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

Bondon, Arnaud; Lamnawar, Khalid; Maazouz, Abderrahim

doi:10.1002/pen.24146

Cited by 15 publications

(9 citation statements)

References 46 publications

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“…Other mechanisms should contribute that need be identified. Recently, in close collaboration with the results presented in the present paper, Bondon et al [26] have analyzed, on lab-formed assembly, the interphase formed between EVOH and tie layer (PP-g-AM plus PP) through electronic microscopy. They have evidenced a roughening of the interface at nanometric scale when the interfacial reaction between EVOH and PP-g-AM was developing.…”

Section: Introductionsupporting

confidence: 53%

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Controlling interfacial instabilities in PP/EVOH coextruded multilayer films through the surface density of interfacial copolymers

Vuong

Léger

Restagno

2020

Polymer Engineering & Sci

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Co-extruded polypropylene/tie/ethylene vinyl alcohol/tie/polypropylene (PP/tie/EVOH/tie/PP) films often exhibit optical defects which appear as randomly distributed scattering objects, in the sub-millimeter range. These defects may strongly affect the film transparency and prevent their practical use in packaging. Based on an objective optical test aimed at quantifying the film transparency, and on a systematic analysis, through optical microscopy, of transverse cuts of films obtained in various co-extrusion conditions, the nature of the defects could be identified as resulting from a modulation of the thickness of the inner EVOH Layer, with no variation in the overall thickness of the multilayer films. Thanks to a recently developed method to dose the surface density of interfacial copolymers, a clear correlation between the amplitude of the thickness modulation of the inner EVOH layer and the density of co-polymer molecules formed in situ at the EVOH/tie layer interface during the co-extrusion process was established. These results open the way to a better design of tie layers composition to avoid these kinds of defects.

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Section: Introductionsupporting

confidence: 53%

“…One can notice that the amplitude of the thickness oscillations of the inner EVOH film observed in real coextruded film is much larger than observed on the same polymer sandwiches but made with no shear [26].…”

Section: Iii21 Notesmentioning

confidence: 69%

Controlling interfacial instabilities in PP/EVOH coextruded multilayer films through the surface density of interfacial copolymers

Vuong

Léger

Restagno

2020

Polymer Engineering & Sci

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“…However, at the interface, PP- g -MA bonds with both PA and EVOH phases, thus forming cross-linked structures. Bondon et al 29 studied the interface morphology of PA and PP- g -MA as well as EVOH and PP- g -MA in a multilayered co-extruded film where PP- g -MA was used as a tie layer. The authors found that the interface of EVOH/PP- g -MA is much thicker than the interface of PA/PP- g -MA, indicating the formation of a complex copolymer architecture.…”

Section: Results and Discussionmentioning

confidence: 99%

Mechanism of Thermal Degradation-Induced Gel Formation in Polyamide 6/Ethylene Vinyl Alcohol Blend Nanocomposites Studied by Time-Resolved Rheology and Hyphenated Thermogravimetric Analyzer Fourier Transform Infrared Spectroscopy Mass Spectroscopy: Synergistic Role of Nanoparticles and Maleic-anhydride-Grafted Polypropylene

2019

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In this study, polyamide 6 (PA) is blended with ethylene vinyl alcohol (EVOH) to yield packaging materials with a balance of mechanical and gas barrier properties. However, the formation of gel-like structures in both polymers because of thermal degradation at high temperatures leads to a processing challenge, particularly during thin-gauge film extrusion. To address this challenge, nanoclays are introduced either directly or via a masterbatch of maleic-anhydride-grafted polypropylene to the PA/EVOH blend and time-resolved rheometry is used to study the effect of different modes of nanoclay incorporation on the kinetics of thermo-oxidative degradation of PA/EVOH blend and its nanocomposites. Time-resolved rheometry measurements allow the acquisition of accurate frequency-dependent linear viscoelastic behavior and offer insights into the rate of degradation or gel formation kinetics and cross-link density. The thermal degradation was studied by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy and mass spectroscopy, allowing the prediction of the possible reactions that take place during the rheological property measurements. The results show that when nanoclays are incorporated directly, the oxidative reactions occur faster. In contrast, in the masterbatch method, oxidative degradation is hindered. The difference in the behaviors is shown to lie in the different nanoclay distributions in the blends; in the blends prepared by the masterbatch method, the nanoclays are dispersed at the interface. In conclusion, the masterbatch-containing blend nanocomposite would benefit processing and product development.

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“…Particularly, under real coextrusion flows, with these copolymers of complex architecture, interfacial roughness and irregularities are further enlarged in the die exit as compared to those in the feedblock due to the accelerated reaction kinetics ( Figure 10 ). Additionally, the higher surface density of the EVOH- co -PP- g -MA copolymers generated at the interfaces further leads to an optical grainy defect and a loss of transparency in the resulting multilayer films [ 82 , 84 ].…”

Section: Interfacial Phenomena At Polymer–polymer Interfacesmentioning

confidence: 99%

Interfacial Phenomena in Multi-Micro-/Nanolayered Polymer Coextrusion: A Review of Fundamental and Engineering Aspects

et al. 2021

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The multilayer coextrusion process is known to be a reliable technique for the continuous fabrication of high-performance micro-/nanolayered polymeric products. Using laminar flow conditions to combine polymer pairs, one can produce multilayer films and composites with a large number of interfaces at the polymer-polymer boundary. Interfacial phenomena, including interlayer diffusion, interlayer reaction, interfacial instabilities, and interfacial geometrical confinement, are always present during multilayer coextrusion depending on the processed polymers. They are critical in defining the microstructural development and resulting macroscopic properties of multilayered products. This paper, therefore, presents a comprehensive review of these interfacial phenomena and illustrates systematically how these phenomena develop and influence the resulting physicochemical properties. This review will promote the understanding of interfacial evolution in the micro-/nanolayer coextrusion process while enabling the better control of the microstructure and end use properties.

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

Cited by 15 publications

References 46 publications

Controlling interfacial instabilities in PP/EVOH coextruded multilayer films through the surface density of interfacial copolymers

Controlling interfacial instabilities in PP/EVOH coextruded multilayer films through the surface density of interfacial copolymers

Interfacial Phenomena in Multi-Micro-/Nanolayered Polymer Coextrusion: A Review of Fundamental and Engineering Aspects

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