Effects of Silanol Group on the Hybridization of Rubber and Silica.

et al. 2002

Polym J

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ABSTRACT:The effects of surface chemistry of silica particles on the mechanical properties were studied for silica filled styrene-butadiene rubber (SBR) systems. The samples were prepared from different kinds of silicas and of silane coupling agents. The breakdown of the agglomerate formed by silica particles was successfully detected by transmission electron microscopy (TEM) observations when the strain was applied to silica filled vulcanizates. The degree of breakdown of the agglomerate of silica particles by the strain was more prominent in the larger one of which size was controlled by the number of silanol group per unit surface area of silica particles. The amount of entrapped rubber within the agglomerate seemed to be decreased with the decrease in the agglomerate size. Also, the initial agglomerate size and the change of agglomerate by the strain became small by the introduction of silane coupling agent, such as bis(3-triethoxysilylpropyl)tetrasulfane (TESPT). At a given degree of vulcanization, the initial modulus of silica filled vulcanizates was governed by the size of agglomerate formed by silica particles and the amount of entrapped rubber phase. On the other hand, at a larger strain, the tensile strength of the filled vulcanizates increased by the introduction of interfacial combination between silica particles and rubber matrix by TESPT. These results indicate that the stress-strain behavior of filled vulcanizate is affected by the agglomerate of the fillers and the interactions between filler and rubber matrix.KEY WORDS Silica / Styrene-Butadiene Rubber / Silane Coupling Agent / Transmission Electron Microscopy (TEM) / Agglomerate / Mechanical Properties / Silicas have been used as fillers for rubber reinforcement. 1-3 However, the utilization of silica caused two serious problems. One was a bad processability, such as a lower dispersiblity of silica particles in rubber matrix and a high viscosity of silica filled unvulcanizates. [2][3][4][5][6][7][8] The other one was a poor reinforcement, such as a low tensile strength, low abrasion resistance and so on, in comparison with carbon black filled rubber composites. [1][2][3][4][5][6][7][8] The chemical environment of silica particle is quite different from that of carbon black due to the existence of silanol groups in the particles. Thus, the primary discussion on the properties of silica filled rubber composites has been concerned with the interactions between silica particles and the interactions between silica particles and rubber molecules. Wolff and Wang studied the effects of surface energies of fillers on rubber reinforcement, and reported 7 that the surface energies of silica were characterized by a dispersive and specific components. The higher specific component led to the higher viscosity of the rubber composites due to the strong interactions among silica particles. On the other hand, the lower dispersive component caused weak filler-rubber interactions, leading to the lower † To whom correspondence should be addressed. content of bound...

Section: Structural Change Of Agglomerate By a Strain In Silica Fillesupporting

confidence: 93%

Section: Effects Of Interfacial Combination Of Fillers With Rubber Mamentioning

confidence: 99%

Section: Structural Change Of Agglomerate By a Strain In Silica Fillementioning

confidence: 99%

mentioning

confidence: 99%

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Effects of Surface Chemistry of Silica Particles on the Mechanical Properties of Silica Filled Styrene–Butadiene Rubber Systems

Yatsuyanagi

et al. 2002

Polym J

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“…Silica filled vulcanizates also showed three T 2 Јs at 30°C, T 2L , T 2M and T 2S . Although the origin of T 2S has been discussed in some literatures [28][29][30] , the details are still uncertain. We reported that the content of filler-gel in silica filled vulcanizates prepared by mechanical mixing was very small 31,32) .…”

Section: Nmr Resultsmentioning

confidence: 99%

Chain Scissions of Rubber Molecules by a Tensile Force in Filled Rubber Systems

2005

e-J. Soft Mater.

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Effects of interfacial interactions between rubber matrix and filler surface on the structural changes of rubber matrix upon a tensile deformation of filled styrene-butadiene rubber (SBR) vulcanizates were studied by ESR and pulsed NMR. The interfacial interactions were controlled by using several kinds of surface modified silicas and carbon blacks. For silica filled systems, the degree of chain scission during tensile deformation of the samples could be evaluated from ESR results. Information on the structural changes of rubber matrix upon a tensile deformation for both carbon black filled and silica filled SBR vulcanizates could be obtained from the results of pulsed NMR. The combination of ESR and NMR results revealed that the degree of chain scission was dependent on the strength of interfacial bondings between filler and rubber molecules and the chain scissions are suggested to occur in the interfacial regions between rubber molecules and fillers.

Effects of surface chemistry of silica particles on secondary structure and tensile properties of silica‐filled rubber systems

Yatsuyanagi

J of Applied Polymer Sci

et al. 2002

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Silica particles were treated by silane coupling agents to study the effects of surface chemistry of silica particles on the secondary structure formed by silica particles in styrene-butadiene rubber (SBR). The relation between the size of secondary structure and tensile properties of silica-filled SBR vulcanizates was also investigated. The water molecules adsorbed on the silica surface enhanced both the reactivity of the coupling agents with silanol groups on the silica surface and the condensation reaction between coupling agents. The averaged size of one agglomerate in the filled vulcanizate (S agg ) decreased with the increase of the hydrophobic character of silica particles, which were obtained by the introduction of coupling agents with alkyl groups. The initial slope of stress-strain curves for silicafilled vulcanizates decreased with the decrease of S agg . Further, a clear Payne effect was observed in all silica-filled vulcanizates, with this tendency more prominent in the larger S agg .