针对风力发电叶片在多风沙环境下的固体粒子冲蚀磨损行为,研究了风力发电叶片专用环氧树脂(EPIKOTETM RIM 135、EPIKURETM RIM H 137)、传统玻纤增强环氧复合材料和新型碳纳米纤维纸-玻纤/环氧复合材料的固体粒子冲蚀磨损行为,并测试了...针对风力发电叶片在多风沙环境下的固体粒子冲蚀磨损行为,研究了风力发电叶片专用环氧树脂(EPIKOTETM RIM 135、EPIKURETM RIM H 137)、传统玻纤增强环氧复合材料和新型碳纳米纤维纸-玻纤/环氧复合材料的固体粒子冲蚀磨损行为,并测试了不同材料的玻璃化转变温度,进而对比分析了其对冲蚀磨损的影响;针对风力发电叶片在寒冷环境下表面容易结冰的现象,研究了上述三种材料表面的疏水性能,并测试了它们对水的接触角大小。结果表明:碳纳米纤维纸-玻纤/环氧复合材料具有良好的界面结合,且碳纳米纤维纸的引入提高了碳纳米纤维纸-玻纤/环氧复合材料的玻璃化转变温度(从55℃提高到63℃),从而改善了其耐固体粒子冲蚀磨损性能;同时,碳纳米纤维纸的加入改善了碳纳米纤维纸-玻纤/环氧复合材料的表面疏水性能(接触角从104°提高到131°)。展开更多
In this study, the characteristics of nanocellulose extracted from bleached softwood and hardwood pulps by formic acid hydrolysis followed by TEMPO-mediated oxidation were compared using transmission electron microsco...In this study, the characteristics of nanocellulose extracted from bleached softwood and hardwood pulps by formic acid hydrolysis followed by TEMPO-mediated oxidation were compared using transmission electron microscopy(TEM), atomic force microscopy(AFM), Fourier transform infrared analysis(FT-IR), X-ray diffraction(XRD), and thermal gravimetric analysis(TGA). The experimental results showed that the nanocellulose products derived from spruce pulp exhibited a relatively larger particle size, higher crystallinity, and higher thermal stability, compared with the corresponding products obtained from aspen pulp under the same conditions.Furthermore, the study helped establish that the properties of the nanocellulose products were highly dependent on the nature of the starting materials under identical processing conditions.展开更多
Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the...Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the residual sulfuric acid and improve the thermal stability of the CNC particles. Then, poly（ethylene oxide） （PEO） was employed to modify the nanocrystals through entanglement and physical adsorption. The goal was to further improve the thermal stability and weaken the hydrophilicity of CNCs. Original and modifed CNCs were dosed into a polylactic acid （PLA） matrix to prepare nanocomposites using a hot compression process. Results of the thermogravimetric analysis showed that the initial thermal decomposition temperature of the modifed CNCs showed a 120℃ improvement compared to the original CNCs. That is, the thermal stability of the modified CNCs improved because of their shielding and wrapping by a PEO layer on their surface. Results from scanning electron microscopy and ultraviolet-visible spectrophotometry showed that the compatibility of the modifed CNCs with organic PLA improved, which was attributed to the compatibility of the PEO chains adsorbed on the surface of the CNCs. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.展开更多
Cellulose nanocrystal was modified with poly(N,N-diethylaminomethyl methacrylate) to prepare an adsorbent containing amine groups for removing anionic dyes from waste water. The prepared adsorbent was characterized by...Cellulose nanocrystal was modified with poly(N,N-diethylaminomethyl methacrylate) to prepare an adsorbent containing amine groups for removing anionic dyes from waste water. The prepared adsorbent was characterized by Fourier-transform infrared spectrometry(FT-IR), X-ray photoelectron spectroscopy(XPS), and thermogravimetric analysis(TGA). The adsorption was affected by various factors, such as the contact time, adsorbent dosage, dye solution pH value, initial dye concentration, and ionic strength. The results revealed that amine functional groups mainly contribute to the adsorption of azo dyes(AO7). The adsorbent showed pseudo-secondorder adsorption kinetics, indicating that the dye molecules were chemisorbed on the adsorbent. The adsorption isotherm was found to fit better with the Langmuir isotherm model than with the Freundlich isotherm model.展开更多
