Estudo das propriedades físico-químicas de membranas de acetato de celulose/glicerol incorporadas com aditivos de lignina extraída do endocarpo da Macaúba (Acrocomia aculeata) e seus derivados modificados quimicamente

Abstract

Eight membranes of commercial cellulose acetate were prepared incorporating various additives, which changed their physicochemical properties. The membranes were divided into two groups (I and II) and their properties were evaluated. The four membranes of group they were prepared by adding, at a concentration of 0.1% (m / m) of the lignins extracted from the macaúba endocarp (Acrocomia aculeata) after purification and chemical modification. These four membranes were classified as to their composition as: (A) no additives (pure acetate); (B) with the purified lignin; (C) with the carboxymethylated lignin and complexed with Na+ (CML-Na) and (D) with carboxymethylated lignin and complexed with Al3+ (CML-Al). The other four membranes of group II has the same composition of Group I, but with added glycerol at a concentration of 10% (m / m). All eight membranes were prepared using a standard technique of spreading (casting method), after the dissolution in acetone. The percentage of 10% glycerol in membrane composition was determined in a previous study where the membranes prepared by the same technique, with a variable composition glycerol were studied and characterized. In this preliminary study membranes at concentrations of 0, 2.5, 5.0, 10.0, 15.0 and 20.0% (w / w) glycerol with acetate were dissolved in two solvents: acetone and a mixture acetone / water (80/20, v / v). The membranes with 10% glycerol shown in both solvents an increase of mechanical properties. The glycerol, as well as having plasticizer properties, is produced in large scale by first generation biodiesel industry, which uses the reaction transestrificação oils and fats. Concurrent with these studies, composition of the macaúba wendocarp was determined as the content of lignin, cellulose and hemicellulose. The large amount of lignin present in the endocarp (40.5%) and after purification (59.8%) showed that this residue has great potential for use of lignin. The macaúba after extraction of oils used in pharmaceutical industries and biodiesel discards lot of this waste without proper use. The characterization of the materials were made for determining the properties: morphology, by Scanning Electron Microscopy, SEM, structural: X-Ray Diffraction-XDR, hydrophobicity and barrier properties (contact angle and permeability to water vapor), thermal and thermomechanical properties: Differential Scanning Calorimetry - DSC, Thermo Gravimetric Analysis - TGA and Dynamical Mechanical Analysis - DMTA.