Description :
Context : Currently, nanostructured multilayer films have attracted tremendous interest because of their unique properties from the multiscale assembly, spatial confinement and interfacial effects. The challenge of this field is to design such nanostructured materials with controlled architectures and properties. Such nanostructured materials with controlled architectures and performances can be obtained by an innovative processing based on co-extrusion. Based on the concept of layer multiplication, this technology renders it possible to control the layer architecture and thickness from the micro- to the nano-scale. Herein, the multi-nanolayer film maximizes interface/interphase contributions and/or confinement-induced phenomena. The obtained nanostructured multilayer polymer films demonstrate in general highly tunable mechanical, electrical/dielectric, optical, gas/water barrier, and shape memory properties, arising mainly from the layer-layer interface effect. During processing, some interfacial instabilities (viscous encapsulation or secondary flows) occur. Moreover, interfacial distortions, layer heterogeneities, nano-droplets or layer breakup can be generated. Under such conditions, the interfacial properties are far from being well understood to optimize the process and customize the target properties. In our recent works, a great effort has been dedicated to investigate the rheology, dynamics and processing of multi-micro/nanolayered polymers based on compatible or incompatible pairs. The keywords for this research are : structure-rheology-processing-property relationships (See example of quoted and recent references in the field).

Objectives : The main objective of the present thesis is to develop new films with controlled and enhanced performances such as highly transparent and improved transport/barrier properties. By using innovative design to fabricate a multi-functional materials composed of multi-nanolayers, it is the targeted to increase the gas barrier efficiency and/or the optical gradient of at least one or two orders of magnitude. Moreover, well controlled properties are expected to result from the improvement of interlayer continuity and crystallization thanks of a better understanding of layers’ shear and elongational flow properties. Numerous packaging applications could take benefit from these unique properties, especially in cosmetic, pharmaceutical, food, optics or photovoltaic, etc. There are also promising prospect highlighted by first recycling trials that indicating a better compatibility of polymer multiphase systems obtained from nanolayered film fragments.
The originality/focus of the thesis is to gain a true understanding from macro to nanoscale of the interfacial phenomena generated by this new technology, which is rarely present in the literature. The project will present new attempts to reach homogeneous nanolayer distributions of dissimilar polymers used in layer multiplexing systems with a stable flow during coextrusion in one step with or without bi-stretching process. This project also aims to validate such higher recycling ability compared to current 5 barrier multilayer films. For packaging applications, the system chosen for this thesis will be only based on PE, (EVOH or PA6) as gas barrier layers to get rid of the tie layers used today between these functional layers in the classical multi-microlayer configurations. Therefore, it will allow to move from three polymers towards two polymers with controlled transparency and gas barrier properties through thousand layers. One-dimensional confinement of crystalline thin layers could also provide an advantage over the classical technology by drastically improving the oxygen and water barrier properties with controlled transparency. It will thus be very interesting to tailor and study these properties depending on the flow kinematics which may acting on the formation of long, single like crystal lamellae sandwiched in more or less thick external layers. Such new generation of barrier films will offer high potential for packaging and also photovoltaic applications, which are looking for barrier properties for example from medium to very high level (10-1 to 10-6 g.cc-1.m-2) with high transparency.
The ambition of this project being to understand in depth the interface starting from the molecular level (nano-scale), proceeding up to microscopic dynamics and macroscopic behaviour. Furthermore, a technological challenge deals with the development of a new technology without step of stretch, with control of the kinematic flow (especially elongation) for high rheological contrast, residence time (Drawback of the current systems). Layer homogeneity and morphological properties will be studied in turn by AFM, TEM depending of the developed design and coextrusion technology. The developed crystalline properties in Nano layered structures will be in turn evaluated by WAXS and SAXS. Overall, based on the understandings of the fundamentals of the interfacial phenomena over multi-scales, the outcome of the thesis should foster development of new coextruded multi-, micro- and nano-layer films with tailored transport and tuned optical and gradient properties.
Overall, the outcome of the project should foster development of new coextruded multi-, micro- and nano-layer films with controlled and improved optical and barrier properties. Lastly, a scale up from laboratory to pilot will be managed in collaboration with the research institute partner (IPC) dedicated to transfer the plastic technology towards French plastic industries.

Profile of candidate and expected skills : the PhD candidate should have an interdisciplinary profile either in rheology and/or polymer processing, tool design and modelling.
Responsibilities and expected outputs :

 To conduct and develop an individual research topic,

 Potential supervision of early stage researchers,

 Presentation of the results at the company and during the internal lab meetings …

 Experience in topics related to the project

 Fluency in written and spoken English.

Cross salary : 1550 € neat/month including the French social insurance.
Duration : 36 months.
Deadline : (Urgent) The selection will start asap.
To apply : The application must include : (i) the candidate’s detailed CV, (ii) letters of intent, (iii) copies of degrees. The successful applicant is expected to be an enthusiastic and self-motivated person with strong intellect who is able to take a creative approach to scientific tasks. The applicant should have the skills necessary to be an independent researcher in his respective areas of specialization. The ability to lead and a communicative personality are strong advantages.

Contacts : Khalid LAMNAWAR (Professor Associate -HDR, IMP @INSA de Lyon), Tel. 04 74 81 93 09 ou 06 73 80 56 98.
Khalid.lamnawar@insa-lyon.fr


Websites :
www.imp.cnrs.fr : UMR CNRS 2223 « Ingénierie des Matériaux Polymères, IMP », Pôle de compétences-Sterhéo : Structure et rhéologie des polymères – procédés et Modélisation.
www.insa-lyon.fr : Institut National Des Sciences Appliquées.
https://ct-ipc.com : Centre Technique Industriel de la Plasturgie et des Composites.
.
Example of Authors’ quoted references in the field :
[1] Lu B., Alcouffe P., Sudre G., Purvost S., Serghein A., Liu Chuntai, Maazouz A., Lamnawar K. 2020 Macromol. Materials & Engineering, 305, 5, 2000076. link
[2] Lu B., Lamnawar K., Maazouz A., Sudre G. 2018. ACS Appl. Mater. Interfaces 10 (34), 29019–29037 link
[3] Zhang H., Lamnawar K, Maazouz A., Maia J. 2016 J. of Rheo. 60-1-23 link
[4] Zhang, H. ; Lamnawar, K. ; Maazouz, A. Macromol. 2013, 46(1),276-29 link
[5] Lamnawar K., Zhang H., Maazouz A. 2013. A State of the art on the coextrusion process : Encycl. of PST. (Wiley library, New York, 2013) link

Reference : Thèse CIFRE-IMP-IPC

Date de démarrage : 01 novembre 2020

Durée : 36 mois

Contacter :
IMP (Lyon & Oyonnax)/IPC (Oyonnax, Alençon)
khalid Lamnawar
Institut National Des Sciences Appliquées INSA Lyon UMR CNRS 2223 « Ingénierie des Matériaux Polymères, IMP », Pôle de compétences-Sterhéo : Structure et rhéologie des polymères – procédés et Modélisation.
email : khalid.lamnawar@insa-lyon.fr
Téléphone : 0673805698

Page web : www.imp.cnrs.fr