聚對苯二甲酸乙二醇酯/鎂鋁或鋰鋁層狀雙氫氧化合物奈米複材之製備、結晶性及物性研究

Preparation, Crystallization and Properties of PET/MgAl or LiAl Layered Double Hydroxides Nanocomposites

呂紹文(Shao-Wen Lu)

指導教授 ： 蔡宗燕

中原大學/理學院/化學研究所/博士(2012年)

https://doi.org/10.6840/cycu201201079

摘要

本論文以聚對苯二甲酸乙二醇酯(Poly-ethylene terephthalate, PET)的單體對苯二甲酸乙二酯(Bis(2-hydroxyethyl) terephthalate, BHET)與具有磺酸根離子之胺基苯磺酸鈉(Sulfanilic acid sodium salt hydrate, SAS)與1,3-苯二甲酸二甲酯-5-磺酸鈉(Dimethyl 5-sulfoisophthalate, DMSI)經過親有機化改質之鎂鋁或鋰鋁層狀雙氫氧化合物(Layered double Hydroxides, LDH)，藉由聚縮合反應的方式將BHET與改質型層狀雙氫氧化物置備成PET/LDH奈米複合材料。研究中將兩個系列之LDH的組成成分、添加量與改質劑插層量的差異性對於PET/LDH奈米複合材料的結晶行為、機械性質、熱穩定性與阻隔特性進行分析與探討。
以水熱法(hydro-thermal mothod)合成出不同視徑比(Aspect ratio)與陰離子交換容量(Anionic exchange capacity，AEC)之MgAl LDH與LiAl LDH，藉由有機改質劑SAS或DMSI以離子交換的方式置換LDH層間離子，藉此提升與高分子基材的相容性。利用X光繞射儀（X-ray Diffraction, XRD）觀察無機層材之層間距變化，並以粉末繞射資料庫(Joint Committee on Powder Diffraction Standars, JCPDS)比對佐證其結晶相；傅立葉轉換紅外線光譜儀（Fourier Transform Infrared, FT-IR）鑑定改質LDH層間或表面之有機與無機的官能基，證明SAS或DMSI的官能基存在於LDH層間。熱重分析儀（Thermogravimetry Analyzer, TGA）定量分析改質LDH中的改質劑的插層量、熱穩定性與吸水率。
將PET/MgAl LDH-SAS、PET/MgAl LDH-DMSI、PET/LiAl LDH-SAS與PET/LiAl LDH-DMSI奈米複材，以X光繞射儀的鑑定分析可初步判定改質型LDH是否均勻分散於高分子基材中，再利用穿透式電子顯微鏡（Transmission electron microscopy, TEM）直接觀測改質型LDH於高分子基材中的分散型態。藉由穿透式電子顯微鏡觀測可知PET/MgAl LDH-SAS奈米複材為島型插層型分散為主，但部分是以脫層分散的型態，PET/MgAl LDH-DMSI奈米複材為島型插層型分散型態，PET/LiAl LDH-SAS與PET/LiAl LDH-DMSI奈米複材層狀結構被打散，分散型態為海型插層與脫層型分散。
將PET/MgAl LDH-SAS、PET/MgAl LDH-DMSI、PET/LiAl LDH-SAS與PET/LiAl LDH-DMSI奈米複材以微差掃描熱卡計 (Differential Scanning Calorimetry，DSC)進行結晶學探討。結晶行為鑑定結果顯示，經由第一次升降溫、第二次升降溫以及非等溫結晶動力學得知，其奈米複材之結晶速率由快到慢分別為: PET/LiAl LDH-DMSI > PET/MgAl LDH-SAS > PET/LiAl LDH-SAS >PET/MgAl LDH-SAS奈米複材。
將PET/MgAl LDH-SAS、PET/MgAl LDH-DMSI、PET/LiAl LDH-SAS與PET/LiAl LDH-DMSI奈米複材進行機械性質、熱穩定性質以及機能性質探討。藉由動態機械分析儀 (Dynamic Mechanical Analyzer，DMA)分析結果得知MgAl LDH-SAS添加1.0 %於PET高分子中表現出最佳機械性質，可由純的PET之儲存模數 (Storage modulus)為1790 Mpa提升至PET/MgAl LDH-SAS-1.0 wt%為3271 Mpa，儲存模數增加了1.8倍。LiAl LDH-SAS與LiAl LDH-DMSI添加1.0 %於PET高分子中表現出最佳熱裂解溫度（Decomposed temperature, T5d），藉由熱重分析儀 (Thermal Gravimetry Analyzer，TGA)分析結果得知可由純的PET之熱裂解溫度為383 ℃提升至PET/LiAl LDH-SAS-1.0 wt%與PET/LiAl LDH-DMSI-1.0 wt%為405 ℃，熱裂解溫度提升了22 ℃。藉由紫外-可見光分析儀 (UV-Visible Spectrophotometer)檢測紫外光-可見光之阻隔特性，LiAl LDH-SAS添加1.0 %於PET高分子中表現出最佳抗紫外光能力，可由純的PET之紫外光在波長375 nm時，穿透度由79.3 %下降至PET/LiAl LDH-SAS-1.0 wt%的39.3 %，穿透度下降了40 %。藉由氣體滲透分析儀 (Gas Permeability A nalyzer，GPA)檢測氣體之阻隔特性，其結果是以視徑比較大的PET/LiAl LDH-SAS-1.0 wt%奈米複材的效果最佳，其阻隔改善因子(Barrier Improvement Factor, BIF)分別為4.5(氧氣)、5.3 (氮氣)與8.6 (二氧化碳)。

