Geraldo Bortoletto Júnior

Propriedades físicas e mecânicas de painéis MDF de diferentes massas específicas e teores de resina.

MDF Panelboards of Pinus spp. fibers were prepared in laboratorial scale, within a range of densities (600 - 800 kg/m3) and urea-formaldehyde resin content (6, 8, 10, 12 and 14 wt. %), with the purpose of evaluating their mechanical and physical properties. The effect of density and resin content and their interactions were analyzed based on panel mechanical and physical properties. Mechanical properties evaluated were modulus of rupture and modulus of elasticity and internal bond, while physical properties studied were thickness swelling and water absorption. All the physical and mechanical properties of the MDF panels were significantly related to the resin content and density. Models have been proposed to evaluate the physical and mechanical variables of the MDF panels taking into account the average density and resin content.

Relação entre Perfil de Densidade e Ligação Interna de Painéis OSB de Pinus spp / Relationship between Density Profile and Internal Bond of Pinus spp. OSB panels

This study aimed to determine the density, by gravimetric method and X-ray densitometry, of Oriented Strand Boards (OSB) produced with Pinus taeda and Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis, to obtain densitometric profiles and observe their correlation with the internal bond. The average density of the panels produced was determined by the methodology of X-ray densitometry and the gravimetric method, using 3 specimens (50 × 50 mm) per treatment. After apparent density measurement, the 24 specimens were subjected to the internal bond test. The gravimetric method applied for the determination of apparent density of the panels presented significantly higher results compared with the densitometric method. It was possible to observe that the minimum density of the board, obtained by the method of X-ray densitometry, has a strong influence on its average density. Correlation was observed between the apparent densities of the panels and the results of internal bond.

Resistência ao ataque de fungos apodrecedores em painéis OSB termicamente tratados

O objetivo foi de avaliar o efeito do pre e pos-tratamento termico sobre a resistencia dos paineis OSB ao ataque de fungos apodrecedores, e comparar essas duas formas de tratamento termico com algumas variaveis de producao. O delineamento experimental se constituiu de sete tratamentos, com a avaliacao de duas temperaturas de pre-tratamento das particulas (200 e 240oC), por um periodo de 60 minutos; do pos-tratamento termico dos paineis, produzidos com e sem a aplicacao de parafina, sob temperatura de 220oC por um periodo de 12 minutos; e do aumento do teor de adesivo e a aplicacao de parafina em paineis sem tratamento termico. Para cada tratamento, foram produzidos tres paineis com densidade nominal de 0,65 g/cm³ e adesivo a base de fenol-formaldeido. Mediante a analise dos resultados foi possivel concluir que os paineis com pre-tratamento termico a 240oC apresentaram-se com grande potencial de inibicao ao ataque dos fungos Trametes versicolor e Gloeophyllum trabeum, porem, com efeito equivalente ao obtido com o aumento do teor de adesivo fenol-formaldeido. O pos-tratamento termico nao proporcionou melhoria significativa para a resistencia biologica dos paineis OSB.