The prime application of elastomeric composites is tire compounds. The tuning of dynamic rigidity and hysteresis is key to achieve the desired tire performances. Car tires require hysteresis to be high at low temperatures, to promote wet traction, and low at medium-high temperatures, for low energy dissipations. To achieve these properties amorphous precipitated silica is commonly selected as reinforcing filler due to its nano dimensions and the possibility of establishing chemical bonds with the elastomers’ chains. Carbon black (CB), another common filler for tire compounds, does not have functional groups able to promote chemical bonds with the rubber matrix yet it would be highly desirable. A CB with a cradle to gate LCA comparable if not even better than silica’s LCA could be used in replacement of silica in tire compounds. In this work, a pyrrole compound (PyC) containing a thiol group was used to functionalize CB by the so-called “pyrrole methodology” . The thiol group was expected to react with the sulphur-based crosslinking system, thus forming chemical bonds with the rubber chains. The synthesis of the PyC and the functionalization reaction were characterized by high atom efficiency. A poly(styrene-co-butadiene) copolymer from anionic solution polymerization was used as the main rubber for the compound preparation. The crosslinked composite material filled with functionalized CB revealed substantial improvements with respect to the composite with pristine CB, in particular: high rigidity and low hysteresis at high temperature. These findings seem to confirm the formation of the expected rubber-filler chemical bond and are even comparable to those of silica- based rubber composites. The results here reported pave the way to CB-based rubber composites with a low environmental impact.

Functionalized carbon black for elastomer composites with low hysteresis

G. Prioglio;V. Barbera;M. Galimberti
2022-01-01

Abstract

The prime application of elastomeric composites is tire compounds. The tuning of dynamic rigidity and hysteresis is key to achieve the desired tire performances. Car tires require hysteresis to be high at low temperatures, to promote wet traction, and low at medium-high temperatures, for low energy dissipations. To achieve these properties amorphous precipitated silica is commonly selected as reinforcing filler due to its nano dimensions and the possibility of establishing chemical bonds with the elastomers’ chains. Carbon black (CB), another common filler for tire compounds, does not have functional groups able to promote chemical bonds with the rubber matrix yet it would be highly desirable. A CB with a cradle to gate LCA comparable if not even better than silica’s LCA could be used in replacement of silica in tire compounds. In this work, a pyrrole compound (PyC) containing a thiol group was used to functionalize CB by the so-called “pyrrole methodology” . The thiol group was expected to react with the sulphur-based crosslinking system, thus forming chemical bonds with the rubber chains. The synthesis of the PyC and the functionalization reaction were characterized by high atom efficiency. A poly(styrene-co-butadiene) copolymer from anionic solution polymerization was used as the main rubber for the compound preparation. The crosslinked composite material filled with functionalized CB revealed substantial improvements with respect to the composite with pristine CB, in particular: high rigidity and low hysteresis at high temperature. These findings seem to confirm the formation of the expected rubber-filler chemical bond and are even comparable to those of silica- based rubber composites. The results here reported pave the way to CB-based rubber composites with a low environmental impact.
2022
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1234438
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