Transfer in polymers

Context

The plastic shaping processes all include an essential phase which involves heating or cooling the material and / or its environment. A better understanding of the thermomechanical behavior of polymeric materials during their transformation is therefore essential for the optimization of the process and the control of production costs. In this perspective, modeling is an essential tool: it allows the development of numerical simulations aimed at to optimize the operation of machines and thus make the process more competitive by improving the quality of products and reducing energy consumption. In addition, the fields of scientific investigation concerning polymers and composites are vast and important basic research work remains to be conducted. Laws of behavior of the materials during their transformation as well in liquid phase as solid, influence of the parameters of the process on the properties of the finished object, adaptation and optimization of the tools, reduction of the energies of implementation are as many current subjects of basic scientific research that technological locks for industrialists.

Objectives

Our activities aim to better understand the physical phenomena related to the transformation of polymer and composite materials in order to model them and to optimize the processes of their shaping. They include an experimental component (observation, understanding, characterization) and a theoretical component (modeling and numerical simulation). The scientific perspectives are on transfers in materials, processes and material-process interfaces. They are guided by the multiphysical couplings, mainly thermomechanical and rheological, which govern these materials and processes at different scales, but also by the complex interaction that represents the triptych process / structure / behavior of the materials. Our researches are spread out according to a continuum of scales, from local to global, from fundamental to application:

• firstly, separate analysis of the physical phenomena governing the behavior of the material with the contribution of knowledge when it is necessary / possible: thermal (conduction, convection, radiation), mechanics (flow, shear), rheological (viscoelasticity) and physico-chemical (crystallization)

• then study of the interdependence of these phenomena and the optimization of the performances of the processes in relation with the structure and / or the behavior of the material

• and lastly, the identification of parameters, measures and instrumentation of tools for a better correlation between model and industrial reality, allowing forecasts and practical recommendations for improving performance.

One of our scientific goals is the development of models linking the kinetics of microstructure transformation of materials to the thermal kinetics applied to them. This analysis implements global parameter identification models, generalizable, but based on the knowledge of the physics of these materials. The reduction of models makes it possible to experimentally identify these parameters by fine measurements but simple enough to be implemented directly for different types of materials.

Scientific skills

• Characterization of the thermophysical properties of polymers and composites

• Rheology and constitutive laws of materials

• Modeling the crystallization of polymers under flow: prediction and characterization of the structure of polymer materials, composites:

• Crystallization under flow

• Prediction and characterization of semi-crystalline structures of polymeric and composite materials

• Quantification of thermal and mechanical effects on crystallization.

• Thermal transfers at mold-material interfaces in plastics processes (instrumentation and development of metrology based on inverse methods);

• Optimization of heat transfer in processes: modeling the coupling structure / process / behavior of materials);

• Hydrodynamic instabilities in viscous and viscoelastic fluid flows: application to painting, extrusion of film materials, etc.

• Numerical simulation of processes: injection, extrusion, pultrusion, rotational molding, infrared or laser sintering.

Some international collaborations

University of Santiago de Chile, Mc Gill University (Canada), CREPEC Canada, SIGMASOFT® Germany, University of Tiziouzou (Algeria), University of Carthage (Tunisia), Vrije Universiteit BRUSSEL, Universidad Politecnica de MADRID.

Some national collaborations

LMFA- University Lyon 1, University of Strasbourg, LTN-University of Nantes, University of Haute Alsace (Mulhouse), ENSAM Paris, Plastipolis Competitiveness Cluster, GDR MIC Composite Materials.

Recent industrial partnerships

European Plastics Pole (France), Compose Tools (France), Solvay (Rhodia France), Roctool (France), Plastic Ominum (France), EVE System (France), Influtherm (France), Mecaplast (Monaco), Olesa Iidustrials de Moldes SA (Portugal), Centro Ricerche FIAT (Italy), Repol SL (Spain).

Keywords

Thermal transfers, Materials, Polymers, Composites, Rheology, viscoelasticity, crystallization, transformation processes (injection, thermoforming, pultrusion, rotomolding, sintering, etc.), plastics, thermal instrumentation, thermophysical characterization.

INSAVALOR Training (Advanced R & D Training)

Thermal molds in plastics

Involvement in scientific networks

Members of the AFM, ASME, SF2M (President of the South East Section), PPS