Durability of Urea-Resin Glues Modified with Polyvinyl Acetate and Blood

Room-temperature-setting glues tested in this study included urea formaldehyde and three urea modified glues of polyvinyl acetate. Hot press glues tested included urea-formaldehyde and three urea-modified glues of blood and urea-formaldehyde in the ratio of 9/91, 17/83 and 28/72, respectively. Twelve-by 12-inch panels were made with each of the nine glue formulations. Each panel was made of three plies of 1/16-inch yellow birch veneer. From each panel 30 standard shear specimens were cut; 240 specimens for each of the nine glue formulations were combined into one group, from which specimens for control tests and exposure tests were obtained. Specimens and tests were as specified in ASTM D 906-491. Experimental results indicated that the modified urea-resin glues generally improved the durability of the plywood joints. The unmodified room-temperature-setting urea-resin glue was not as durable as the unmodified hot-pressed urea-resin glue. The high moisture sensitivity of a 100 percent polyvinyl acetate glue was observed. This glue also gave greatest variability in performance. The best performances were provided by modifying urea resins with polyvinyl acetate at a 46/54 ratio and with blood at a 17/83 ratio. The use of blood or polyvinyl acetate at higher levels of addition gave less satisfactory performance due to increases in moisture sensitivity.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member