About the Influence of Materials Parameters on the Ultimate and Fatigue Properties of Elastomers

Abstract

The aim of this chapter is to revisit the historical works, mechanisms and modeling approaches available in the field of fatigue crack growth resistance and rupture properties. After introducing the methodology developed to evaluate these properties, the impact of testing parameters such as temperature, loading speed and pre-deformation will be highlighted. We will then review the influence of some material characteristics on rupture and crack propagation and the local mechanisms involved. Finally, a theoretical framework primarily dedicated to the description of crack propagation under static load will be discussed, that aims to underline the connection between resistance to crack growth and the ability of a material to dissipate energy.

Crack propagation in filled elastomers: 3D study of mechanisms involving the filler agglomerates

“…Past studies correlated the energy dissipation during high strain loading to the crack propagation resistance [21,39,50]. Thus, the better resistance to crack propagation for filled elastomers vs unfilled one was partially attributed to an increase in the strain energy release rate, brought by the energy dissipated by the Mullins effect [16,18,50,51]. Similarly, the studies by Ducrot et al [39] and Slootman [52] showed that mechanisms involving sacrificial bonds, by dissipating more energy in the crack tip vicinity, also improve the fracture toughness.…”

Largely improved generating energy density, efficiency, and fatigue life of DEG by designing TiO2/LNBR/SiR DE composites with a self-assembled structure

“…30 The TiO 2 /SiR composite shows largely increased N FL because of the combined effect of the signicantly increased tensile toughness as well as the separation of TiO 2 aggregates and interfacial debonding during cyclic stretching that facilitates the energy dissipation. 31 The 5L/SiR blend also shows high N FL because of the much higher tensile toughness than pure SiR, whereas further increasing LNBR to 10 phr results in the largely decreased N FL , which could be due to the signicant increase in hysteresis loss, similar to that of the VHB material. Interestingly, at the same content of LNBR, the N FL at 200% strain of 10T/LNBR/SiR composites is much higher than that of LNBR/SiR blends.…”

Relationship between macromolecular network and fatigue properties of unfilled polychloroprene rubber

“…Here the strain energy density W is related to G by G = 2KW. Factor K depends on the maximum extension max through 𝐾 = 𝜋 √𝜆 𝑚𝑎𝑥 ⁄  B and β are the material properties related to crack propagation [20]. According to the classical theory of rubber elasticity, the strain energy density is related to max by equation 3 [39,40]: 𝑊 = 𝜌𝑅𝑇𝜈(𝜆 𝑚𝑎𝑥 + 2/𝜆 𝑚𝑎𝑥 − 3) ⁄ 2 (Eq.…”

“…For given test conditions, the fatigue life of rubber also depends on the nature of the gum [10][11] and the additives used for the formulation (fillers and stabilizers [12][13], process conditions, and as expected, ageing of the material before testing [14][15][16]). From the existing studies, if it clearly emerges that the nature of the macromolecular network is one of the key parameters when considering the fatigue behavior of rubber [17][18][19], the network properties of an elastomer have not yet been successfully linked to its fatigue life [20]. As a result, we propose in this study to investigate the influence of macromolecular modifications induced by oxidation, the final purpose here is to relate chemical ageing and fatigue properties which is poorly documented in the literature to our knowledge [15,16] even non-existent in the case of neoprene.…”

“…Considering in a first approach that the crosslinking density is a key parameter determining the mechanical properties, our objective here is to study the possible relationships between the fatigue behavior and the changes in crosslinking density induced by oxidation It is known that polychloroprene rubbers (CR), like natural rubber, undergoes strain-induced crystallization (SIC) when stretched [27][28]. This phenomenon has been widely studied [20,[29][30][31][32][33], confirming that it drastically reduces the crack propagation rate due to the formation of crystallites at the crack tip (where the local strain is the largest). This results in a large increase in the fatigue life of rubbers.…”