Publication Date:
2018-05-03
Description:
With an attempt to economically and efficiently improve the water resistance of defatted soya bean flour (DSF)-based wood adhesives, DSF was subjected to thermal treatment at various temperatures (65°C, 80°C, 95°C, 110°C and 125°C) for 30 min. The effects of thermal treatment temperature onto the chemical structure, crystalline degree, water-insoluble content and acetaldehyde value of the thermally treated DSF (T-DSF) were investigated. The thermal stabilities and bonding properties of soya bean adhesives prepared from T-DSF and cross-linker epichlorohydrin-modified polyamide (EMPA) were also investigated. Test results indicated that both the water-insoluble content and the acetaldehyde value of T-DSF increased after thermal treatment, reaching the highest values of 27.28% and 26.81 mg g –1 , respectively. All plywood bonded with the T-DSF-based adhesive withstood a 28 h boiling–dry–boiling accelerated ageing treatment, while plywood bonded with the DSF-based adhesive delaminated after 4 h of water boiling, demonstrating the significantly improved water resistance of the T-DSF-based adhesives. Related analyses also confirmed that this improvement was due to: (i) the formation of insoluble cross-linked structures of T-DSF resulting from protein–protein self-cross-linking reactions and the protein–carbohydrate Maillard reaction and (ii) increased cross-linking efficiency between T-DSF and cross-linker EMPA owing to more T-DSF-reactive groups being released after thermal treatment.
Keywords:
materials science
Electronic ISSN:
2054-5703
Topics:
Natural Sciences in General
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