Incidencia de la impregnación de madera con alcohol polivinilico y polietilenglicol en algunas propiedades físicas y mecánicas de pino oocarpa

This research was performed with Pinus oocarpa Schiede ex Schltdl. Var. Ochoterenai of Forest Plantation of Colombia, which presents some important troubles that limiting its use, due to its low dimensional stability and mechanical resistance.  Polymer impregnation treatments could reduce deformation and improve physical and mechanical properties of the wood. The aim of this research was evaluated the effect of polyethylene glycol impregnation with molecular weight 600 and 1500, polyvinyl alcohol and zeolite addition, on density, dimensional stability, static flexion and compression parallel to Grain. The samples were impregnated in hot bath at 95 °C for 8 hours, and then impregnated at room temperature for 16 hours. The assessment of the wood was carried out under the Colombian Technical Standards NTC 290, 663, 784 and other standards. The best results were obtained with the impregnation of polyethylene glycol 1500 where the density increased between 21 % and 24 %; the anti-swelling efficiency was 60 %; in static flexion the modulus rupture increased 20 %, modulus of elasticity 39 % and compression parallel to grain increased 8 %.  Wood changed to the structural lumber category, improving in its mechanical and physical properties.  Treatment with polyethylene glycol 600 provided lower anti-swelling efficiency (14%), and lower improvement in density (8%), and in mechanical properties (1% to 7%)

Incidence of the impregnation of wood with poly vinyl alcohol and polyethylene glycol on some physical and mechanical properties of oocarpa pine

This research was performed with Pinus oocarpa Schiede ex Schltdl. Var. Ochoterenai of Forest Plan-tation of Colombia, specie that have presented some important troubles that have limited its use, due to its dimensional instability and low mechanical resistance. Polymer impregnation treatments have reduced defor-mation and improved physical and mechanical properties of the wood. The aim of this research was evaluated the effect of polyethylene glycol impregnation with molecular weight 600 and 1500, polyvinyl alcohol and zeolite addition, on density, dimensional stability, static flexion and compression parallel to Grain. The samples were impregnated in hot bath at 95 °C for 8 hours, and then impregnated at room temperature for 16 hours. The assessment of the wood was carried out under the Colombian Technical Standards NTC 290, 663, 784 and other standards. The best results were obtained with the impregnation of polyethylene glycol 1500 where the density increased between 21 % and 24 %; the anti-swelling efficiency was 60 %; in static flexion the modulus rupture increased 20 %, modulus of elasticity 39 % and compression parallel to grain increased 8 %. Treat-ment with polyethylene glycol 600 provided lower anti-swelling efficiency (14%), and lower improvement in density (8%), and in mechanical properties (1% to 7%). Impregnation with polymers evidenced wood with greater dimensional stability and better physical and mechanical properties.La presente investigación se desarrolló con la madera Pinus oocarpa Schiede ex Schltdl. Var. Ochoterenai de plantación forestal de Colombia, especie que ha presentado inconvenientes importantes que han limitado su uso, debido a su inestabilidad dimensional y baja resistencia mecánica. Los tratamientos con impregnación de polímeros han permitido reducir las deformaciones, y mejorar las propiedades físicas y mecánicas. El objetivo de esta investigación fue evaluar el efecto de la impregnación de polietilenglicol con peso molecular 600 y 1500, alcohol polivinílico y adición de zeolita, sobre la densidad, estabilidad dimensional, flexión estática y compresión paralela al grano. Las muestras se impregnaron con baño caliente a 95 °C, durante 8 horas, y luego impregnados a temperatura ambiente, por 16 horas. La evaluación de la madera se llevó a cabo bajo las Nor-mas Técnicas Colombianas NTC 290, 663, 784 y otros estándares de la literatura. Los mejores resultados se obtuvieron con la impregnación de polietilenglicol 1500; la densidad aumentó entre el 21 % y 24 %; la eficien-cia anti-hinchazón fue de 60 %; en flexión estática aumentó el módulo ruptura 20 %, el módulo de elasticidad 39 % en compresión paralela al grano aumentó 8 %. El tratamiento con polietilenglicol 600 proporcionó una menor eficacia anti-hinchazón (14 %), y menor mejora en densidad (8 %) y en las propiedades mecánicas (1 % a 7 %). La impregnación con polímeros evidenció madera con mayor estabilidad dimensional y mejores propiedades físicas y mecánica

Effect of Thermal Modification Treatment on Some Physical and Mechanical Properties of <i>Pinus oocarpa</i> Wood

This study deals with the effect of heat treatment on Pinus oocarpa specimens from forest plantations in Colombia. The effects of two heat treatments at 170 and 190 °C for 2.5 h in saturated vapor were evaluated based on the color, dimensional stability, air-dry and basic densities, modulus of elasticity (MOE), and modulus of rupture (MOR) in static bending of samples. The evaluations were carried out following the Colombian Technical Standards NTC 290 and 663, and the color changes resulting from heat treatments were monitored using the CIE-Lab, as well as other standards from the literature. The results show that there was 2.4% and 3.3% mass loss of wood modified at 170 and 190 °C, respectively. The air-dry and basic densities were higher in 170 °C treatment than after 190 °C treatment, and the thermal modifications applied increased the dimensional stability of the treated wood. After treatment at 170 and 190 °C, the lightness to darkness (L*) was reduced by 10% and 22%; the a* coordinate increased by 11% and 26%, causing redness in the treated wood; the b* coordinate increased by 14% and 17%; and the values of the wood color saturation (c*) increased by 14% and 18%, respectively. The general color change (ΔE*) increased gradually with the increase in the treatment temperature, resulting in a high color change to a very different color. The bending strength of thermally modified wood was improved and significantly increased to values higher than those of unmodified Pinus oocarpa wood. The high air-dry and basic densities, improved dimensional stability and resistance to bending, and attractive appearance of the treated wood indicate that thermal modification is a promising alternative for the transformation of Pinus oocarpa wood into a raw material with a high added value