Effects of thermal aging on fatigue of carbon black–reinforced EPDM rubber

Abstract

Deterioration of the parameters measuring the fatigue of rubber compounds as a result of thermal aging was investigated. The energy to break, tear strength, fatigue life, and fatigue crack propagation rate of EPDM rubber compounds reinforced with three different types of carbon black before and after different periods of thermal aging were measured and compared through a series of static and cyclic loading tests. The experimental results indicated that the fatigue resistance of EPDM rubber compounds with different types of carbon black was consistently reduced because of changes in the molecular structure and crosslink density as a result of thermal aging. Meanwhile, the intrinsic flaws of carbon black-reinforced EPDM rubber compounds after 6 months of thermal aging were smaller, regardless of the type of carbon black. Therefore, the effects of thermal aging on the fatigue of rubber compounds are significant and should be taken into account in designing rubber components.

Crack initiation and propagation in circular rubber bearings subjected to cyclic compression

“…Intrinsic flaws in rubbery materials resulting from manufacturing were observed by many researchers 7–10. The size of intrinsic flaws plays an important role in determining the fatigue lives of rubbery materials 11–13. Thus, the fatigue crack in rubbery materials initiates from an intrinsic flaw with the maximum cracking energy density and its crack surface is perpendicular to the direction of principal tensile stress.…”

Fatigue life prediction for circular rubber bearings subjected to cyclic compression

“…The Vulcanizing agent of sulfur was utilized here and then cured at 145°C for 4 h for each rubber compound. The fatigue parameters of these three rubber compounds before and after thermal aging attack were measured by Chou, Huang, and Lin,18 as summarized in Table II. The crack growth rate of rubbers in Regime 1 is assumed to be 5 × 10 −4 cm/Mcycle 13.…”

“…On the other hand, intrinsic flaws resulting from the manufacturing process distribute randomly in rubber, and their size is another essential material parameter in estimating the fatigue life 10, 14. The intrinsic flaw size, c 0 , in rubber compounds depends on carbon black type,15 crosslink density,16 dispersion of compound ingredients,17 and thermal aging attack 18. Consequently, the fatigue crack initiates at the point with maximum cracking energy density from the accumulation of intrinsic flaws in rubber, subsequently propagates along a direction perpendicular to the maximum tensile principal stress.…”

X-Ray Photoelectron Spectroscopy for Characterization of Engineered Elastomer Surfaces

“…In order to provide deeper insight into the mechanisms of elastomer failure, surface chemical composition and SFE were studied before and after friction as a function of the amount of carbon black (CB) filler in EPDM [14]. Carbon black is one of the most widely used reinforcing fillers [47][48][49] that improves the stiffness and the toughness of rubbers, while maintaining high flexibility and good physical and mechanical properties at low manufacturing costs. The amount of CB varied between 0 and 60 parts per hundred rubber (phr).…”