Positron annihilation lifetime spectra measurements were performed on C_(60)-containing chitosan as a function of temperature ranging from 290 to 380K.Both the ortho-positronium annihilation lifetimeт_(3) and its int...Positron annihilation lifetime spectra measurements were performed on C_(60)-containing chitosan as a function of temperature ranging from 290 to 380K.Both the ortho-positronium annihilation lifetimeт_(3) and its intensity Is increase with increasing temperature,however,the values of I_(3) in C_(60)-containing chitosan are smaller than that in pure chitosan,and the slope ofт_(3) with temperature is also suppressed after C_(60) linked.The existing three models for positron annihilation in polymer have been compared to analyze the experiment result.It is realized that only the spur reaction model,combined with the free volume model,can explain it satisfactorily.The ortho-positronium lifetime and intensity were affected by the local physicochemical environment of material,i.e.,free-volume structure,electron scavenging and trapping sites,etc.The linked C_(60) that play a significant chemical inhibition and quenching role on positronium formation and annihilation isfirst observed.The microstructure change brought by C_(60) group has also been discussed.展开更多
目前，我国绝大多数火电厂采用的燃料是煤．产生大量S02气体对外排放。二氧化硫是导致酸雨产生的主要原因之一．每年因酸雨造成的直接经济损失已超过1000亿元。据统计．我国火电厂的二氧化硫排放大约占总量的1／3左右。因而对火电厂烟...目前，我国绝大多数火电厂采用的燃料是煤．产生大量S02气体对外排放。二氧化硫是导致酸雨产生的主要原因之一．每年因酸雨造成的直接经济损失已超过1000亿元。据统计．我国火电厂的二氧化硫排放大约占总量的1／3左右。因而对火电厂烟气脱硫（Flue Gas Desulfurization，FGD）控制系统的研究与设计对于解决我国当前的环境问题十分重要。展开更多
Positron annihilation lifetime spectroscopy has been used to study the free volume properties of the cross-linked polyurethane network as a function of temperature in the range from 15K to 300K.The glass transition of...Positron annihilation lifetime spectroscopy has been used to study the free volume properties of the cross-linked polyurethane network as a function of temperature in the range from 15K to 300K.The glass transition of polyurethane was observed and the thermal expansion coefficient of the free volume was calculated.Analysis of the ortho-positronium(o-Ps)lifetime distribution shows that the distribution of the free volume in polyurethane is slightly broadened with the increasing temperature in the glassy state,and then significantly broadened with the increasing temperature above the glass transition.展开更多
The positron lifetime spectra and electrical conductivities have been measured for polyaniline as a function of protonation level ([H+] from 10-7-1000.8 mol/L). Weobserved that (1) the short lifetime τ1, which was re...The positron lifetime spectra and electrical conductivities have been measured for polyaniline as a function of protonation level ([H+] from 10-7-1000.8 mol/L). Weobserved that (1) the short lifetime τ1, which was related to electron density in bulk,decreased with the protonation level; (2) the intermediate lifetime τ2≈360ps, almost remaining constant, whereas its intensity I2 increased with increasing protonation level which was related to the conductivity of material. These results are discussed in terms of conducting island model.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.29674020.
文摘Positron annihilation lifetime spectra measurements were performed on C_(60)-containing chitosan as a function of temperature ranging from 290 to 380K.Both the ortho-positronium annihilation lifetimeт_(3) and its intensity Is increase with increasing temperature,however,the values of I_(3) in C_(60)-containing chitosan are smaller than that in pure chitosan,and the slope ofт_(3) with temperature is also suppressed after C_(60) linked.The existing three models for positron annihilation in polymer have been compared to analyze the experiment result.It is realized that only the spur reaction model,combined with the free volume model,can explain it satisfactorily.The ortho-positronium lifetime and intensity were affected by the local physicochemical environment of material,i.e.,free-volume structure,electron scavenging and trapping sites,etc.The linked C_(60) that play a significant chemical inhibition and quenching role on positronium formation and annihilation isfirst observed.The microstructure change brought by C_(60) group has also been discussed.
文摘目前，我国绝大多数火电厂采用的燃料是煤．产生大量S02气体对外排放。二氧化硫是导致酸雨产生的主要原因之一．每年因酸雨造成的直接经济损失已超过1000亿元。据统计．我国火电厂的二氧化硫排放大约占总量的1／3左右。因而对火电厂烟气脱硫（Flue Gas Desulfurization，FGD）控制系统的研究与设计对于解决我国当前的环境问题十分重要。
基金Supported by the National Natural Science Foundation of China under Grant No.29674020the Education Minstry of China.
文摘Positron annihilation lifetime spectroscopy has been used to study the free volume properties of the cross-linked polyurethane network as a function of temperature in the range from 15K to 300K.The glass transition of polyurethane was observed and the thermal expansion coefficient of the free volume was calculated.Analysis of the ortho-positronium(o-Ps)lifetime distribution shows that the distribution of the free volume in polyurethane is slightly broadened with the increasing temperature in the glassy state,and then significantly broadened with the increasing temperature above the glass transition.
文摘The positron lifetime spectra and electrical conductivities have been measured for polyaniline as a function of protonation level ([H+] from 10-7-1000.8 mol/L). Weobserved that (1) the short lifetime τ1, which was related to electron density in bulk,decreased with the protonation level; (2) the intermediate lifetime τ2≈360ps, almost remaining constant, whereas its intensity I2 increased with increasing protonation level which was related to the conductivity of material. These results are discussed in terms of conducting island model.
