Pirelli, Milan researchers showcase 'Janus' rubber chemicals

EDINBURGH, U.K.—While relatively few in the rubber and tire industry will have heard of Janus, the ancient Roman god of pathways, transition and related themes, that could soon be set to change.

At the recent RubberCon 2023, researchers from Pirelli and Politecnico di Milano, presented several studies showing how so-called Janus chemicals can significantly improve the performance of rubber compounds.

These included papers by Federica Magaletti, Gea Prioglio, Maurizio Galimberti, Vincenzina Barbera and Stefania Gallo of the University of Milan's department of chemistry, materials and chemical engineering.

Mythical god Janus, usually depicted with two faces, also was featured prominently in a related conference presentation by Silvia Guerra of Pirelli Tyre S.p.A., "Eco-tyre with low environmental impact."

In her paper, Guerra detailed Pirelli's research showing how a serinol pyrrole [2-(2,5-dimethyl-1H-pyrrol-1-yl)propane-1,3-diol] derived from a bio-based glycerine could reduce the Payne effect and rolling resistance in tires.

A key aspect in these performance gains, she said, was the improved dispersion in rubber compounds achieved by reacting the carbon-allotropes with the pyrrole.

As Galimberti said, Janus molecules such as serinol pyrrole have been found to introduce functionalization to carbon black- and silica-based rubber filler systems.

The cycloaddition reactions with graphitic substrates, he said, involve straightforward mixing and heating, rather than extreme temperatures, pressures or aggressive chemicals.

The Milan researchers also showed how a bio-sourced serinol pyrrole could improve the efficiency of silica-elastomer coupling in rubber compounds—replacing a conventional sulfur-based silane, said to be a significant emitter of CO2.

In a separate poster presentation, the team detailed the use of the Janus molecule to enable the part-substitution of silica with hexagonal boron nitride to improve the processability and physical properties of SSBR compounds.