Interactions, filler-elastomer

As a simplified— but slightly incorrect—picture, it can be considered that trains have a lowered transition temperature (Kaufmann et al., 1971 De Candia et al., 1996). The exact thickness of this layer remains disputed (O Brien et al., 1976 Leisen et al., 1998 Semaan et al., 2001), but values of 1-5 nm are usually considered (Kraus, 1971). Anyway, it is very noticeable that such thickness corresponds at least to 3-15% of total elastomeric phase (Rigbi, 1993). Taking into account carbon black structure/tortuosity, values as high as 30% have been proposed. 

A more accurate approach considers that elastomeric chains present a gradient of mobility coming from carbon black surface to bulk. 

The bonding of carbon black aggregates constitutes the filler network. 

When the extraction temperature increases, the bound rubber decreases and, above about 80°C, samples completely delitate, indicating the disappearance of the continuous networking of carbon black aggregates by elastomer chains. 

Because bound rubber measures elastomer adsorption onto filler surface, it is highly dependent on filler loading, specific surface, and strucfure, which are parameters that can be measured independently (Meissner, 1974). However, at given loading and carbon black surface area and structure, it has been demonstrated that bound rubber is also dependent on carbon black surface energy (Wolff et ah, 1993). 

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Wang, M.-J., Effect of Filler-Elastomer Interaction on Hysteresis, Wet Eriction and Abrasion of EiUed Vulcanizates, Paper presented at a meeting of the Rubber Division, ACS, Akron, May 8-10, 2006. 

After a screening of the different parameters available for the characterization of reinforcing fillers, the nature of filler-elastomer interactions is examined (occluded and bound rubber). 

Effect of Filler-Elastomer Interactions on Vulcanizate Properties.117... 

From the technological standpoint, numerous empirical parameters have been used to characterize the effect of reinforcement. Two of them based on rheometry and filler-elastomer interactions will be discussed the aF parameter17) and the reinforcement factor RF ]8 20). 

By plotting the percentage of carbon particles separated from the vulcanizate versus the stress applied to the sample during extension, Hess et al. determined the stress at which the arbitrary quantity of 20% of the black had been separated from the matrix. This stress was indicated as the adhesion index. It appears (Fig. 12) that blacks of higher structures are associated with an increase of the adhesion index, i.e., with an enhancement of filler-elastomer interactions. 

It appears, beyond all doubt, that filler-elastomer interactions result in the formation of chemical bonds between the polymer and the solid surface, which are due to a reaction of the macromolecule either with the surface chemical groups or with the surface hydrogen atoms. Is, however, the formation of covalent filler elastomer bonds a prerequisite for reinforcement to occur ... 

Another way for increasing filler-elastomer interactions could be the grafting of a polymer on the solid surface. A number of methods exist to secure the attachment of macromolecules to the surface of carbon black particles e.g., a polymeric chain may be grown on an initiation site on the surface, small molecules previously attached to the surface may be copolymerized with a monomer, a polymeric chain, either radical, cationic, or anionic in nature, may be terminated on an active site of the solid surface, etc. 55 63). 

Dannenberg, E. M. Influence of filler-elastomer interactions on reinforcement behavior . In Le renforcement des elastomeres. Paris CNRS 1975, pp. 129-135... 

The reinforcement of rubber composites by CB and/or silica is greatly affected by the rubber filler interactions, the agglomeration of the filler particles within the rubber matrices, and the occlusion of the rubber into the internal voids of the dispersed aggregates. Furthermore, filler-elastomer interactions play a major role in the filler dispersion achievable during mixing process. 

The combination of TEM and AIA techniques makes it possible to obtain quantitative and representative information on the filler distribution in the elastomer matrix (homogeneity of the dispersion, size and shape distribution of the aggregates) and, consequently, on the filler-elastomer interactions. 

Berriot J, Lequeux F, Mmmerie L, Montes H, Long D, Sotta P (2002) Filler-elastomer interaction in model filled rubbers, a IH NMR study. J Non Crystal Solids 307-310 719-724... 

Wolff, S. Wang, J. (1992). Filler— Elastomer Interactions. Part IV. The Effect of the Surface Energies of Fillers on Elastomer Reinforcement. Rubber Chemistry and Technology, 65, 329-342. 

Wang M J and Wolff S (1992) Filler-elastomer interactions, Kaut Gum Kunst 45 11-17. 

M.J. Wang, S. Wolff, J.B. Donnet. Filler-elastomer interactions. Part I silica surface energies and interactions with model compounds. Rubb. Chem. TechnoL, 64, 559-576,1991. 

M.J. Wang. Effect of filler-elastomer interaction on tire tread performance. Part ni. Kautsch. Gummi, Kunstst., 61 (4), 159-165, 2008. 

S. Wolff, M-J. Wang, E-H. Tan. Filler-elastomer interaction. Part VII. Study on bound rubber. Rubb. Chem. Technol, 66,163-177,1993. 

J. Frohlich, W. Niedermeier and H. D. Luginsland, The effect of filler-filler and filler-elastomer interaction on rubber reinforcemen. Composites Part A., 36, 9,449-460 (2005). 

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