Produção e caracterização de filmes poliméricos à base de ágar-ágar

Abstract

Biopolymers have been used as alternative to fossil polymers and, in this context, agar-agar, a polysaccharide extracted from seaweed, has been drawing attention due to its properties on the formulations of polymeric films. In a scenario where synthetic polymers waste has become a problem due to the pollution caused by them and due to the low recycling rates, biopolymers have become attractive for being bio-based and/or for their fast degradation (in case of biodegradable polymers), without leaving environmentally harmful residues. Therefore, in this work, agar-agar was used in association with glycerol and glutaraldehyde on the formulation of polymeric films produced using the casting method of a solution where water was used as solvent. The produced films had their water interaction determined by swelling, solubility and contact angle tests. Mechanical and physical properties were determined by tensile test and thickness measurement. Optical microscopy was used to analyze the surface and scanning electron microscopy was used to analyze the surface and the cross section of the films. Spectroscopic properties were obtained by Fourier transform infrared spectroscopy, energy dispersive spectroscopy, color measurement and ultraviolet-visible spectroscopy. Thermal degradation was determined by thermogravimetric analysis and ageing of the material was evaluated by exposure to accelerated weathering. Using agar-agar, it was possible to produce polymeric films with thickness of about 120 μm and mechanical properties similar to those of low-density polyethylene, presenting tensile strength between 15-16 MPa. The solubility of the obtained material was 42% and the swelling ranged between 349 and 555% in mass, depending on the concentration of glutaraldehyde added to the formulation of the films. The addition of glutaraldehyde did not improve the properties of the polymer to the extent that its use would be advantageous. The polymer made from agar-agar show great potential for use as an alternative to some commercial polymers for packaging through analysis of the requirements of each application. [resumo fornecido pelo autor]