Biomedical Engineering, Biomaterials, General Agricultural and Biological Sciences
2
Scopus Publications
Scopus Publications
Design of Experiments-Based Optimization of Recovered Carbon Black–Reinforced Isobutylene–Isoprene Rubber in Comparison With Conventional Carbon Black Systems Vinícius Guedes Gobbi, Ester Costa de Almeida, Roberta Helena Mendonça, Marysilvia Ferreira da Costa Journal of Applied Polymer Science, 2026 Recovered carbon black (rCB) obtained from end‐of‐life tire pyrolysis is a promising sustainable alternative to conventional carbon black (CB) in elastomer formulations; however, its lower reinforcing efficiency often limits direct substitution in industrial applications. Previous studies have shown that iso‐mass and iso‐volume replacement of CB by rCB in isobutylene–isoprene rubber (IIR) weakens filler networking due to high inorganic content and altered surface chemistry, reducing tensile performance. In this work, rCB‐filled IIR composites were optimized through formulation design, without physicochemical modification of the rCB. A central composite design was employed to evaluate the effects of rCB loading, plasticizer content, and sulfur level on Shore A hardness and index rupture energy (IRE). Shore A hardness exhibited a predominantly linear response with excellent model fit ( R 2 = 98.13%), whereas IRE showed significant curvature and interaction effects, requiring a quadratic response surface model ( R 2 _adj = 90.44%). Multi‐response optimization identified rCB–IIR formulations achieving Shore A hardness comparable to the CB‐filled reference and substantially improved IRE relative to non‐optimized rCB systems. Under the investigated conditions, full CB replacement by rCB in IIR composites can be achieved without compromising static mechanical properties; however, validation through dynamic and aging performance remains necessary for industrial implementation.
Comparative Study of Recovered Carbon Black Versus Conventional Carbon Black as a Reinforcing Filler in Isobutylene-Isoprene Rubber Vinícius Guedes Gobbi, Ester Costa de Almeida, Roberta Helena Mendonça, Marysilvia Ferreira da Costa Journal of Applied Polymer Science, 2026 Pyrolysis has emerged as a cost‐effective circular strategy for valorizing end‐of‐life tires, producing recovered carbon black (rCB) as a sustainable filler alternative. This study investigates rCB as a reinforcing filler in isobutylene–isoprene rubber (IIR) composites, comparing iso‐mass (CEII‐rCBm) and iso‐volume (CEII‐rCBv) replacement strategies against a conventional carbon black (CB) reference (CEII‐CB). Ash analysis revealed an inorganic content of 16.2% in rCB, along with a lower oil absorption number and a distinct micro‐porous surface morphology observed by scanning electron microscopy. X‐ray diffraction and X‐ray fluorescence confirmed the presence of zinc and silicon, while energy‐dispersive spectroscopy identified additional impurities including calcium, sodium, and iron. Fourier‐transform infrared spectroscopy detected polar surface groups on rCB, which impaired compatibility with the non‐polar IIR and weakened the filler network, as reflected by a threefold reduction in the Payne effect measured via the rubber process analyzer. CEII‐rCBv enhanced low‐strain modulus and Shore A hardness (+18%) compared to CEII‐rCBm, although its higher filler loading reduced tensile strength by 32%, likely due to poor interfacial adhesion and micro‐defects. Despite these drawbacks, rCB‐composites maintained comparable rheology (moving die rheometer and Mooney viscosity results), supporting the feasibility of partial rCB substitution in IIR formulations, in line with circular economy goals.
