Efeitos dos desvios da grã nas variáveis dendrométricas e propriedades físico-mecânicas em madeiras de eucalipto
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Data
2016-10-27
Autores
Coelho, José Clailson Franco
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Universidade Federal do Espírito Santo
Resumo
The aim of this work was to analyze the effect of the growth conditions of eucalyptus trees on the grain, to determine its variability in the stem and its relation with the dendrometric variables and the physical-mechanical properties of the wood. Two populations of distinct genetic materials were used: (i) 16 clones of Eucalyptus grandis x E. urophylla, seven years old, from clonal test established in Montezuma, State of Minas Gerais and Nova Almeida, State of Espírito Santo; and (ii) seven clones of E. grandis x E. urophylla, with 13 years old, from commercial plantations established in Alcobaça, State of Bahia. The effects of the growth conditions and dendrometric variables of the trees on grain deviations of the wood were evaluated in the clones of the first population, having previously measured the breast height diameter (DBH), commercial height, volume and shape factor. The variation of grain in the pith-bark and base-top directions were determined in the clonal materials of the second population. For both populations, the maximum angular deviation (MAD) was determined by the radial division method, with subsequent image analysis; the wave propagation velocity and the dynamic modulus of elasticity obtained by non-destructive ultrasound technique, stress wave and transverse vibration; the compressive and shearcrescimento strength, modulus of rupture and modulus of elasticity by static bending, the basic density, the anisotropic factor and the volumetric shrinkage of the wood. It was observed that there was no significant difference of the MAD values between the two growth conditions, however, with a trend of larger deviations of grain in the wood of clones that grew in Nova Almeida. For some clones at the age of 7 years, there were significant positive correlations between MAD and physical and mechanical properties. The propagation velocity of the ultrasonic waves correlated negatively with grain to 12.5% of the clones at the age of 7 years. There was a decrease of 8.99% in grain base deviations from the base to the top and 31.28% increase in the pith direction of the trees, and significant correlations with the propagation velocity of stress waves and volumetric shrinkage of the wood, for the genetic materials of the age of 13 years. For DB, CV, compressive strength parallel to fibers, MOR and MOE in static bending, MOEd by stress wave, ultrasound and transverse vibration, and propagation velocity of ultrasonic waves in wood clones at 13 years, there were no correlations with the deviations of grain.
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Palavras-chave
Maximum angular deviation , Non-destructive methods , Máximo desvio angular , Contrasting environments , Métodos não destrutivos , Wood quality , Ambientes contrastantes
Citação
COELHO, José Clailson Franco. Efeitos dos desvios da grã nas variáveis dendrométricas e propriedades físico-mecânicas em madeiras de eucalipto. 2016. 58 f. Dissertação (Mestrado em Ciências Florestais) – Programa de Pós-Graduação em Ciências Florestais, Universidade Federal do Espírito Santo, Centro de Ciências Agrárias e Engenharias, Jerônimo Monteiro, 2016.