Fatigue crack growth behavior and morphological analysis of natural rubber compounds with varying particle size and structure of carbon black

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 degrees C), 70 degrees C, and 100 degrees C. Significant increase in FCG rate was observed with increase in temperature due to the thermo-oxidative degradation and reduction of strain-induced crystallization.

Automated summary

In this study, the fatigue crack growth (FCG) behavior of natural rubber compounds filled with different particle sizes and structures of carbon black (CB) was investigated. It was found that compounds with smaller particle size and higher structure CB showed better distribution and dispersion of CB throughout the matrix, resulting in superior fatigue resistance.