Ref.: MpoBel11-001
Apresentador: Amanda Faria Baruel
Autores (Instituição): Baruel, A.F.(Instituto Tecnológico da Aeronáutica / Instituto de Aeronáutica e Espaço); Rosa, G.B.(Instituto Tecnológico de Aeronáutica / Instituto de Aeronáutica e Espaço); Mello, S.A.(Instituto de Aeronáutica e Espaço); Petroni, S.L.(Instituto de Aeronáutica e Espaço); Cassu, S.N.(Instituto Tecnológico de Aeronáutica / Instituto de Aeronáutica e Espaço);
Resumo:
Elastomer is a class of polymeric materials that has ability to undergo large reversible elastic stress, meaning that after elastic stress, the material returns to its original shape without permanent deformation. Elastomers are widely used in various industries, such as aeronautics, automotive, and civil engineering. For the rubber to achieve its properties, vulcanization is a necessary process, which involves heating the rubber in the presence of vulcanization agents, such as sulfur, peroxides or zinc oxide, in order to form cross-links. The number and type of cross-links formed during vulcanization significantly affect the final properties of the rubber. Currently, vulcanization evaluation is typically conducted using rheometers, such as Oscillating Disc Rheometer (ODR) and Moving Die Rheometer (MDR). These methods measure the torque required to oscillate at a given amplitude, generating a vulcanization curve. This curve can be separated into three stages, induction, vulcanization, and reversion. The monitored parameters are Minimum Torque (ML), Maximum Torque (MH), which correspond to the viscosity of the rubber; processability time or scorch time (ts2), and optimal vulcanization time (t90). In this study, the analyses conducted on an MDR rheometer were compared with those performed using a dynamic-mechanical analyzer (DMA), to obtain vulcanization curves. DMA was carried out using shear mode with isothermal testing. The storage modulus and tan? curves were used to evaluate reversion, t90, ts1, MH and ML, to determine which produces results most similar to the MDR curve. Storage modulus could accurately evaluate the reversion. The tan? curve presented similar values of ts1 and t90 to those found in the MDR. Regarding the MH and ML values of the rubbers, although these values were not directly obtained from DMA, it is possible through the tan? curve to verify the tendency of increase or decrease when compared between the rubber blends.