Wolff Siegfried

Bio: Wolff Siegfried is an academic researcher from Durham University. The author has contributed to research in topics: Natural rubber & Vulcanization. The author has an hindex of 17, co-authored 53 publications receiving 1599 citations.

Chemical aspects of rubber reinforcement by fillers

Abstract: For decades, the rubber industry, and the tire industry in particular, have been using mainly carbon blacks as reinforcing fillers. Since their structure and specific surface area can be varied over a wide range, carbon blacks are capable of meeting a wide range of different requirements. Even today, we are unable to exert a specific influence on the third component of reinforcement, the “surface activity” (surface energy) of carbon blacks. This problem and new, more stringent tire performance requirements lend new significance to the need for further carbon black research and development. Silicas, which were developed during the nineteen forties and fifties, were mainly used in shoe soling materials. Specific surface area and structure of the silicas were constantly adjusted to meet new requirements in this area. As our knowledge of the reinforcing mechanism of silicas in rubber increased, the benefits and drawbacks of silicas in rubber, in comparison to carbon blacks, became more and more appar...

Filler-Elastomer Interactions. Part VII. Study on Bound Rubber

Abstract: SBR compounds were filled with 17 carbon blacks covering the whole range of rubber grades and tested for bound-rubber content. It was found that the bound-rubber content of a polymer at hi...

Filler—Elastomer Interactions. Part IV. The Effect of the Surface Energies of Fillers on Elastomer Reinforcement

Abstract: Carbon black N110 and a precipitated silica, which have comparable surface area and structure, were selected as model fillers to study the effect of filler surface energies on rubber reinf...

Filler—Elastomer Interactions. Part III. Carbon-Black-Surface Energies and Interactions with Elastomer Analogs

Abstract: The surface energies, both the dispersive component, γsd, and the specific component, γssp, of dry- and wet-pelletized carbon blacks, ranging from N110 to N990, were evaluated by inverse gas-solid chromatography at infinite dilution. The results indicate that the dispersive components of the surface energy of carbon blacks increase with increasing surface area. This dependence may essentially reflect an effect of microstructure on the surface energies, which can be confirmed by the relationship between the crystallographic parameters of crystallites and the graphitization of the carbon blacks. It was found that smaller crystallites characterized by a lower value of Lc lead to higher surface energy, whereas graphitization of the carbon black points toward lower surface energy, perhaps resulting from the growth of the quasi-graphite structure. Surface area dependence of the specific component of the surface energy characterized by the specific energy of adsorption of a polar probe follows the same ...

Filler-Elastomer Interactions. Part VIII. The Role of the Distance between Filler Aggregates in the Dynamic Properties of Filled Vulcanizates

Abstract: Based on the concepts of the occlusion of rubber and random packing of spheres whose volume is equivalent to that permeated by individual aggregates, an equation was deduced to estimate the distance between carbon-black aggregates in filled rubber. It was found that when the interaggregate distance reaches a critical point which is approximately identical for all carbon blacks investigated (furnace blacks), the elastic modulus measured at very low strain deviates from the modified Guth-Gold equation. Tan δ and resilience are mainly determined by the distance between aggregates. These phenomena are related to filler networking which is determined by the attractive potential and the distance between individual aggregates. Since the factor Sf, used to characterize the strength of secondary filler networks in hydrocarbon rubbers and measured by means of inverse gas chromatography, is approximately the same for all furnace blacks, the interaggregate distance seems to determine filler networking. A com...

The effect of filler–filler and filler–elastomer interaction on rubber reinforcement

Abstract: The role of active fillers like carbon black and silica has been studied in the rubber matrix for a better understanding of the rubber performance and the mechanism of reinforcement. In particular the influence of basic properties of carbon blacks, such as specific surface area, structure and surface activity on the Payne-effect, was investigated with the Rubber-Process-Analyzer (RPA) which allows a testing of the strength of the filler network and the filler-polymer interaction in the green compound as well as in the vulcanizate in a wide range of shear amplitudes. A comparison between carbon black and the silica-silane system leads to further scientific findings for the understanding of the dynamic behavior of filled rubber compounds.

Reinforcement of Elastomers

Abstract: The review describes recent research about reinforcement in elastomers where the main intention is to gain insight into the relationship between disordered filler structure on different length scales and reinforcement and to microscopic mechanisms of strain enhancement. Several theoretical concepts will be discussed together with very recent experimental findings related to hydrodynamic reinforcement, rigid filler aggregates with fractal structure and polymer adsorption on heterogeneous filler surfaces. Based on the new concepts, we present several recent efforts to understand typical effects in filled rubbers that have an extraordinary practical importance (for example, stress softening of carbon black filled rubbers during repeated large strain stretching and during small strain dynamic excitations).

Silica reinforced rubber composition and use in tires

Abstract: The invention relates to the preparation of a composite of an elastomer composition containing silica-based reinforcement created by a controlled alkoxysilane condensation reaction within the elastomer matrix. The invention also relates to such composite and to a tire having at least one component of such composite.