NITROGEN-CONTAINING SILANE COUPLING AGENTS: SYNTHESIS AND STRUCTURE EFFECT ON TIRE PERFORMANCE OF SILICA/SSBR/BR COMPOSITES
We report synthesis of nitrogen-containing silane coupling agents (N-SCAs) and their use in a 1:1 mixture by weight with bis(triethoxysilylpropyl)tetrasulfide in preparation of silica/solution SBR (SSBR)/BR composites. These N-SCAs contain in their structures, inter alia, a tertiary amine center (N1, N2), a carbamate (N3), or a urea (N4) group. In addition, N1, N3, and N4 were equipped with allyl side arms to increase the hydrophobization effect of silica particle as well as to achieve a balance between the filler–filler and filler–matrix networks being formed. By contrast, N2 consists of glycidyl side arms that contribute to the filler–filler interaction even more. The silica/SSBR/BR blends and subsequent vulcanizates were prepared and then thoroughly investigated via dynamic mechanical analysis, rubber process analysis, and tensile testing. The composite based on N1 (V/N1) exhibited exceptionally great tensile strength, abrasion resistance, and winter traction, accompanied by soft hysteresis. Therefore, N1 has potential applications in preparation of winter tire tread materials.ABSTRACT

Synthesis of the N-SCAs. [Pt] = PtO2.

GC analysis results confirming thermal stability of N3 and N4.

Vulcanization characteristics at 170 °C (dependence of torque on time).

RPA measurements of G′ of the vulcanizates vs strain.

Payne effect of the raw compounds. G′x = G′ measured at x% of strain.

Temperature dependence of tan δ of the vulcanizates. From −50 to −5 °C: frequency = 10 Hz, dynamic strain = 0.1%, and static strain = 2.0%. From −5 to +65 °C: frequency = 10 Hz, dynamic strain = 2%, and static strain = 4%.

ATR-FTIR spectra of N1 (a, black curve), initial reaction mixture before heating (b, green curve), and vitrified reaction mixture after the heating (c, red curve).

Proposed reaction pathways of N1 in the rubber blend during vulcanization. (a) Anionic activation of a sulfur molecule with creation of an N1-Sx adduct. (b) Reaction of N1-Sx with a rubber macromolecule. (c) Reaction of N1-Sx with another N1 species. Pol = rubber polymer chain.

Relative tire performance of V/N-SCAs in reference to V/TESPT as 100%. Higher values are more desirable.
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