利用小角度X光散射和廣角度X光繞射探討聚環氧乙烷於醇類中的結晶現象

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Title:	利用小角度X光散射和廣角度X光繞射探討聚環氧乙烷於醇類中的結晶現象
Authors:	胡婉瑜;Hu, Wan-Yu
Contributors:	化學工程與材料工程學系
Keywords:	均聚物;結晶;凝膠
Date:	2023-07-27
Issue Date:	2024-09-19 14:47:13 (UTC+8)
Publisher:	國立中央大學
Abstract:	聚環氧乙烷 (Poly(ethylene oxide), PEO) 因其材料特性和複雜的相行為成為高分子科學中有趣的研究領域之一。本研究實驗結果表明，PEO在熔點以上完全溶解於不同種類的醇（甲醇、乙醇、異丙醇和丁醇）中。然而，將樣品靜置於室溫數分鐘至數天，或是將其進行冰浴，會發現其從原本的溶液態轉變形成不透明的凝膠狀混合物，而這樣的凝膠狀結構是具有熱可逆性的。為了研究溶液-凝膠的轉變，使用了掃描式微分熱卡計 (Differential scanning calorimetry , DSC)來進行熱行為之測定，其量測結果表明，所觀察到溶液因溫度變化而產生凝膠化的現象，與其結晶行為密切相關。利用小角度X光散射 (SAXS)和廣角度 X光繞射 (WAXS) 進行量測，並結合模型的擬合，證明了溶液-凝膠的轉變和PEO結晶行為之間的相關性。研究結果表明，PEO 在高溫下完全溶解並均勻分散在溶液中，當冷卻溫度低於臨界溫度後，PEO的結晶會以層狀堆疊的方式形成，凝膠由三維的網狀結構構成。;Poly(ethylene oxide) (PEO) is one of the most intriguing research field in macromolecular science due to materials properties and complex behavior. The results demonstrated that PEO is completely dissolved in different kinds of alcohols (methyl alcohol, ethyl alcohol, isopropyl alcohol, and butyl alcohol) above crystal-melting points. However, after quenching the mixtures to room temperature, the solutions form an opaque gel-like mixture. The gel-like structure is thermally reversible. To investigate sol-gel transitions, differential scanning calorimetry (DSC) was used. DSC curves show that the gelation behavior in PEO solutions could occur and correlate with crystalline morphology. Correlations between the phase separation behavior and crystalline morphology was investigated through in-situ small-angle X-rays scattering (SAXS), wide-angle X-rays scattering (WAXS), and model fitting. The study shows that PEO is completely well dissolved in the solution at high temperature. After cooling down to a critical temperature, PEO crystallizes into a three-dimensional network of lamellar stacks. The 3D network results in a hard gel for PEO in ethanol, propanol and butanol.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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