Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-o...Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-oxidative ageing differs,such that the UV ageing performance cannot be determined based on the thermal-oxidative ageing performance.Previous researches mainly focused on the chemical composite and technical performance changes of asphalt binder during UV ageing,and the UV light parameters effect on the ageing rate of asphalt binder.However,the theory for characterizing and explaining the development of UV ageing depth does not get too much attentions,and the UV ageing mechanism of asphalt binder is not very clear.Therefore,it cannot guide to develop or select the good methods or anti-UV ageing additives for asphalt binders.This paper focuses on the latest researches of the mechanisms and anti-ageing methods of asphalt binders.With the increase of UV ageing time,the UV ageing of asphalt binder develops gradually from the surface to inner part.There are various methods,such as low-penetration grade asphalt,less air void ratio,UV stabilizers and UV light absorbers,that can improve the UV ageing resistance of asphalt binders.A new theory of sensitive wavelengths of asphalt UV ageing is proposed,which can enrich the basic theory of asphalt UV ageing.Depending on this theory,different wavelengths of UV light have different ageing effects on asphalt binder.The composite anti-UV ageing additives with barrier and specific absorption effects on UV light is proposed,and may have better improvement effect on the anti-UV ageing performance of asphalt binder.展开更多
Neodymium complexes containing N heterocyclic carbene(NHC)ligands,NdCl5[1,3,R(NCH=)2C]-THF,(Nd1:R=2,6-Pr2C6H3,x=0;Nd2:R=2,6-Et2C6H3,x=1;Nd3:R=2.4,6-Me3C6H2,x=1)were synthesized and employed as precatalysts for the coo...Neodymium complexes containing N heterocyclic carbene(NHC)ligands,NdCl5[1,3,R(NCH=)2C]-THF,(Nd1:R=2,6-Pr2C6H3,x=0;Nd2:R=2,6-Et2C6H3,x=1;Nd3:R=2.4,6-Me3C6H2,x=1)were synthesized and employed as precatalysts for the coordination polymerization of conjugated dienes(butadiene and isoprene).In combination with trisobutylaluminium(TIBA),Nd1 promoted butadiene polymerization to produce extremely high cis-1,4(up to 99.0%)polybutadienes with high molecular weight(Mw=250-780 kg·mol 1).The Nd1/TIBA catalytic system also exhibited both high catalytic activity and cis-1,4 selectivity(up to 97.8%)for isoprene polymerization.The catalytic activity,molecular weight and molecular weight distribution of resulting polydienes were directly influenced by Al/Nd molar ratio,aging method,and polymerization temperature.Very interestingly,the high cis-1,4 selectivity of the catalyst towards butadiene and isoprene kept almost unchanged under different reaction conditions.The cis-1,4 polyisoprenes with high molecular weight(Mw=210-530 kg·mol 1)and narrow molecular weight distribution (Mw/Mn=1.9-2.7)as well as high cis-1.4 selectivity(-~97%)could be synthesized by using the aged Nd1/TIBA catalytic system in the presence of isoprene(100 equivalent to Nd)at low AlNd molar ratios of 6-10.Polyisoprenes with low molecular weights(Mw=12-76 kg·mol-7)and narrow molecular weight distributions (Mw/Mn=1.7-2.6)were obtained by using Nd2 and Nd3 as precatalysts,indicating that the molecular weight of resulting polyisoprenes can be adjusted by changing the substitutes of ligand in Nd complex.展开更多
Five boehmite adsorbents with high percentage of exposed(020)facets and large specific surface area were prepared by the separate nucleation and aging steps(SNAS)method at different rotating speeds,namely B-n(n=rotati...Five boehmite adsorbents with high percentage of exposed(020)facets and large specific surface area were prepared by the separate nucleation and aging steps(SNAS)method at different rotating speeds,namely B-n(n=rotating speeds)from 500 to 1500 rpm of the rotating liquidfilm reactor(RLFR).From 500 rpm to 1500 rpm,both specific surface area and percentage of exposed(020)facets increased by ca.10.8%and 16.9%,respectively.For all the samples,the adsorption behavior followed the pseudo-second order model and Langmuir isotherm model towards Congo red(CR).The B-1500 sample exhibited the best adsorption performance for CR with the maximum adsorption quantity of 1298.3 mg g^(−1) in neutral pH solution because of the smallest average particle size(d=55.6 nm),highest specific surface area(BET=224.42 m^(2)g^(−1)),and highest percentage of exposed(020)facets(55.18%).In particular,the boehmite pellets shaped with the alginate-assisted moulding method showed promising practical applications for the removal of CR in water through afixed-bed adsorption column;for example,ca.600 mL of boehmite pellets including ca.15.0 g of boehmite powder has the removal effciency of 75%in 3500 mL of aqueous solution with 100 mg L^(−1)CR.展开更多
基金The authors acknowledge the financial supported by National Natural Science Foundation of China(No.52108415 and No.51808517)the National Key R&D Program of China(No.2018YFB1600200)+5 种基金the Key Technical Innovation Projects of Hubei Province(No.2019AEE023)the Key R&D Program of Hubei Province(No.2020BCB064)the State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(No.SYSJJ2022-21),the Transportation Technology Project of Department of Transport of Hubei Province(No.2022-11-1-10)the European Union's Horizon 2020 Research and Innovation Programme Under the Marie Skłodowska-Curie Grant Agreement(No.101030767)the Scientific Research Fund Project of Wuhan Institute of Technology(No.K2021032)the Open Fund of National&Local Joint Engineering Laboratory of Traffic Civil Engineering Materials,Chongqing Jiaotong University(No.LHSYS-2020-004).
