• Wang, Chunyan
  The Graduate School, University of Maine
  

The interaction of moister wood cell walls leads to the development of swelling pressures that potentially cause the failure of resin bonds and the dislocation of fibers in the wood based composites. Moreover, the activities of failures and dislocations may result in abrupt stress changes eventually triggering the generation of acoustic emissions (AE). Resin levels and wax levels in the composites effectively limit this interaction and additionally, the sharpness of refiner plates positively changes the sensitivity of the composites to moisture sorption. In this research, acoustic emission technology was used to measure the effects of the variation of resin and wax levels in the wood based composites as well as the sharpness of refiner plates on the acoustic emissions in terms of cumulative counts.

Two resin levels and three wax levels in two type composites, medium density fiberboard and particleboard, were tested in this study. Medium density fiberboard produced by worn and new refiner plates were also tested in this study. All samples were immersed in distilled water for 120 minutes. Average cumulative AE counts, internal bond strength, density and moisture content gains were measured during testing.

Results from the study provided evidence that resin levels and wax levels in the wood based composites significantly affected the generation of acoustic emissions from the immersed samples. The results also indicated that the sharpness of refiner plates had a great influence on the AE counts.