Membranas de poliamida 11 por inversão de fase: um estudo de miscibilidade, morfologia e estrutura
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Data
2020-02-18
Autores
Lima, Rayanne Penha Wandenkolken
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Universidade Federal do Espírito Santo
Resumo
Polyamide 11 (PA11) membranes are prepared by phase inversion (PI) methodology using formic acid (FA) as solvent. The membranes morphology was investigated by Scanning Electronic Microscopy (SEM) analysis. The polyamide film showed a dense and homogenous structure, on the contrary the composition of 15% (w/w) polymer membrane showed macrovoids. In the other hand, de 20 and 25% (w/w) polymer membranes showed sponge like pores structures from a thermodynamic domain. These membranes have medium pores diameters between 0-10 µm calculated by image analysis. The X-Ray Diffraction (XRD) analysis show peaks at 2θ ~ 22° characteristic of γ crystalline form for 15% (w/w) polymer membrane and predominant peak 2θ~21° attributed to α form in 20% and 25% (w/w) membranes. The convection of phase γ to α occurred in function of increase of polymer concentration in membranes and this phenomenon was observed by an additional exothermic peak in Differential Scanning Calorimetry (DSC) curves. The degree of crystallinity was 8.2%, 10.9% and 11,3% for membranes with 15%, 20% and 25% (w/w), respectively. FTIR analysis showed characteristic bands of polyamide 11 for the membrane spectrum. Corresponding in the spectrogram that more intense bands were founded in the 719 cm-1 region indicating the presence of the γ phase. Moreover, the C=O stretch (amide I) and –NH-CO- vibration group (amide II) was observed in theoretical and experimental results. The stress-strain analysis of membranes shows a proportional dependence of Young’s modulus with the increase of polymer concentration in each membrane. The observed values of Young’s Module are 2.8, 3.2 and 3.5 MPa for 15, 20 and 25% (w/w), respectively. Cellulose fibers reinforced the rigidity of the membranes, decreasing the ductility and the variation or elastic module. Was observed the presence of cellulose fibers in all membranes, since the polymeric matrix behaves like the matrix of membranes without adding cellulose reinforcement. Thus evidencing that there was no influenced of the cellulose fiber on the thermodynamic parameters of the ternary system PA11/AF/H2O during the process of reorganization of the polymeric chain in the coagulation bath
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Membranas de poliamida , Morfologia , Análise mecânica , Polyamide membrane , Morphology , Mechanical analyse