The phase transition from tetragonal form II to hexagonal form I was studied for the butene-1/ethylene and butene-1/1,5- hexadiene random copolymers, which have comparable molecular weight but distinct linear ethylene...The phase transition from tetragonal form II to hexagonal form I was studied for the butene-1/ethylene and butene-1/1,5- hexadiene random copolymers, which have comparable molecular weight but distinct linear ethylene and ringlike methylene-1,3- cyclopentane （MCP） structural co-units, respectively. It is known that this solid phase transition follows the nucleation-growth mechanism, so the stepwise annealing protocol was utilized to investigate the influences of co-units on the optimal nucleation and growth temperatures. Compared with optimal nucleation and growth temperatures of-10 and 3 5 ℃, respectively, in polybutene-1 homopolymer, two butene-1/ethylene copolymers with 1.5 mol% and 4.3 mol% co-units have the slightly lower optimal nucleation temperature of-15 ℃ but much higher optimal growth temperature of 50 ℃. Clearly, the effect of ethylene co-unit is more significant on varying optimal temperature for growth than for nucleation. Furthermore, when the incorporated co-unit is ringlike MCP, the optimal nucleation temperature is -15 ℃ for 2.15 mol% co-units, the same with above BE copolymers, but -13 ℃ for a very low concentration of 0.65 mol%. Interestingly, the optimal growth temperature of butene-1/1,5-hexadiene copolymers with 0.65 mo1%-2.15 mol% MCP co- units increases to 55 ℃, which is also independent on co-unit concentration. These obtained values of optimal temperatures provide crucial parameters for rapid II-I phase transition.展开更多
针对传统输电网和主动配电网(active distribution network,ADN)独立的调度方式致使“源-网-荷”各环节资源协同潜力挖掘不充分,难以实现输-配系统经济高效运行的问题,提出了市场环境下考虑配电网络重构和需求响应的输配优化调度方法。...针对传统输电网和主动配电网(active distribution network,ADN)独立的调度方式致使“源-网-荷”各环节资源协同潜力挖掘不充分,难以实现输-配系统经济高效运行的问题,提出了市场环境下考虑配电网络重构和需求响应的输配优化调度方法。首先,剖析电力市场机制下输-配电网间的耦合机理,构建考虑机组组合的输电网市场出清模型,以发挥“源侧”应对电力负荷波动的能力;以节点边际电价为引导信号,提出同时考虑ADN网络重构和需求侧响应的输配协同双层优化模型,旨在挖掘ADN在“网侧”和“荷侧”的双侧协同潜力,从而提高输-配电网中“源-网-荷”各环节资源间的协同能力。其次,针对输-配模型上、下层级的物理特点,采用随机规划L形算法,引入虚拟变量实现输配协同模型的解耦,基于对偶理论,获取反映资源利用情况的对偶乘子集合,进而计算次梯度参数并生成仿射割集,优化输-配耦合变量,加速模型收敛,实现对输-配协同模型的分布式高效求解。最后,以6节点输电网和7节点配电网构成的T6+D7系统和118节点输电网和8个20节点配电网构成的T118+8*D20系统为例,验证所提模型和方法的有效性,研究结果表明:输配系统的整体经济性提升了8.68%,所提模型和方法具有明显优势。展开更多
The dimethylpyridylamidohafnium catalyst was used to synthesize 1-butene/cyclohexene and 1-butene/vinylcyclohexane random copolymers,which have extra six-membered cyclic co-units in main chain and side chain,respectiv...The dimethylpyridylamidohafnium catalyst was used to synthesize 1-butene/cyclohexene and 1-butene/vinylcyclohexane random copolymers,which have extra six-membered cyclic co-units in main chain and side chain,respectively.For the obtained copolymers of different incorporations,the crystallization from amorphous melt and the solid phase transition from tetragonal to trigonal phases were investigated with differential scanning calorimetry.Both of the incorporated cyclic co-units decrease the crystallization kinetics,but the presence of cyclohexene keeps the melting temperature of copolymers constant.Interestingly,the strong memory effect of crystallization can appear at the elevated temperature even above the equilibrium melting temperature,as the content of co-units was increased.The 1-butene/vinylcyclohexane copolymer with 1.52 mol%co-units exhibits a rather strong memory effect with the broad Domain Ila width of 43℃and the crystallization temperature raising of 24℃.Furthermore,the transition of tetragonal phase into trigonal phase was also explored for different co-units and incorporations.It was found that both of the cyclohexene co-units and vinylcyclohexane co-units effectively slow down the kinetics of phase transition.However,the vinylcyclohexane co-units have a much higher efficiency in suppressing phase transition than the cyclohexene co-units,where 0.53 mol%vinylcyclohexane can com-pletely stop phase transition within 1320 h.Considering the fact that copolymers with vinylcyclohexane co-units actually have lower glass transition temperatures,it was indicated that the suppression of phase transition is also largely influenced by the steric co-units in the side chain for the helical and positional adjustments,not only by the segmental mobility.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51573132 and 51633009)Tianjin Natural Science Foundation(No.16JCQNJC02700)
