Banca de QUALIFICAÇÃO: PRISCILA ALMEIDA LUCIO CAMPINI
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.DISCENTE : PRISCILA ALMEIDA LUCIO CAMPINI
Data: 31/07/2026
HORA: 09:00
LOCAL: por participação remota
TÍTULO:
CHEMICAL DEVULCANIZATION OF ETHYLENE-PROPYLENE-DIENE (EPDM) RUBBER COMPOUNDS ASSISTED BY SUPERCRITICAL CO2
PÁGINAS: 100
RESUMO:
Rubber materials are characterized by great deformability and damping properties, used in various applications such as tires and sealing purposes. To obtain these properties, the vulcanization process promotes the formation of sulfur crosslink bonds between the polymer chains, which impairs the polymer recycling through simple thermo-physical methods. Recycling rubber materials can be performed through different technological routes. The “golden one” is the devulcanization route, that aims to selectively cleaving the sulfidic crosslink bonds, preserving the polymer chains, which is challenging considering the similar energies of S-S, C-S, and C-C bonds. Among the approaches, chemical devulcanization is considered a promising method as promotes a higher selectivity by using devulcanizing agents (DA) that can react with the sulfidic bond and cleave it. In the supercritical CO2 (scCO2) assisted chemical devulcanization, the reaction is performed in scCO2 media, which promotes the rubber swelling, stretching the sulfide links, and can carry the DA into the rubber, facilitating the reaction with crosslink bonds. At the end of the reaction, the high-pressure cell is depressurized, and CO2 comes back to its gaseous state, letting the devulcanized rubber free from solvent traces. This project has explored the chemical devulcanization assisted by scCO2 of EPDM. EPDM, the third most used rubber, is an ethylene-propylene-diene random terpolymer with low content (<10 %) of unsaturated diene units, that allows sulfur-based vulcanization. Diphenyl disulfide (DD) was selected as the DA. Devulcanization operational conditions, such as pressurization and depressurization stages, the proportion of DD in relation to rubber mass, and the system arrangement, were investigated to improve devulcanization efficiency (determined as the decrease of crosslink density, evaluated by swelling tests) and selective cleavage of the crosslink bonds (evaluated by Horikx’ Model, which expresses the devulcanization percentage as a function of sol fraction). A Design of Experiments was applied to optimize the temperature (100-200 °C) and pressure (10-30 MPa) in fixed reaction time (2 h). FTIR spectra showed that higher pressures (20 MPa) promoted a more efficient devulcanization, evidenced by the decrease of peak intensity at 600-400 cm-1 range, related to the crosslink bonds that were broken during the devulcanization process, while lower pressures (10 MPa) promoted the polymer modification, with increase intensity of peaks at 872 cm-1, related to the DD grafting onto polymeric chains after crosslink scission, and at 1200-1000 cm-1 range, attributed to oxidation products. High devulcanization efficiency was achieved at 200 °C and 20 MPa. Different cure system resulted in different %Devulcanization. The scCO2-assisted chemical devulcanization showed to be a promising recycling process for EPDM compounds.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1761120 - DANILO JUSTINO CARASTAN
Membro Titular - Examinador(a) Externo ao Programa - 1085298 - JULIANA MARTIN DO PRADO
Membro Titular - Examinador(a) Externo à Instituição - MARIANELLA HERNÁNDEZ SANTANA
Membro Titular - Examinador(a) Externo à Instituição - SANDRA REGINA SCAGLIUSI
Membro Suplente - Examinador(a) Interno ao Programa - 1768959 - FERNANDO CARLOS GIACOMELLI
Membro Suplente - Examinador(a) Interno ao Programa - ***.991.506-** - JULIANA DA SILVA BERNARDES - UFABC
Membro Suplente - Examinador(a) Externo ao Programa - 1850090 - ANNE CRISTINE CHINELLATO
Membro Suplente - Examinador(a) Externo ao Programa - 1730526 - SUEL ERIC VIDOTTI