Caracterização físico-química e estudo reológico de asfaltos modificados pelos polímeros PEAD, PEBD e PELBD e contribuição ao estudo do envelhecimento do cimento asfáltico de petróleo

• Ano de defesa: 2015
• Autor(a) principal: Getúlio Francisco Manoel
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Engenharia Química; Engenharia quimica
• Link de acesso: http://hdl.handle.net/1843/BUBD-A3ZG8A

In this work, asphalt cement of petroleum AC was studied, involving its modification by the thermoplastic polymers high density polyethylene (HDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE), the last two having different grades, and the CAP aging study based on ASTM D2872 standard-RTFOT method, without and with the addition of RARO (aromatic extract, byproduct of petroleum catalytic cracking), with concentrations varying from 2 to 14 w%. The AC modified by polymers (ACMPs) were obtained with different compositions of polymers (from 1 to 7 w%), the mixtures were characterized physicochemically and their rheological behavior was studied. The degree of cristallinity of the used PEs, determined by differential scanning calorimetry (DSC), varied from 36% to 57%. The results obtained from the physicochemical and rheological characterization of the ACMPs showed that their behavior is a consequence of multiple factors compromise, highlighting the influence of the PEs degree of cristallinity in such behavior. All the obtained ACMPs, relatively to pure AC, showed a lower penetration, a higher softening point and a higher viscosity. The changes were more significant for the polymers with higher degree of cristallinity and at higher concentrations. The analysis of MPA considering the degree of crystallinity of the polymer showed the influence of this parameter on the solubilization of the polymers in CAP. The higher the degree of crystallinity, the greater the difficulty in solubilizing it on the CAP. This fact is of fundamental importance in the AMPs production process. It was observed, from the rheological study, a reduction of the phase angle and an increase of the G*/sin parameter with the addition of polymer, relatively to pure AC, both effects being concentration dependent. Such results point out to an increase in the elasticity (increasing of the elastic modulus) and a higher resistance to permanent deformation of the ACMPs, comparatively to pure AC. A correlation between the cristallinity of the polymers incorporated to AC and the obtained rheological parameters was also observed. This fact is a demonstration of the importance of polymer morphology on the ACMP behavior. It was verified that that the changes caused by the addition of PEs are significantly greater that those caused by the addition of poly(styrene-co-butadiene-co-styrene) (SBS), at 4% concentration. This fact suggests that the PEs can be used at lower concentrations. An increase on PG (performance grade) of SUPERPAVE specification, by polymer addition, was also identified, the higher values obtained when LLDPEs were incorporated (PG = 82). So, the addition of PEs makes viable the use of ACMPs as ligands for pavement subjected to high temperatures or to high traffic volume. Through this work, it was possible to achieve a better understanding of the rheological behavior of the ACMPs and of the polymer / AC interactions and the obtainment of various correlations with regard to physicochemical and thermal properties modifications as a result of the aging process, establishing the basis for the construction of a predictive model for AC aging. Additionally, thermodynamic properties values were calculated in order to know how the CAP aging occurs and how it could be predicted. This knowledge is important, considering two aspects: first, with respect to the production process during the oil refining, which becomes mandatory predict the properties of products before they are produced in order to maximize the process and avoid product losses. The second point is related to the machining process of ACMP and asphalt mixture (mixture with aggregates).