Analyzing Process Related, In-Plane Mechanical Variation of High Density Fiber Boards (HDF) Across the Feed Direction

Abstract

Mechanical properties of the core layer (in-plane) of high density fiberboards (HDF) were analyzed across the width of the board (i.e. across the feed direction). The tests were performed by means of a newly developed double cantilever I beam (DCIB) testing system, with analysis of internal bond strength and bending strength. The specimens were selected from a large-scale experiment in a central European HDF plant, including a completely different machine setting for each sample set. Homogeneous density and property distributions across the feed direction of the boards were generally assumed. During this trial the question arose as to whether processing leads to unequal mechanical properties across the feed direction. In total, 20 sample sets were tested longitudinally and laterally to the feed direction at eight measurement points, revealing 320 test specimens per testing procedure. In contrast to standard testing procedures, the specific fracture energy and the stress intensity factor revealed significant differences between the centre and the edge across the feed direction. This study revealed variations of mechanical properties across the width of the board using the DCIB approach.

Particleboard Production from Paulownia tomentosa (Thunb.) Steud. Grown in Portugal

“…The relationship between resin content and density appears to be linear, at least between 8-12% resin content. Similar results were presented before by Rathke et al [33] that tested the effects of alternative raw materials and varying resin content on the mechanical properties of particleboards. Nevertheless, higher resin contents increase the price of the boards and the formaldehyde release during use.…”

“…Also, particleboards produced using isocyanate resins result in better mechanical properties and dimensional stability than those produced using urea formaldehyde resins [32]. Higher amounts of resin generally improve the board properties, mainly thickness swelling and mechanical properties as stated before by Rathke et al [33] in a study of particleboards made from willow, poplar, and locust, or by Nemli et al [23] in a study of particleboard panels consisting of 45% beech (Fagus orientalis), 35% pine (Pinus nigra) and 20% poplar (Populus nigra), or even by Arabi et al [34] who reported that higher resin content lead to increased mechanical properties for single-layer particleboards made from poplar wood. Increased hot pressing time and temperature has often been mentioned to improve the mechanical properties of the particleboards, like, for instance, for Asian bamboo [31] or Jatropha Fruit Hulls treated in acidic conditions, particleboard made from sorghum bagasse as reported by Iswanto et al [35,36] or particleboard made from recycled particles bonded with a new natural adhesive composed of tannin and sucrose [37].…”

“…Similar results were presented before by, for instance, Lehmann [50] with 2 percent resin solids of urea-formaldehyde resin that obtained increases in both strength and modulus of elasticity, by Nemli et al [51] with kiwi (Actinidia Planch.) pruning particleboard or by Rathke et al [33] with different wood specie et al [34] stated that MOR and MOE increased with resin content, and that an exp function can better describe the simultaneous effect of slenderness and resin cont the linear equation. On the other hand, Kimoto et al [52] tested resin contents from and stated that only minor improvements were found in strength with 15% resin compared to 10%.…”

Utilization of Kattha (Acacia catechu) extracted wood chips in combination with PF (Phenol-Formaldehyde) resin as a binder to produce a medium-density particle board

“…The mechanical characteristics of particleboards made from Acacia catechu particles at various resin contents and pressures, including static bending strength, tensile strength perpendicular to the surface, and screw and nail pullout strength, are shown in Tables 9 and 10 below, respectively. [14,16,1] . [2] , this is because the phases are incompatible with one another.…”

Effect of crack length on fracture behavior of particleboard

“…Therefore, the density of the crack tip location mainly affects the crack resistance of PB (Sinn et al 2008;Scorza et al 2019). The fracture properties of woodbased composites are also influenced by additional effects such as fiber bridging, particle size, layering, and particle orientation (Rathke et al 2012b(Rathke et al , 2013. The crack length is another factor.…”