Influence of TESPT content on crosslink types and rheological behaviors of natural rubber compounds reinforced with silica

Abstract

Rheological behaviors in the rheographs and crosslink types of silica-filled natural rubber compounds with differing contents of silane coupling agent were investigated. Bis-(3-(triethoxysilyl)-propyl)-tetrasulfide (TESPT) was used as a silane coupling agent. In the rheographs of the silica-filled compounds containing TESPT, the local minimum torque regions after the maximum torque were observed, and the time to reach the local minimum torque was found to become faster with increase of the TESPT content. The reversion ratio, on the whole, was decreased by increasing the TESPT content. By increasing the TESPT content, the crosslink densities of the mono-, di-, and polysulfides were increased. Ratio of the polysulfides of the total crosslink density increased, while those of the monoand disulfides decreased with increase of the TESPT content. Changes of the crosslink densities after thermal aging were also investigated. The experimental results were explained with the reduction of curatives adsorbed on the silica, increase of sulfur content, and crosslink formation between the silica and rubber by adding TESPT.

Effect of Silanes on Mechanical and Thermal Properties of Silicone Rubber/EPDM Blends

“…It has been reported that composites with silane coupling agent treated silica showed improved crosslink density, thermal stability, and strong reinforcement and toughing effects in these systems. [4][5][6][7][8][9][10] The results could be explained by the fact that the organic functional groups of silica surfaces by silane surface treatments lead to an increase of the adhesion at interfaces between silicas and the polymer matrix. The dynamic mechanical properties of the composites are also much affected by the addition of silanized silica.…”

Water swelling behaviors of silica-reinforced NBR composites in deionized water and salt solution

“…Since silica has a number of hydroxyl groups (silanol, Si-OH) and intermolecular hydrogen bonds between silanol groups on the silica surface are very strong, it can aggregate tightly so that it causes a poor dispersion of silica in a rubber compound and it can absorb water [13][14][15]. In general, silane coupling agent such as bis-(3-(triethoxysilyl)-propyl)-tetrasulfide (TESPT) is used to improve the silica dispersion and to prevent the adsorption of curatives on the silica surface [16][17][18]. Since acrylonitrile of NBR is polar, NBR makes silica dispersion improve [19][20][21][22].…”

Study on the effect of modified and unmodified silica on the properties of natural rubber vulcanizates

“…[4][5][6][7] Silane modified silica promotes vulcanization reaction, rises network density due to the formation of sunfite bonds between rubber and filler surface. [8,9] Thus, the properties of vulcanizate change obviously.…”