Production of pyrolytic lignin for the phenolic resin synthesis via fast pyrolysis

Recycling of waste wood into resol type phenol-formaldehyde (PF) resins via fast pyrolysis was demonstrated. Waste wood collected from the building demolition site in Finland was pyrolyzed with 20 kg/h circulating fluidized bed pyrolysis pilot unit. Pilot was operated with high organic liquid yield (60 wt% on average) and the produced fast pyrolysis bio-oil was fractionated by water addition into aqueous phase and water insoluble phase. The obtained fractions were characterized, and the water-insoluble viscous lignin fraction was used in the synthesis of PF-resins. Commercial phenol was successfully replaced by pyrolytic lignin fraction at 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% producing resins of low in free formaldehyde content, but resins with high replacement ratio exhibited higher viscosities. The use of H2O/n-butanol mixture as solvent at a ratio 70:30 wt/wt% proved capable to prolong the storage time of the resin and helped to maintain the viscosity at acceptable values for at least 2 weeks before their use in the targeted application. Finally, the gluing performance of the resins was evaluated by measuring the tensile shear strength of lap joints formed by gluing 5 mm thick beech wood veneers. All the produced resins fulfilled a dry strength limit of ≥ 10 N/mm2. Wet strength limit ≥ 7 N/mm2 was fulfilled by the resins with the replacement ratio up 40 wt%, but resins with replacement ratio of 50 wt% had somewhat reduced wet strength. These results confirm a promising protentional application of pyrolysis derived lignin fraction in phenolic wood adhesives, at least in dry conditions

Room-Temperature Self-Healable Blends of Waterborne Polyurethanes with 2-Hydroxyethyl Methacrylate-Based Polymers

The design of self-healing agents is a topic of important scientific interest for the development of high-performance materials for coating applications. Herein, two series of copolymers of 2-hydroxyethyl methacrylate (HEMA) with either the hydrophilic N,N-dimethylacrylamide (DMAM) or the epoxy group-bearing hydrophobic glycidyl methacrylate were synthesized and studied as potential self-healing agents of waterborne polyurethanes (WPU). The molar percentage of DMAM or GMA units in the P(HEMA-co-DMAMy) and P(HEMA-co-GMAy) copolymers varies from 0% up to 80%. WPU/polymer composites with a 10% w/w or 20% w/w copolymer content were prepared with the facile method of solution mixing. Thanks to the presence of P(HEMA-co-DMAMy) copolymers, WPU/P(HEMA-co-DMAMy) composite films exhibited surface hydrophilicity (water contact angle studies), and tendency for water uptake (water sorption kinetics studies). In contrast, the surfaces of the WPU/P(HEMA-co-GMAy) composites were less hydrophilic compared with the WPU/P(HEMA-co-DMAMy) ones. The room-temperature, water-mediated self-healing ability of these composites was investigated through addition of water drops on the damaged area. Both copolymer series exhibited healing abilities, with the hydrophilic P(HEMA-co-DMAMy) copolymers being more promising. This green healing procedure, in combination with the simple film fabrication process and simple healing triggering, makes these materials attractive for practical applications

Room-Temperature Self-Healable Blends of Waterborne Polyurethanes with 2-Hydroxyethyl Methacrylate-Based Polymers

The design of self-healing agents is a topic of important scientific interest for the development of high-performance materials for coating applications. Herein, two series of copolymers of 2-hydroxyethyl methacrylate (HEMA) with either the hydrophilic N,N-dimethylacrylamide (DMAM) or the epoxy group-bearing hydrophobic glycidyl methacrylate were synthesized and studied as potential self-healing agents of waterborne polyurethanes (WPU). The molar percentage of DMAM or GMA units in the P(HEMA-co-DMAMy) and P(HEMA-co-GMAy) copolymers varies from 0% up to 80%. WPU/polymer composites with a 10% w/w or 20% w/w copolymer content were prepared with the facile method of solution mixing. Thanks to the presence of P(HEMA-co-DMAMy) copolymers, WPU/P(HEMA-co-DMAMy) composite films exhibited surface hydrophilicity (water contact angle studies), and tendency for water uptake (water sorption kinetics studies). In contrast, the surfaces of the WPU/P(HEMA-co-GMAy) composites were less hydrophilic compared with the WPU/P(HEMA-co-DMAMy) ones. The room-temperature, water-mediated self-healing ability of these composites was investigated through addition of water drops on the damaged area. Both copolymer series exhibited healing abilities, with the hydrophilic P(HEMA-co-DMAMy) copolymers being more promising. This green healing procedure, in combination with the simple film fabrication process and simple healing triggering, makes these materials attractive for practical applications