Juan Eduardo Díaz-vaz

COMPRESSION WOOD IN Pinus radiata II: DENSITY AND CHEMICAL COMPOSITION

Ten 22 year old radiata pine trees growing in two stands in Chile, one in clay and the other in humid sand soils showing some lean, were assessed for chemical composition and wood density of compression wood. Signifi cant differences in type of wood in density (33 kg/m 3 ), lignin (1.944 %), alpha-cellulose (-2.634 %), ethanol toluene extractives (0.567 %) and pentose (0.742 %) were found between matched sample of compression and opposite woods. Differences in juvenile and mature wood were signifi cant for both density (-4 kg/m 3 ) and pentose (1.628 %), and site differences were found for wood density (28 kg/m 3 ), extractives (0.978 %) and apparent for alpha cellulose (1.223%).

Testing New In-Kiln Meter for Monitoring Lumber Moisture Content during Drying

The objective of this study was to test a new in-kiln sensor for monitoring lumber moisture content during industrial drying. The theoretical foundation of the technology was already known, because it is based on electrical conductivity, but the mechanism of implementation was new and required validation. For this reason, the technology was compared with two other widely used methods for assessing lumber moisture content, namely, the oven-drying and electrical capacitance methods. The tests were performed in a 120-m3 industrial kiln operated by a sawmill in the eighth region of Chile, and the results showed that the average moisture content at the end of drying was satisfactorily determined by the new in-line sensor. As predicted by theory, the sensor was not able to accurately measure moisture content above 25%, but it was still able to provide the equivalent of a drying curve for monitoring of the drying process.

PROPERTY CHARACTERIZATION OF Chusquea culeou, A BAMBOO GROWING IN CHILE

Property characterization of Chusquea culeou Desv. (colihue), a bamboo growing in Chile, was conducted. Physical, chemical and mechanical properties were determined as a function of plant diameter, position in culm length and nodal or internodal sections. The results show that fi bre length increased from the base to the top of the culms. Differences in the fi bre length between nodes and internodes were observed. In the internodes higher moisture content, lower specifi c gravity and lower extractive content were also found. Extracts and ash content in the samples tested were higher than those determined for commercial Chilean woods. Hemicellulose, cellulose, and lignin proportion indicate that the colihue could be used as raw material for pulp and paper production. The measured mechanical properties (bending strength, compression, hardness, shear strength) are higher than those of poplar wood but lower than radiata pine growing in Chile.

MADERA DE COMPRESIÓN EN PINUS RADIATA D. DON: I, CARACTERÍSTICAS ANATÓMICAS

Compression wood in 10 Pinus radiata D. Don trees with lean smaller to 10o from two sites were characterized. The tracheid diameters of the trees of the humid sand site were statistically greater than those from the clay site; but they were not different when comparing juvenile wood with mature wood or to it compares compression wood with opposite wood. Significant differences were determined in the tracheid length between sites (humid sand-clay), type of wood (compression-opposite wood) and age (juvenile-mature wood), were similar results with other authors. For coarseness non significant differences between sites, as well as between juvenile and mature wood and compression and opposite and agree and different from those of other authors who compare trees of different sites. The discrepancies and coincidences of these results with those of other authors are explained considering the behavior from the cellular dimensions of the earlywood and latewood wood and the differences between severe compression and mild compression wood.

Análisis de conservación y estructura celular de la madera de seis canoas monóxilas del centro sur de Chile

La madera, a pesar de ser un material organico biodegradable, es suficientemente resistente al deterioro bajo ciertas condiciones naturales. Restos y artefactos de madera saturados en agua y de origen cultural se han registrado en diferentes sitios arqueologicos del sur de Chile. Sin embargo, el estudio de este tipo de materiales culturales aun es insuficiente en nuestro pais, ya que en la mayoria de los casos no se han aplicado metodologias adecuadas para su analisis y preservacion. A partir de este estudio planteamos la necesidad de introducir nuevas perspectivas en torno a esta tematica y esperamos iniciar una renovada etapa en las investigaciones arqueologicas de esta materialidad en el sur de Chile.

Predicción del contenido de humedad de equilibrio de la madera en función del peso específico de la pared celular y variables ambientales

The equilibrium moisture content (EMC) variation owing to the time in species with different basic density (BD) was determined. Further, of generating a model for the prediction of EMC as a function of environmental factors and some physical properties of wood. Small samples of 2.5 x 7.5 x 20 cm in depth, width and length, respectively, from 3 conifers and 6 hardwoods were located in a shed at the exterior. And the weight of small samples (WSS), as well as, the temperature (T) and relative humidity (RH) of air were controlled, once a week and for 2 years. After finishing the trial the basic density (BD), oven dry density (ODD), specific gravity of the cell wall (SGCW) and porosity (P) of the small samples were determined. EMC variation of wood in relation to the time was higher, in species with lower BD and higher V. The predicting model that considered the T, RH, SGCW and WSS as independent variables explained in a 98.5 % the variation of EMC. The correlation coefficient (R) between measured EMC and estimated EMC by the predicting model was 0.979.

CONDICIONANTES DE LAS GRIETAS INTERNAS DENTRO DE LOS ANILLOS DURANTE EL SECADO DE PINO RADIATA

The internal checking during the industrial drying of radiata pine is studied. The percentage of internal checking is determined and some factors influencing the internal checking are analyzed during the industrial drying at conventional temperatures. The runs are made in a 150 m 3 capacity dry kiln in an industrial plant of the Eighth Region (Chile). The experimental design includes as variables, the origin site of the wood (clay, sand), the wood localization (central-wood, lateral-wood and transition-wood) and the type of cut (radial, tangential and mixed). The results indicate that the percentage of internal checking varies between 1 and 18% and that the origin site of the wood and the wood localization significantly condition the percentage of internal checking during the radiata pine industrial drying at conventional temperatures.