Elias Taylor Durgante Severo

Decay resistance of thermally-modified Eucalyptus grandis wood at 140 °C, 160 °C, 180 °C, 200 °C and 220 °C

The objective of this study was to evaluate the effect of thermal treatment on the biological resistance of Eucalyptus grandis wood to the decay fungus Picnoporus sanguineus. Boards from 5 years and 11 months old E. grandis trees, taken from the stock possessed by the Duratex-SA company, were thermally-modified at 140 degrees C, 160 degrees C, 180 degrees C, 200 degrees C and 220 degrees C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, Brazil. Samples of each treatment were treated according to ASTM D-2017 (1994). The experiment tested the accelerated decay caused by the decay fungus P. sanguineus on a system of soil-block wood. The results of thermal treatment showed that an increase of temperature of 180-220 degrees C caused reductions of between 15.7% and 82.4% in the weight loss in the samples from E. grandis incubated with P. sanguineus.

Efeito da vaporização de toras na redução dos defeitos associados a tensões de crescimento de Eucalyptus grandis .

The present study was carried out to evaluate log steaming effect on the reduction of defects associated with residual growth stress of Eucalyptus grandis wood. There were used logs with diameter of 20 to <25, 25 to <30 and 30 to <35 cm, from the Horto Florestal, Manduri, Sao Paulo. Half of the logs was steamed during 20 hours at 90oC of temperature and 100% of relative humidity. Subsequently, the logs were live sawn and the defects resulting from the growth stresses in logs of various diameter were measured. The results indicate that log steaming provided the release of a great part of the growth stresses, without eliminating them completely, showing, nevertheless, that this treatment is feasible and advisable for growth stress relief; the boards coming from heated logs of 20 to <25 cm presented, in general, larger defect reduction, showing that the smaller the log diameter the higher the efficiency of steam treatment at 90oC of temperature during 20 hours.

Selection of fungi for accelerated decay in stumps of Eucalyptus spp.

The objective of this study was to select decay fungi for biological degradation of stumps and roots from Eucalyptus spp. in forest stands. Five fungal isolates were cultured. Subsequently, inoculated in accelerated-decay tests and field tests with tree stumps of Eucalyptus spp. present in a stand belonging to Votorantim Company were conducted. The results showed that: (1) the decay of stumps by Pycnoporus sanguineus and Ganoderma applanatum increased by up to 49.2% and 48.9%, respectively; (2) the enclosing stumps in a polyninyl chloride resulted in a reduced on the resistance due to enhanced decay as measured by an inpact penetrometer in the forest stands at Luiz Antônio, Capão Bonito, and Jacareí, SP, Brazil; and (3) the selected fungi did not show any pathogenic potential toward seedlings and adult trees. This study presents the foundation for the development of a biological system for stump removal in forest stands comprising Eucalyptus spp.

Lumber quality of Eucalyptus grandis as a function of diametrical position and log steaming.

The objective of this study was to evaluate the effect of log steaming and of the diametrical position of boards on the timber quality of Eucalyptus grandis. Logs with diameters between 20 and 25 cm, between 25 and 30 cm and between 30 and 35 cm were studied. Half of logs were kept in its original condition, and the other half was steamed at 90 degrees C for 20 h. Later, the logs were cut into flat saw boards, and defects due to growth stress relief were measured. The results show that: (1) boards from control logs show different magnitudes of cracking according to the diameter of the log and the diametrical position of the board; (2) boards from logs with diameters between 30 and 35 cm and those from next to the pith develop larger cracks; and (3) boards from steamed logs show a reduction in the magnitude of cracking and a homogenous distribution of this defect relative to diametrical position within the log.

Effect of steam thermal treatment on the drying process of Eucalyptus dunnii variables

The aim of this study was to evaluate the effect of steam treatment prior to drying on the initial moisture content, moisture gradient, and drying rate in Eucalyptus dunnii Maiden wood. Boards were steamed at 100oC for 3 h after 1 h of heating-up. Part of these boards was dried in a drying electric oven at 50oC, and part was dried at kiln. The results showed that the steaming prior to drying of wood: (1) significantly reduced by 9.2% the initial moisture content; (2) significantly increased by 6.2% the drying rate; (3) significantly decreased by 15.6 and 14.8% the moisture gradient between the outer layer and the center of boards and between the outer and intermediate layers of boards, respectively. Steamed boards when dried in an oven showed drying rate of 0.007065 whereas in kiln were 0.008200 and 0.034300 from green to 17 and 17 to 12% moisture content, respectively. It was demonstrated that the steaming prior to drying can be suitable for reduces the drying times of this kind of wood.

