99%

“…1 are idealized; there is tight individual layer thickness control across the film widths and there is a linear interface between the different layers. 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].…”

Section: Introductionmentioning

confidence: 99%

“…Interfacial curvature can have a detrimental effect on the final film properties [3]. To reduce this and produce a desired linear interface (see Fig.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modeling of multilayer film coextrusion with experimental validation

2014

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Interfacial curvature can have a detrimental effect on the final film properties [3]. To reduce this and produce a desired linear interface (see Fig.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modeling of multilayer film coextrusion with experimental validation

2014

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Rheological Measurements

2013

Encyclopedia of Polymer Science and Technology

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Rheology is the science to study the flow and deformation of matter. It becomes an important field in material science and engineering, food, biotechnology, and so on. The objects in rheological study are not the ideal solid and ideal fluid, which can be described by the Hookean elastic model and the Newtonian viscous model, respectively. Instead, the rheological study often focuses on materials that can exhibit viscous, elastic, and plastic behavior under different flow conditions. They are often termed as complex fluids or soft matter, which include polymers, gels, suspensions, emulsions, biofluids, foods, inks (1). In contrast to hydrodynamics, which often accounts for the complex flow behavior of simple fluids, simple geometry is utilized in rheological measurements to understand the rather complicated relationship between the mechanical input and output of complex fluids. The real flow fields encountered in many applications (such as polymer extrusion, injection molding, blow molding, fiber spinning, inkjet printing, coating) are rather complicated (2). It becomes a problem whether the rheological measurements that performed under simple flow fields are useful in understanding the complicated flow behaviors of complex fluids. Fortunately, it has been proved in many examples that the properties determined from simple rheological measurements are sufficient to quantify the material parameters in various constitutive equations, which have been used widely and successfully to simulate the flow behaviors in polymer processing (3-11). The most frequently used simple flow fields are simple shear flow and simple extensional flow.The simplest geometry that defines the simple shear is two infinite parallel plates separated by a distance h. The liquid is set between two plates with one plate moving parallel to the other (Fig. 1). In reality, when the length L and the width B are much larger than the gap h, the flow in the center regime resembles the flow between two infinite plates. It means that the edge effects are ignored in most experimental shear geometries. In rheological measurements, the flow between two plates should be laminar. Moreover, it is usually assumed that the velocity across the gap satisfies a linear profile. As shown in Fig. 1, if the bottom plate is fixed and the upper plate moves horizontally with the velocity V, the fluid velocity varies linearly from 0 at the bottom plate to V at the upper plate if the no-slip boundary condition is satisfied. The linear velocity profile generates a constant velocity gradient, which is known as the shear rate. Then, the flow field between two parallel plates is homogeneous in the shear rate. The homogeneous assumption is nontrivial in the rheological tests since the actual velocity

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Experimental investigation of a new type of interfacial instability in a reactive coextrusion process

Bondon

Lamnawar

Maazouz

2015

Polymer Engineering & Sci

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This paper deals with the study of new interfacial instabilities, called “grainy” defects, in coextrusion process of reactive multilayer polymers. The main objective was to better understand this phenomenon since no help can be found in the literature. The fundamental approach from a micro‐scale to a macro‐scale involves the study of relationships between polymer structure, processing, and interfacial properties. The influence of these parameters on the generation of “grainy” defects during coextrusion has been assessed in correlation with physicochemical properties. Through this work, rheological properties and the interfacial morphology between tie and barrier layers have been investigated by shear stress relaxation experiments and transmission electronic microscopy, respectively. Depending on the reactive polymers, the interfacial coupling was found to significantly alter the stress relaxation behavior by extending the relaxation time and generating an interfacial roughness. Hence, relations between the copolymer architecture, the relaxation process, and the interfacial morphology were established in correlation with the generation of grainy defects in coextrusion process. POLYM. ENG. SCI., 55:2542–2552, 2015. © 2015 Society of Plastics Engineers

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Imaging and analysis of wave type interfacial instability in the coextrusion of low-density polyethylene melts

Cited by 33 publications

References 37 publications

Numerical modeling of multilayer film coextrusion with experimental validation

Numerical modeling of multilayer film coextrusion with experimental validation

Rheological Measurements

Experimental investigation of a new type of interfacial instability in a reactive coextrusion process

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