Monte Carlo Simulation of Short Chain Branched Polyolefins in the Molten State
Monte Carlo Simulation of Short Chain Branched Polyolefins in the Molten State
复制标题
DOI：
10.1021/ma071615k
复制
发表时间：
2007-11
期刊：
影响因子：
5.5
通讯作者：
J. Ramos;L. Peristeras;D. Theodorou
中科院分区：
文献类型：
--
作者：
J. Ramos;L. Peristeras;D. Theodorou
采用蒙特卡罗（MC）和分子动力学（MD）方法对以短链支化聚烯烃为模型的茂金属乙烯/α-烯烃共聚物进行了模拟。在等温-等压系综（NPT - MD）中，熔体密度随SCB含量的增加而略有增加。为了将分支整合到模拟中，我们采用了不同MC移动的混合，并修改了连接改变移动，例如端桥接。这种MC模拟策略在平衡熔融SCB共聚物的所有长度尺度上都表现得非常好。讨论了从MC模拟中得到的熔体中的链尺寸和局部堆积。在一定的主链长度下，由旋转半径量化的链长随着分支数的增加而减小。另一方面，短分支的存在导致熔体中不太有效的分子间局部填充。在蒙特卡罗原子模拟的基础上，讨论了共聚物的流变性能。
Short chain branched (SCB) polyolefins as a model of metallocene ethylene/α-olefin copolymers were simulated by Monte Carlo (MC) and molecular dynamics (MD) methods. Melt density, which was evaluated by MD in the isothermal−isobaric ensemble (NPT−MD), slightly increases with the SCB content. A mix of different MC moves was adopted and connectivity-altering moves, such as end-bridging, were modified in order to incorporate the branches into the simulation. This MC simulation strategy performed very well in equilibrating molten SCB copolymers at all length scales. The chain size and local packing in the melt, as obtained from the MC simulations, are discussed. At given backbone length, chain size, as quantified by the radius of gyration, decreases with the number of branches. On the other hand, the presence of short branches leads to a less effective intermolecular local packing in the melt. Rheological properties of the copolymers are discussed based on a mapping of the Monte Carlo atomistic simulations on...