Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N',N"-trimesoyltricaprolactam. A high polyme...Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N',N"-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactam magnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity (1.51 ), decreased melting temperature (218 ℃) and lower crystallinity (24.2%). The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.展开更多
We analyze the drawbacks of generally distributed time transition stochastic Petri nets(GDTT_SPN) in evaluating the performance of parallel systems,and propose a more general model,stochastic individual predicate/tran...We analyze the drawbacks of generally distributed time transition stochastic Petri nets(GDTT_SPN) in evaluating the performance of parallel systems,and propose a more general model,stochastic individual predicate/transition nets(SIPTN). SIPTN has higher modeling power and could provide more realistic models compared to GDTT_SPN,because in SIPTN the sojourn time distribution is determined not only by the transition,but also by the individuals. It is further proved that GDTT_SPN is a subset of SIPTN. As SIPTN introduces folding techniques from predicate/transition nets,SIPTN models have simpler and more intuitive graphic notations and accordingly higher usability,and thus are suitable for constructing simulation models for parallel systems.展开更多
基金supported by a grant from the National High Technology Research and Development Program of China(No.2014AA021201)the National Basic Research Program of China(No.2012CB721104)+1 种基金China Postdoctoral Science Foundation(No.2014M551574)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N',N"-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactam magnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity (1.51 ), decreased melting temperature (218 ℃) and lower crystallinity (24.2%). The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.
基金supported by the National Natural Science Foundation of China (No. 60576027)the Hi-Tech Research and Development Program (863) of China (No. 2006AA01Z415)
文摘We analyze the drawbacks of generally distributed time transition stochastic Petri nets(GDTT_SPN) in evaluating the performance of parallel systems,and propose a more general model,stochastic individual predicate/transition nets(SIPTN). SIPTN has higher modeling power and could provide more realistic models compared to GDTT_SPN,because in SIPTN the sojourn time distribution is determined not only by the transition,but also by the individuals. It is further proved that GDTT_SPN is a subset of SIPTN. As SIPTN introduces folding techniques from predicate/transition nets,SIPTN models have simpler and more intuitive graphic notations and accordingly higher usability,and thus are suitable for constructing simulation models for parallel systems.