Effect of Density and Fiber Size on Porosity and Thermal Conductivity of Fiberboard Mats

Abstract

The thermal conductivity and porosity of fiberboard mats are crucial parameters for efficient energy consumption of the hot-pressing process and for final panel quality. In this work, the effect of fiber size and mat density on porosity and thermal conductivity of the mat were investigated. The fiber size was characterized as fine, medium and coarse. The mat porosity was measured by image analysis using the black and white contrast method. The thermal conductivity was determined at different density levels with a temperature gradient of 1.6 °C mm−1 and 7.6% (s = 0.3) moisture content. The results showed that fiber size was a dominant variable governing heat conduction and mat porosity. The mats made with medium size fibers showed a higher resistance to compression. The thermal conductivity of coarse fiber mats decreased drastically between 700 kg m−3 and 810 kg m−3. This was likely due to a higher fracture frequency observed for coarse fibers in comparison to the other fiber sizes studied. Hence, the fine and medium fibers conducted heat more efficiently. Moreover, fiber bundles and fractured fibers were observed during the mat porosity measurements, principally in mats made with fine fiber size.

Thermo-Mechanical Properties of a Wood Fiber Insulation Board Using a Bio-Based Adhesive as a Binder

“…In [31], the authors also reported a decrease in porosity percentage of particleboard, although the increase in adhesive content was higher. The porosity percentage was lower in comparison to that reported by [32]. Nevertheless, the technique used for porosity determination was different.…”

“…The internal bond values meet requirements for roof insulation board (grade 1 and grade 2), wall sheathing regular and structural, and ceiling panels. (22) 672 (17) 113 (21) 1142 (10) Board-CG1:CA0.66-20% 338 (4) 1.10 25692 (10) 154 (25) 1062 (13) Board-CG1:CA1-14% 332 70.91 (29) 651 (18) 117 (18) 1206 (8) Board-CG1:CA1-20% 332 71.13 (23) 575 (32) 141 (30) 1030 (10) ASTM C208-12 1 160-497 0.97-2.76 345-1379 23.9-38.3 100-105…”

“…The porosity was greater using CG1:CA0.66 formulation. The total porosity influenced the thermal conductivity (λ) values of insulation boards, which decreased as the porosity increased [32]. The thermal conductivity (λ) decreased as CG1:CA0.66 formulation was used in insulation boards' manufacturing ( Figure 7).…”

Thermophysical Properties of Larch Bark Composite Panels

“…In the case of fine fraction of the bark boards, the pores are smaller and closed. That is why the static and convection effect is minor compared to the coarse fraction boards at the same density [ 6 , 52 , 64 , 65 ].…”

Influence of agricultural fibers size on mechanical and insulating properties of innovative chitosan-based insulators

“…One of the most important parameters influencing these factors is the size of the fibres. Many researchers have studied the effect of changing the size of natural fibre particles in the thermoplastic matrix like polyester, polylactic acid, polyvinyl chloride, polypropylene polyethylene and others [23][24][25][26][27][28][29][30][31]. They have obtained different results which sometimes lead to contradictory conclusions.…”