Determination of fiber length and juvenile and mature wood zones from Hevea brasiliensis trees grown in Brazil

The aim of this study was to verify the average fiber length and the juvenile and mature wood zones from Hevea brasiliensis proveniences from a reforestation area in São Paulo, Brazil. For this purpose, five Hevea brasiliensis trees were randomly collected from a 50-year-old plantation, located in Balsamo, São Paulo, Brazil. The trees were cut and five flat sawn boards were obtained. The juvenile and mature wood zones were determined by fiber length measurement from the pith to the bark. The results showed that: (a) the juvenile wood of this species occurred approx. between 40 and 55 mm, from the pith, and from this point forward, the mature wood zone was found; (b) there was a significant difference between the average fiber length of juvenile wood (1.26 mm) and mature wood (1.51 mm).

Physical and chemical changes in juvenile and mature woods of Pinus elliottii var. elliottii by thermal modification

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Kraft pulp from juvenile and mature woods of corymbia citriodora

Kraft pulp produced from juvenile and mature wood from thirty-two-year-old Corymbia citriodora trees was evaluated. The stem was subdivided into regions of juvenile and mature wood, and then it was transformed into chips. These materials were then cooked in the Laboratory of Pulp and Paper at São Paulo State University (UNESP, Botucatu, SP, Brazil) and the physico-mechanical properties of the pulps were determined. The results showed that: (1) the pulp yields of mature wood were up to 4.4% greater in comparison to the juvenile wood, (2) the juvenile wood pulp required a shorter refining time than mature wood to reach the same Schopper-Riegler degree, (3) the juvenile wood pulp presented lower specific volume, and (4) the mature wood pulp presented greater air resistance, tensile, tear and burst index values, stress-strain factor, and stretch than the juvenile wood pulp.

Effect of thermal modification on the physical properties of juvenile and mature woods of Eucalyptus grandis

This study aimed to evaluate the effect of thermal treatment on the physical properties of juvenile and mature woods of Eucalyptus grandis. Boards were taken from 30-year-old E. grandis trees. The boards were thermally modified at 180 °C in the Laboratory of Wood Drying and Preservation at UNESP, Botucatu, Sao Paulo state, Brazil. The results showed that thermal modification caused: (1) decrease of 6.8% in the density at 0% equilibrium moisture content of mature wood; (2) significant decreases of 14.7% and 35.6% in the maximum volumetric swellings of juvenile and mature woods, respectively; (3) significant decreases of 13.7% and 21.3% in the equilibrium moisture content of juvenile and mature woods, respectively. The influence of thermal modification in juvenile wood was lower than in mature wood and caused greater uniformity in the physical variations between these types of wood in E. grandis.

Properties of juvenile and mature woods of Hevea brasiliensis untapped and with tapping panels

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades físicas dos lenhos juvenil e adulto de Pinus elliottii Engelm var. elliottii e de Eucalyptus grandis Hill ex Maiden

The juvenile wood presents great difference in its anatomical and physical properties in relation to the mature wood. That heterogeneity of the wood causes a series of upset for the processing industry. The present research had as objective the study of the physical properties of the juvenile and mature wood of Pinus elliottii Engelm var. elliottii, with 25 years of age and of Eucalyptus grandis Hill ex Maiden, with 30 years of age, coming from the Experimental Station of Itapetininga and State Forest of Santa Barbara, belonging to the Forest Institute of the state of São Paulo. From both species there were taken from radial boards, specimens with dimensions of 20x30x50 mm, for the determination of density, swelling and swelling coefficient of the juvenile and mature wood. The results of the species showed that the mature compared with the juvenile wood presented: (1) an increase in the values of the basic density, at 0% and at 12% of moisture content and of the volumetric, radial and tangential swelling at 12% moisture content and maximum coefficient of radial and tangential swelling; (2) a reduction in the values of longitudinal swelling at 12% and maximum and of the longitudinal swelling coefficient.

Propriedades de resistência e rigidez da madeira juvenil e adulta de Pinus taeda L.

O objetivo do presente trabalho foi o estudo da variabilidade das propriedades de resistência e rigidez à flexão estática e à densidade aparente (12%) entre a madeira juvenil e adulta de Pinus taeda L., de 37 anos de idade, procedente do Horto Florestal de Manduri, Estado de São Paulo. Na primeira parte do trabalho foram determinadas a região de madeira juvenil, a região de transição e a região de madeira adulta, por meio de estudos anatômicos (comprimento dos traqueídes axiais), segundo as recomendações das normas ABNT e IAWA. Os resultados mostraram que a região de madeira juvenil dessa espécie ocorre aproximadamente até o 18º anel de crescimento. Na segunda parte do trabalho foram analisados a resistência (módulo de ruptura - MOR) à flexão, o módulo de elasticidade (MOE) nessa mesma solicitação e a densidade aparente (12%) para as madeiras juvenil e adulta. Os resultados mostraram que o MOE e o MOR da madeira juvenil foram menores e mais variáveis que aqueles obtidos para madeira adulta. A densidade apresentou a mesma tendência observada nas propriedades avaliadas no ensaio de flexão estática.

