Phase Selective Localization of Filler in Ternary Rubber Blends

Abstract

The present work introduces a new concept based on the analysis of the rubber–filler gel for the determination of the phase selective filler localization in ternary rubber blends. Natural rubber (NR)/styrene–butadiene rubber (SBR)/ethylene–propylene rubber (EPDM) blends filled with silica were the focus of the experimental investigations. Because of the higher wetting rate of the NR component to silica, in the first stage of the preparation of SBR/NR/EPDM blends, more silica is found in the NR phase than in the SBR and EPDM phase. In the subsequent stage, silica is transferred from the NR phase to the SBR phase until the loosely bound NR-layer at the silica surface is fully replaced by SBR molecules. An extremely low amount of silica was found in the EPDM phase because of the poor EPDM–silica interaction. After a long mixing time, a large amount of silica whose surface was not yet wetted by any rubber phase could be found in the composites that can lead to fatal effects on the mechanical performance of the composites.

Silica Transfer in Ternary Rubber Blends: Calculation and Experimental Determination

“…In this period, silica gradually migrates from the NR to SBR phase. The transfer of silica from the NR to SBR phase was also observed in our previous works for binary SBR/NR blends36, 37 and ternary SBR/NR/EPDM blends 38. After 20 min blending the equilibrium values of filler loading in SBR and NR phase are still not reached.…”

“…It is obvious that the phase selective filler localization could not be characterized in both images. That is the main reason for developing indirect methods for the quantification of filler localization in highly filled binary blends19–25, 35–37 and ternary blends 38…”

“…In our previous works35–37 a new method, the so‐called wetting concept , was proposed for the experimental determination of the phase selective distribution of CB and silica in binary rubber blends 36,. This concept was extended for ternary blends SBR/NR/EPDM and it became possible to characterize the free filler fraction and the fraction of filler in separate blend phases as a function of mixing time 38. In most of the works mentioned above the preferred localization of the filler is actually governed by thermodynamics apart from the rheological effects.…”

Maleated glycidyl 3-pentadecenyl phenyl ether with styrene: synthesis and application as compatibilizer in SBR/silica composite

“…When filler is mixed with a single rubber, a part of the rubber chains will be bonded to the active center which is available on the filler surface. If the rubber is extracted from the uncured filled rubber compound with a suitable solvent, the rubber chains bound on the filler surface remain in the rubber–filler gel . Since interaction of functional groups in MGS would form crossing structure, the BRC of SBR‐g‐MGS was investigated, and the real BRC of compound with MGS is obtained after substrate SBR‐g‐MGS's.…”

“…As literature reported higher molecular weight is beneficial to increase entanglement between two phases . Meanwhile, adding styrene (St) to copolymerization system as a comonomer could significantly enhance MAH graft degree . Thus, in the present work, copolymer of GPPE, MAH and St was synthesized and applied as a compatibilizer for SBR/silica composites.…”