学位論文 Enhancement of glass transition temperature of polar polymer using salt

Viknasvarri, Ayerdurai

2016-09
内容記述
Introduction: Poly(methyl methacrylate) (PMMA) has various attractive properties such astransparency, mechanical toughness, light weight and good weatherability [1]. Therefore, it isa candidate as a substitute for inorganic glass especially in the automobile industry due tohigh demand for a lightweight vehicle. In order to replace an inorganic glass, however, thethermal stability must be improved as it has a low glass transition temperature (Tg) (ca.105 oC). Generally, the introduction of cross-linking and hydrogen bonding is known toenhance Tg of a polymer. Nevertheless, these methods have disadvantages such as losingthermoplastic nature. In this study, a salt with low lattice energy is mixed with PMMA by thesolution blend technique. The salt used in this study is well mixed with PMMA and enhancesthe Tg without sacrificing the transparency and flowability of the material.Experiment: PMMA and 5 to 60 wt% of lithium trifluoromethanesulfonate (LiCF3SO3,LiFMS) or lithium perchlorate (LiClO4) were dissolved in the mixture solvent ofdichloromethane (90 wt%) and methanol (10 wt%) and stirred for 1 hour. The solution wascast on the Teflon plate and dried at 160 ºC for 30 hours. The obtained mixtures werecompressed into flat sheets with a thickness of 300 μm by a compression-molding machinefor 3 min at 240 ºC under 10 MPa and subsequently cooled at 25 ºC. Tg of the samples wasmeasured by using a dynamical mechanical analyzer and a differential scanning calorimeter.3. Results and Discussion: Figure 1 shows Tg, measured by differential scanningcalorimeter of the blends containing various amounts of the salts, in which the salt amount isexpressed by the molar ratio of the lithium to the carbonyl group in PMMA. The resultindicates that the salt addition greatly enhances Tg without scarifying its transparency. TheTg enhancement is presumably caused by the electrostatic interaction between Li-cation andcarbonyl group in PMMA as indicated in attenuated total reflection results. As a result, theblends show high Tg. Moreover, all the blends are found to be transparent for PMMA/LiFMS in the experimental range, while the blends with more than 50 wt% of LiClO4 areopaque.4. Conclusion: The Tg enhancement of PMMA was observed by the addition of the lithiumsalts. Electrostatic interaction between lithium cation and the carbonyl group is responsiblefor the Tg enhancement.
Contents Abstract i Acknowledgements ii Chapter 1 General Introduction 1 1.1 Amorphous polymer 1 1.2 Glass transition temperature of amorphous polymer 2 1.2.1 Williams-Landel-Ferry equation 3 1.2.2 Factor affecting Tg 6 1.2.3 Methods to enhance Tg 7 1.2.3.1 Addition of nanofiller 7 1.2.3.2 Cross-linking 8 1.3 Ionic interaction 9 1.3.1 Poly(electrolyte) 10 1.3.2 Ionomer 11 1.4 Processing method 14 1.4.1 Melt intercalation 14 1.4.2 Solution mixing 15 1.5 Objective 16 References 18 Contents v Chapter 2 PMMA Containing LiFMS 23 2.1 Introduction 23 2.2 Experimental 25 2.2.1 Materials 25 2.2.2 Method 25 2.2.3 Measurements 26 2.3 Results and Discussion 27 2.3.1 Transparency 27 2.3.2 Thermal properties 28 2.3.3 Functional group 31 2.3.2 Rheology 33 2.4 Conclusion 36 References 37 Chapter 3 Effect of cations and anions 39 3.1 Introduction 41 3.2 Experimental 41 3.2.1 Materials 42 3.2.2 Method 42 3.2.3 Measurements 42 3.3 Results and Discussion 44 Contents vi 3.3.1 Effect of molar ratio 44 3.3.2 Effect of anions 50 3.3.2.1 Halogens 50 3.3.2.1 Other salts 52 3.3.3 Effect of cations 55 3.3.3.1 Perchlorate 55 3.3.3.2 Trifluoromethane sulfonate 57 3.4 Conclusion 60 References 61 Chapter 4 Polar Polymers Containing Lithium Salt 63 4.1 Introduction 63 4.2 Experimental 65 4.2.1 Materials 65 4.2.2 Method 66 4.2.3 Measurements 68 4.3 Results and Discussion 69 4.3.1 Polystyrene 69 4.3.2 Polyamide 70 4.3.3 Poly(lactic acid) 71 4.3.4 Polyacrylonitrile 72 Contents vii 4.3.5 Poly(ethylene terephthalate-co-ethylene isophthalate) 73 4.4 Conclusion 77 References 78 Chapter 5 General Conclusion 80 Achievements 82
Supervisor:山口 政之
マテリアルサイエンス研究科
修士

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