添加奈米TiO2/SiO2粉體對PET瓶材料特性提升及其應用之研究

Application and Performance Enhancement of PET Bottles by TiO2/SiO2 Nanopowders

朱北松(Pei-Song Chu)

指導教授 ： 林錕松

元智大學/工程學院/化學工程與材料科學學系/碩士(2007年)

摘要

近年來，奈米粉體的各項特殊性質應用在高分子的研究上相當廣泛，其中奈米二氧化矽為網狀結構，具有相當好的機械性質、耐化學性質與耐熱性質，可作為高分子的補強或填充材料。而二氧化鈦因具有化學穩定性、無毒性、紫外線吸收及容易取得之優點，故應用性極具潛力。奈米高分子複合材料的透明性、剛性、氣體穿透率之改善、耐燃性、熱變形溫度等補強效率大於一般填充補強材料，且提升了原材料之氣體阻隔性能，使材料的吸濕性、耐化性提升。因此，本研究之主要目的在於對高分子Polyethylene Terephthalate (PET，寶特瓶)添加不同比例之奈米二氧化矽及二氧化鈦進行討論，並探討其結晶行為與微結構之變化，並測試其氣密性能、耐壓強度及對紫外線(UV)照射強度遮透能力，另以場發掃描式電子顯微鏡(FE-SEM)、穿透式電子顯微鏡(TEM)、X光粉末繞射儀(XRPD)、紫外-可見光譜儀(UV-Vis)、熱示差掃瞄卡量計分析儀(DSC)、動態機械分析儀(DMA)、傅利葉轉換紅外線光譜儀(FTIR)及感應耦合電漿質譜儀(ICP-MS)來鑑定分析高分子PET添加不同比例之奈米二氧化矽及二氧化鈦複合材料之特性及成分。
實驗主要部份包括：使用高分子PET，以不同比例之奈米二氧化矽及二氧化鈦添加量進行改質，使改質後的PET瓶增加其耐壓強度及對紫外線照射強度遮透能力提升；並以XRPD、FE-SEM、TEM來觀察其為結構之變化，再以UV-Vis、DSC、DMA、FTIR及ICP-MS來分析改質後之PET瓶其機械性質與熱性質變化。經XRPD測試發現煅燒後的P-25晶型較為顯著，而二氧化矽奈米粒子本身為非晶相結構無孔洞的存在，為一圓球狀之顆粒，但也因凝聚的因素，造成粒子間形成所謂的網狀結構，其奈米複合材料具有二氧化鈦銳鈦礦的晶相，而且發現在添加不同比例TiO2-SiO2時其訊號的強度也會有所改變。再經FE-SEM及TEM測試得知TiO2及SiO2粉末在未研磨時皆為聚集現象，奈米粒子粒徑分佈約在50 nm左右，研磨之後奈米粒子粒徑分佈約介於20 ~ 50 nm。此外，於紫外光的照射下發現其吸收波長有明顯地變化，而調配比例在2：8 ~ 8：2時紫外光吸收範圍能涵蓋市面常見啤酒之玻璃瓶，並且發現在比例5：5時吸收波長起始點可提前至440 nm。由DSC及DMA測試發現Tg、Tm、Tcc及貯存模數(Storage Modulus)等變化得知，添加適當比例的奈米TiO2/SiO2對PET之熱性質及機械性質有改善的效果，Tg及Tm均提升了3 ~ 5℃、Tcc也上升了14 ~ 21℃。因此，可推測PET瓶經添加奈米TiO2/SiO2無機氧化物後，可以達到改質之效果及目的，而且其耐熱溫度已超過啤酒殺菌溫度。由FTIR光譜分析得知隨著TiO2-SiO2添加量的增加，C=O (1700-1750 cm-1)、COO (1304 cm-1)及C-H (730-770 cm-1)吸收峰值卻隨著減少，表示TiO2-SiO2已與PET分子鏈產生結合。由ICP-MS分析得知改質後的PET瓶隨著奈米氧化物添加量的改變，其Tg點也隨著改變，進而亦影響銻原子溶出的速率。由XANES實驗數據分析結果可知奈米TiO2經添加不同比例SiO2後，並不會改變其價數(Ti4+)及晶型結構。由EXAFS之數據中顯示，未添加SiO2之TiO2其O的配位數為3.96 ± 0.05，Ti-O鍵長為1.96 ± 0.01 Å，而添加不同比例之SiO2後，由結構參數特性顯示，添加金屬會造成Ti配位數及鍵長的改變，可以證明奈米SiO2與奈米TiO2鍵結產生Si-O-Ti。
由氣密性測試可以發現，添加0、0.3及5%奈米TiO2-SiO2時，其壓力下降速率大小分別是0.3＜5＜0%，因此可推測PET經添加奈米TiO2-SiO2後，可以減緩氧氣的逸散。在相同吹瓶製程溫度下發現添加5%奈米TiO2-SiO2時，其PET瓶的透明度變差且呈現霧狀，尤其在拉伸度最大的頸部其厚度最薄且外皮觸感非常粗糙；觀察添加0.3%奈米TiO2-SiO2的PET瓶，其透明度良好但是略偏淡黃色，而且其外皮觸感光滑。因此可知PET經添加適當奈米TiO2-SiO2之後，外觀透明度上已經達到改質的效果及目的。

