Contrat doctoral : OPTIMISATION DE L’IMPREGNATION DE FILS A BASE D’ETOUPES DE CHANVRE DESTINES [...]

Organisation/Company Université de Haute-Alsace Department LPMT Research Field Physics Other Researcher Profile First Stage Researcher (R1) Positions PhD Positions Application Deadline 20 Apr 2026 - 17:00 (Europe/Paris) Country France Type of Contract Temporary Job Status Full-time Hours Per Week 37.5 Offer Starting Date 1 Oct 2026 Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure? No

Offer Description

This PhD project proposes a multiscale approach focused on the study of hemp yarn within the context of ecological transition. Biocomposites reinforced with plant-based fibers represent a credible alternative to synthetic composites (1). Currently, many biocomposites available on the market are reinforced with short fibers, which provide limited mechanical benefits due to their small size, suboptimal orientation, and low volume fraction. In contrast, the use of continuous reinforcements in the form of yarns significantly enhances the mechanical properties of the final materials through improved load transfer and directional control of the reinforcement (2).

The architecture of conventional textile yarns, obtained through twisting, reduces radial permeability and hinders the homogeneous penetration of the matrix into the core of the fiber bundle. A wrapped yarn (guipé yarn), consisting of parallelized fibers around which a binding thread is helically wound, enables alignment of the fibrous core while ensuring its cohesion. This configuration promotes better matrix accessibility and more homogeneous impregnation (3).

The objective of this PhD is to optimize the impregnation of hemp wrapped yarns intended for composite applications by controlling all transformation processes from the fiber to the impregnated yarn. A sensitivity analysis linking process parameters, yarn architecture, and final mechanical performance will be established. The yarns will be produced from slivers derived from scutching and/or combing processes (4), in order to valorize this by-product of the hemp industry for higher value-added applications. A bio-based thermoplastic polymer such as PLA (5) will be used both as a binding component and as the composite matrix, ensuring optimal compatibility and phase continuity during melting.

One of the main scientific challenges lies in understanding and optimizing the properties of the fiber/matrix interface; this aspect will be thoroughly investigated across the different scales considered. The work will be structured into three complementary stages:(i) optimization of the hemp sliver or roving (parallelization, regularity),(ii) development of optimized wrapped yarns and study of the influence of wrapping parameters,(iii) yarn impregnation and composite manufacturing using various processes (thermocompression, additive manufacturing) in order to evaluate mechanical performance.

Characterization will focus on morphological and mechanical properties at the different scales of the sliver, yarn, and composite. Particular attention will be paid to fiber/matrix interfacial performance, notably through nanoindentation testing.

Where to apply

E-mail

Requirements

Research Field Physics Education Level Master Degree or equivalent

Internal Application form(s) needed