本文關鍵詞： 共擠成型 多相流動 黏彈性 黏性包圍 機理 數值模擬　出處：《南昌大學》2017年碩士論文　論文類型：學位論文

【摘要】：共擠成型技術是目前聚合物多層復合材料的制造技術,如何控制聚合物多層復合材料共擠成型過程的層厚均勻性是制備高性能多層復合材料的主要技術瓶頸。聚合物多層復合材料共擠成型過程中由于黏性包圍現象會導致分層界面變形畸變和層厚重構,嚴重影響高性能多層復合材料制品性能,解決這一技術瓶頸,方能實現聚合物多層復合材料共擠成型過程的層厚均勻性精密控制。而解決這一技術瓶頸的理論關鍵在于研究并建立黏性包圍形成的機理理論,以此揭示多層黏彈性熔體共擠成型流動的黏性包圍的形成機理,這對于解決目前制備高性能多層復合材料的主要技術瓶頸具有重要的理論和工程應用價值,因此本文系統(tǒng)研究了聚合物黏彈性流變性能參數和過程參數對多相多層黏彈性矩形共擠流動成型過程的黏性包圍的影響。通過研究建立黏性包圍——二次流動——第二法向應力差的關聯理論,試圖建立具有普適性和科學性的多相多層黏彈性熔體流動的黏性包圍機理理論,為研發(fā)聚合物多層復合材料共擠成型過程的層厚均勻性的精密控形技術奠定科學的理論基礎。首次研究提出了多相分層黏彈性熔體流動的黏性包圍是由分層界面附近熔體的第二法向應力差驅動的二次流動所誘發(fā)的科學假設,科學假設認為黏性包圍的趨勢由分層界面附近熔體二次流動的方向控制,而黏性包圍程度由分層界面附近熔體的二次流動速度控制;研究發(fā)現當上層熔體松弛時間由0.4s增至1.8s時,多層共擠成型分層界面三維黏性包圍形貌先呈正向黏性包圍現象,但隨著上層熔體松弛時間增大,分層界面形貌轉化為反向黏性包圍現象,且三維黏性包圍程度隨著上層熔體松弛時間增大而增大。顯然這一研究結果與低黏度熔體包圍高黏度熔體的最小黏性耗散原理相矛盾,也與分層界面法向應力平衡黏性包圍原理提出的在同時存在黏性和彈性分層時,黏性包圍主要由熔體的黏性控制的結論相矛盾,傳統(tǒng)機理理論無法詮釋這一演化;當上層熔體材料系數由0.2增至0.8時,二層共擠成型分層界面三維黏性包圍形貌先呈正向黏性包圍,但隨著上層熔體材料系數增大,分層界面形貌轉化為反向黏性包圍,且其包圍程度隨著上層熔體材料系數增加而增大,顯然這一研究結果與最小黏性耗散黏性包圍原理相矛盾,也與分層界面法向應力平衡黏性包圍原理提出的在黏性分層一定時,黏性包圍主要由熔體彈性控制的結論相矛盾;隨著低黏度上層熔體進口流量的增加,二層共擠成型黏性包圍分層界面界形貌主要體現為高黏度下層熔體包圍低黏度上層熔體的反向黏性包圍現象,其包圍程度隨著上層熔體進口流量的增加而增大;按本文提出的黏性包圍機理科學假設,熔體黏彈性流變性能參數和過程參數變化誘發(fā)的正反向黏性包圍的機理推論結果與其黏性包圍界面形貌的模擬結果完全吻合,且按本文提出的黏性包圍機理可知,由分層界面附近熔體第二法向應力差推論預測的熔體二次流動方向和二次流動強度與二次流動模擬研究結果完全吻合,充分驗證了本文黏性包圍的機理理論在不同熔體黏彈性流變性參數和過程參數條件下均具有普適性和可靠性。
[Abstract]:Coextrusion molding technology is the manufacturing technology of polymer multilayer composite materials, how to control the co extrusion process of composite multilayer polymer layer thickness uniformity is the main bottleneck of technology for preparing high performance multilayer composite materials. Composite polymer multilayer coextrusion molding process due to viscous encapsulation phenomena will lead to distortion and deformation of interfacial layer thickness reconstruction, serious effect of high performance multilayer composite products, solve the technical bottleneck, in order to achieve the co extrusion process of composite multilayer polymer layer thickness uniformity and precision control. To solve the key technical bottleneck theory is to study and establish the theory mechanism of viscous encapsulation is formed, in order to reveal the formation mechanism of viscous flow of viscoelastic melt surrounded by multilayer coextrusion the formation of this system, to solve the technical bottleneck of preparing high performance multi-layer composite material has Important theoretical and engineering application value, this paper studied the effect of viscous polymer system by viscoelastic rheological parameters and process parameters of multiphase multilayer coextrusion molding process of viscoelastic rectangular flow. Through the research on the establishment of Relevance Theory -- the two surrounded by the viscous flow of the second normal stress difference, trying to establish a universal and the science of multiphase multilayer viscous viscoelastic melt flow by theory, laid the scientific theoretical foundation for the research and development of polymer multilayer coextrusion molding process of composites layer thickness uniformity of the precision shape control technology. The first study of the multiphase stratified viscous viscoelastic melt flow is surrounded by two flow induced by the scientific hypothesis by second method stratified near the interface