Stress softening in natural rubber vulcanizates. Part III. Carbon black‐filled vulcanizates

Abstract

SynopsisStress softening (Mullins effect) occurs in rubber vulcanizates during the first and subsequent deformations. This paper shows the similarity of the degree of stress softening in both unfilled and carbon black-filled vulcanizates of natural rubber when stressed almost to break. This confirms the earlier investigations which were confined to moderate stresses. A simple interpretation of the tensile stress-strain results for filled rubbers is that the strain in the rubber is increased by the presence of the filler, so that the ratio of the average strain in the rubber to the measured overall strain is given by a \train amplification factor. The usefulness of this concept is confirmed by showing the similarity of the stress-softened curves after normalizing the strains, provided the vulcanizates of both gum and filled vulcanizates were subjected to the same initial stress.

Preparation and properties of natural rubber/organo-montmorillonite: from lab samples to bulk material

“…The loss modulus increases slightly with the increase of the frequency. This behavior is in correlation with the information found in the literature regarding this specific matter [39].…”

“…Then, when the material is stretched for a second time, the network is already in a "preferred" configuration. This is more evident in rubber with higher filler content [39].…”

Strain-Induced Crystallization of Natural Rubber: A Review of X-Ray Diffraction Investigations

“…[87][88][89] As shown in Figure 16(a), the addition of carbon black (50 phr in that example) stiffens the material: for a given λ, the stress is higher in filled rubber than in unfilled one. 71 The corresponding crystallinity is shown in Figure 16(b).…”

Effect of Cyclic Deformations on the Dynamic‐Mechanical Properties of Silica‐Filled Butyl Rubber

“…However, the values of C 1 and consequently, r must not be affected too strongly by the addition of the filler, [28][29][30] as the same procedure were used for all of these samples; in other words, the density of chemical cross-links in the rubber compartment should be the same. Therefore, the cross-link density of the filled elastomers can also, as suggested by Eisele, [28] be analyzed with the aid of the following assumption: the strain in the macroscopic sample is not Scheme 1.…”