層狀共聚物之奈米彎曲行為與其機械性質;Exploring the Nanoscale Buckling Deformation and Mechanical Properties of Lamellae-Forming Copolymer

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题名:	層狀共聚物之奈米彎曲行為與其機械性質;Exploring the Nanoscale Buckling Deformation and Mechanical Properties of Lamellae-Forming Copolymer
作者:	蔡雨彤;Tsai, Yu-Tung
贡献者:	化學工程與材料工程學系
关键词:	奈米結構;機械性質;奈米拉伸;nanostructure;mechanical properties;nanotensile
日期:	2025-07-15
上传时间:	2025-10-17 11:15:46 (UTC+8)
出版者:	國立中央大學
摘要:	本研究利用單軸拉伸層狀三嵌段共聚物並探討在奈米尺度下層狀結構的演化行為與其機械性質。我們選用polystyrene-b-polyisoprene-b-polystyrene (PS-b-PI-b-PS)三嵌段共聚物，透過剪切誘導產生高方向性的奈米層狀結構，並使用穿透式電子顯微鏡觀察臨場拉伸過程，包括傾斜晶界的形成與奈米尺度的彎曲行為，並比較chevron與omega兩傾斜晶界與平行層狀的幾何結構變化。在拉伸過程中，隨傾斜角度增加，傾斜晶界會由chevron形態轉變至omega形態；相反地，平行層狀結構的傾斜角度保持不變。在高應變(ε=1.7)下，PI層(橡膠相)中會發生孔洞化以釋放應力，導致結構破壞。我們進一步利用Delaunay triangulation分析單軸拉伸下平行層狀與chevron的應變分佈。研究結果顯示，chevron的彎曲結構與孔洞化有利於應力釋放，與材料的應變軟化及形變行為有密切相關。此奈米尺度的彎曲行為有助於深入了解層狀傾斜晶界如何影響材料機械性質，進而為開發具備優異機械性能的材料奠定理論依據。;This study explores the evolution of nanoscale lamellae and the mechanical properties of lamellae-forming copolymers under uniaxial stretching using a nano-tensile holder. We employ the triblock copolymer polystyrene-b-polyisoprene-b-polystyrene (PS-b-PI-b-PS) with the shear-induced method to generate highly oriented lamellar nanostructures. Transmission electron microscopy is used to examine the nanoscale buckling behavior of tilt boundaries in the deformed lamellar triblock copolymer, comparing the morphological changes at chevron and omega tilt boundaries with those of parallel lamellae. Under tensile deformation, the tilt boundaries transition from the chevron to the omega structure as the tilt angle increases, whereas the tilt angle remains the same for the parallel lamellae. Stress concentration is found at the tilt boundaries, increasing the tilt angle and structural transformation during stretching. At higher strain (ε=1.7), cavitation occurs in the rubbery phase of polyisoprene, forming voids to release stress. Delaunay triangulation is applied to analyze the strain distribution between parallel lamellae and tilt boundaries under tensile stress. The results indicate that the buckling and cavitation of tilt boundaries facilitate stress release, which is related to strain softening and making deformation easier. This nanoscale buckling behavior provides insights into the role of tilt boundaries in mechanical performance and offers a foundation for designing materials with enhanced mechanical properties.
显示于类别:	[化學工程與材料工程研究所] 博碩士論文

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