關鍵字

奈米二氧化鈦/二氧化矽微粒、聚對苯二甲酸乙二醇酯、氣體滲透性、紫外線照射強度遮透能力、奈米複合材料、銻溶出試驗、同步輻射光譜

並列摘要

Recently, nanotechnology had been applied on polyethylene terephthalate (PET) synthesis processes. The SiO2 nanoparticles have good mechanics, acid-resisting, and heat-proof properties by their network structures. TiO2 nanoparticles also have excellent chemical stability, nontoxicity, and shadowing of the ultra-violet properties. Therefore, in this research, different ratio of TiO2 and SiO2 could reduce gas permeability, pressure-proof, and ultra-violet shadowing characteristics of PET bottles. Moreover, the physcochemical, crystal microstructures, and morphological properties of PET bottle chips were also determined by FE-SEM, XRPD, TEM, UV-Vis spectra, DSC/DMA, FTIR, and ICP-MS.
The XRPD patterns showed that the TiO2 ratio increased as the enhanced P-25 peaks, in contrast the SiO2 ratio increased as the reductive P-25 peaks. The diameter of TiO2/SiO2 nanoparticles without lapping measured by FE-SEM were 50 nm, on the contrary, after lapping the nanoparticles size were decreased to 20-50 nm. Meanwhile the ratios of TiO2/SiO2 (2:8 ~ 8:2) dopped into PET made the ultra-violet shadowing property of PET reach the extent of other commercial beer bottles. In addition, the ultra-violet absorption wavelength was shifted toword 440 nm when compared to other beer bottle merchandises at doped ratio 5:5 TiO2/SiO2 into PET. After doping TiO2/SiO2 into PET showed the value of Tg, Tm or Tcc and modulus properties were significantly improved. The value of Tg or Tm was raised about 3 ~ 5℃ and the one of Tcc was raised about 14 ~ 21℃ as determined by DSC and DMA techniques. Moreover, the increase of Tg, Tm or Tcc value made the heat-proof of PET bottles meet the Pasteurizer standard procedure. The FTIR spectra showed that the peak of C=O (1700-1750 cm-1), COO (1304 cm-1) and C-H (730-770 cm-1) were shifted when dopping ratio increased. The FTIR spectra indicated that the TiO2/SiO2 nanocomposites had been linked up into PET microstructures. From the ICP-MS analyses, with doping TiO2/SiO2 nanoparticles made the leaching temperture of Sb(III) ions increased from 50 to 70℃ and lower the leaching concentration of Sb(III) ions in nanaocompositive PET bottles. Without doping SiO2 into the TiO2 for PET bottles, the coordination numbers (CN) of Ti atom and crystal structure were not changed. Ti EXAFS spectra also indicated that the CN and the bond distances were 3.96 ± 0.05 and 1.96 ± 0.01 Å respectively. After doping different ratios of TiO2/SiO2 (1:9 ~ 9:1) into PET bottless, it showed that the CN and bond distances were notably changed. Moreover, it could prove the TiO2 and SiO2 nanoparticles were reacted and formed into Ti-O-Si bonding eventually.
After gas permeability test, with different doping ratios of TiO2/SiO2 nanoparticles into PET bottles showed that the minimum pressure drop ratio was 0.3%. In other words, it indicated that the TiO2/SiO2 nanocomposites had been linked up into PET microstructures strongly and well sealed off oxygen gases for the PET bottles. In addition, at the same temperature of injection molding process, with doping 0.3% TiO2/SiO2 nanoparticles into PET bottles, it made the degree of pellucidity or hand handle higher than that one of 5% and can meet the commercial standards of pellucidity and hand handle.

並列關鍵字

TiO2/SiO2 nanoparticles, Polyethylene terephthalate, Gas permeability, Ultra-violet shadowing ability, Nanocomposites, Sb(III) leaching test, XANES/EXAFS.

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