關鍵字

層狀雙氫氧化合物 ； 聚對苯二甲酸乙二醇酯 ； 奈米複合材料

並列摘要

Poly-ethylene terephthalate (PET)/ MgAl or LiAl layered double hydroxides (LDH) nanocomposites were successfully prepared by polycondensation of bis(2-hydroxyethyl) terephthalate (BHET) mixing sulfanilic acid sodium salt hydrate (SAS) modified - LDH or dimethyl 5-sulfoisophthalate (DMSI) - modified LDH. Effects of MgAl or LiAl LDH contents on the crystallization, mechanical properties, thermal stability and barrier properties of the PET/LDH nanocomposites were discussed.
The MgAl LDH and LiAl LDH were synthesized by hydrothermal reaction with the different of aspect ratio and AEC (anionic exchange capacity). The modified LDH, synthesized by hydrothermal reaction, can promote the compatibility both of LDH and PET matrix. The d-spacing of modified- LDH by XRD (X-ray diffraction) measurement and corroboration by JCPDS (Joint Committee on Powder Diffraction Standars). Function groups of modified agents intercalated into LDH galleries, were provide by FT-IR (Fouier Transform Infrared) spectrum. Not only interlayer anion of modified LDH, but also contents of modified agents were calculated and analyzed by TGA (Thermogravimetry Analyzer).
Both XRD data and TEM (Transmission Electron Microscopy) micrographs of PET/MgAl LDH-SAS nanocomposites indicate the co-existence of island type exfoliated and intercalated morphologies. TEM images provide the island type intercalated morphologies of PET/MgAl LDH-DMSI whereas sea type intercalated and exforliated morphologies of PET/LiAl LDH nanocomposites.
The crystallization behaviors and kinetics of PET and PET/LDH nanocomposites were investigated by using DSC (Differential Scanning Calorimetry). Two stages heating/cooling and non-isothermal melt-crystallization results show that the addition LDH into PET induced nucleation in the crystallization that significantly increases crystallization rate. Decreasing of the crystallization rate is PET/LiAl LDH-DMSI > PET/MgAl LDH-SAS > PET/LiAl LDH-SAS > PET/MgAl LDH-SAS.
Mechanical properties of PET and PET/LDH nanocomposites were investigated by using DMA (Dynamic Mechanical Analyzer). The result indicate that the best of storage modulus is increased from 1790 Mpa for pristine PET to 3271 Mpa for PET/MgAl LDH-SAS-1.0 wt% nanocomposites.
Thermal properties of PET and PET/LDH nanocomposites were investigated using TGA (Thermal Gravimetry Analyzer). The result indicate the best of decomposed temperature is increased from 383 ℃ for pristine PET to 405 ℃ for PET/LiAl LDH-SAS-1.0 wt% and PET/ LiAl LDH-DMSI 1.0 wt% nanocomposites.
The UV-visible barrier properties of PET and PET/LDH nanocomposites were measured by UV-visible spectrophotometer. It indicates that the UV light transmittance is decreased from 79.3 % for pristine PET to 39.3 % for PET/LiAl LDH-SAS-1.0 wt% nanocomposites at the wavelength 375 nm.
The gas barrier property of PET and PET/LDH nanocomposites were measured by GPA (gas permeability analyzer). The result indicate the best of BIF (Barrier Improvement Factor) is 4.5 (O2), 5.3 (N2) and 8.6 (CO2) for PET/MgAl LDH-SAS-1.0 wt% nanocomposites.

並列關鍵字

PET ； Layered double hydroxides ； Nanocomposites

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