PhD and Postdoctoral Positions

Open PhD position: Damage mechanisms in insulating polymer materials under electric field : theory and simulations.

The aim of the PhD is to describe damaging mechanisms under applied electrical fields which lead eventually to electrical breakdown of the material. This is a theoretical work which follows earlier experimental and theoretical studies on damaging under mechanical stress [1,2] and an on-going experimental PhD regarding damaging under applied electric field. Currently, we study the microscopic mechanisms under medium to high electric field, in long lifetime regime. The dielectric properties of materials are investigated along electrical fatigue tests on different polymer samples combined with various characterizations methods.  Based on these works, we have identified various damaging mechanisms on the microscopic scale. A theoretical model will be developed and implemented into a 3D numerical model. The results of the simulations will be compared to experimental results.  

This PhD is part of a collaboration between Nexans, a worldwide leading company for electric networking, Solvay and Laboratoire Polymères et Matériaux Avancés (LPMA), within the context of the “Lyons Polymer Science and Enineering” collaborative network. The PhD will take place at LPMA. 

[1] E. Mourglia-Seignobos, D.R. Long, L. Odoni, L. Vanel, P. Sotta, C. Rochas, "Physical Mechanisms of Fatigue in Neat Polyamide 6,6", Macromolecules,  47, 3880-3894 (2014)

[2] C. Fusco, D.R. Long, L. Vanel,Brittle-to-ductile transition in creep rupture of 2D disordered elastic materials,to appear, Journal of Statistical Physic (2019)

The Solvay/CNRS Joint Laboratory (UMR: Unité Mixte de Recherche) ‘Advanced Materials Laboratory’, is located near Lyon, France. The objective of the lab is to develop fundamental research on physical properties of heterogeneous polymer materials, in order to be able to propose innovative materials with tailored properties and improved usage properties for new applications.

This PhD project is suitable for applicants graduated in polymer physics and/or condensed matter physcis and/or statistical physics and/or mechanics and material science with a strong theoretical and numerical background. 

Please send application (detailed CV, application letter) to the following contact persons

D. Long  

Email: didier.long-exterieur@solvay.com

tel: +33 (0)4 28 27 10 30 

P. Sotta 

Email: paul.sotta-exterieur@solvay.com


tel: +33 (0)4 28 27 10 29

Open PhD position: Large amplitude plastic deformations and damage mechanisms in amorphous polymers

We have studied recently the microscopic mechanisms of damaging in plasticized cellulose acetate under tensile deformation, how they appear and develop during the course of deformation until failure. Based on USAXS and electronic microscopy experiments, we proposed that damages are initiated by the nucleation of cavities. We showed that their initial growth after nucleation is blocked at a size of order 100 nm by the strain hardening in their immediate vicinity where deformation and stress are amplified. Macroscopically, the strain-hardening corresponds to a regime where the stress increases linearly during plastic deformation. The strain hardening behavior appears thus to be key for preventing an early failure and conferring a high ductility to a polymer material. We propose in this new PhD thesis to study various modified polymers synthesized internally, in order to characterize their mechanical properties up to the strain-hardening behavior according to the chemical modifications, and to characterize also their ultimate properties and toidentify the elementary mechanisms of damaging, and how they grow and develop during plastic deformation.

The CNRS/Solvay Joint Laboratory (UMR: Unité Mixte de Recherche) ‘Advanced Polymer Materials Laboratory’ (LPMA) is located near Lyon, France. The objective of this Laboratory is to develop fundamental research on physical properties of heterogeneous polymer materials, with the view to enable Solvay to propose materials with tailored properties and improved usage properties for the customer. We aim at hiring PhD students willing to pursue a carrier either in the academia, or in the industry. This experimental PhD project is suitable for applicants graduated in polymer physics and/or chemical physics and/or material science. A strong background in polymer processing, structure and physical properties of polymers will be valued. 

[1] E. Mourglia-Seignobos, D.R. Long, L. Odoni, L. Vanel, P. Sotta, C. Rochas, "Physical Mechanisms of Fatigue in Neat Polyamide 6,6", Macromolecules,  47, 3880-3894 (2014)

[2] A. Charvet, “Etude des propriétés mécaniques et des mécanismes d’endommagement dans un polymère bio-sourcé: l’acétate de cellulose plastifié”, PhD thesis, Université de Lyon (2019)

Please send application (detailed CV, application letter) to the following contact persons

Didier LONG  

Email: didier.long-exterieur@solvay.com

tel: +33 (0)4 28 27 10 30  

Caroll VERGELATI

Email: caroll.vergelati@solvay.com

tel: +33 (0)4 28 27 10 18