melt to stress difference driven, scientific hypothesis that surrounded the trend by interfacial viscous melt near two Control the direction of flow, and surrounded by two degree viscous flow velocity control layer near the interface of the melt; it was found that when the upper melt relaxation time from 0.4s to 1.8s, multilayer coextrusion molding stratified interface of 3D viscous morphology showed a positive first surrounded by viscous encapsulation phenomenon, but with the increase of the melt relaxation time, layered interfacial morphology into the reverse viscous encapsulation phenomenon, and three-dimensional viscous encapsulation increases with the increase of the upper melt relaxation time. The minimum principle of viscous dissipation obviously this results with low viscosity and high viscosity melt melt surrounded by contradiction, and interfacial normal stress balance principle of viscous encapsulation in the presence of the viscous and elastic layer, viscosity enclosed is mainly controlled by the melt viscosity of the conflicting results, the mechanism of the traditional theory cannot explain this evolution; when the upper melt material number by 0 .2 increased to 0.8, two layer coextrusion layered interface morphology showed a positive first surrounded by three-dimensional viscous viscous surrounded, but with increasing upper melt material coefficient, interfacial morphology into reverse viscosity surrounded, and its surrounding degree with the increase of the upper melt material coefficient increases obviously, the results of this study and the minimum bounding viscosity viscous dissipation principle with the contradiction, interfacial normal stress balance principle of viscous encapsulation in viscous stratification is surrounded mainly by viscous melt elasticity control conflicting results; with the increase of low viscosity melt into the upper mouth flow, two layer coextrusion molding clay layered interface morphology mainly surrounded by circles for high viscosity lower melt viscosity reverse surrounded by the upper melt surrounded by low viscosity phenomenon, which surrounds a degree increases with the upper melt inlet flow; viscous surrounded by this paper The mechanism of scientific hypothesis, simulation results and the morphology of the interface mechanism of viscous encapsulation surrounded by positive and negative viscous melt rheological properties of viscoelastic parameters and process parameters change induced by the inference result, and the viscosity by using this mechanism that surrounded by a layered interface, the melt near the second normal stress difference inference prediction two melt flow direction and two flow intensity and two flow simulation results agree well, fully verify the theoretical mechanism of the viscosity were surrounded with universality and reliability in different parameters of melt viscoelastic rheological parameters and process.

【學位授予單位】：南昌大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB33

【參考文獻】

相關期刊論文 前4條

1 周國發(fā);王梅媚;張宇;;聚合物多相分層流動黏彈性包圍機制的數值模擬[J];復合材料學報;2014年06期

2 周文彥;周國發(fā);;聚合物多層氣輔共擠精密成型機制的數值分析[J];復合材料學報;2009年03期

3 戚寧;柳和生;黃興元;;聚合物共擠出技術及其應用[J];工程塑料應用;2009年04期

4 陳新輝;;多層共擠中空容器及生產裝備發(fā)展狀況[J];塑料包裝;2007年01期

相關博士學位論文 前1條

1 王宣平;非牛頓黏彈性流動模擬中穩(wěn)定化方法和三維自由面追蹤問題研究[D];大連理工大學;2012年

，

本文編號：1553864