Influência das características anatômicas e do teor de extrativos totais da madeira de <i>Eucalyptus grandis</i> W. Hill ex Maiden na qualidade da colagem

Abstract

RESUMOO trabalho teve como objetivo caracterizar anatomicamente e quantificar os extrativos totais em diferentes posições de toras de Eucalyptus grandis W. Hill ex Maiden com 18 anos de idade e avaliar a influência dessas características sobre a resistência ao cisalhamento e percentagem de falhas na madeira de juntas coladas com adesivo termoendurecedor resorcinol-formaldeído. Foram preparadas lâminas histológicas para o estudo anatômico e determinou-se o teor de extrativos totais. A preparação das juntas coladas foi feita de acordo com a norma ASTM D 2339ASTM D -98(2000. Utilizou-se o coeficiente de correlação de Pearson, a 1 % de probabilidade pelo teste t de Student, para avaliar as correlações existentes entre as características anatômicas e teor de extrativos com a qualidade das juntas coladas. Verificou-se que houve correlação entre resistência ao cisalhamento com as seguintes características: diâmetro do vaso, espessura da parede, largura e comprimento da fibra, largura do raio e teor de extrativos totais. E, em relação à percentagem de falhas na madeira, houve correlação entre esta com as seguintes características: frequência de vasos, espessura do lume da fibra, frequência e altura do raio. Tanto no sentido radial quanto no sentido longitudinal das toras, houve variação dos valores encontrados para a mensuração dos elementos anatômicos, quantidade de extrativos totais, resistência ao cisalhamento e percentagem de falhas na madeira. Palavras-chave: anatomia da madeira; teor de extrativos; qualidade da colagem. ABSTRACTThe study aimed to anatomically characterize and to quantify the total extractives in different positions of the log of Eucalyptus grandis W. Hill ex Maiden with 18 years of age and to assess their influence on the shear strength and percentage of wood failure in adhesive bonded joints with thermosetting resorcinolformaldehyde. Histological slides were prepared for an anatomical study and determined the total extractive content. The preparation of bonded joints was made according to ASTM D 2339ASTM D -98(2000. It was used the correlation coefficient of Pearson, 1 % probability by t test to evaluate the correlation between the anatomical and extractives content with the quality of the glued joints. It was found that there was a correlation between the shear strength with the following characteristics: vessel diameter, wall width, length and width of the fiber, the width of the radius and total extractives content. For the percentage of wood failure, there was a correlation between this with the following characteristics: the frequency of vessels, thickness of the heat of fiber, and high frequency of lightning. Both the radial direction as in the longitudinal direction of the logs there was change in the values found for the measurement of the anatomical elements, the total amount of extractives, the shear test strength and the percentage of wood failure.

Influence of anatomy on the adhesion performance of four wood species

“…The greater the fiber diameter and ray width, the greater the adhesive penetration in the cells, and consequently the greater the adhesion between the wood pieces and the shear strength in the glue line (Albino et al, 2012). However, this fact was not observed for Kiri wood, which exhibited the lowest shear strength.…”

“…The type of adhesive to be used during the adhesion process should also be considered. For example, resorcinol formaldehyde is a widely used adhesive in structural parts because it gives bonded joints, resistance against mechanical stress, moisture and temperature, despite its high cost (Tienne et al, 2011;Albino et al, 2012). A strategy to reduce costs is the use of resorcinol in wood species with different anatomical structures, which provides an accurate diagnosis to adjust its behavior in the bonding.…”

“…Research on adhesives have been dedicated to optimizing adhesion in wood of some species, which promoted the development of intrinsic adhesives for bonding these materials (Vital et al, 2006). However, information on the effect of the wood's anatomical structures on the performance of bonded joints is still necessary (Albino et al, 2012), given the diversity of species with industrial potential.…”

<b>Properties of multi-laminated plywood produced with <i>Hovenia dulcis</i> Thunb. and <i>Pinus elliottii</i> wood under different pressing pressures

“…According to results obtained by Albino, Mori and Mendes (2012), when pore diameter dimension, the width and the fiber length and ray width are too high, they might result in a thick glue line since more adhesive is absorbed.…”

Technological Feasibility of Hovenia dulcis thunb. Species for the Production of Edge Glued Panels

“…In evaluating the influence of the anatomical characteristics and the total extractive content in Eucalyptus grandis wood on the quality of the bonding, Albino et al (2012) showed that the extractive content in the region of the pith and on top of the log were 6.10% and 7.98%, respectively. Loiola (2015) analyzed the drying of teak wood (Tectona grandis L. f) and found total extractive values of 11.13%.…”