Síntese e caracterização de adesivos de lignina kraft de eucalipto

Dissertação apresentada à Universidade Federal de Lavras, como parte das exigências do Programa de Pós-Graduação em Ciência e Tecnologia da Madeira, para a obtenção do título de Mestre. ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Lignin is obtained on a large scale around the world, as a byproduct of the wood pulping. It has been the subject of several studies aiming to increase its value. One alternative would be the use of lignin in adhesives phenolic for wood. However, due to the low reactivity of Kraft lignin Eucalyptus with formaldehyde, there is the need of studies involving synthesis of adhesives based of this lignin type. The objective of this study was to synthesize and characterize Kraft adhesive lignin of Eucalyptus. Lignin was obtained from the precipitation of black liquor generated in the process of Kraft pulping of Eucalyptus. Analysis of pH, color and infrared of Kraft lignin were made. In the synthesis of adhesives, Kraft lignin was used as a partial substitute of phenol in the adhesive formulations (30; 40; 50 and 60 % by mass). It was also synthesized phenol formaldehyde adhesive without lignin as a witness. The adhesives were prepared by reaction of the Kraft lignin and phenol with formaldehyde and methanol in the presence of an alkaline catalyst at high temperatures. It was used starch-based extensors with the objective of improved basic properties. The adhesives extended and not extended, had their basic properties measured and subsequently were prepared glued joints for evaluating the glue line. The strength of the glue line was evaluated according to recommendations in ASTM D-2339 2008 (2011). This review was conducted in two states after acclimatization (20º C and 65% RH) and after 24 hours of immersion in water. After the burst test was analyzed the wood failure using criteria established by the ASTM D-3110 (ASTM, 1994). The adhesives basic properties showed differences, however, the resistance value of the glue line for adhesives without extensors showed no ...