Produção e caracterização de membranas de acetato de celulose híbridas

Abstract

The objective of this dissertation is to develop and assess the potential of pure and hybrid cellulose acetate membranes, containing titanium / silicon / nitrogen-based compounds, to serve a wide range of applications of two hybrid materials. For this effect, membranes are synthesized via the sol-gel process and phase inversion, through three precursors, tetraethyl orthosilicate (TEOS), 3-aminopropyl triethoxysilane (APTES) and titanium isopropoxide (TiPOT), in the presence of nitric acid (HNO3). Foram tested different concentrations of 0, 25, 50, 75 and 100% (m/m) of TEOS and APTES, in which for either cellulose acetate and or TiPOT have their fixed concentrations. The synthesized membranes were characterized by Fourier transform spectroscopy in the infravermel region, FTIR, and thermogravimetric analysis, TG/DTG. Além gives kinetics of thermal degradation with 3 methods, Friedman, Flynn and Kissenger. Forams verified through spectroscopy to the presence of ligations and functional groups characteristic of hybrid cellulose acetate membranes. The thermal analyzes will allow to assess the presence of mass loss events, showing the presence of a complex degradation process. The kinetics of degradation confirmed that the modification in the composition increases the thermal resistance of the samples. This is shown by the increase in the activation energy of the pure membrane, ACPURO, 248.85; e for B100//0-30, 482.13 KJ/mol. These results are foram da first battle using the Friedman method. The comparative behavior of the two samples, AC-PURO and B100//0- 30, is maintained in the other methods applied, corresponding to a variation of 233.3 to 452.73 KJ/mol for the first batch in the Flynn method and the 241.06 to 467.04 KJ/mol in the first batch using the Kissenger method. It was observed during the analysis, that mainly the non-theoretical increase of TEOS, attributed to the samples greater thermal and chemical stability.