Determinação do módulo de elasticidade da madeira juvenil e adulta de Pinus taeda por ultra-som

A madeira de Pinus sp. tem utilização crescente na indústria madeireira brasileira. O decréscimo constante do suprimento de árvores adultas com grandes diâmetros, provenientes de florestas naturais, tornou comum a produção de madeira em ciclos curtos, com grande proporção de madeira juvenil. Resultados de diversas pesquisas têm reportado que o módulo de elasticidade e a resistência a diferentes solicitações mecânicas são seriamente afetados pela presença de madeira juvenil. Este trabalho teve por objetivo determinar o módulo de elasticidade da madeira juvenil e adulta de Pinus taeda L. a partir da constante dinâmica C LL, obtida em ensaios não-destrutivos de ultra-som. A madeira de P. taeda era originária de plantios da Estação Experimental de Itapeva - SP, sendo amostrados seis indivíduos arbóreos com 34 anos de idade. Os corpos-de-prova (4 cm x 4 cm x 45 cm) foram obtidos separadamente das regiões de madeira juvenil e adulta da prancha central, previamente submetida à secagem industrial (umidade final de 12%), para a determinação da constante dinâmica por meio de ensaios de ultra-som. Para avaliar a sensibilidade do método do ultra-som, os corpos-de-prova foram ensaiados destrutivamente à compressão paralela. Os resultados mostraram boa sensibilidade do método do ultra-som (R² » 0,90) na avaliação desse parâmetro mecânico da madeira juvenil e adulta.

Propriedades de contração na madeira juvenil e adulta de Pinus taeda L.

This paper had the objective of studying variability of radial, tangential, longitudinal and volumetric shrinkage between the juvenile and mature wood, from a 35 year-old Pinus taeda L., from Horto Florestal of Manduri at São Paulo State, Brazil. First of all the experimental program determinations were related to the juvenile wood, region of the transition and region of the mature wood, using anatomical analysis (length of the axial tracheids), according to ABNT and IAWA codes. Results had shown that the area of juvenile wood of this species occurs approximately until the 20th growth ring, being more representative until the 12th ring. The transition area of this wood occurs between the 12th and 20th growth ring. In the second part of the work the shrinkage of the juvenile and mature wood were evaluated. Values of the radial, tangential and volumetric shrinkage were smaller and more variable on the juvenile wood. The longitudinal shrinkage did not present significant differences between the two wood types; medium values were slightly inferior and very variable on juvenile wood related to mature wood.

Mensuração do comprimento das fibras para a determinação da madeira juvenil em Eucalyptus citriodora

The juvenile wood has peculiar characteristics from the anatomical structure and physical-mechanical properties, considering these aspects the knowledge of the wood is essential for wood adequate utilization. The aim of this work was to determinate the zone of juvenile wood of pith-bark direction in Eucalyptus citriodora. The juvenile and mature wood zones were determined across fiber length measurement in various height in the tree stem. Results showed that juvenile wood zone occurs approximately up to the 45 at 55 mm from the pith.

Delimitação entre os lenhos juvenil e adulto de pinus elliottii engelm

Trees produce different types of woody tissue during growth. The xylem produced in the first years until a certain cambial age is called juvenile wood and has different physical, mechanical, chemical and anatomical characteristics from that produced later, when the cambial cells have matured. Thus, prior knowledge of the quality of the wood is of fundamental importance for choosing the best use of the material. This work aimed at using data from length of the tracheid and wood density to define the age transition from juvenile to mature wood. For this, three Pinus elliottii var. elliottii trees, aged 35 years, were collected at the Itapetininga Experimental Station, located in the state of São Paulo, Brazil. From each tree, disks of about 5 cm thick were obtained 0.05 m above the ground and used to determine the radial density by the gamma ray attenuation method and to measure the length of the tracheids. The results obtained by linear regression analysis showed that juvenile wood is limited to the first seven years of tree growth and the formation of mature wood occurs after twenty years. For the mature wood, there are significant differences among the averages obtained from the tracheid length and wood density.

Influência das características dos anéis de crescimento na densidade, resistência e rigidez da madeira de Pinus taeda L

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Determinação das propriedades físicas e químicas da madeira de Hevea brasiliensis em relação ao painel de extração de látex

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação das propriedades físico-mecânicas da madeira de árvores de Hevea Brasiliensis em três condições de sanidade no Estado de São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo da estrutura anatômica e das propriedades físicas e mecânicas da madeira de Corymbia (Eucalyptus) citriodora e Eucalyptus grandis

Pós-graduação em Agronomia (Energia na Agricultura) - FCA