Comparative study on the properties of cellulose nanofiber (CNF) and cellulose nanocrystals (CNC) reinforced 1C-PUR adhesive bonded wooden joints. (15th August 2022)

• Record Type: Journal Article
• Authors: Kamboj, Gourav; Gaff, Milan; Smardzewski, Jerzy; Haviarová, Eva; Hui, David; Rousek, Radim; Das, Sumanta; Rezaei, Fatemeh; Sethy, Anil Kumar
• Is Part Of: Construction & building materials. Volume 344(2022)
• Publication Date: 2022-08-15
• Subjects: PUR-N-B Pure PUR beech wood joint (at 12% moisture) -- PUR-C-B Pure PUR beech wood joint (cycling 8-19-8%) -- PUR-0.5-N-B PUR with 0.5% nanocellulose beech wood joint (at 12% moisture) -- PUR-0.5-C-B PUR with 0.5% nanocellulose beech wood joint (cycling 8-19-8%) -- PUR-1-N-B PUR with 1% nanocellulose beech wood joint (at 12% moisture) -- PUR-1-C-B PUR with 1% nanocellulose beech wood joint (cycling 8-19-8%) -- PUR-2-N-B PUR with 2% nanocellulose beech wood joint (at 12% moisture) -- PUR-2-C-B PUR with 2% nanocellulose beech wood joint (cycling 8-19-8%) -- PUR-0.5-N-S PUR with 0.5% nanocellulose spruce wood joint (at 12% moisture) -- PUR-0.5-C-S PUR with 0.5% nanocellulose spruce wood joint (cycling 8-19-8%) -- PUR-1-N-S PUR with 1% nanocellulose spruce wood joint (at 12% moisture) -- PUR-1-C-S PUR with 1% nanocellulose spruce wood joint (cycling 8-19-8%) -- PUR-2-N-S PUR with 2% nanocellulose spruce wood joint (at 12% moisture) -- PUR-2-C-S PUR withd 2% nanocellulose spruce wood joint (cycling 8-19-8%) -- MC Moisture Content -- RH Relative humidity -- EMC Equlibrium moisture content; Cellulose nanofiber -- Cellulose nanocrystal -- PUR adhesive -- Acetylation -- Elastic modulus -- Shear strength; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.128262
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The addition of nanocellulose in PUR adhesive improved spruce wood joints' elastic stiffness and shear strength at 12% moisture and after moisture cycling condition (8–19%). In beech wood joints there is no significant difference after the addition of CNF and CNC in PUR adhesive. Among the three (0.5%, 1%, and 2%) concentrations of nanocellulose (CNF and CNC) reinforcement, 1% addition was found to be the optimum for elastic stiffness and shear strength. SEM analysis shows the morphology studies, and nanocellulose reinforced adhesive shows a relative improvement on the bond-line by the good dispersion of CNF and CNC addition to PUR adhesive. The DSC study indicated that the glass transition temperature increased of PUR adhesive by the reinforcement of CNF and CNC. Abstract: Polyurethane (PUR) adhesive was reinforced with cellulose nanocrystal (CNC) and acetylated cellulose nanofiber (CNF) to enhance its bonding performance. The reinforced adhesive was used to prepare lap joints using spruce and beech wood. Cyclic moisture exposure was carried out to assess the effect of moisture variation on the bond performance. Elastic modulus and shear strength were determined to ascertain the bonding behavior of adhesives. Reinforcement of PUR with nanocellulose significantly improved (33%) the elastic modulus in spruce wood while the improvement was only marginal (12%) in beech wood. Cyclic moisture exposure reduced the elastic modulus of CNC reinforced PUR in both the species, while the value increased by 5% for 0.5% CNF reinforced PUR joints. Reinforcement of PUR with nanocellulose significantly improved the shear strength. The improvent was more in spruce (45%) as compared to beech wood (35%). Moisture exposure caused a significant improvement in the shear strength of pure and reinforced PUR bonded joints, however, the values decreased for spruce wood except for 0.5% CNF loading where it was marginally higher. SEM micrographs revealed improved bond line with nanocellulose reinforcement in both the wood species. The glass transition temperature of PUR adhesive slightly decreased due nanocellulose reinforcement.