Influence of the Density in Binderless Particleboards Made from Sorghum

Abstract

In order to fight climate change and decouple economic growth from material use, valorization of waste will be fundamental. Sorghum is one of the most important summer crops in the world. The non-edible parts of the plant, the stalks and leaves are left over and must be disposed of. This work proposes to use sorghum waste particles as a raw material to manufacture boards and analyze the influence of its density. Particles were sprayed with 10% wt of water and placed in a hot press at 2.1 MPa and 110 °C for 30 min. Eight types of panels were produced with densities ranging from 950 kg/m3 to 1250 kg/m3. The results indicated that the water absorption (WA), modulus of rupture (MOR), modulus of elasticity (MOE) and internal bounding strength (IB) depended on the density. With higher densities, the particleboards showed better physical and mechanical behavior. This study demonstrates that it is technically possible to manufacture adhesive-free particleboards from sorghum residues that comply with European standards and can be used as boards for general applications. The use of these particleboards could be beneficial in fighting climate change and in minimizing the use of natural wood.

Sustainable Particleboards Based on Brewer’s Spent Grains

“…The properties observed in BBG170 indicate that reducing the particle size of BSG and increasing the pressing temperature up to 170 °C facilitate chemical bonding and mechanical interlocking and improve the structural integrity of the boards. The MOE, MOR, and IB values of the BBG170 sample show similar results to those reported by [ 77 ] for sorghum-based binderless boards within the same density range.…”

“…The properties observed in BBG170 indicate that reducing the particle size of BSG and increasing the pressing temperature up to 170 • C facilitate chemical bonding and mechanical interlocking and improve the structural integrity of the boards. The MOE, MOR, and IB values of the BBG170 sample show similar results to those reported by [77] for sorghum-based binderless boards within the same density range. On the other hand, the particleboard PAB bonded with PF (control) exhibited the best mechanical properties owing to the intrinsic chemical nature of the synthetic adhesive and its favorable interactions with the lignocellulosic substrate [12].…”

“…The impact of particle size on the mechanical performance of the binderless board was also analyzed. BBG170 showed significantly higher MOR, MOE, and IB values compared to BB170 (p < 0.05), indicating that smaller particles contribute favorably to mechanical contact between particles, as previously described for boards derived from other lignocellulosic materials [3,4,77]. This behavior is likely attributed to the larger surface area and effective bonding between particles, involving the chemical compounds of BSG (hemicellulose, lignin, among others), as discussed previously [3,18,75].…”

“…It is also evident that the porous cellular structure of the husk is retained despite the pressing process. The enhanced adhesion among particles at 170 • C significantly improved the mechanical strength and water resistance of the binderless boards [3,77]. PAB board (control) (Figure 5a,b) exhibits a densified structure and effective particleto-particle contact due to the incorporation of PA.…”

Advanced Eco-Friendly Wood-Based Composites II

“…The adverse free formaldehyde emission from wood-based composites can be mitigated by coating the surfaces of finished composites, by adding various organic or inorganic formaldehyde scavengers to synthetic wood adhesives, or by using bio-based, environmentally friendly wood adhesives [40][41][42][43][44][45][46][47][48][49]. The manufacture of binderless wood-based composites is another viable option since wood as a natural raw material is composed of biopolymeric constituents, i.e., cellulose, lignin, and hemicelluloses [50][51][52][53][54].…”