Resistência de painéis aglomerados de Acacia mangium Willd. colados com ureia-formaldeído e taninos a organismos xilófagos

Abstract

RESUMOObjetivou-se avaliar a resistência de aglomerados confeccionados com madeira de Acacia mangium Willd. colada com adesivo à base de ureia-formaldeído e taninos a organismos xilófagos. Os painéis foram produzidos com 40 × 40 × 1,27 cm (largura × comprimento × espessura); ao adesivo, foram adicionados 10, 20 e 30% de taninos, sendo empregadas quatro razões de compactação (1,39; 1,55; 1,73 e 2,00). Nos ensaios com fungos e térmitas, utilizaram-se amostras de 2,50 × 2,50 × 1,27 cm (largura × comprimento × espessura ABSTRACTThis study aimed to evaluate the resistance of particleboards made of Acacia mangium Willd. wood, bonded with urea-formaldehyde and tannins as adhesive, against xylophagous organisms. Panels of 40 × 40 × 1.27 cm (width x length x thickness) were produced; 10, 20 and 30% of tannins were added to the adhesive; four compaction ratios (1.39; 1.55; 1.73 and 2.00) were employed. Samples of 2.50 × 2.50 × 1.27 cm (width x length x thickness) were used in the tests with fungi and termites. Gloeophyllum trabeum and Trametes versicolor (12 weeks) fungi and Nasutitermes sp. (45 days) termites were employed in the tests. Panels with the highest compaction ratio and proportion of tannins provided the most effective resistance to Gloeophyllum trabeum. No difference between the adhesives and compaction ratios was observed for Trametes versicolor. Gloeophyllum trabeum caused greater mass loss than Trametes versicolor. The samples were completely consumed by the termites.

Wood Particleboards Reinforced With Thermoplastics to Improve Thickness Swelling and Mechanical Properties

“…For the panel control one of the disadvantages, when compared to the plastic wood, it is the non-return rate in thickness. This is because the total thickness swelling of these compounds is given by the sum of two main factors, one related to the hygroscopic nature of the wood, and the other related to the release of compression stresses (Gonçalves et al, 2014). This process is usually accompanied by the loss of resistance of the panel, which can be demonstrated when comparing the mechanical properties between the panels tested in this study.…”

Relação entre propriedades elásticas e biológicas em painéis aglomerados feitos com resíduos de madeira de eucalipto

“…Em geral, a maioria dos fungos degradam de forma seletiva os compostos de celulose e hemicelulose, ao passo que os fungos da podridão parda, a exemplo do Brunneoporus malicola que provoca a degradação de todos os componentes da madeira [48], em especial a lignina [49]. Entre os fungos estudados, o B. malicola promoveu maior perda de massa, destacando-se aqueles painéis com maiores proporções de tanino em relação à ureia formaldeído comprometendo as propriedades físicas e de resistência do material [13,50].…”

“…Alguns trabalhos publicados [8][9][10][11][12][13] tiveram como objetivo avaliar a resistência de painéis aglomerados ao ataque de organismos xilófagos (fungos e cupins), mediante o uso de adesivos a base de ureia-formaldeído e ou tanino-formaldeído, apresentando resultados variados em função dos diferentes tratamentos aplicados. Porém, de forma geral, foram satisfatórios.…”

Mechanical properties and resistance to fungi and termite in particleboard of eucalyptus

“…This behavior is similar to that found in the present work, since the adhesives that lost more mass were the combinations of urea-formaldehyde with tannin (in proportions of 10% and 20%). In agglomerated panels produced with acacia wood glued with urea-formaldehyde-based adhesive and proportions of tannins (10, 20 and 30%) in the presence of all adhesives, the classification was mentioned as resistant to white rot fungus (Trametes versicolor) (Gonçalves, Brocco, Paes, Loiola, & Lelis, 2014). The same authors also observed that there is a tendency of improvement in the resistance of the panels with the increase of the compaction ratio, but unrelated to the increase of the proportion of tannins in the ureaformaldehyde.…”