Carbon black (CB) is an essential ingredient of any rubber compound to achieve the desired strength, stiffness, wear, and fatigue resistance. Depending on the function of a tire component (tread, sidewall, apex, etc.), different types of CBs, varying in particle sizes and structures, are used. On prolonged exposure to cyclic loading, rubber compounds lose their strength due to mechanical fatigue. In this study, the fatigue crack growth (FCG) behavior of unfilled and CB‐filled natural rubber compounds is investigated with varying particle size and structure (N115, N134, N220, N234, N330, and N339). FCG properties have been measured using a Tear and Fatigue Analyzer under various strain levels and temperatures. Microscopic analysis revealed that compounds with lower particle size and high structure CB showed better distribution and dispersion of CB throughout the whole matrix. Lower particle size with higher surface area displayed superior FCG resistance compared to the higher particle size CB. FCG of above compounds has also been studied at three different temperatures such as room temperature (25°C), 70°C, and 100°C. Significant increase in FCG rate was observed with increase in temperature due to the thermo‐oxidative degradation and reduction of strain‐induced crystallization.

Based on the viscous energy dissipation parameter around the crack tip, several intrinsic factors tend to govern the dissipation factor which in turn leads to the characteristic crack growth mechanism of the rubber vulcanizate. Herein, the crack growth behavior of different filled natural rubber (NR), styrene butadiene rubber (SBR), and NR/SBR blends was studied. It was deciphered that the 80/20 NR‐SBR (NSS) compound exhibited the lowest crack growth (dc/dn) value at all strain percentages which was in good accordance with its highest viscous energy dissipation as observed from the DMA (strain sweep) results. Also, from the theoretical calculations, dissipated energy per unit volume for NSS was 4.73 MPa, which was the highest out of all the compounds. This led to a decrement in crack growth. The lowest intensity peak in tan δ versus temperature curve, 6.5% decrement in ΔE'(storage modulus), and almost 44% decrement in ΔG’ (Payne Effect) indicates higher polymer‐filler interaction and lower filler‐filler disintegration respectively, as compared to 100 NR (NRS). The results from optical microscopy and scanning electron microscope suggested that NSS exudes the smallest crack deviation and extent of crack growth with lesser filler agglomerates making NSS the best fatigue‐resistant compound.