Vibration-assisted 2D printing of thermoplastic particle suspensions – Improvibrations

In this project, our goal is to develop a process for the 2D printing of composite materials with optimal optical, electrical or mechanical properties. In order to have a good spatial resolution of the patterns as well as good mechanical properties, it is necessary to use yield stress fluids in these processes. In this study, we propose in an original way to use highly concentrated suspensions prepared in their solid phase, beyond their critical packing fraction, and to fluidify them transiently during the printing phase by using mechanical and / or ultrasonic vibrations.
The films will be obtained by 2D printing of suspensions of fillers and polymer particles in a green solvent or of fillers in a polymerizable solvent. A complete study of the behavior and of the mechanisms involved will be carried out. This will include understanding the role of vibrations: opening of contacts, variation of the microscopic coefficient of friction, erosion of particles, other mechanisms. In addition, the material homogeneity throughout the process will have to be controlled
To do this, we will rely on cutting-edge experiments: concentration profiles using X-ray imaging, measurement of the friction coefficient at the particle scale under ultrasonic vibration. A vibrating printing device will be set up, with an initial printing resolution of the structures of 500 µm. The specifications for the process will be proposed. Functionally gradient materials will be printed and tested in a high throughput approach. The impact of the process will be assessed by measuring the electrical and mechanical properties of a polymer composite with carbon black particles. To carry out this project, we have brought together two laboratories, LOF (Bordeaux) and CBI (Paris ESPCI PSL), which are used to working together and whose expertise is complimentary. Funding for two PhD and a 1-year post-doctoral internship are requested from the ANR. The project led by Guillaume Ovarlez will last 54 months.