OPTIMIZATION OF MIXING CONDITIONS FOR SILICA-REINFORCED NATURAL RUBBER TIRE TREAD COMPOUNDS

Abstract The dump temperature and mixing interval between rubber, silica, and silane coupling agent for silica-filled natural rubber (NR) tire tread compounds using bis-triethoxysilylpropyl tetrasulfide (TESPT) as silane were optimized. The dump temperature turns out to be the key parameter governing the properties of the silica-filled NR compounds. The increase in viscosity of the compounds by changing the dump temperature from 100 to 150 °C indicates that inevitably some cross-linking of NR occurs by sulfur contained in TESPT, simultaneous with the silanization reaction between silica and silane. However, the viscosity decreases again when dump temperatures above 150 °C are applied, indicating a dominant occurrence of degradation of the NR molecules. The results are in good agreement with bound rubber contents. The overall properties indicate that a dump temperature in the range of 135–150 °C and a silica–silane–rubber mixing interval of 10 min are the most appropriate mixing conditions for silica-filled NR compounds with TESPT as coupling agent.

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MORPHOLOGY OF SILICA-REINFORCED NATURAL RUBBER: THE EFFECT OF SILANE COUPLING AGENT

Rubber Chemistry and Technology ◽

10.5254/rct.15.86936 ◽

2015 ◽

Vol 88 (3) ◽

pp. 359-372 ◽

Cited By ~ 17

Author(s):

S. Salina Sarkawi ◽

Wilma K. Dierkes ◽

Jacques W. M. Noordermeer

Keyword(s):

Natural Rubber ◽

Coupling Agent ◽

Silane Coupling Agent ◽

Phase Imaging ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Bound Rubber ◽

Silane Coupling ◽

Deproteinized Natural Rubber

ABSTRACT A good dispersion of silica in a rubber vulcanizate is important as it influences the filler-to-rubber interaction and consequently the final properties. This article presents an investigation into the morphology of silica-reinforced natural rubber (NR) in the presence and absence of a silane coupling agent, bis(triethoxysilylpropyl) tetrasulfide (TESPT). Micro- and nano-dispersion morphologies of silica in NR and deproteinized natural rubber (DPNR) are studied by using atomic force microscopy (AFM). Using a special network visualization technique based on transmission electron microscopy (TEM), insight into the silica and rubber interaction in the NR and DPNR is gained. In the absence of silane, vacuoles around the silica particles are formed as a result of a weak filler–polymer interaction, whereas the presence of silane leads to strong filler-to-rubber bonding, which prevents formation of vacuoles. Improvement of the micro-dispersion of silica in the NR and DPNR vulcanizates with the use of TESPT is observed from AFM phase imaging. The correlation between the filler-to-rubber interaction as analyzed by TEM and AFM and bound rubber contents as well as the Payne effect is discussed.

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Optimization of Epoxidation Degree and Silane Coupling Agent Content for Silica-Filled Epoxidized Natural Rubber Tire Tread Compounds

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.844.243 ◽

2013 ◽

Vol 844 ◽

pp. 243-246 ◽

Cited By ~ 1

Author(s):

Wisut Kaewsakul ◽

Kannika Sahakaro ◽

Wilma Dierkes ◽

Jacques W.M. Noordermeer

Keyword(s):

Natural Rubber ◽

Coupling Agent ◽

Silane Coupling Agent ◽

Silica Content ◽

Epoxidized Natural Rubber ◽

Rubber Tire ◽

Rubber Compounds ◽

Silane Coupling ◽

Reinforcement Efficiency

Parallel studies on the influence of epoxide contents in epoxidized natural rubbers (ENRs) in the absence of bis-(triethoxysilylpropyl) tetrasulfide (TESPT) coupling agent, as well as a combination of ENRs with different loadings of TESPT on the properties of ENR compounds, are carried out in this work. The results suggests that the best possible combination to optimize processibility and to improve reinforcement efficiency is to utilize ENR with an epoxide content in the range of 20 30 mol%, together with 2 4 wt% relative to the silica content of TESPT. This leads to a reduction of TESPT when compared to the conventional natural rubber compounds.

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REINFORCEMENT OF NATURAL RUBBER BY PRECIPITATED SILICA: THE INFLUENCE OF PROCESSING TEMPERATURE

Rubber Chemistry and Technology ◽

10.5254/rct.13.87925 ◽

2014 ◽

Vol 87 (1) ◽

pp. 103-119 ◽

Cited By ~ 3

Author(s):

S. Salina Sarkawi ◽

Wilma K. Dierkes ◽

Jacques W. M. Noordermeer

Keyword(s):

Natural Rubber ◽

Coupling Agent ◽

Thermal History ◽

Silane Coupling Agent ◽

The Other ◽

Processing Temperature ◽

Precipitated Silica ◽

Bound Rubber ◽

Silane Coupling ◽

Deproteinized Natural Rubber

ABSTRACT The thermal history, and in particular the mixing dump temperature, is a parameter of paramount importance in mixing rubber and silica with a silane coupling agent in order to achieve proper silanization of silica and to avoid premature scorch reactions. The influence of the mixing dump temperature on the performance of silica-reinforced natural rubber (NR) is investigated. The investigation also includes the effect of nonrubber constituents, primarily proteins in NR, by using deproteinized natural rubber (DPNR) and synthetic polyisoprene (IR). The vulcanization properties and rubber-to-filler interactions of silica-reinforced NR in the presence and absence of a silane coupling agent are highlighted. With increasing mixing dump temperature, the silanization reaction between silica and silane coupling agent proceeds further. At a sufficiently high dump temperature, filler–filler interactions in the NR–silica compounds are reduced and the silica–rubber interaction improved, as evidenced by a drop in the Payne effect and increment in chemically bound rubber. It is demonstrated that NR and IR compounds mixed until they are above the optimum dump temperature exhibit cure reversion and reduction in tensile properties. On the other hand, DPNR–silica vulcanizates show slightly more constant physical properties.

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Effect of Surface Oxidation of Carbon Black on Its Bonding with Epoxidized Natural Rubber in the Presence of Silane Coupling Agent

Rubber Chemistry and Technology ◽

10.5254/1.3538810 ◽

1999 ◽

Vol 72 (2) ◽

pp. 398-409 ◽

Cited By ~ 7

Author(s):

Ajay K. Manna ◽

P. P. De ◽

D. K. Tripathy ◽

S. K. De ◽

M. K. Chatterjee

Keyword(s):

Carbon Black ◽

Natural Rubber ◽

Coupling Agent ◽

Silane Coupling Agent ◽

Surface Oxidation ◽

Spectroscopic Studies ◽

Epoxidized Natural Rubber ◽

Silyl Ether ◽

Silane Coupling ◽

Swelling Studies

Abstract Results of bound rubber determination, Monsanto rheometry, solvent swelling studies and measurement of physical properties reveal that high temperature molding of epoxidized natural rubber (ENR) filled with intermediate super abrasion furnace (ISAF) carbon black and surface oxidized ISAF carbon black, in the presence of silane coupling agent, namely, N-(4-vinylbenzyl)-N′-[3-(trimethoxysilyl)propyl]ethane-1,2-diamine monoHCl salt, results in crosslinking of the rubber phase, even in the absence of the vulcanizing agents. Infrared spectroscopic studies show formation of silyl ether, in the case of ISAF carbon black, whereas the oxidized grade forms both silyl ether as well as silyl ester and amide linkage. Oxidation of ISAF carbon black causes an increase in the extent of coupling bond formation.

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