文摘针对风力发电叶片在多风沙环境下的固体粒子冲蚀磨损行为,研究了风力发电叶片专用环氧树脂(EPIKOTETM RIM 135、EPIKURETM RIM H 137)、传统玻纤增强环氧复合材料和新型碳纳米纤维纸-玻纤/环氧复合材料的固体粒子冲蚀磨损行为,并测试了不同材料的玻璃化转变温度,进而对比分析了其对冲蚀磨损的影响;针对风力发电叶片在寒冷环境下表面容易结冰的现象,研究了上述三种材料表面的疏水性能,并测试了它们对水的接触角大小。结果表明:碳纳米纤维纸-玻纤/环氧复合材料具有良好的界面结合,且碳纳米纤维纸的引入提高了碳纳米纤维纸-玻纤/环氧复合材料的玻璃化转变温度(从55℃提高到63℃),从而改善了其耐固体粒子冲蚀磨损性能;同时,碳纳米纤维纸的加入改善了碳纳米纤维纸-玻纤/环氧复合材料的表面疏水性能(接触角从104°提高到131°)。
基金the Johan GadolinScholarship Programme at the Johan Gadolin Process Chemistry Centre at Abo Akademi University (Finland)the National Natural Science Foundation of China (No. 31470609)
文摘In this study, the characteristics of nanocellulose extracted from bleached softwood and hardwood pulps by formic acid hydrolysis followed by TEMPO-mediated oxidation were compared using transmission electron microscopy(TEM), atomic force microscopy(AFM), Fourier transform infrared analysis(FT-IR), X-ray diffraction(XRD), and thermal gravimetric analysis(TGA). The experimental results showed that the nanocellulose products derived from spruce pulp exhibited a relatively larger particle size, higher crystallinity, and higher thermal stability, compared with the corresponding products obtained from aspen pulp under the same conditions.Furthermore, the study helped establish that the properties of the nanocellulose products were highly dependent on the nature of the starting materials under identical processing conditions.
基金the National Natural Science Foundation of China (grant Nos. 31570578 and 31270632)the Fundamental Research Funds for the Central Universities (grant No. JUSRP51622A)the State Key Laboratory of Pulp and Paper Engineering (grant No. 201809)
文摘Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the residual sulfuric acid and improve the thermal stability of the CNC particles. Then, poly（ethylene oxide） （PEO） was employed to modify the nanocrystals through entanglement and physical adsorption. The goal was to further improve the thermal stability and weaken the hydrophilicity of CNCs. Original and modifed CNCs were dosed into a polylactic acid （PLA） matrix to prepare nanocomposites using a hot compression process. Results of the thermogravimetric analysis showed that the initial thermal decomposition temperature of the modifed CNCs showed a 120℃ improvement compared to the original CNCs. That is, the thermal stability of the modified CNCs improved because of their shielding and wrapping by a PEO layer on their surface. Results from scanning electron microscopy and ultraviolet-visible spectrophotometry showed that the compatibility of the modifed CNCs with organic PLA improved, which was attributed to the compatibility of the PEO chains adsorbed on the surface of the CNCs. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.
基金supported by the Science and Technology Program of Guangzhou (No. 201704020038)the foundation of State Key Laboratory of Pulp and Paper Engineering (No. 2017QN01)National Natural Science Foundation of China (No. 31570569)
文摘Cellulose nanocrystal was modified with poly(N,N-diethylaminomethyl methacrylate) to prepare an adsorbent containing amine groups for removing anionic dyes from waste water. The prepared adsorbent was characterized by Fourier-transform infrared spectrometry(FT-IR), X-ray photoelectron spectroscopy(XPS), and thermogravimetric analysis(TGA). The adsorption was affected by various factors, such as the contact time, adsorbent dosage, dye solution pH value, initial dye concentration, and ionic strength. The results revealed that amine functional groups mainly contribute to the adsorption of azo dyes(AO7). The adsorbent showed pseudo-secondorder adsorption kinetics, indicating that the dye molecules were chemisorbed on the adsorbent. The adsorption isotherm was found to fit better with the Langmuir isotherm model than with the Freundlich isotherm model.
