A Monte Carlo Simulation for the Effect of Compression on an Amorphous Polyethylene Melt in Very Thin Confined Geometry
A Monte Carlo Simulation for the Effect of Compression on an Amorphous Polyethylene Melt in Very Thin Confined Geometry
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非常薄的受限几何形状中压缩对非晶态聚乙烯熔体影响的蒙特卡罗模拟
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发表时间：
2000
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通讯作者：
W. Mattice
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作者：
Jee Hwan Jang;W. Mattice
用高配位点阵的Monte Carlo模拟方法研究了压缩对由20条C120聚乙烯链组成的熔体在两个不可穿透的固体壁之间的影响。压缩是通过改变两个板之间的壁分离在限定的几何形状从103 R g到102 R g，这产生的整体密度范围从0.70到0.95 g/cm 3。近壁处的密度随着压缩而增加，这归因于反式构象的增加。壁附近的局部构象变化的效果被传递到中间区域，珠密度分布的振荡和笨拙构象的增加。对于分子形状，在整个受限几何区域内观察到各向异性，并且各向异性的程度在界面区域附近较大。在较高的压缩和较低的温度下，观察到更有序的结构在小尺度上。压缩时，沿平行于壁面方向的短时间质心扩散率沿着方向比垂直分量受到更大的抑制，尽管在特定的压缩下，平行分量总是大于法向分量。
The effect of compression on a melt composed of 20 chains of C 120 polyethylene between two impenetrable solid walls has been studied by a Monte Carlo simulation on a high coordination lattice. The compression is controlled by changing the wall separation between two plates in the confined geometry from ∼3R g to ∼2R g , which produced the overall densities ranging from 0.70 to 0.95 g/cm 3 . The density near the walls increases with the compression, which is attributed to an increase of the trans conformation. The effect of the local conformational change near the walls is delivered into the middle region with an oscillation of the bead density profile and an increase of the gauche conformation. For the molecular shape, anisotropy is observed in the whole region of the confined geometry, and the extent of the anisotropy is larger near the interfacial area. The more ordered structure at small scale is observed at the higher compression and the lower temperature. The short time center-of-mass diffusivity along the direction parallel to the wall is much more suppressed than the perpendicular component with the compression, though the parallel component is always larger than the normal component at a specific compression.