Efecto de la humedad de equilibrio en la rugosidad de tableros de fibras de densidad media (MDF)

La rugosidad superficial es primariamente una función de las propiedades de la materia prima, pero otros factores como la cantidad y el tipo de resina, ciclo de prensado, lijado y contenido de humedad de los tableros pueden afectar la rugosidad y otras propiedades de la superficie. En este estudio los efectos del contenido de humedad de equilibro en superficies de tableros de densidad media (MDF), fueron evaluados usando diferentes materias primas en sus superficies como también diferentes adhesivos. El análisis estadístico confirma que la relación entre el contenido de humedad de equilibrio y la rugosidad media es una compleja función de interacciones entre muchas variables, pero donde tiene un papel relevante desde el punto de vista practico el tipo de adhesivos. AbstractThe surface roughness is primarily a function of the raw material properties, but other factors like type and amount of resin, press cycle, sanding and moisture content of the boards may also affect the roughness and other surface properties. In this study the effect of the equilibrium moisture content on medium density fiberboards (MDF) surfaces was evaluate using different raw materials in their surface layers as well as different binders. The statistical analysis confirmed that the relationship between equilibrium moisture content and average roughness are a complex function of interactions between many variables

Extraíbles de cortezas chilenas: Efecto sobre la luminiscencia de bacterias

Se determinó la disminución de la bioluminiscencia de bacterias como indicador de la actividad biológica de extractos de corteza. Se analizaron cuatro cortezas nativas chilenas. La reducción de la bioluminiscencia fue diferente dependiendo de la especie de corteza.El aumento del tiempo de un tratamiento térmico de la corteza (24, 48, 72 y 144 horas con 103ºC) produjo una reducción de la actividad biológica de los extractos. El estudio indica que los terpenos podrían ser responsables del efecto señalado. AbstractBioluminescence decrease of bacteria as a biological activity indicator for bark water extracts was determinate. Four Chilean barks were tested. A different reduction on bioluminescence depending on bark species was observed.Increasing time of thermal treatment of bark (24, 48, 72 and 144 hours with 103ºC) produced a reduction of the biological activity of extracts. The study indicates that the terpenes could be responsible for the described effect

On the formaldehyde release of wood

The paper addresses the role of the main components of wood cellulose, hemicellulose, and lignin as well as of wood extractives as a potential source of formaldehyde. Lignin seems to have a higher emission potential than cellulose and hemicellulose. Moreover, the results reveal that on the one hand extractives release formaldehyde and on the other hand that certain wood extractives react with formaldehyde and hence act as a formaldehyde scavenger. Formaldehyde emanates from wood at temperatures as low as 40 degreesC. Higher temperatures increase the formaldehyde emission tremendously. Therefore, thermo-mechanical pulping enhances formaldehyde release exorbitantely. Differences in the formaldehyde emission between wood species are discussed and related to differences in their chemical composition

Efecto de la humedad de equilibrio en la rugosidad de tableros de fibras de densidad media (MDF)

The surface roughness is primarily a function of the raw material properties, but other factors like type and amount of resin, press cycle, sanding and moisture content of the boards may also affect the roughness and other surface properties. In this study the effect of the equilibrium moisture content on medium density fiberboards (MDF) surfaces was evaluate using different raw materials in their surface layers as well as different binders. The statistical analysis confirmed that the relationship between equilibrium moisture content and average roughness are a complex function of interactions between many variables.La rugosidad superficial es primariamente una función de las propiedades de la materia prima, pero otros factores como la cantidad y el tipo de resina, ciclo de prensado, lijado y contenido de humedad de los tableros pueden afectar la rugosidad y otras propiedades de la superficie. En este estudio los efectos del contenido de humedad de equilibro en superficies de tableros de densidad media (MDF), fueron evaluados usando diferentes materias primas en sus superficies como también diferentes adhesivos. El análisis estadístico confirma que la relación entre el contenido de humedad de equilibrio y la rugosidad media es una compleja función de interacciones entre muchas variables, pero donde tiene un papel relevante desde el punto de vista practico el tipo de adhesivos.

Effect of the equilibrium moisture on the roughness of medium density fiberboards (mdf)

The surface roughness is primarily a function of the raw material properties, but other factors like type and amount of resin, press cycle, sanding and moisture content of the boards may also affect the roughness and other surface properties. In this study the effect of the equilibrium moisture content on medium density fiberboards (MDF) surfaces was evaluate using different raw materials in their surface layers as well as different binders. The statistical analysis confirmed that the relationship between equilibrium moisture content and average roughness are a complex function of interactions between many variables

Influence of climatic conditions and surface roughness on the wettability of medium density fiberboards (MDF)

Wettability of wood surface is measured by the contact angle between the liquid and the surface of the wood. In this study, the wettability of MDF surfaces was measured using different mixtures of distilled water and isopropanol. The results reveal that TF-bonded MDF made from fresh and recycled fibers showed better wettability than the corresponding MUF-bonded MDF. Moreover, the entire results indicate that roughness is one of the most important influencing factors on the wettability of MDF surfaces

Verringerung der Emission von Thermoholz durch nachträgliche Behandlung mit Ammoniak

Thermally modified timber (TMT) emits a high amount of aldehydes (furfural, formaldehyde) and volatile organic acids (formic and acetic acids). The release of alde- hydes and acids, as assessed by the flask-method (EN 717- 3), can be reduced significantly by ammonia fumigation. The emission of formaldehyde is attenuated by more than 90%. Emission of furfuraldehyde decreased in most cases by more than 70%. The pH-value of TMT increased due to ammonia fumigation above the neutral point indicating buffering of the volatile acids.ISSN:0018-3768ISSN:1436-736

Extraíbles de cortezas chilenas: Efecto sobre la luminiscencia de bacterias

Se determinó la disminución de la bioluminiscencia de bacterias como indicador de la actividad biológica de extractos de corteza. Se analizaron cuatro cortezas nativas chilenas. La reducción de la bioluminiscencia fue diferente dependiendo de la especie de corteza.El aumento del tiempo de un tratamiento térmico de la corteza (24, 48, 72 y 144 horas con 103ºC) produjo una reducción de la actividad biológica de los extractos. El estudio indica que los terpenos podrían ser responsables del efecto señalado. AbstractBioluminescence decrease of bacteria as a biological activity indicator for bark water extracts was determinate. Four Chilean barks were tested. A different reduction on bioluminescence depending on bark species was observed.Increasing time of thermal treatment of bark (24, 48, 72 and 144 hours with 103ºC) produced a reduction of the biological activity of extracts. The study indicates that the terpenes could be responsible for the described effect