Abstract
The thermo-mechanical properties of carbon black reinforced natural and styrene butadiene rubbers are investigated under rapid adiabatic conditions. Eleven carbon black grades with varying surface area and structure properties at 40 parts per hundred (phr) loading are studied and the unreinforced equivalents are included for reference. The results show a strong correlation of the modulus, mechanical hysteresis, temperature rise and calculated crystallinity of the rubbers measured in tensile extension with strain amplification factors. This highlights the influence of matrix overstraining on microstructural deformations of the rubber upon extension. The strain amplification factors are calculated via the Guth-Gold equation directly from carbon black type and loading, allowing a correlation of the fundamental morphological properties of carbon black with thermal and mechanical properties of rubbers upon extension. Analysis of the thermal measurements of the rubber compounds upon extension and retraction and contrasting between crystallizing and non-crystallizing rubbers reveals that a substantial irreversible heat generation is present upon extension of the rubber compounds. These irreversible effects most likely originate from microstructural damage mechanisms which have been proposed to account for the Mullins Effect in particle reinforced rubbers.
Highlights
Particle reinforced rubbers are an important class of materials
The carbon black (CB) with higher strain amplification factors, which is the result of higher structure level of the CB, have a higher incremental modulus response versus CBs with lower strain amplification factors and a lower structure
Strong linear correlations between the stress value at 300% and strain amplification factors are observed for each cycle level (R2 values are indicated in the Figure)
Summary
Particle reinforced rubbers are an important class of materials. Despite their ubiquity, there is still a lack of understanding of the mechanisms controlling their behaviors at both small and large strains. The cyclic stress softening and strain history dependence are often referred to as the Mullins effect (Mullins, 1948). The microstructural origins of this large strain behavior and the Mullins Effect are still not entirely clear. Strain history and hysteresis effects are commonly ascribed to several prosed microstructural damage mechanisms (Diani et al, 2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
