Effect of juvenile wood on strength properties and dimensional stability of black spruce medium-density fiberboard panels

Abstract

Abstract Strength properties and dimensional stability of medium-density fiberboard (MDF) panels made from black spruce (Picea mariana [Mill.] BSP.) 0–20, 21–40, and over 40 year old fiber were studied. An analysis of covariance (ANCOVA) was performed to examine the differences in modulus of rupture (MOR), modulus of elasticity (MOE), and thickness swell (TS) of the three types of panels, while panel density was treated as a covariate in order to adjust the mean values that were partly attributed to panel density. The results indicate that MOR, internal bond (IB), and water absorption of MDF panels made from 0–20 year old fiber, which contained 100% juvenile wood, were significantly superior to those of panels made from 21–40 and over 40 year old fiber; but linear expansion (LE) of MDF panels made from 0–20 year old fiber was significantly larger than that of panels from the other two age classes. The differences in MOR, IB, water absorption, and LE between panels made from 21–40 and over 40 year old fiber were not significant. The comparisons of panel MOE and TS were relatively dependent on panel density due to existence of interactions among the three age groups.