Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these ...Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.展开更多
Based on the facts that the adhered lactic acid bacteria on raw corn stovers are rare and the fermentation and silage quality of corn stovers are poor, we carried out this research to study the utilization prospects o...Based on the facts that the adhered lactic acid bacteria on raw corn stovers are rare and the fermentation and silage quality of corn stovers are poor, we carried out this research to study the utilization prospects of additives containing lactic acid bacteria and enzymes in preparation of green corn stover silage. The lactic acid bacteria and enzymes were screened out and propagated. The isolated Lactobacil us species included Lactococcus lactis （Enterococcus, Leuconostoc, Labto-coccus, Streptococcus, etc.） and Lactobacil us. The additives would not only improve the silage quality, but also reduce the fermentation losses.展开更多
The catalytic transformation of cellulose into key building-block or platform chemicals such as 5-hydoxymethylfurfural(HMF),levulinic acid,and lactic acid under mild conditions,has attracted much attention in recent y...The catalytic transformation of cellulose into key building-block or platform chemicals such as 5-hydoxymethylfurfural(HMF),levulinic acid,and lactic acid under mild conditions,has attracted much attention in recent years,as these conversions can be operated without consumption of hydrogen or oxygen and thus are more economical compared to the hydrogenolysis or oxidation of cellulose.This review article highlights recent advances in the development of novel catalysts or catalytic processes for the conversion of cellulose and its derived carbohydrates into HMF,levulinic acid,and lactic acid or their esters under inert atmosphere.We also analyze efficient catalytic systems for HMF production,in particular Lewis acids combined with ionic liquid or biphasic systems.For the formations of levulinic and lactic acids or their esters,we focus on the reactions in aqueous and alcohol media catalyzed by multifunctional catalysts that combine the functions of hydrolysis,isomerization,and dehydration-rehydration or retro-aldol reactions.The reaction mechanism for each process will also be discussed to gain insights into the activation of C–O and C–C bonds in the absence of hydrogen or oxygen.展开更多
In this work, a phosphorous-based compound （DOPO-ICN） was obtained by a two-step process. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide （DOPO） reacted with formaldehyde firstly, followed with reacting with 1...In this work, a phosphorous-based compound （DOPO-ICN） was obtained by a two-step process. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide （DOPO） reacted with formaldehyde firstly, followed with reacting with 1,6-hexane diisocyanate （HD1）. The chemical structure of DOPO-ICN was confirmed by Fourier transform infrared spectroscopy （FTIR） and 1H NMR. The influence of DOPO-1CN on the mechanical and flammability properties ofjute/PLA composites was studied. Compared to DOPO, DOPO-ICN improved the tensile, flexural and impact strength of the flame retardant jute/PLA composites. Moreover, the flammability ofjute/PLA composites with different DOPO and DOPO-MA loading was investigated by thermogravimetric analysis （TGA）, UL 94 test and limiting oxygen index （LOI） measurements. The results showed that DOPO-ICN imparted the flame retardancy to the jute/PLA composites.展开更多
基金supported by the Program for Creation of Interdisciplinary Research and Ensemble Program of Frontier Research Institute for Interdisciplinary Sciences,Tohoku University。
文摘Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.
文摘Based on the facts that the adhered lactic acid bacteria on raw corn stovers are rare and the fermentation and silage quality of corn stovers are poor, we carried out this research to study the utilization prospects of additives containing lactic acid bacteria and enzymes in preparation of green corn stover silage. The lactic acid bacteria and enzymes were screened out and propagated. The isolated Lactobacil us species included Lactococcus lactis （Enterococcus, Leuconostoc, Labto-coccus, Streptococcus, etc.） and Lactobacil us. The additives would not only improve the silage quality, but also reduce the fermentation losses.
基金supported by the National Natural Science Foundation of China(21173172,21103143,21033006)the Research Fund for the Doctorial Program of Higher Education(20130121130001)the Program for Changjiang Scholars and Innovative Research Team in University(IRT1036)
文摘The catalytic transformation of cellulose into key building-block or platform chemicals such as 5-hydoxymethylfurfural(HMF),levulinic acid,and lactic acid under mild conditions,has attracted much attention in recent years,as these conversions can be operated without consumption of hydrogen or oxygen and thus are more economical compared to the hydrogenolysis or oxidation of cellulose.This review article highlights recent advances in the development of novel catalysts or catalytic processes for the conversion of cellulose and its derived carbohydrates into HMF,levulinic acid,and lactic acid or their esters under inert atmosphere.We also analyze efficient catalytic systems for HMF production,in particular Lewis acids combined with ionic liquid or biphasic systems.For the formations of levulinic and lactic acids or their esters,we focus on the reactions in aqueous and alcohol media catalyzed by multifunctional catalysts that combine the functions of hydrolysis,isomerization,and dehydration-rehydration or retro-aldol reactions.The reaction mechanism for each process will also be discussed to gain insights into the activation of C–O and C–C bonds in the absence of hydrogen or oxygen.
基金supported by the Ministry of Industry and Information Technology of China(Grant No.MJ-2015-H-G-103)the National Natural Science Foundation of China(Grant Nos.51103108,11172212)the Fundamental Research Funds for the Central Universities
文摘In this work, a phosphorous-based compound （DOPO-ICN） was obtained by a two-step process. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide （DOPO） reacted with formaldehyde firstly, followed with reacting with 1,6-hexane diisocyanate （HD1）. The chemical structure of DOPO-ICN was confirmed by Fourier transform infrared spectroscopy （FTIR） and 1H NMR. The influence of DOPO-1CN on the mechanical and flammability properties ofjute/PLA composites was studied. Compared to DOPO, DOPO-ICN improved the tensile, flexural and impact strength of the flame retardant jute/PLA composites. Moreover, the flammability ofjute/PLA composites with different DOPO and DOPO-MA loading was investigated by thermogravimetric analysis （TGA）, UL 94 test and limiting oxygen index （LOI） measurements. The results showed that DOPO-ICN imparted the flame retardancy to the jute/PLA composites.
