Produção e caracterização de impermeabilizante a base da resina de breu branco da Amazônia: prospecção da resina de breu branco da Amazônia como impermeabilizante de fibras naturais em compósitos

Abstract

Currently the biggest challenge for civil construction is to combine the performance of a given material with the reduction of the environmental impact of its production without this process being too expensive. Another highlight is the problem of premature degradation in composites reinforced with natural fibers, which influences the performance of the cementitious matrix, as the concrete presents a greater permeability, during hydration allows other aggressive elements to enter, leading to carbonation and attack of chloride ions resulting in corrosion problems promoting the alkalinity of the cementitious matrix. In composites reinforced with natural fibers, the water present in the pores is highly alkaline, causing dissolution of hemicellulose and lignin and alkaline hydrolysis of cellulose molecules, reducing the degree of polymerization and resistance of the fibers. In addition, hydration products, especially calcium hydroxide, migrate to the walls, lumens and voids of the fibers, causing mineralization of the fibers.In view of the search for new sources of renewable energy aiming at the practice of actions for sustainable development. The white pitch resin stands out as a waterproofing agent, due to its hydrophobicity, observed in the caulking of boats, which can contribute to the waterproofing of fibers, for the realization of light concrete, exhausting the attack on carbonation in cementitious matrices, as well as polymeric matrix in production of composites reinforced with vegetable fibers, contributing to a highly renewable development, and green when compared to resins based on polyurethanes obtained by isocyanates. In the present study, the extraction and characterization of the white rosin resin from the Amazon was carried out and the potential of the resin was evaluated in the waterproofing of açaí residues from Amazonas and jute and mauve fabric, in making natural composites. The pitch resin characterization was performed by CG / EM mass spectrometry techniques, infrared analysis coupled to FT / IR fourrier transform, and X-ray diffraction analysis, which validated the extraction fractions in ethanol and acetate the composition of the constituents of the main rosin genus Protium Hepthaphyllum, the pentacyclic compounds of alpha and beta amirine and ammonia. The thermal stability of the extracts was investigated through TGA thermogravimetric analysis, the compounds are made up of OH groups, which results in a strong intermolecular bond, on average the thermal stability guides 250 ° C. In aqueous media, the extracts resulted in a solid hydrophobic dispersion, as a result of this quality in water absorption tests, the pitch resins extracted in ethanol and acetate were evaluated, which did not show dispersion when compared to industrial resin. As for prospecting for the waterproofing potential of rosin resins, it was evaluated by pouring it as a surface coating on açaí stone residues in order to qualify the waterproofing potential amid the severe alkaline attacks promoted during the hydration of the cementitious mass, the best waterproofing method was used for heated pitch resin, the specimens that had the aggregates, waterproofed with the resin had a resistance of 6.49 MPa, resisting and inhibiting severe conditions of alkalinity and carbonation of the cementitious matrix. For the production of laminated composites, the use of extracted or heated pitch resin did not promote the protection of the fibers in the cement matrix, nor did it promote the resistance quality. As for the flexion test, the best resistance index was given to the covering of the jute and mauve fabrics, waterproofed with the industrial resin that promoted resistance on average of 7.87 (MPa).

Key words: White rosin from the Amazon; Description; Light composites; Laminated composites.