A study was conducted to investigate the bendability of four selected
hardwood species after being treated with creosote. A completely rando
mized block factorial design was employed. Experimental factors includ
ed five wood species (chestnut oak, red oak, red maple, yellow-poplar,
and southern pine), five adhesive systems (elevated temperature cure
phenol-resorcinol-formaldehyde, room temperature cure phenol-resorcino
l-formaldehyde, resorcinol-formaldehyde, emulsion polymer isocyanate,
and low-viscosity formulation emulsion polymer isocyanate) and two exp
osure levels (ambient room and vacuum/pressure/soak conditions). Expos
ure levels effects on the different wood species resulted in highly va
riable adhesive system performance. Exposure level effects were most e
vident for the higher density oaks. Shear strength and percent wood fa
ilure results for all wood species revealed a general trend towards a
higher performance for the two phenol-resorcinol-formaldehyde systems.
Resorcinol-based adhesive systems had the highest shear strength valu
es. Percent wood failure values were highest for the elevated temperat
ure cure phenol-resorcinol-formaldehyde system for all species. Elevat
ed temperature cure adhesive systems appeared to be required to succes
sfully bond high-density creosote treated species. Successful bonding
of medium-density species can be accomplished at room temperatures giv
en proper adhesive system selection.