Moisture effects on improved hydrolysis reaction for TESPT and TESPD-silica compounds

Abstract

The moisture(55 wt%)-treated silica compounds, bis(triethoxysilylpropyl)disulfide (TESPD)/silica/carbon black (CB)/SBR and bis(triethoxysilylpropyl)tetrasulfide (TESPT)/silica/CB/ SBR, have been processed in a batch mixer and they are investigated with respect to the alcohol residue level in silane, the processability, the vulcanization characteristics, and the mechanical properties.The alcohol level is low at the moisture treated compounds. The TESPD compounds show lower alcohol level than the TESPT ones on moisture treated and untreated compounds. The probe temperatures of the moisture treated compounds are lower than the drop temperature, while those of the untreated compounds are higher than the drop ones, respectively. The vulcanization properties of the compounds are changed by the moisture treatment and this improves the physical properties of the compounds.The moisture treatment on silica surface increases the hydrolysis reaction of the alkoxy silane and the hydrolyzed silane improved the coupling reaction with the hydroxyl group on silica surface during reactive batch processing. It also reduces the rate of temperature rise during batch mixing due to the latent heat of the moisture and the endothermic reaction between silica and silane. At the vulcanization stage, it seems to further increase the coupling reaction between silica and silane.The steric hindrance theory of an alkoxy silane (TESPT) has to be reconsidered with a large amount of moisture treated silica/TESPD/CB/S-SBR compound system.

Effects of Accelerators on the Vulcanization Properties of Silica vs. Carbon Black Filled Natural Rubber Compounds

“…And then they formed a 3-dimensional network structure between silica and rubber chain. 14,21,[35][36][37]60 Overall, comparing the silica/NR and the CB/NR compounds with various accelerators, the t s2 , t 10 , and t 90 values of the silica filled compounds showed longer than those of the CB filled ones, respectively. This was due to polar characteristic of silica surface 53 and water molecules in the compound.…”

“…5 After Thurn et al 11 first discovered the use of silica in combination with bis(3-triethoxysilylpropyl) tetrasulfane (TESPT) and natural rubber (NR), Rauline patented this for practical 'green tire' application in 1992. 12 Since then, considerable efforts have been made on studies of silica-silane reinforcement in rubber compounds, 13 silica dispersion, [14][15][16][17][18] silica-silane reaction, 14,15,[19][20][21][22][23][24][25][26][27] silane-rubber reaction, 28-30 zinc ion-, 25,31-34 moisture-, 35,36 temperature-, 37 and accelerator effects on vulcanization properties, 38,39 effects of processing geometry, 18 and effects of polymer blends. 26,27,40,41 † To whom correspondence should be addressed.…”

Interfacial Adhesion in Silica-Silane Filled NR Composites: A Short Review

“…Thurn et al [12] first discovered the use of silica in combination with bis(3-triethoxysilylpropyl) tetrasulfane (TESPT) and NR, and this was patented for practical 'green tire' application in 1992 [13]. Since then, considerable efforts have been made on studies of silica-silane reinforcement in rubber compounds [14], silica dispersion [15][16][17][18][19], silica-silane reaction [15,16,[20][21][22][23][24][25][26][27][28], silane-rubber reaction [29][30][31], zinc ion- [26,[32][33][34][35], moisture- [36,37], temperature- [38], and accelerator effects on vulcanization properties [39,40], effects of processing geometry [19], and effects of polymer blends [27,28,41,42].…”

Effect of Different Silane Coupling Agents In-Situ Modified Sepiolite on the Structure and Properties of Natural Rubber Composites Prepared by Latex Compounding Method

“…In this study, we selected three silane coupling agents with different functional groups (see Table 1 ) to modify sepiolite. Our modification mechanism [ 38 , 39 , 40 ] involved the hydrolysis of Si–O–C 2 H 5 in the silane coupling agent and the subsequent condensation of hydroxyl groups on the surface of sepiolite, with C=C in VTES, -HS- in MPTES, and –S 4 – in TESPT all able to participate in the vulcanization process of natural rubber and form strong chemical bonds. Hydrolysis of silane coupling agents is known to be slow, often requiring the addition of acid to promote hydrolysis [ 41 , 42 ] and improve the efficiency of hydroxyl condensation with the inorganic filler surface.…”