Reinforcement Mechanisms in Carbon Black and Silica Loaded Rubber Melts at Low Stresses

Abstract

For a range of different fillers, silicas and carbon blacks, added to a rubber melt at various concentrations, dynamic moduli in the linear viscoelastic limit have been determined. It is shown that reinforcement is due to hydrodynamic effects and the formation of a secondary particulate structure within the rubber matrix. Both mechanisms can be distinguished experimentally by a frequency sweep. Hydrodynamic reinforcement depends on the filler volume to which immobilized polymer must be added. Its concentration dependence is well described by the semiempirical exponential Thomas Equation. Nominal and effective filler loadings are related by concentration-independent effectiveness factors which can be modelled for all types of fillers considering an immobilized layer of constant height around an agglomerated cluster of filler particles. This provides an explanation for the well-known dependence of reinforcement ability on surface area at small stresses. The chemical and microscopic structure of the filler surface appears to be less important with respect to immobilization ability in the linear viscoelasic regime. The secondary structure formed by the particles is found to be tied together by the elastomer. Its modulus correlates with the filler's immobilization ability and shows little dependence on the filler nature. Due to formation of a filler-polymer structure with individual relaxation times, a strict separability of hydrodynamic and interparticular-reinforcement mechanisms at very high loadings no longer applies.

Physicomechanical properties of α‐cellulose–filled styrene–butadiene rubber composites

“…This confirms the studies of Vilgis and Heinrich 23 on rubber reinforcement, which emphasized that no consistent model exists that may be used to explain rubber reinforcement. Also, as indicated in Eggers and Schummer, 24 these equations apply only to uncured systems. Once the rubber is vulcanized, these models no longer apply.…”

A methodology for developing high damping materials with application to noise reduction of railway track

“…As stated in Chapter 2, unfilled EPDM has a low stiffness and low tensile strength (Eggers & Schmmer, 1996). It must therefore be reinforced to achieve useful properties.…”

Analysis of structures of rubber-filler systems with combined scattering methods

“…For example, in rubber-carbon black (CB) systems, the CB primary particles are not distributed independently but coalesce into aggregates, which are indestructible units of CB, during conventional compounding processes. 2 The aggregates of CB, which are called aggregates or agglomerates, can also lead to the formation of hierarchical structures, which consist of higher levels of ordered structure. 2 It is believed that the hierarchical structures affect the efficiency of filler reinforcement.…”

“…2 The aggregates of CB, which are called aggregates or agglomerates, can also lead to the formation of hierarchical structures, which consist of higher levels of ordered structure. 2 It is believed that the hierarchical structures affect the efficiency of filler reinforcement. Other rubber-filler systems also form hierarchical structures; furthermore, the characteristic lengths and morphologies of each level of ordered structure, such as agglomerates, vary with the specific combination of rubber and filler used in the system in addition to the compounding processes.…”

“…[1][2][3][4][5][6] The use of fillers in rubber compounds reinforces the rubber material and improves the barrier properties. There are several important factors for controlling the efficiency of rubber reinforcement by fillers.…”