Bonding strength of heat treated compressed Eastern redcedar wood

The objective of this study was to evaluate effect of heat treatment and compression on some properties of Eastern redcedar (Juniperus virginiana) including bonding strength, hardness and surface quality. Specimens were exposed to three temperature levels of 120 °C, 160 °C and 190 °C for 6 h before they were compressed using 2.5 MPa pressure for 5 min. Polyvinyl acetate (PVAc) bonded specimens showed 23.6% reduction in their shear strength when they were exposed to a temperature of 120 °C. Such strength reduction values were 44.4% and 64.1% for the specimens exposed to temperature levels of 160 °C and 190 °C, respectively. The lowest average Janka hardness value of 214.08 kg was determined for the samples exposed to a temperature of 190 °C while those treated with a temperature of 120 °C had the highest hardness value of 397.73 kg. It appears that combination of heat treatment and compression enchanced overall surface quality of the samples in the form of their roughness determined using stylus type equipment.

► Shear strength, hardness and surface quality of compressed samples.
► 120 °C resulted in the lowest reduction of shear strength and hardness values.
► Overall surface roughness of the samples improved as a result of heat treatment.