Understanding polymer dissolution: the impact of hydrodynamics at different scales

In the context of reducing the environmental impact in polymer manufacturing, the use of recycled plastics will rise. Mechanical recycling is simple and economic, but faces limitations in product quality and appearance. Solvent-based recycling, also known as deformulation, has the potential of delivering higher quality products for a wide range of polymers. In this process, the dissolution operation consists in the dispersion and homogenization of two miscible fluids, the solvent, and the molten polymer, which present strong differences in viscosity and density. While substantial effort is invested in characterizing the chemistry and interactions in polymer/solvent systems, the aim of this Ph.D. thesis is to study the influence of the hydrodynamics on the transport phenomena during the dissolution to propose an optimized design of the industrial operations. Given the severe conditions at which dissolution is operated (high T and P), it is complex to directly investigate a real system. Therefore, the PhD candidate will first characterize the polymer/solvent system (rheology, kinetics, limiting phenomena) and then propose and validate one or more model fluids which will be used to carry out experiments at room temperature. First the dispersion of the molten polymer due to the hydrodynamic stresses will be addressed. Then the dissolution phenomena will be investigated using a water-soluble viscous solution. The system will be studied using non-invasive techniques such as the PIV for the flow field, ERT for mass transfer and granulometry to investigate the polymer droplets size distribution. The candidate will use the experimental data to understand the important fluid dynamic criteria and propose empirical correlation for the up-scaling of the industrial equipment. The research will take place both in Lyon and Bologna in an international environment. Periodical report of its activities will be required as well as the redaction of the final manuscript of the research activity. The candidate will divulge its findings at international conferences as well as in peer-reviewed articles for scientific journals.

Keywords: Plastic Recycling, Dissolution, Fluid Dynamics

• Academic supervisors    Prof. Giuseppina MONTANTE, Università di Bologna, ORCID: 0000-0001-5075-8010 & Prof. Federico ALBERINI, Università di Bologna, ORCID: 0000-0001-8479-6330
• Doctoral School    Università di Bologna
• IFPEN supervisors    Dr Enrico AGOSTINI, ORCID: 0000-0003-0687-4414 & Dr. HDR Frédéric Augier
• PhD location    IFPEN, Lyon, France & Università di Bologna, Bologna, Italy   
• Duration and start date    3 years, starting in the fourth quarter 2024 (Novembre 4)
• Employer    IFPEN
• Academic requirements    Master’s degree in Chemical Engineering, Industrial Chemistry, Fluid Mechanics   
• Language requirements    English level B2 (CEFR, IELTS, TOEFL)
• Other requirements    Interest for research, flexibility, communication, problem solving, motivation

To apply, please send your cover letter and CV to the IFPEN supervisor indicated below.