Plasma assisted vulcanization-bonding – Plasma-Bond

The project is developing an assembly procedure that respects the environment and health, with the dry preparation of a single adhesive layer using plasma technology. The quality of the deposit and the adhesive bond is controlled using simulation tools, in situ diagnostics of plasma and assembly, in particular through non-destructive testing and evaluation by propagation of acoustic waves. The consortium studies both modification and plasma deposition aspects on different types of substrates chosen for their wide distribution in industrial applications, or for the technological barrier represented by fluoropolymers. The elastomers to be vulcanized are representative of the production of industrial partners, namely “standard” elastomers, silicone or fluorocarbon. The treated surfaces and the interfaces obtained are characterized before assembly and after separation by the usual chemical and morphological surface analysis techniques but also by another more innovative in situ approach thanks to the implementation of non-control. destructive during vulcanization.

The primary, secondary adhesion layers effectively substituted by a single, homogeneous layer derived from plasma technology result in a more reliable and robust assembly. Its mechanisms of growth and adhesion with the elastomer are characterized. This green technology is transferable to industrial partners. The monitoring of vulcanization by propagation of sound waves in the elastomer or at the interfaces makes it possible to consider implementing industrial molds and to ensure the homogeneity of the assembly avoiding destructive mechanical tests.

The use of plasma technologies meets the users demand of elastomers and metals assemblies chemically or thermally resistant. The substitution of manual coating of toxic primary and secondary adhesion layers by a more homogeneous single coat obtained by the dry process allows compliance with the Reach Directive. These criteria, combined with monitoring vulcanization and controlling the robustness of the assembly by propagating sound waves, make it possible to sustainably develop already acquired markets and open up other types of markets. Other materials can benefit from this new process.

The results of the project have been translated by 9 publications, 2 PhD, 17 international or national conferences and one patent is being drafted to consider industrial exploitation for one of the partners.

In many different sectors of industry, final products originate from the assembling of various materials including elastomers, like rubber. The adhesive bonding is in such cases established with adhesion agents, coated onto the substrate, during the vulcanization of the rubber.
The need for high performance has resulted in more complex deposition processes of one or more adhesive layers often run by repetitive manual coatings due to complex geometries. As a consequence of such processes, the number of rejects due to poor mechanical strength induced by an inhomogeneous adhesive bond is increased. As a consequence of the Reach regulation, most of the assembly procedures become obsolete. Indeed, the primary or secondary adhesive layers are aqueous or organic liquid phases containing highly toxic products. Plasma-Bond project is developing a more eco-friendly assembly process, focusing on the preparation of unique bonding layer obtained by plasma technology, as a substitution of the current solution chemistry and coating procedures. The quality of the deposition and the adhesive bond is controlled thanks to the tools of simulation, in situ diagnostics of the plasma and the assembly thanks in particular to the non-destructive control and evaluation by propagation of acoustic waves. The consortium proposes to study both aspects of modification and plasma deposition on different types of substrates chosen for their wide diffusion in industrial applications or for the technological lock that it represents as PTFE. The elastomers to be vulcanized are also representative of the production of industrial partners, ie, "standard", silicone or fluorocarbon elastomers. Treated surfaces and the obtained interfaces will be characterized before the assembly and after the separation by the usual analysis techniques (XPS, TOF-SIMS, surface energy, FTIR, MEB, AFM ...) but also by another more innovative approach through the establishment of nondestructive testing during vulcanization.