Dynamic Testing and Reinforcement of Rubber

Abstract

A series of experiments have been run to determine which mechanisms dominate carbon black reinforcement of rubber. A broad range of compounds using oil-extended and non-oil-extended rubbers and carbon blacks covering the spectrum of tread blacks have been tested. The results for measurements made in an all-SBR formulation are reported here. The primary experiment consisted of measurement of the dynamic modulus and hysteresis of the cured and uncured compounds over a broad range of frequencies, temperatures, and strains. Ternperatures ranged from −70°C to +90°C; frequencies varied from 0.01 to 10 Hz; double strain amplitudes varied from 0.5% to 35%. From a discussion of the literature and evaluation of the experimental results, two mechanisms have been found to control the primary effects of carbon black on rubber reinforcement, where reinforcement refers to a general enhancement of properties, such as modulus, as well as the tensile strength of the compound. Hydrodynamic interaction, which is the increase in properties caused by the modification of strain fields in the region of an aggregate, dominates the large-strain dynamic and tensile properties of the compound. The primary carbon black variable in this mechanism is the effective aggregate size, such as measured by tint, which controls the effective volume loading of the carbon black at a given weight loading of carbon black. At low strains, the modulus is even higher than that predicted from the hydrodynamic-interaction/effective-volume model. This additional reinforcement is caused by the entanglement network formed between the tightly absorbed bound rubber on the carbon black surface and the bulk rubber far removed from the surface. The main carbon black variables in this mechanism are surface area and surface chemistry. The strain dependence of modulus is caused by the breaking and reforming of effective crosslinks in the rubber forming a transition zone between the bound rubber and the bulk rubber. To a large extent, this mechanism is dominated by the rubber properties, such as molecular weight and molecular-weight distribution. However, the dynamics of the entanglement network may be modified by altering specific interactions between carbon black and rubber.

A comparative investigation on strain induced crystallization for graphene and carbon nanotubes filled natural rubber composites

“…Although the tube model has reliability in investigating stress-strain behavior to determine the network parameters of the unfilled rubber, it is not applicable in depicting the filled rubber network because of its complexity [23]. Funt [24] first proposed an entanglement bound rubber tube (EBT) model to describe the contribution of entanglement, which extends tube model to the filled system. Thereafter, EBT model has been used to describe the effect of carbon black [25] and clay [26] on the mechanical behavior of rubber.…”

Interactive effects between carbon allotrope fillers on the mechanical reinforcement of polyisoprene based nanocomposites

“…As mentioned in the Introduction, nanofillers are known to promote a remarkable Payne effect [12]. Several models have been developed in order to explain such an effect on the basis of two main interpretations: the first one, related to the filler networking concept, assumes an agglomeration-deagglomeration process of the filler network above the filler percolation threshold [12,[32][33][34], the second one, related to filler-matrix interaction, assumes matrix-filler bonding and debonding mechanisms [35][36][37][38][39][40][41][42][43]. It is not within the scope of this work to discuss the physical mechanisms occurring in the composites.…”

sp2 carbon allotropes in elastomer matrix: From master curves for the mechanical reinforcement to lightweight materials

“…The modulus reduction is much larger for CNT(N) based composites than for CB based composite. This phenomenon, known as Payne effect [52], is mainly explained with models based on two main interpretations, which make reference either to filler-filler or to polymer-filler interactions: agglomeration-de-agglomeration process of the filler network above the filler percolation threshold [52][53][54][55] or polymer-filler bonding and debonding [56][57][58][59][60][61][62][63][64]. The reduction of storage modulus G′ with the increase of the strain amplitude is linearly correlated with the increase of the maximum value of loss modulus G″.…”