Cassava residue was liquefied by using ethylene glycol(EG), ethylene carbonate, propylene carbonate and polyethylene glycol(molecular weight: 400 g/mol) as the liquefaction reagent respectively at the temperature of 1...Cassava residue was liquefied by using ethylene glycol(EG), ethylene carbonate, propylene carbonate and polyethylene glycol(molecular weight: 400 g/mol) as the liquefaction reagent respectively at the temperature of 130-170 ℃ with sulfuric acid as the catalyst. The influences of liquefaction parameters, such as the type of liquefaction reagents, mass ratio of EG/cassava residue, liquefaction temperature and time on the properties of the products were discussed. The optimum liquefaction conditions were obtained when the mass ratio of EG/cassava residue was 6:1(w/w), the liquefaction temperature was 150 ℃, the liquefaction time was3 h and the mass fraction of concentrated sulfuric acid/EG was 2.5 wt%. The hydroxyl numbers and residue content of the liquefied products at optimal conditions were 1 137 mgKOH/g and 0.43%, respectively. FT-IR spectrum showed that the liquefaction product of cassava residue was polyether polyol and could be used to prepare polyurethane material or alkyd resins.展开更多
Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibit...Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.展开更多
Polyurethanes(PUs)are among the most studied,manufactured,and employed polymers due to their versatility and wide range of applications.However,their synthesis generally relies on toxic,non-renewable,and harmful petro...Polyurethanes(PUs)are among the most studied,manufactured,and employed polymers due to their versatility and wide range of applications.However,their synthesis generally relies on toxic,non-renewable,and harmful petroleum-based chemicals.In recent decades,driven by urgent environmental needs,research activities for the development of alternative synthetic routes for their production have significantly increased,especially to find more sustainable raw materials and procedures that,for example,no longer require dangerous solvents.Given these premises,the main purpose of this review is to highlight the most recent advances in the production of bioderived polyurethanes.After briefly discussing the chemistry of polyurethanes,we focused on the generation of bio-polyols and bio-isocyanates from plant oils and lignocellulosic biomass(e.g.lignin and sugars),as well as on the most recent trends in non-isocyanates polyurethanes(NIPUs)production.Discussions on their fields of application will be key to giving readers an overview of the actual capabilities of these materials.This review aims to cover and discuss the most recent contributions appearing in the literature up to the beginning of 2023.展开更多
基金Funded by the National Natural Science Foundation of China(No.51503041)the Natural Science Foundation of Fujian Province,China(No.2018J01752)
文摘Cassava residue was liquefied by using ethylene glycol(EG), ethylene carbonate, propylene carbonate and polyethylene glycol(molecular weight: 400 g/mol) as the liquefaction reagent respectively at the temperature of 130-170 ℃ with sulfuric acid as the catalyst. The influences of liquefaction parameters, such as the type of liquefaction reagents, mass ratio of EG/cassava residue, liquefaction temperature and time on the properties of the products were discussed. The optimum liquefaction conditions were obtained when the mass ratio of EG/cassava residue was 6:1(w/w), the liquefaction temperature was 150 ℃, the liquefaction time was3 h and the mass fraction of concentrated sulfuric acid/EG was 2.5 wt%. The hydroxyl numbers and residue content of the liquefied products at optimal conditions were 1 137 mgKOH/g and 0.43%, respectively. FT-IR spectrum showed that the liquefaction product of cassava residue was polyether polyol and could be used to prepare polyurethane material or alkyd resins.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00451587)supported by Post-plastic Specialized Graduate Program through the Korea Environmental Industry&Technology Institute(KEITI)funded by the Ministry of Environment(MOE).
文摘Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.
基金funded by the European Union-NextGenerationEU under the Italian Ministry of University and Research(MUR)National Innovation Ecosystem grant(No.ECS00000041-VITALITY)Universit a degli Studi di Perugia and MUR for support within the project Vitality.The University of Perugia is acknowledged for financial support to the university project“Fondo Ricerca di Ateneo,edizione 2022”.MUR is also thanked for PRIN-PNRR 2022 project(No.P2022XKWH7-CircularWaste)been supported by RUDN University Strategic Academic Leadership Program(R.Luque).
文摘Polyurethanes(PUs)are among the most studied,manufactured,and employed polymers due to their versatility and wide range of applications.However,their synthesis generally relies on toxic,non-renewable,and harmful petroleum-based chemicals.In recent decades,driven by urgent environmental needs,research activities for the development of alternative synthetic routes for their production have significantly increased,especially to find more sustainable raw materials and procedures that,for example,no longer require dangerous solvents.Given these premises,the main purpose of this review is to highlight the most recent advances in the production of bioderived polyurethanes.After briefly discussing the chemistry of polyurethanes,we focused on the generation of bio-polyols and bio-isocyanates from plant oils and lignocellulosic biomass(e.g.lignin and sugars),as well as on the most recent trends in non-isocyanates polyurethanes(NIPUs)production.Discussions on their fields of application will be key to giving readers an overview of the actual capabilities of these materials.This review aims to cover and discuss the most recent contributions appearing in the literature up to the beginning of 2023.
