以分子動力學模擬奈米尺度下射出成型之充填過程

Molecular Dynamics Simulation of Molding Filling in Nano-Injection Molding Process

王唯讚(Wei-Tsan Wang)

指導教授 ： 張榮語

國立清華大學/工學院/化學工程學系/碩士(2006年)

摘要

本研究應用分子動力學模擬聚丙烯在奈米尺度下射出成型之充填過程。首先以分子動力學模擬高分子之玻璃轉化溫度，並且與文獻驗證。第二階段模擬高分子在射出成型系統中之充填過程，以預測高分子在奈米尺度之射出成型加工過程之流變現象。
(一) 玻璃轉化溫度：以分子動力學模擬在不同鏈長(分子量)下的高分子之玻璃轉化溫度，所採用的碳鏈長分別為200、400、800個原子團，探討玻璃轉化溫度與分子量大小的關係。
(二) 非穩態射出充填過程：將高分子置入系統之中進行加工模擬，探討在奈米尺度下充填過程中所可能產生的問題，並觀察在充填過程中，高分子的各項性質隨著時間的變化，包含密度、應力、末端末端距離、分子鏈的排向性等性質。接著更進一步探討在不同加工速度下或不同加工溫度下對充填過程所造成的影響。由模擬結果可知，加工速度越大時，高分子進入模穴之吸附現象越不明顯，此外狹窄流道及模穴前方模壁處有較明顯的排向性，且高分子拉伸現象在狹窄流道內較為明顯。當加工溫度為T=350 K時，可看出高分子與牆的吸附現象較不顯著且流動性較差，且在相同射出速度下系統內高分子之平均壓力較大。故加工溫度以T=450 K以上為佳。

關鍵字

分子動力學模擬 ； 聚丙烯 ； 玻璃轉化溫度 ； 奈米尺度 ； 射出成型 ； 充填過程

並列摘要

In this research, molecular dynamics simulation is adopted to simulate the molding filling in nano-injection molding process. Our work divided into two parts is as follows.

(I) Glass transition temperature : Molecular dynamics is adopted to simulate the glass transition temperature of polypropylene at different chain length, and the chain length has 200, 400 and 800 , respectively. The simulated purpose is to explore the relation between the chain length(molecular weight) of polymer and the glass transition temperature of polymer.

(II) We adopt molecular dynamics to simulate the nano-scale injection molding process, and investigate the defects during molding filling process. With decreasing the injection velocity, the adsorption phenomena at the entrance of mold will become more obvious. The orientation of polymer is obvious at the wall of runner and the wall which faces the entrance of mold. While the temperature of system at 350 K, polymer has less tendency to adsorb on the wall.

並列關鍵字

Molecular dynamics simulation ； Polypropylene ； Glass transition temperature ； Nano scale ； Injection molding ； Molding filling process

參考文獻

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14.C.A.Heiber and S.F. Shen, “A Finite Element/Finite Difference Simulation of the Injection-Molding Filling Process”, Journal of Non-Newtonian Fluid Mechanics, Vol.7,pp.1-32,(1980)