Valorization of rubber waste nano-powders in polypropylene (nTPU-PP) for the development of flexible and recyclable 3D-Printing Filaments

Created on January 1, 2011, the LSPM (UPR3407) is a CNRS unit located on the Villetaneuse campus of the University Sorbonne Paris-Nord (USPN), within the Galileo Institute. The unit, composed of researchers and teacher-researchers in process engineering, mechanics, physics and chemistry, has the general objective to develop research in the fields of processes and materials. This research aims to respond to major societal challenges such as energy, transportation and nanotechnology.

Context and Objectives

Recycling rubber waste—mainly originating from end-of-life tires—has become a major environmental and industrial challenge, as they are flammable, non-biodegradable and may encompass traces of toxins. A promising strategy consists in reintegrating micron- or nanometer-sized rubber powders into thermoplastic matrices such as polypropylene (PP) to develop new flexible composites with reduced environmental impact. Therefore, it is of interest to explore the interaction of Ground Tire Rubber in a thermoplastic matrix for compatibility. [1-3].

The objective of this Master’s research project is to investigate different formulations of PP combined with rubber waste powders in order to produce composite materials suitable for additive manufacturing by extrusion (FFF).

These new materials will be evaluated for flexible structural applications, adhesion of the 2 compounds for compatibility with a particular focus on the design of soft or bendable pipelines, which can easily be manufactured using conventional processes.

A key aspect of the project is the production of 3D-printing filaments from the developed composites and the assessment of their potential for closed-loop recycling, fully aligned with a circular life-cycle approach.

Work Program

The project will begin with a review of recent advances on PP/rubber composites, including compatibilization strategies and structure–property relationships. Composite formulations will be prepared using compounding instruments to optimize particle loading, dispersion, and interfacial adhesion. The produced composites will then be extruded into 3D-printing filaments, enabling the fabrication of complex geometries such as curved pipelines and flexible structures.

A comprehensive experimental campaign will be conducted, including:

• Rheological analyses: Flow behavior, viscosity curves, melt properties, and processability to evaluate printability, material and filament stability.
• Mechanical testing: Tensile, flexural, impact resistance, and flexibility assessments on extruded and printed samples.
• Thermal analyses: Differential Scanning Calorimetry (DSC), Thermal conductivity Analysis (TGA), and crystallinity evaluation to understand thermal stability and polymer phase evolution.
• Microstructural characterization: Particle dispersion, morphology, and interface quality (SEM or optical methods).
• Manufacturing processes: Exploring manufacturing through Compounding, Injection moulding, and Compression molding.
• Composite preparation: Produce pellets, explore the mixing criteria for structural output and compatibility (barrel temperature, mixing time, screw speed, pressure gradient)
• Composite formulation: Testing with various composition in mass/vol% of PP/Rubber mixture for eg. 90/10, 75/25, 60/40.

A recyclability study will be carried out using repeated cycles of grinding → re-compounding → re-printing to determine performance (mechanical properties) degradation and feasibility of a circular life cycle. Finally, micromechanical homogenization models (Mori–Tanaka, self-consistent, Eshelby) will be employed to predict the effective properties of the composites based on rubber-powder content.

Duration: 4–6 months
(2 months at the Haßfurt Technology Transfer Centre, Würzburg-Schweinfurt University of Applied Sciences, and 2–4 months at LSPM)

Location:

The candidate will carry out the internship between the LSPM laboratory in France (2–4 months) and Würzburg-Schweinfurt University of Applied Sciences (THWS) in Germany (2 months), through an Erasmus+ mobility for traineeship.

Supervision at LSPM:

• Salma Barboura (Associate Professor, LSPM)
• Azziz Hocini (CNRS Research Engineer)

Supervision at TTZ-HAS THWS:

• Prof. Dr.-Ing. Johannes Krückel
• Mahin Rahman (Scientific Researcher)

The candidate should have:

A solid background in materials science, ideally in polymer/composite chemistry, with additional skills in solid mechanics and physics (including thermal).

Strong interest in experimental work and in mechanical, chemical, and physical characterization of solid materials.

Knowledge of polymer extrusion and 3D printing (a strong plus).

Good organizational skills, autonomy, and strong abilities in analysis and synthesis.

Good command of English for discussions with project partners.