School of Agriculture, Food and Ecosystem Sciences - Research Publications
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ItemEffects of mat composition and pressing time on citric acid-bonded ultra-low-density hemp hurd particleboard(Elsevier, 2024-04-01)This study investigated the feasibility of using citric acid (CA) as a biobased and formaldehyde-free binder for producing ultra-low-density (320 to 338 kg/m3) hemp hurd particleboard (ULHPB). Mechanically decorticated hemp hurd chips were milled and then separated into fine (F), medium (M), and coarse (C) particle sizes. Three particle size mixes (PSM) were used to fabricate the panels: 100% C, 100% M, and a 50/50% mixture of CM. Each PSM was combined with low and high CA contents (20 and 30 wt%) and subjected to short and long pressing times (8 and 12 min) at 200 °C. Physico-mechanical characteristics were evaluated following Australian standard AS/NZS 1859.1 (2017) for reconstituted wood-based panels. Thermo-chemical analyses were performed to understand the properties of the raw hurd and to investigate the binding mechanisms in CA-ULHPB. The PSM had a significant impact on panel expansion (springback), internal bond strength (IB), water absorption (WA), and thickness swelling (TS) in most CA-ULHPB variants. PSM-C panels exhibited superior IB when pressed with 30 wt% CA for 12 min. The effect of PSMs diminished for WA and TS but CA content and pressing time remained highly significant. Py-GC/MS, FTIR spectroscopy and TGA indicated the formation of ester linkages with carbohydrate-derived OH-groups and the involvement of lignin moieties in the CA-ULHPB. This research identified optimal panel compositions and processing parameters for fabricating environmentally friendly composite panels using CA as a natural adhesive and hemp hurd as an agricultural by-product. The panels exhibited excellent properties and would be well suited as core layers in lightweight sandwich composites given their ultra-low-density range.
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ItemGluing characteristics of Papua New Guinea timber species for various non-structural applications(Universidad del Bío-Bío, 2023)Papua New Guinea (PNG) has abundant natural forest resources but there are many constraints which need to be addressed to support the development of competitive value-added wood industries. There is a need to develop knowledge and capacity in wood science and processing technologies which support successful domestic value-adding wood processing enterprises. A comprehensive testing program has been developed to assess the glue‐bond strength and performance of selected commercial PNG timber species in various climatic conditions to simulate service conditions in potential market destinations. Two criteria namely shear strength and wood failure have been used to determine if a species can meet the minimum requirements for either dry use or wet use applications. The performance of 24 different PNG commercial timber species has been assessed using a one-component cross-linking polyvinyl acetate emulsion adhesive. The bondability of the selected species has been carefully estimated considering the wood density and wood moisture content for the strength and durability in dry- and wet-use conditions. The testing results show that as the wood density as a wood property factor and moisture content as a service condition factor increase, high shear strength with high wood failure become more difficult to achieve consistently. The highest shear strength and wood failure results were achieved by softwood plantation species and low-density hardwood species. Based on the testing results, the selected species have been classified into bondability classes (bond very well, bond well, bond with difficulty, very difficult to bond).
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ItemInfluence of particle granulometry and panel composition on the physico-mechanical properties of ultra-low-density hemp hurd particleboard(Wiley, 2023)This study investigated Australian hemp hurd (Cannabis sativa L., “Frog One”) as a lignocellulosic raw material for ultra-low-density hemp particleboard (ULHPB) with densities ranging from 213 to 309 kg/m3. The hurd was first milled and fractionated into three particle size categories, that is, fine (F), medium (M), and coarse (C). Twelve unique ULHPB variants were then fabricated comprising varying particle loadings from four particle size mixes, that is, 100% C, 100% M, 50%/50% CM, 25%/50%/25% CMF, and adhesive contents of bio-epoxy (EPX), phenol resorcinol formaldehyde (PRF), and emulsifiable methylene diphenyl diisocyanate (MDI), respectively. The panel assessments, conducted in accordance with the Australian reconstituted wood-based panels standard AS/NZS 1859.1 (2017), revealed a significant effect of particle dimension on most physico-mechanical properties. Furthermore, the resination method and pressing temperature controlled post-cure panel expansion and additional panel characteristics. Notably, MDI-ULHPB exhibited drastically different behavior and properties compared to EPX and PRF equivalents, demonstrating greater bending strength, stiffness, screw withdrawal strength, and dimensional stability. Importantly, all MDI variants conformed to the 15% thickness swelling limit for moisture resistant particleboard. Surface lamination of MDI-bonded ULHPB with sheets of aluminum, Masonite, and Kraft liner significantly improved the inherently low flexural properties, suggesting the potential suitability of ULHPB as a core layer in lightweight sandwich composite panels. The integration of agricultural by-products, such as hemp hurd, into engineered building materials presents a promising opportunity to mitigate the depletion of finite timber resources and aligns well with circular economy principles. Highlights • Utilizing agricultural residue as sustainable raw material in building products. • Hemp hurd enables ultra-low-density particleboard with thermosetting resins. • Coarse particle size mix enhances mechanical performance in panels. • Panel characteristics controlled by resination method and pressing temperature. • Lamination enhances functionality of lightweight hemp hurd sandwich panel.
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ItemAssessing the potential of hemp hurd (Cannabis sativa L.) for the production of environmentally friendly lightweight panels(The Industrial Hemp Western Australia Association Inc, 2020)Presentation prepared for the 2nd Australian Industrial Hemp Conference in Fremantle, WA from 25 -28 February 2020. Abstract and slides.