Wood-gluing test

Novolaks were prepared using a phenol-to-formaldehyde molar ratio of 4 1 with 5 mole percent of H2SO4 added as a catalyst. Typically, 47 g liquid phenol (91.7% assay), 3 g paraformaldehyde, and 30 mL water plus the required acid catalyst were added to a three-neck, 250-mL round bottom flask. The flask was fitted with a reflux condenser and stirrer. The mixture was refluxed for 2 to 4 hours with the oil bath at 115 °C then, the mixture was neutralized with 50% (w/w) NaOH and the excess phenol removed by steam distillation for 5 to 6 hours. The remaining viscous oily residue was washed repeatedly with boiling water. A novolak with the P/N fraction was prepared as described above with 1 1 by volume phenol and P/N fraction and half of the amount of formaldehyde. Initial wood-gluing testing with this novolak indicates wood failure rather than glueline failure. 

D-4317. Specification for Polyvinyl Acetate-Based Emulsion Adhesives. Somewhat similar in scope to D-3110, this standard employs the D-0905 block shear and D-0906 plywood shear tests in evaluating polyvinyl acetate based adhesives for common wood gluing applications. 

A total of 45 single lap shear specimens made of beech wood were produced by the adhesive manufacturer as described in Section 3.2. The samples were glued with the five adhesive types used in the delamination test 3 plastic adhesives no. 009, 013 and 014, and 2 elastic adhesives no. 062 and 071. The adhesive layers of the lap shear specimens had the following nominal thicknesses 0.5, 1.0 and 3.0 mm. For each adhesive type and thickness batch, 3 specimens per batch were tested. 

Within the scope of the project several new adhesive formulations were developed and tested. The formulations were based on DME (dimethoxyethanal) resin and the products derived from it to produce formaldehyde-free wood adhesives. The investigated adhesives were evaluated on laboratory scale in order to study their technical performances, their gluing parameters, their reactivity as well as their formaldehyde emissions. It was found that all formulations met the requirements of current standards EN 319 1993-08 and that for class P2 particleboards for general uses. From the technical point of view, major advantages of the tested systems were found to be colourless, low toxicity, easy handling, and high stability at room temperature (long shelf-life, pot-life and open-time). The formaldehyde emissions of the boards produced were found to be comparable with those of solid untreated wood (F JIS A 1460 2001 standard). 

The bonding of maple wood samples with urea-formaldehyde resins at 5 psi gluing pressure was tested in shear as a result of surface treatment. 

High-speed-cured wood adhesive has been developed, and a "hone3mioon gluing scheme (Fig. 3) has been proposed. With the use of m-aminophenol, the boil-dry test results are comparable to those of phenol-resorcinol system. 

Structural Adhesives for Fingeijointing Lumber. A recent standard detailing the testing of finger joints when used as end joints in structural glued, laminated timbers (see also D-2559 in wood adhesive specifications). 

D-2559 (on adhesives for exterior-use glued, laminated, wood) uses specimens cut from small laminated beams and tests for delamination after exposure to a multi-step accelerated aging treatment. See earlier listing under wood adhesive specifications. 

Wooden test pieces glued with various adhesives. Lower specimen shows fracture entirely in the wood. 

An estimated 75 % of the mastic products sold in North America indicate compH-ance to stringent AFG-01 (i.e. Adhesives for Field Gluing ) requirements. ASTM D 3498 is quite similar to the AFG-01 standard originally written by the American Plywood Association. These methods define a series of six test specifications (Fig. 8-28), five of which involve shearing plywood to lumber wood block specimens in compression mode after various carefully controlled material conditioning and specimen curing protocols (Fig. 8-29). 

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