Caracterização de geis tixotropicos utilizados em telecomunicações

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

This work is enclosed in a project of development of national technology in Telecommunications with participation of UNICAMP and TELEBRÁS Research and Development Center. Today, a number of the materials used in optical cables are imported, without a specific knowledge of their behavior in the Brazilian climate conditions. The gels used for cable filling are included in these materials. The aim of this work is the characterization of these gels, in respect to the above consideration, which can provide relevant data to their applicability in the brazilian telecommunication system and lead to their eventual production in Brazil. Two types of gels, with different working temperature range were studied: one is used between -46 to 90°C (Gel Gf) and the other is used between -90 to 100°C (Gel Gq). The gels do not differ in density, fulgor point and elementar analysis significantly, suggesting that they have similar composition. Infra-red spectra show small differences for both gels. The gels are significantly different in properties as: drop point (Gel Gf = 244 °C and Gel Gq >300 °C), solid content (Gel Gf = 10.0 % and Gel Gq = 8.5 % w/w) and volatiles content (Gel Gf = 26.7 % and Gel Gq = 23.5 % w/w). Quantitative separation was achieved after extration with xilol followed by extration in soxhlet with toluene. Results show that the gels are composed of an oil (hydrocarbon) and a silica gellant (funcionalized with organic compound). The characterization of the gel-components was made by infra-red spectroscopy, proton nuclear magnetic resonance spectroscopy, X-ray fluorecence and scanning eletronic microscopy. Both hydrocarbons are differents in viscosity (Gel Gf = 52 cps and Gel Gq = 7060 cps) and average molecular weight (Gel Gf = 0.54 kg.mol and Gel Gq = 0.44 kg.mol). We suggest that the oil of the Gel Gq is a mixture of synthetic and mineral oils; while the oil mixture of the Gel Gf has less synthetic oil than Gel Gq or is composed only by mineral oil. This fact justifies the different working temperature ranges of these gels. Results show that both silica gellants are funcionalized with an organic compound. The surface area of the silica is 56 m.g in the gel Gf and 40 m.g in the gel Gq, quantities used are 10.0 % w/w in the Gel Gf and 8.5 % w/w in the gel Gq. The results of shear thinning index (Gel Gf = 4.4 and Gel Gq = 6.5) and degree of thixotropy (Gel Gf = 1.3 and Gel Gq = 1.0) show that the higher the viscosity of the gel, the higher the pressure needed for its extrusion, as predicted by Non-Newtonians fluids theories.

ASSUNTO(S)

fisico-quimica materia - propriedades coloides

ACESSO AO ARTIGO

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