文摘The phase transition from tetragonal form II to hexagonal form I was studied for the butene-1/ethylene and butene-1/1,5- hexadiene random copolymers, which have comparable molecular weight but distinct linear ethylene and ringlike methylene-1,3- cyclopentane （MCP） structural co-units, respectively. It is known that this solid phase transition follows the nucleation-growth mechanism, so the stepwise annealing protocol was utilized to investigate the influences of co-units on the optimal nucleation and growth temperatures. Compared with optimal nucleation and growth temperatures of-10 and 3 5 ℃, respectively, in polybutene-1 homopolymer, two butene-1/ethylene copolymers with 1.5 mol% and 4.3 mol% co-units have the slightly lower optimal nucleation temperature of-15 ℃ but much higher optimal growth temperature of 50 ℃. Clearly, the effect of ethylene co-unit is more significant on varying optimal temperature for growth than for nucleation. Furthermore, when the incorporated co-unit is ringlike MCP, the optimal nucleation temperature is -15 ℃ for 2.15 mol% co-units, the same with above BE copolymers, but -13 ℃ for a very low concentration of 0.65 mol%. Interestingly, the optimal growth temperature of butene-1/1,5-hexadiene copolymers with 0.65 mo1%-2.15 mol% MCP co- units increases to 55 ℃, which is also independent on co-unit concentration. These obtained values of optimal temperatures provide crucial parameters for rapid II-I phase transition.
文摘针对传统输电网和主动配电网(active distribution network,ADN)独立的调度方式致使“源-网-荷”各环节资源协同潜力挖掘不充分,难以实现输-配系统经济高效运行的问题,提出了市场环境下考虑配电网络重构和需求响应的输配优化调度方法。首先,剖析电力市场机制下输-配电网间的耦合机理,构建考虑机组组合的输电网市场出清模型,以发挥“源侧”应对电力负荷波动的能力;以节点边际电价为引导信号,提出同时考虑ADN网络重构和需求侧响应的输配协同双层优化模型,旨在挖掘ADN在“网侧”和“荷侧”的双侧协同潜力,从而提高输-配电网中“源-网-荷”各环节资源间的协同能力。其次,针对输-配模型上、下层级的物理特点,采用随机规划L形算法,引入虚拟变量实现输配协同模型的解耦,基于对偶理论,获取反映资源利用情况的对偶乘子集合,进而计算次梯度参数并生成仿射割集,优化输-配耦合变量,加速模型收敛,实现对输-配协同模型的分布式高效求解。最后,以6节点输电网和7节点配电网构成的T6+D7系统和118节点输电网和8个20节点配电网构成的T118+8*D20系统为例,验证所提模型和方法的有效性,研究结果表明:输配系统的整体经济性提升了8.68%,所提模型和方法具有明显优势。
基金the National Natural Science Foundation of China(Nos.51873151 and 52022065).
文摘The dimethylpyridylamidohafnium catalyst was used to synthesize 1-butene/cyclohexene and 1-butene/vinylcyclohexane random copolymers,which have extra six-membered cyclic co-units in main chain and side chain,respectively.For the obtained copolymers of different incorporations,the crystallization from amorphous melt and the solid phase transition from tetragonal to trigonal phases were investigated with differential scanning calorimetry.Both of the incorporated cyclic co-units decrease the crystallization kinetics,but the presence of cyclohexene keeps the melting temperature of copolymers constant.Interestingly,the strong memory effect of crystallization can appear at the elevated temperature even above the equilibrium melting temperature,as the content of co-units was increased.The 1-butene/vinylcyclohexane copolymer with 1.52 mol%co-units exhibits a rather strong memory effect with the broad Domain Ila width of 43℃and the crystallization temperature raising of 24℃.Furthermore,the transition of tetragonal phase into trigonal phase was also explored for different co-units and incorporations.It was found that both of the cyclohexene co-units and vinylcyclohexane co-units effectively slow down the kinetics of phase transition.However,the vinylcyclohexane co-units have a much higher efficiency in suppressing phase transition than the cyclohexene co-units,where 0.53 mol%vinylcyclohexane can com-pletely stop phase transition within 1320 h.Considering the fact that copolymers with vinylcyclohexane co-units actually have lower glass transition temperatures,it was indicated that the suppression of phase transition is also largely influenced by the steric co-units in the side chain for the helical and positional adjustments,not only by the segmental mobility.