文摘Asphalt binder is inevitably aged by ultraviolet(UV)light during its service period.UV ageing can significantly decrease the technical properties of asphalt binder.The sensitivity of asphalt to UV ageing and thermal-oxidative ageing differs,such that the UV ageing performance cannot be determined based on the thermal-oxidative ageing performance.Previous researches mainly focused on the chemical composite and technical performance changes of asphalt binder during UV ageing,and the UV light parameters effect on the ageing rate of asphalt binder.However,the theory for characterizing and explaining the development of UV ageing depth does not get too much attentions,and the UV ageing mechanism of asphalt binder is not very clear.Therefore,it cannot guide to develop or select the good methods or anti-UV ageing additives for asphalt binders.This paper focuses on the latest researches of the mechanisms and anti-ageing methods of asphalt binders.With the increase of UV ageing time,the UV ageing of asphalt binder develops gradually from the surface to inner part.There are various methods,such as low-penetration grade asphalt,less air void ratio,UV stabilizers and UV light absorbers,that can improve the UV ageing resistance of asphalt binders.A new theory of sensitive wavelengths of asphalt UV ageing is proposed,which can enrich the basic theory of asphalt UV ageing.Depending on this theory,different wavelengths of UV light have different ageing effects on asphalt binder.The composite anti-UV ageing additives with barrier and specific absorption effects on UV light is proposed,and may have better improvement effect on the anti-UV ageing performance of asphalt binder.
基金supported by the National Natural Science Foundation of China(No.21634002)the Fundamental Research Funds for the Central Universities(Nos.XK1802-2 and XK1802-1).
文摘Neodymium complexes containing N heterocyclic carbene(NHC)ligands,NdCl5[1,3,R(NCH=)2C]-THF,(Nd1:R=2,6-Pr2C6H3,x=0;Nd2:R=2,6-Et2C6H3,x=1;Nd3:R=2.4,6-Me3C6H2,x=1)were synthesized and employed as precatalysts for the coordination polymerization of conjugated dienes(butadiene and isoprene).In combination with trisobutylaluminium(TIBA),Nd1 promoted butadiene polymerization to produce extremely high cis-1,4(up to 99.0%)polybutadienes with high molecular weight(Mw=250-780 kg·mol 1).The Nd1/TIBA catalytic system also exhibited both high catalytic activity and cis-1,4 selectivity(up to 97.8%)for isoprene polymerization.The catalytic activity,molecular weight and molecular weight distribution of resulting polydienes were directly influenced by Al/Nd molar ratio,aging method,and polymerization temperature.Very interestingly,the high cis-1,4 selectivity of the catalyst towards butadiene and isoprene kept almost unchanged under different reaction conditions.The cis-1,4 polyisoprenes with high molecular weight(Mw=210-530 kg·mol 1)and narrow molecular weight distribution (Mw/Mn=1.9-2.7)as well as high cis-1.4 selectivity(-~97%)could be synthesized by using the aged Nd1/TIBA catalytic system in the presence of isoprene(100 equivalent to Nd)at low AlNd molar ratios of 6-10.Polyisoprenes with low molecular weights(Mw=12-76 kg·mol-7)and narrow molecular weight distributions (Mw/Mn=1.7-2.6)were obtained by using Nd2 and Nd3 as precatalysts,indicating that the molecular weight of resulting polyisoprenes can be adjusted by changing the substitutes of ligand in Nd complex.
基金supported by National Key R&D Program of China(No.2016YFB0301600)the National Natural Science Foundation of China(21627813)+1 种基金the Fundamental Research Funds for the Central Universities(JD1716,12060093063)Distinguished Professor of Kunlun Scholars in Tarim University.
文摘Five boehmite adsorbents with high percentage of exposed(020)facets and large specific surface area were prepared by the separate nucleation and aging steps(SNAS)method at different rotating speeds,namely B-n(n=rotating speeds)from 500 to 1500 rpm of the rotating liquidfilm reactor(RLFR).From 500 rpm to 1500 rpm,both specific surface area and percentage of exposed(020)facets increased by ca.10.8%and 16.9%,respectively.For all the samples,the adsorption behavior followed the pseudo-second order model and Langmuir isotherm model towards Congo red(CR).The B-1500 sample exhibited the best adsorption performance for CR with the maximum adsorption quantity of 1298.3 mg g^(−1) in neutral pH solution because of the smallest average particle size(d=55.6 nm),highest specific surface area(BET=224.42 m^(2)g^(−1)),and highest percentage of exposed(020)facets(55.18%).In particular,the boehmite pellets shaped with the alginate-assisted moulding method showed promising practical applications for the removal of CR in water through afixed-bed adsorption column;for example,ca.600 mL of boehmite pellets including ca.15.0 g of boehmite powder has the removal effciency of 75%in 3500 mL of aqueous solution with 100 mg L^(−1)CR.
