Processing of tropical agro-industrial waste for particleboard manufacture: Dimensional stability and mechanical performance

Abstract

Agro-industrial by-product shells are an interesting ecological and economical option to reduce the use of wood in particleboard formulation. However, knowledge of the thermal stability and physical properties of these shells is required for their use in construction materials. In this work, Doum Palm (DPS) and Balanite (BS) tropical fruit shells from the sub-Saharan region of Cameroon were characterised and processed as fillers for the manufacture of polyester-bonded particleboard. Gravimetric tests showed that water absorption and porosity were minimal for BS compared to DPS. In addition, thermogravimetric analyses indicated that both shells had almost the same thermal stability. Fifteen classes of particleboard were then manufactured by hot pressing from the prepared blends with particle sizes of 500–1250 μm, 1250–2500 μm and 2500–4000 μm, with Balanite/palm Doum (B/D) hybridisation ratios of 0/70, 20/50, 35/35, 50/20 and 70/0 by volume. The dimensional stability and mechanical performance of the samples were analysed by means of water immersion tests, and bending and internal adhesion tests, respectively. Analysis of variance (ANOVA) revealed a significant increase in density in samples containing at least 20% BS regardless of particle size, resulting in a decrease in porosity and water sensitivity with an increasing B/P ratio. The performance of the samples was much better when both shells were used in equal proportions (35/35), with density (612 kg.m−3), thickness swelling (8%) and internal bond strength (1.12 MPa) in accordance with EN312. In addition, the bending strength (4.3 MPa) and stiffness (510 MPa) were in line with literature values for shell-based particleboards. These performances make DPS and BS promising biobased fillers for the manufacture of particleboards for construction purposes.