Navegando por Palavras-chave "Polyurethane"

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    A comparative study of epoxy and polyurethane based coatings containing polyaniline-DBSA pigments for corrosion protection on mild steel
    (Elsevier B.V., 2013-05-01) Diniz, F. B.; De Andrade, G. F.; Martins, C. R. [UNIFESP]; De Azevedo, W. M.; Universidade Federal de Pernambuco (UFPE); Universidade Federal de São Paulo (UNIFESP)
    Organic coatings based on epoxy and polyurethane matrices containing polyaniline doped with dodecyl benzene sulfonic acid (Pani-DBSA) were prepared and applied over steel plates (SAE 1020). the plates were submitted to salt spray chamber for up to 30 days in order to evaluate the corrosion protection of these coatings. the properties of the coated plates were analyzed as a function of time by electrochemical impedance spectroscopy, open circuit potential, optical microscopy, and Raman spectroscopy. in general, results indicate a decrease in the electrical resistance, increase in capacitance and decrease in open circuit potential. Epoxy based coatings have improved performance when Pani-DBSA is used as pigment, whereas for the polyurethane coatings, Pani-DBSA seems to play an adverse effect. Raman spectroscopy indicates a possible chlorination of the epoxy matrix after 30 days exposure to salt spray chamber. (C) 2013 Elsevier B.V. All rights reserved.
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    O papel da poliuretana de mamona como substituto do enxerto ósseo autógeno em coelhos
    (Colégio Brasileiro de Cirurgiões, 2004-08-01) Jacques, José Wilson; Fagundes, Djalma José [UNIFESP]; Figueiredo, Arthur Silveira De; Inouye, Celso Massaschi; Scapulatempo, Rafael Perez; Sassioto, Maria Cristina Pita; UFMS Departamento de Clínica Cirúrgica; Universidade Federal de São Paulo (UNIFESP); UFMS
    BACKGROUND: The aim was to verify the integration of the castor oil plant polyurethane, applied in the form of handmade biomass, as a biological alternative substitute of the autogenous bone graft in rabbits. METHODS: Twenty rabbits (New Zealand) were submitted to a standard femoral condilar defect, with dimensions of 6x10mm, and ramdomly assigned for implantation of autogenous bone graft in one side and castor oil plant polyurethane in the other. The animals were observed for a period of 45 and 90 days. Evaluation of the macro and microscopic studies were analysed with statistical tests (p < 0.05). RESULTS: Macroscopic analysis showed that the presence of femoral fractures were not significant in both groups. In all autogenous bone grafts there were the presence of cortical healing (p = 0.0010), at 45 and at 90 days, while in the femurs that received polyurethane, this healing was absent at 45 days. Regarding the presence of ripe bone in the transition area between the implant and the receiving bone, the microscopic observation showed that it was completely absent, at 45 days. At 90 days, it was present in all animals that received autogenous bone graft (p = 0.0010) and in none of those who received polyurethane of castor oil plant, showing the presence of only immature bone. CONCLUSION: Castor oil plant polyurethane becomes complete to the receiving bone in a slower fashion than autogenous bone graft. However the proposal for the use of a handmade biomass to fill out the bone flaw, was shown feasible and promising in the research of the castor oil plant polymer as biological bone substitute.