Particleboards of high-level sugar beet pulp content: structural, mechanical, and chemical comparisons

In the particleboard production, replacing wood with agricultural waste offers an appealing alternative for further re-use of renewable resources. This study investigates the use of sugar beet pulp (SBP) as a wood substitute in a spruce particleboard manufacturing. In contrast to spruce particles, SBP offers higher mass density, distinct particle shape, and most importantly substantially higher water swelling capability. These characteristics become eminent in particleboard with a high proportion of SBP. By using isocyanate (pMDI) resin as a bonding agent, we were able to substitute a substantial amount of spruce wood particles: 25 %, 50 %, 75 % and 100 %, which exhibited high internal bonding strength comparable to that of pure spruce particleboard. The results of thorough mechanical testing of prepared SBP particleboards, correlated with optical observation of the boards' microstructure, are presented. For this sake a natural UV fluorescence of SBP was employed to get highly resolved images of boards microstructure. In addition, FTIR spectroscopy was used to investigate chemical interaction between SBP reactive groups and pMDI resin. Higher SBP proportions (75 % and 100 %) reduced board bending performance. However, increasing density from 600 to 750 kg/m³ mitigated this effect. Notably, 100 % SBP boards at 750 kg/m³ showed a 25 % higher IB strength than those at 600 kg/m³ . In general, the use of SBP in particleboard production reduces the dependency on virgin wood while also helping to reduce waste.