Analysis of glue line and correlations between density and anatomical characteristics of Eucalyptus grandis × Eucalyptus urophylla glulam

This study aimed to analyze the glue line thickness effect and its relation with density and anatomical characteristics of eucalyptus wood. Thus, the thickness of main and secondary glue lines was measured as well as their interaction with apparent density of elements glued with resorcinol-formaldehyde (RF) and castor oil polyurethane (CP) adhesives. Anatomical wood characterization of Eucalyptus grandis × E. urophylla was performed by correlating glue line thickness. According to normative instruction, specimens were produced for delamination tests. The experiment was conducted in a completely random 2 × 2 design factorial scheme (two classes of wood apparent density and two adhesives). Pearson correlation (t < 0,01) was performed among variables. It was found that there was adhesive penetration into vessels and rays of wood. Glue line thickness was higher in woods with density higher than to 0,58 g∙cm-3 glued with RF adhesive. There was a low correlation between wood density and vessel diameter to main and secondary glue lines (t < 0,01)

Eficiência da colagem em madeira de kiri japonês (Paulownia tomentosa)

The collage on pieces of wood using adhesives has been performed since the Pharaoh era. Over the years, technologies have been developed especially for adhesives and different species of wood, adapting to the desired diverse uses. In this context we can also infer the methods of analysis and its efficiency. The aim of this study was to evaluate the resistance in the glue-line by using adhesives in Paulownia tomentosa wood (Japanese kiri). The bonded joints were prepared with resorcinol formaldehyde and melamine urea formaldehyde adhesives. The wood-adhesive interface was evaluated by means of the thickness of the main and secondary glue-lines using photomicrographs, shear strength, and percentage of wood imperfections. The adhesives presented non-uniform behavior in the glue-line. It was possible to observe that the adhesives penetrated in the wood anatomical structures (elements of vessels and rays). The resorcinol formaldehyde adhesive had higher penetration values. The kiri wood imperfection percentage was greater than 92%, independent of the adhesive. The high efficiency observed in bonding with both adhesives allows the use of wood of Paulownia tomentosa in Brazil for furniture and civil construction.A colagem em peças de madeira por meio de adesivos é realizada desde a época dos faraós. Com o passar dos anos as tecnologias foram desenvolvidas sobretudo nos adesivos e nas diferentes espécies madeireiras existentes, adaptando-se aos diversos usos pretendidos. Neste contexto também se pode inferir sobre os métodos de análises de sua eficácia. O objetivo desse estudo foi avaliar a resistência na linha de cola mediante o uso de dois adesivos em madeira de Paulownia tomentosa (kiri japonês). As juntas coladas foram preparadas com adesivos resorcinol formaldeído e melamina ureia formaldeído. Avaliou-se a interface madeira-adesivo por meio da espessura da linha de cola principal e secundária com uso de fotomicrografias, resistência ao cisalhamento e percentagem de falha na madeira. Os adesivos apresentaram comportamento desuniforme ao longo da linha da cola. O adesivo resorcinol formaldeído penetrou de forma mais incisiva nos elementos de vasos e raios. A madeira de kiri apresentou percentual de falha superior a 92%, independente do adesivo. A eficiência na colagem com ambos adesivos testados possibilita o uso da madeira de Paulownia tomentosa no Brasil em movelaria e construção civil

Performance of eucalypt particleboard with the addition of farm waste

Wood residues, as well as those from poultry farming, are generally disposed of irregularly, which causes damage to the environment, and thus poses a great challenge in terms of their use, a possible alternative is the manufacture of particleboards. For this, the following mechanical properties of the panels were evaluated: static bending (elasticity – MOE and rupture – MOR), internal bond strength (IB), Janka hardness (DJ), screw withdrawal resistance (SW), thickness swelling (TS), water absorption (WA), moisture, apparent density (DA) and density profile, in addition to morphological characterization by scanning electron microscope image. With the results obtained, it was possible to observe that the amount of residue influenced the density of the panel. The panel compaction ratio showed little variation (1.22–1.32), remaining close to the value considered ideal of 1.33. The percentage of waste added to the panels also influenced the increase in WA and TS, limiting the use of the panels to environments without humidity. The addition of the eggshell in the process negatively affected the mechanical characteristics of formulated particleboards, except for Janka hardness. The application of the resin together with the wood particles and eggshells can improve the mechanical properties. Based on the findings from this study, the medium-density particleboard produced can be used for making furniture and room partitioning without structural character