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In order to estimate mode I fracture strain energy release rate of a rubber upon monotonic loadings, the material is submitted to pure shear and single edge notch tension tests. Catastrophic failure happens suddenly for both tests, revealing mirror-like crack surfaces, assessing the fragile fracture. Nonetheless, Griffith failure analysis could be carried out on pure shear tests only. This analysis leads to an energy release rate value that allows challenging approximate expressions existing in the literature for pure shear and single edge notch tension tests. The pure shear approximate expression provides quantities that match the Griffith analysis. Meanwhile, the strain energy release rate values calculated directly from the single edge notch tension tests differ significantly from the values obtained in pure shear. This discrepancy is explored and possible explanations are discussed showing that pure shear tests should be favored.

The resistance to mode I failure of rubbers is studied by submitting single edge notch samples to uniaxial tension. Reproducing the seminal work of Rivlin and Thomas (1953), single edge notch tension specimens, presenting notches of various lengths, are stretched until break. A styrene butadiene rubber, unfilled and filled with carbon-black, and an unfilled rubber from the latter mentioned work, were considered. When the notch is smaller than one fifth of the sample width, mode I crack opening is observed, leading to catastrophic failure that creates smooth mirror-like crack surfaces. Nonetheless, the experimental force-elongation responses show that the mode I critical energy release rate cannot be calculated by a classical Griffith elastic failure analysis. When notches are longer, the SENT samples are not submitted to pure uniaxial tension only. Structural bending leads to uncontrolled mixed mode crack propagation. The surfaces created when the long notches propagate are rough and bifurcations are witnessed for the filled rubbers.

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An important property affecting the integrity of a tyre is the adhesion between rubber and reinforcements such as metal cords. Standard tests used to evaluate rubber-metal adhesion fail to predict the intrinsic interfacial behaviour. A novel test protocol, referred to as the Rubber Cord Adhesion Inflation Test (RCAIT), has therefore been developed. In this work, RCAIT is used to compare the performance of four different adhesive systems (two rubber types and two cord coatings). In addition, the effect of fluid injection rate on crack propagation pressure is evaluated and is correlated to the sensitivity of the tensile behaviour of the rubber to strain rate. Some improvements in the RCAIT analysis are also proposed here. A thick rubber tube inflation model is proposed in conjunction with the Ogden model for hyperelastic behaviour that can be applied to other elastomeric models as well. In conclusion, the relationship between crack propagation speed and Critical Strain Energy Release Rate (SERR) is discussed.