以分子動力學模擬不同濃度與分子量下聚丙烯的擴散行為

Diffusion Behavior of Polypropylene in Different Concentrations and Molecular Weight by Molecular Dynamics Simulation

馮震泓(Chen-Hung Feng)

指導教授 ： 張榮語

國立清華大學/工學院/化學工程學系/碩士(2009年)

摘要

摘要
隨著日新月異的時代演變，本篇論文首先指出科技的大方向—輕薄短小，而分子動力學剛好就是ㄧ種研究小尺度的好方法，接著介紹一些微觀尺度的演進，進一步對未來的我們，在判斷工程相關的事物時，能有簡單的方向和想法，並且介紹聚丙烯材料的相關特性及應用。
接著對於分子動力學、聚丙烯、溶液性質、擴散性質，將相關研究結果以簡單的敘述做文獻回顧，再將研究的方法、勢能函式列在第三章，其中包括模擬流程圖、初始化方法、演算法、力的計算方式、週期性邊界及烷類和聚丙烯的勢能參數。
利用分子動力學模擬聚丙烯溶液的末端末端距離、迴旋半徑和動態性質—擴散係數，分別用濃度和鏈長作為操縱變因，討論模擬結果。由研究結果發現，當重量百分濃度增加時，擴散物質的體積與濃度的關係平緩，故擴散係數與濃度的關係亦平緩；當鏈長增加時，則聚丙烯所佔有的體積變大(亦可由末端末端距離和迴旋半徑看出)，因而前進時容易受阻，故擴散係數下降。
關鍵字：分子動力學、聚丙烯、擴散係數

關鍵字

分子動力學 ； 聚丙烯 ； 擴散係數

並列摘要

This study pointed out the direction of science technology, small, and molecular dynamics was one of the good methods to research small scale world. We introduce the developments of small scale to help us to solve engineering problems that can make us have simple directions and ideas. This study introduced the features and applications of polypropylene simply.
There were easy words for related researches about molecular dynamics、polypropylene、solution properties、diffusion properties. In chapter 3, we showed study methods and potential functions including a simulation flow chat、initial methods、algorithm、calculation method of force、periodic boundary condition and potential parameter of alkane series and polypropylene.
Molecular dynamics simulation was used to measure end-to-end distance、radius of gyration and diffusion coefficient of polypropylene solution. The chain length and concentration were control variances to discuss simulation results. Because the change for diffusion substance was small, the diffusion coefficient changed little with weight percent concentration, too. The diffusion coefficient decreased with increasing chain length, because the raising size of polypropylene hindered substance moving.
Key Word：Molecular Dynamics、Polypropylene、Diffusion Coefficient

並列關鍵字

Molecular dynamics ； Polypropylene ； Diffusion Coefficient

參考文獻

[1] James Elliott，Department of Materials Science & Metallurgy，University of Cambridge，http://www.msm.cam.ac.uk/Department/DeptInfo/StaffProfiles/ResearchFigs/Elliott.jpg

[10] Harutun G. Karian ，HANDBOOK OF POLYPROPY1ENE AND POLYPROPYLENE COMPOSITES，RheTech. Inc，2003

[12] M. Meunier，Diffusion coefficients of small gas molecules in amorphous cis-1,4-polybutadiene estimated by molecular dynamics simulations ，J. Chem. Phys. ，Vol. 123， pp.134906-1~ 134906-7 ，2005

[13] Mechthild Franke, Nicolaus Rehse， “Nucleation of branches in elastomeric polypropylene ”，Polymer， Vol. 49， Issue 20， pp. 4328-4331， 2008

[16] Georgia Evangelia Logotheti and Doros N. Theodorou, Segmental and Chain Dynamics of isotactic Polypropylene Melts， Macromolecules，Vol. 40，pp. 2235-2245，2007