Paper documents experience severe acidification and embrittlement.Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength.However,little re...Paper documents experience severe acidification and embrittlement.Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength.However,little research has been conducted on the aging resistance of nanocellulose-reinforced paper.In this study,six types of nanocelluloses were used to reinforce aged paper.The reinforcement and anti-aging performances were evaluated,and the anti-aging mechanism was further clarified.Nanocellulose with a high degree of polymerization can better enhance aged paper,and non-chemical nanocellulose also shows better anti-aging performance,such as nanocellulose prepared by mechanical or biological methods.However,nanocellulose prepared using chemical methods exhibits poor reinforcement and anti-aging performance.This is because it has a small particle size that is not beneficial for physical crosslinking with paper fibers.More importantly,the introduction of acidic or oxidizing groups on nanocellulose accelerates the acid hydrolysis and oxidation rate of paper fibers,especially nanocellulose prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation,which should not be used to protect paper documents.展开更多
Biobased urea nowadays attracts increasing attention as a biomass resource with giant potential,which benefits from the development of biobased ammonia and ecological sanitation system.Urea is an ideal feedstock for c...Biobased urea nowadays attracts increasing attention as a biomass resource with giant potential,which benefits from the development of biobased ammonia and ecological sanitation system.Urea is an ideal feedstock for chemical industry and developing new urea-based polymer materials can take advantage of the urea resource.In this work,a class of renewable linear polyesters,namely polyisocyanuratoesters(PICEs)were synthesized from a urea-based monomer bis(2-carbomethoxyethyl)isocyanurate and biobased aliphatic diols.Compared with conventional aliphatic polyesters,PICEs containing isocyanurate rings in the polymer chain backbone exhibit outstanding flame retardancy that both PICE-4(the number‘4’refers to the number of methylene in diols,e.g.4 for butylene and 6 for hexylene)and PICE-6 have high limiting oxygen index values over 30%.In the UL 94 tests,PICE-6 reaches V-1 rating;while V-2 is found for PICE-10.All PICEs exhibit similar pyrolysis behavior that the temperatures of 5%weight loss are around 320°C.PICEs are found to have glass transition among 20°C-45°C.No crystallization behavior is observed without annealing except for PICE-10,which can crystallize even at room temperature.展开更多
It has been proved that introducing isocyanurate into polymer chains could improve the flame retardancy of polymers.We describe in this work the synthesis and the thermal property study of three thermoplastic polyisoc...It has been proved that introducing isocyanurate into polymer chains could improve the flame retardancy of polymers.We describe in this work the synthesis and the thermal property study of three thermoplastic polyisocyanurates,which are polyisocyanuratoamide(PICA-6),polyisocyanurato(ester amide)(PICEA-6)and polyisocyanurato(urea ester)(PICUE-6).These polymers show similar and improved thermal stability with the existence of isocyanurate rings.PICA-6 is more crystalizable than the rest two and the melting temperature is found to be around 240℃ but it still crystalizes slowly.For PICEA-6 and PICUE-6,only glass transition can be observed on the DSC traces.The glass transition temperature follows the order of PICA-6>PICEA-6>PICUE-6(101.9,77.9 and 28.7℃,respectively).展开更多
基金supported by the Fundamental Research Funds for the Central Universities of South China University of Technology(SCUT),China(No.2022ZYGXZR106)Science and Technology Plan Special Project of Guangzhou,China(No.GZDD201808).
文摘Paper documents experience severe acidification and embrittlement.Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength.However,little research has been conducted on the aging resistance of nanocellulose-reinforced paper.In this study,six types of nanocelluloses were used to reinforce aged paper.The reinforcement and anti-aging performances were evaluated,and the anti-aging mechanism was further clarified.Nanocellulose with a high degree of polymerization can better enhance aged paper,and non-chemical nanocellulose also shows better anti-aging performance,such as nanocellulose prepared by mechanical or biological methods.However,nanocellulose prepared using chemical methods exhibits poor reinforcement and anti-aging performance.This is because it has a small particle size that is not beneficial for physical crosslinking with paper fibers.More importantly,the introduction of acidic or oxidizing groups on nanocellulose accelerates the acid hydrolysis and oxidation rate of paper fibers,especially nanocellulose prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation,which should not be used to protect paper documents.
基金The authors are grateful for the financial supports of the National Science Foundation of China(21404040)the Fundamental Research Funds for the Central Universities(2015ZM053)the State Key Laboratory of Pulp and Paper Engineering(201538).
文摘Biobased urea nowadays attracts increasing attention as a biomass resource with giant potential,which benefits from the development of biobased ammonia and ecological sanitation system.Urea is an ideal feedstock for chemical industry and developing new urea-based polymer materials can take advantage of the urea resource.In this work,a class of renewable linear polyesters,namely polyisocyanuratoesters(PICEs)were synthesized from a urea-based monomer bis(2-carbomethoxyethyl)isocyanurate and biobased aliphatic diols.Compared with conventional aliphatic polyesters,PICEs containing isocyanurate rings in the polymer chain backbone exhibit outstanding flame retardancy that both PICE-4(the number‘4’refers to the number of methylene in diols,e.g.4 for butylene and 6 for hexylene)and PICE-6 have high limiting oxygen index values over 30%.In the UL 94 tests,PICE-6 reaches V-1 rating;while V-2 is found for PICE-10.All PICEs exhibit similar pyrolysis behavior that the temperatures of 5%weight loss are around 320°C.PICEs are found to have glass transition among 20°C-45°C.No crystallization behavior is observed without annealing except for PICE-10,which can crystallize even at room temperature.
基金the financial supports to this work by the National Natural Science Foundation of China(Nos.21404040,21734004,51573061)the Fund of the Key Laboratory of Luminescence from Molecular Aggregates of Guangdong Province,Guangzhou 510640,China(South China University of Technology,No.2019B030301003)the Opening Project Funding of Key Laboratory of Polymer Processing Engineering(South China University of Technology),Ministry of Education,China(No.KFKT1702).
文摘It has been proved that introducing isocyanurate into polymer chains could improve the flame retardancy of polymers.We describe in this work the synthesis and the thermal property study of three thermoplastic polyisocyanurates,which are polyisocyanuratoamide(PICA-6),polyisocyanurato(ester amide)(PICEA-6)and polyisocyanurato(urea ester)(PICUE-6).These polymers show similar and improved thermal stability with the existence of isocyanurate rings.PICA-6 is more crystalizable than the rest two and the melting temperature is found to be around 240℃ but it still crystalizes slowly.For PICEA-6 and PICUE-6,only glass transition can be observed on the DSC traces.The glass transition temperature follows the order of PICA-6>PICEA-6>PICUE-6(101.9,77.9 and 28.7℃,respectively).