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

O lenho juvenil apresenta grande diferenca em suas propriedades anatomicas e fisicas em relacao ao lenho adulto. Essa heterogeneidade da madeira causa uma serie de transtornos para a industria de transformacao e processamento. O presente trabalho teve como objetivo o estudo das propriedades fisicas dos lenhos juvenil e adulto de Pinus elliottii Engelm var. elliottii, com 25 anos de idade, e de Eucalyptus grandis Hill ex Maiden, com 30 anos de idade, provenientes da Estacao Experimental de Itapetininga e da Floresta Estadual de Santa Barbara, pertencentes ao Instituto Florestal do Estado de Sao Paulo. Para tanto, de ambas as especies, foram retirados, de tabuas radiais, corpos de prova com dimensoes de 20x30x50 mm, para a determinacao das massas especificas, dos inchamentos e dos coeficientes de retratibilidade dos lenhos juvenil e adulto. Os resultados das especies mostraram que os lenhos adultos comparados com os lenhos juvenis apresentaram: (1) um aumento nos valores das massas especificas basica, a 0% e a 12% de umidade, dos inchamentos volumetricos e lineares tangencial e radial a 12% de umidade e maximos, e dos coeficientes de retratibilidade tangencial e radial; (2) uma reducao nos valores de inchamentos lineares longitudinais a 12% de umidade e maximos, e do coeficiente de retratibilidade longitudinal.

Use of glass transition temperature for stabilization of board's cracks of Eucalyptus grandis

The Eucalyptus grandis logs temperatures were determined and correlated with the boards cracks during steaming. Thermocouples were inserted in the logs center, registering their temperatures during steaming at 90°C. The logs were sawed and the boards cracks measured. It was concluded that: (1) the logistic S-shaped curve explains the logs temperature variation; (2) the logs with diameter of 20 to <25, 25 to <30 and 30 to <35 cm presented, respectively, 84.2°C, 73.1°C and 45.8°C in the steaming; and (3) the cracks lengths significantly decreased in logs that reached the glass transition temperature.

Drying behavior and decay resistance of rubberwood from steamed log and presteamed lumber

ABSTRACT The objective of this study was to evaluate the effect of log steaming and steaming prior to drying singly and both treatments together on the drying behavior and decay resistance of Hevea brasiliensis wood (rubberwood). Logs with a diameter of 34.6 ± 4.4 cm were used. Half of the logs were kept in their original condition, and the other half were steamed at 90°C for 36 h. Later, the logs were cut into flat sawn boards. Half of the boards were kept in their original condition, and the other half were presteamed at 90°C for 3 h after 1 h of heating-up. These boards were dried in a drying kiln. The drying defects, drying time, drying rate, and decay resistance of wood to the Pycnoporus sanguineus fungus were determined. The results showed that the steaming is not suitable for decreases in the time and the drying rates of this kind of wood, and it neither reduces the drying defects of boards. Furthermore, these treatments adversely affected the decay resistance of rubberwood to P. sanguineus fungi.

ANATOMICAL CHARACTERIZATION OF TENSION WOOD IN Hevea brasiliensis (Willd. ex A. Juss.) Mull. Arg.

O lenho de tracao e uma estrutura anatomica importante, que permite a reorientacao do tronco e participa na arquitetura dos ramos, tendo a funcao de reforco estrutural. Contudo, sua presenca em grande quantidade afeta significativamente as propriedades tecnologicas da madeira, como no caso da seringueira. Entretanto, ainda ha demanda de informacoes acerca de sua origem, distribuicao e caracteristicas estruturais nessa especie. Portanto, esse trabalho objetivou caracterizar as estruturas celulares no lenho de tracao e lenho oposto em Hevea brasiliensis (seringueira) e sua distribuicao radial e longitudinal. Para tanto, discos da base e do meio do fuste comercial foram coletados de tres arvores provenientes de um plantio comercial localizado em Tabapoa - SP. Foram mensurados o diâmetro tangencial dos elementos de vaso, comprimento de fibras (gelatinosas e nao-gelatinosas), ângulo microfibrilar e proporcionalidade de elementos celulares, e a relacao entre a presenca de fibras gelatinosas e o diâmetro de vasos. Foram observadas fibras gelatinosas nos dois tipos de lenho e nas duas alturas do fuste avaliadas. Os dois tipos de lenho foram diferenciados pelo comprimento de fibras gelatinosas e a proporcao de parenquima axial. A regiao de tracao no meio do fuste foi a que mais se diferenciou das demais, com fibras gelatinosas mais compridas e menos abundante, maiores diâmetro e proporcao de vasos.Alem disso, foi observado menor diâmetro de vasos nas regioes com alta proporcao de fibras gelatinosas, sugerindo que a planta investe mais em sustentacao que na conducao de liquidos.