聚乳酸/聚對苯二甲酸丙二酯、聚對苯二甲酸丙二酯/聚丙烯和聚乳酸/聚對苯二甲酸丙二酯/甲基丙烯酸酯-丁二烯-苯乙烯共聚物等摻合體之相容性、機械性及熱性質研究

Miscibility, Mechanical, and Thermal Properties of Melt-mixed PLA/PTT, PTT/PP, and PLA/PTT/MBS Blends

林三外(San-Wai Lin)

指導教授 ： 程耀毅

國立臺北科技大學/工程學院/工程科技研究所/博士(2010年)

摘要

本研究主要探討PLA (聚乳酸)/PTT (聚對苯二甲酸丙二酯)、PTT (聚對苯二甲酸丙二酯)/PP (聚丙烯)和PLA (聚乳酸)/PTT (聚對苯二甲酸丙二酯) /MBS (甲基丙烯酸酯-丁二烯-苯乙烯) 共聚物等摻合體之相容性、機械性及熱性質。不同比例組成之PLA/PTT及PTT/PP摻合體而言，其在DSC (微分掃描熱卡計) 及SEM (掃描式電子顯微鏡) 圖相中皆顯示不相容特性，但是MBS添加5∼10 phr (每100份樹脂添加的份數)時，對於PLA及PLA/PTT 50/50摻合體，則有助於相容性的改善。TGA (熱重損失分析儀) 熱安定性中，添加PTT有利於PLA熱安定性的改善，而PTT之熱安定性，隨PP組成份的增加，亦有改善效果，但是對於PLA、PTT及PLA/ PTT 50/50摻合體而言，MBS的添加5∼10 phr，則對其熱安定性影響不大。在等溫結晶行為中，純PTT及PTT在PLA/PTT、PTT/PP及PLA/PTT/MBS摻合體中，其Avrami指數n值在1.8∼3.1 (相近於2.0∼3.0) 範圍內，其成核方式為成長及成核兩機構混合；一般而言，n值在2.0或3.0，分別依循二維或三維異相成核 (或稱為無熱成核)。在廣角 X-Ray繞射圖譜發現，在冷結晶程序中有利於PLA特徵峰形成，而在融熔結晶程序中卻有利於PTT特徵峰生成。在POM (偏光顯微鏡) 觀察可知，PLA冷結晶球晶較小且密集，較易成核，其堆疊會較融熔結晶為快；而PTT完全反之。MBS添加5∼10 phr時，有利於PTT球晶尺寸大小的增長；而對PLA而言其添加反而更加不利球晶尺寸的成長。在機械性能中，使用雙螺桿T-die押出試片程序，明確觀察到PTT添加比例多之PLA/PTT摻合體與純PLA相較下，具有較低拉伸強度和較高斷裂點伸長率，的確有利於PLA之機械性能提昇；而在塑譜儀摻混程序中，觀察到PP添加比例較多之PTT/PP射出成形試片與純PTT相較下，具有較低拉伸強度和較高斷裂點伸長率，的確有利於PTT之機械性能提昇；在MBS添加5∼10 phr後亦同樣觀察到有利於PLA之機械性能提昇現象 (低拉伸強度、高斷裂點伸長率及耐衝擊強度)；但是在PLA/PTT 50/50摻合體添加MBS 5∼10 phr後，則致其機械性能下降 (高拉伸強度、低斷裂點伸長率及耐衝擊強度)，此現象可能是PTT快速結晶期間MBS在PTT相中分離出來，這個結果類似sPS (對位聚苯乙烯)/HDPE (高密度聚乙烯) 摻合體中使用SEBS (苯乙烯-乙烯/丁烯-苯乙烯共聚物) 增容之系統，推測在界面中PTT結晶有助於MBS之接枝PMMA (聚甲基丙烯酸酯)/PS (聚苯乙烯) 終端基從PTT團塊 (分散相) 中分離出來，因此造成界面鍵結強度減弱。

關鍵字

聚乳酸 ； 聚對苯二甲酸丙二酯 ； 聚丙烯 ； 甲基丙烯酸酯-丁二烯-苯乙烯共聚物 ； 摻合體 ； 熱性質 ； 機械性 ； 相容性

並列摘要

This study examined the miscibility, thermal and mechanical properties of melt-mixed blends of PLA (poly(lactic acid))/PTT (poly(trimethylene terephthalate)), PTT/PP (isotatic polypropylene), and PLA (poly(lactic acid))/PTT/MBS (methyl meth- acrylate- butadiene -styrene copolymer). DSC (differential scanning calorimetry) and SEM (scanning electron microscopy) results indicated that the blends of PLA/PTT and PTT/PP are immiscible, but the miscibility of PLA/PTT blends is improved with adding 5 ~ 10 phr (parts per hundreds of resin) MBS. As revealed from TGA (thermogravimetric analyzer) analyses, the thermal stability of the blends with PLA/PTT and PTT/PP raises as the PTT and PP content increases, respectively. The isothermal crystallization kinetics of the blends is analyzed using the Avrami equation, the n values of PTT mostly range between 1.80 and 3.1 (close to the value of 2 ~3), which indicates that the mechanism is mixed growth and nucleation. Generally, an n value close to 2 or 3 indicates an heterogeneous (athermal) nucleation process followed by a two-dimensional or three-dimensional crystal growth, respectively. The WAXD (Wide angle X-ray diffraction) results show that the PLA characteristic peaks take favorably shape in the cold-crystallization, and PTT forms more quickly in the melt-crystallization. Compared with the pure PLA and pure PTT, PTT-rich in PLA/PTT blends of twin-screw T-die extruder sheet specimens and the PP-rich in PTT/PP blends of injection molding samples possess lower tensile strength at yield and higher breaking elongation, respectively. Both breaking elongation and impact strength of PLA are raised with adding of 5 ~ 10 phr MBS. On the contrary, the impact strength and breaking elongation of 50/50 PLA/PTT blend is reduced with adding of 5 ~ 10 phr MBS, which might be because that MBS is separated from PTT phase during the fast crystallization of PTT. This result is similar to sPS (syndiotactic polystyrene)/HDPE (high-density polyethylene) binary blends compatibilized with SEBS (styrene-ethylene/1-butene- styrene) copolymer system, illustrated by supposing that the crystallization of PTT at the interface favors the separation of the grafted PMMA (poly (methyl methacrylate))/polystyrene end-groups of MBS out of the PTT domain and therefore a declining of the interfacial bonding strength.

並列關鍵字

poly(lactic acid) ； poly(trimethylene Terephthalate) ； isotatic polypropylene ； methyl methacrylate-butadiene-styrene copolymer ； blends ； thermal ； mechanical ； miscibility

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