5 research outputs found
Módulo dinámico por vibraciones transversales de madera densificada de Gyrocarpus americanus
Get PDFEl densificado artificial de la madera incrementa sus propiedades tecnológicas. Como consecuencia, especies poco apreciadas pueden ser empleadas en productos con valor agregado. Los objetivos de la investigación fueron densificar madera de Gyrocarpus americanus con un tratamiento higro-termo-mecánico y evaluar su módulo dinámico antes y después del densificado.
Se determinó la densidad de la madera y se realizaron pruebas de vibraciones transversales antes y después del densificado. Se calcularon los módulos dinámicos y el coeficiente de densificado. Para las variables de respuesta, se realizaron pruebas de normalidad, de diferencias de medias y análisis de regresiones. El tratamiento higro-termo-mecánico fue eficiente para densificar madera de G. americanus. Los valores de la densidad de la madera y del módulo dinámico aumentaron después de densificar la madera de G. americanus y sus magnitudes fueron comparables con los reportados en la bibliografía. Los coeficientes de determinación de regresiones lineales explicaron satisfactoriamente la variación ocasionada por el tratamiento de densificado en la densidad de la madera, la frecuencia y el módulo dinámico
Effects of density profile of MDF on stiffness and strength of nailed joints
Get PDFNail-head pull-through, lateral nail resistance, and single shear nailed joint tests were conducted on medium density fiberboard (MDF) with different density profiles, and the relations between the results of these tests and the density profiles of MDF were investigated. The maximum load of nail-head pull-through and the maximum load of nailed joints were little affected by the density profile. However, the ultimate strength of lateral nail resistance, the stiffness, and the yield strength of nailed joints were affected by the density profile of MDF and showed high values when the surface layer of the MDF had high density. It is known that bending performance is also influenced by density profile. Therefore, the stiffness and the yield strength of nailed joints were compared with the bending performance of MDF. The stiffness of nailed joints was positively correlated with the modulus of elasticity (MOE); in the case of CN65 nails, the initial stiffness of joints changed little in response to changes in MOE. The yield strength of nailed joints had a high positive correlation with the modulus of rupture (MOR). The stiffness and the yield strength of nailed joints showed linear relationships with MOE and MOR, respectively
Retention and absorption of boron salts solution of ten mexican woods
Get PDFLas sales de boro son un agente protector para la madera con un amplio espectro en su acción fungicida e insecticida, de poca toxicidad, inodoras, incoloras e incombustibles, y su aplicación es una de las estrategias más efectivas de preservación. La presente investigación tuvo por objetivo determinar la densidad de la madera, la absorción y la retención de sales de boro de diez maderas mexicanas. Se propuso como hipótesis de trabajo que la capacidad de retención de sales de boro de la madera depende, principalmente, de la especie, y es independiente de la densidad y de la porosidad. Se prepararon 30 litros de solución de sales de boro con una concentración al 3%. Las probetas se impregnaron con el método baño caliente-frío. Se diseñó un experimento de análisis de varianza para comparar los valores medios de la densidad de la madera, de la absorción y de la retención, como las variables de respuesta, evaluadas para cada una de las diez especies de madera. La especie de madera fue considerada el factor de variación. La absorción de sales de boro varió entre 136 kg/m3 y 476 kg/m3. Los valores promedio de retención de sales de boro para todas las especies fueron mayores que el límite inferior tóxico de retención comprendido en el intervalo de retención que va de 0.2 kg/m3 a 4.7 kg/m3, reportado en trabajos anteriores. Se concluye que cada especie tiene una retención de sales de boro diferente, y la capacidad de absorción es particular a cada una de ellas y no está relacionada con su densidad.Boron salts are a wood protector agent with a wide spectrum in their fungicidal and insecticide action and of low toxicity, odorless, colorless and nonflammable, and their application is one of the most effective preservation strategies. This research aims to determine the density of wood, absorption and retention of the boron salts of ten Mexican woods. The working hypothesis proposed in this investigation is that wood retention capacity of boron salts depends mainly on the species and is independent of its density and porosity. Thirty liters of boron salts solution with a concentration of 3 % were prepared, the wood specimens were impregnated by following the “hot-cold bath” method. It was designed an experiment that compared means of the density of wood, the absorption and the retention, as the response variables, assessed for each one of the ten wood species. Wood species was considered as the variation factor. Absorption of Boron salts varied between 136 kg/m3 and 476 kg/m3. Average values of the boron salts retention for all species were higher than lower retention toxicity limit reported in previous researches (0.2 kg/m3 to 4.7 kg/m3). It was concluded that each species has different boron salts retention. Absorption capacity is specific to each species and it is not related to the wood density
Effect of Thermal Treatment on Selected Fire Safety Features of Tropical Wood
No full textThe subject matter of the article is thermally modified tropical wood (Meranti and Merbau) and its reaction on fire. Thermal treatment of wood (thermal wood) is a new technology of wood treatment improving its physical and biological properties and increasing its resistance to biological wood destroying processes and atmospheric effects. The fire and technical properties of thermal wood, especially its reaction to fire, have not been studied sufficiently. The latter is the subject matter of this article. A comparison is made to describe the influence of process temperatures of the thermal modification of selected tropical woody plants. Experimental equipment was non-standardized laboratory equipment using a flame source of higher intensity (flame burner - propane-butane) affecting the test sample in an open environment. This is a simulation of an actual fire. The performance of the thermally treated wood (20 °C, 160 °C, 180 °C) is evaluated by measuring the weight loss and the burning rate. The results are presented in tables and diagrams and are statistically evaluated. This study investigated the effects of the thermal treatment of Merbau and Meranti wood on selected burning characteristics. The results obtained from raw (untreated) wood test specimens were compared to results obtained from the test specimens subjected to thermal treatment at 160 °C, 180 °C and 210 °C. The monitored characteristics were weight loss and the burn rate. The results showed that the thermal treatment of Merbau and Meranti wood significantly increased its flammability and accelerated its combustion. In addition, its burn rate was higher than in untreated wood, reflecting that it is necessary to add fire retardants to thermally treated Merbau and Meranti wood
