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Wood - Adhesive Bonding


Quiz Questions

1.Adhesion is the state in which interfacial forces, which may be valence forces, interlocking action, or both, hold two surfaces together.
True
False
2. What does ASTM stand for?
American Society for Testing and Materials
American Standards for Testing and Materials
American Standard for Testing and Mechanics
None of the above
3.The American Society for Testing and Materials defines an adhesive as a substance capable of holding materials together by surface attachment.
True
False
4.In thermoplastics, the physical change to solid form may occur by either
(a) Loss of solvent from the adhesive through evaporation and diffusion into the wood, or
(b) Cooling of molten adhesive on a cooler surface.
True
False
5.Because adhesives bond by surface attachment, the physical and chemical conditions of the adherend’s surface is not extremely important to satisfactory joint performance.
True
False
6.Wetting of a surface occurs when the contact angle (the angle between the edge of a drop of adhesive and the surface of wood) approaches zero. The contact angle approaches zero when the surface has high attractive energy, the adhesive has an affinity for the adherend, and the surface tension of the adhesive is low.
True
False
7.Over-drying and overheating deteriorates the physical condition of the wood surfaces by forcing extractives to diffuse to the surface, by reorienting surface molecules, and by irreversibly closing the larger micro pores of cell walls.
True
False
8.Extensive research indicates that extractives on wood surfaces are the principal physical and chemical contributors to surface inactivation, hence to poor wettability by adhesives.

True
False
9.The wood properties of veneer are essentially no different from those of lumber; however, manufacturing processes, including cutting, drying, and laminating into plywood, can drastically change physical and chemical surface properties of veneer.
True
False
10.Product manufacturers commonly laminate plastic films and metal foils to wood panels usually. Although high cohesive strength is not required of adhesives to support these materials in an indoor environment, adhesives still must be reasonably compatible with both the wood and non-wood surfaces.
True
False
11.Chemical treatment of wood with preservatives, fire retardants, and dimensional stabilizers do not interfere with adhesion to the treated wood.
True
False
12.What does figure 9-3 illustrate about?
(Refer Pg 9-6)
Surface of cell lumen of CCA-treated Southern Pine covered with chemically fixed deposits of insoluble mixture of chromium, copper, and arsenic oxides
Cross section of a bonded joint between two damaged Douglas-fir surfaces abrasively planed with 36-grit sandpaper
A simple water drop test shows differences in the wettability of a yellow birch veneer surface
None of the above
13.The bondability of wood is not only affected by the surface properties of wood adherends but also by wood’s physical properties, particularly density, porosity, moisture content, and dimensional movement.
True
False
14.The most common fire-retarding chemicals used for wood are inorganic salts based on phosphorous, nitrogen, and boron. These acid salts release acid at elevated temperatures to decrease flammable volatiles and increase char in wood, thereby effectively reducing flame spread.
True
False
15.The porosity of hardwoods and softwoods, both as species groups and as species within a group, varies greatly, which dramatically affects the amount and direction of adhesive flow.
True
False
16.Pits are the small openings between fibers that permit lateral transfer of fluids in living trees. They form a complex capillary system that also allows adhesives to penetrate deeply, even in tangential and radial directions.
True
False
17.Although adhesives for hardwoods and softwoods generally differ by chemical type according to product markets, adhesives must be specifically formulated for hardwoods or softwoods, including specific species within the groups, or have adjustable working properties for specific manufacturing situations.
True
False
18.Water occurs naturally in living trees-as free water in cell lumens and as adsorbed water within cell walls. Total water content of wood can range well above 200% (based on oven-dry weight), but when the free water is removed from cell lumens by drying, approximately 30% remains bound within cell walls
True
False
19.Low-density woods have thick walls and small lumen volumes, whereas High-density woods have thin walls with large lumen volumes.
True
False
20.What does figure 9-7 illustrate about?
(Refer Pg 9-17)
An illustration of the relationships between adhesive consistency and bonding pressure as they affect bond formation by a thermosetting adhesive
An extruder applies continuous and uniformly sized and spaced beads of adhesive to veneer for laminating into LVL
Average equilibrium moisture content for wood in building interiors in regions of the United States
None of the above