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    題名: 聚(3-羥基丁酯)的裂解反應研究及其共聚物的合成
    其他題名: Studies on degradation of poly(3-hydroxybutyrate) for the synthesis of its copolymers
    作者: 廖國華;Liao, Kuo-Hua
    貢獻者: 淡江大學化學工程與材料工程學系碩士班
    董崇民;Don, Trong-Ming
    關鍵詞: 聚羥基丁酯;聚乳酸;摻合物;相容性;PLA;PHB;blends;miscibility
    日期: 2013
    上傳時間: 2013-04-13 11:51:09 (UTC+8)
    摘要: 高分子材料擁有良好的塑造性及功能性,生產成本較低,所以應用發展甚速,不僅廣泛應用在日常生活中,更擴及高科技的應用,增加了生活的便利性。其中,脂肪族熱塑性聚酯類的聚乳酸(Poly(lactic acid),PLA)與聚羥基丁酯(Poly(3-hydroxybutyrate),PHB)由於可以被微生物分泌的酵素所分解而被稱為是對環境友善的生物可分解高分子。由於PHB為一高結晶度且硬脆的高分子,在應用上有一定的難度,因此我們希望添加市面上最常見的生物可分解高分子PLA來改善PHB的機械性質。為了使PLA與PHB摻混相容,因此本研究欲以合成PHB-PLA嵌段寡聚物作為相容劑添加至PHB/PLA摻合體當中,希望能增加兩者之相容性。
    首先將PHB利用甲醇降解使之變成兩端各自帶有甲氧基及羥基的寡聚物,隨著醇解的反應時間增加,PHB寡聚物的分子量隨之降低。接著以PHB寡聚物作為起始劑,開環聚合丙交酯(lactide)成為PHB-b-PLA的嵌段共聚物。將PHB、PLA以及PHB-PLA摻混後以DSC觀察其Tg,發現只有PLA在高比例下(≧90%)的摻合系統中,Tg有所改變,表示有一定的相容性,而在其他比例的摻合系統中,Tg並未改變,表示不相容。當我們只將PLA與PHB-PLA進行摻合時,可以觀察到Tg隨著PHB-PLA添加比例的上升而隨之下降,表示相容的情況良好。
    在結晶形態上,PHB/PLA摻合系統在POM下可以觀察到馬爾它十字以及環帶狀結構,但PLA為一低結晶度高分子,添加比例過高將無法清楚看見結晶的形成,且PLA會被PHB鏈於排列堆積時排擠到晶束與晶束之間,而鑲嵌在PHB球晶之內。
    在結晶動力上,分別求出球晶成長速率與總體結晶速率,球晶成長速率隨著結晶溫度的升高而有一最大值,此最大值溫度為95oC,隨著PLA的摻入會導至球晶成長速率的下降,顯示PLA會降低PHB的鏈移動性;而添加了PHB-PLA後,也會造成球晶成長速率的下降。總體結晶速率則藉由Avrami關係式求得,k1/n與1/t0.5值隨著PLA摻合比例逐漸下降,表示PLA的添加會降低PHB高分子鏈的移動性。
    Because polymeric materials have excellent plasticity, properties and low production costs to raise commoditization. PLA and PHB are the aliphatic thermoplastic polyester and a biodegradation plastic. PHB is hard and brittle due to its high degree of crystallinity. Therefore, it is desirable to blend PHB with PLA to improve its toughness. PLA and PHB are incompatible in all proportions. Therefore, the purpose of this study is to synthesize PHB-b-PLA copolymer as a compatiblizer for the PHB/PLA blends and hopefully increasing the mechanical properties and toughness.
    First, PHB oligomers were produced by methanol alcoholysis of PHB. The PHB oligomers would have methanoyl and hydroxyl groups at the two ends. Second, the PHB oligomers were used to intiate the ring-opening polymerization of lactide to produce PHB-b-PLA block copolymers with different chain lengths. These PHB-b-PLA copolymers were then blended into the PHB and PLA. It was found the compatibility was dependent on the high ratio of PLA(≥90%), the PHB/PLA and PHB-PLA were miscible with a single Tg. In addition, the PLA and PHB-PLA were miscible with a single Tg.
    On the morphology boervation, PHB/PLAsystem have Malt-cross and ring-banded features under POM. But PLA is a low crystalline polymer, if we added too many PLA that we can’t see the spherulite clearly.
    On the crystallization kinetics, the growth rate of spherulites(G) and overall crystallization rate were obtained from POM and DSC, respectively. A maximum value was observed for G as the crystallization temperature increased to 95oC. The G value decreased with increasing blending proportion PLA and PHB-PLA. The growth rate and crystallization rate with the use of Avrami equation, k1/n and 1/t0.5 were decreased with increasing blending proportion PLA.
    顯示於類別:[化學工程與材料工程學系暨研究所] 學位論文

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