| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 88 === This study use differential scanning calorimeter (DSC)、polarizing-light microscope (POM) and scanning electron microscope (SEM) to se how to the structure and molecular weight effect the miscibility and phase morphology in three blend systems- Polystyrene/Poly(4-methyl styrene) (PS/P4MS) 、Poly(4-methylstyrene)/ Poly(-methylstyrene) (P4MS/PMS) and Poly (cyclohexyl methacrylate) /Poly(-methyl-styrene) (PCHMA/PMS). By thermal analysis, we can get a single glass transition temperature (Tg) in all three blend systems. Then we use POM and SEM to get more details about their real phase morphology. In SEM, there exist small phase domains in all components of PS/P4MS system which have the upper critical solution temperature (UCST) behavior. And with the increase of molecular weight, the UCST curve will move to high-temperature range. As for the P4MS/PMS system, we find a homogeneous structure with lower critical solution temperature (LCST) behavior in POM and SEM. However, if we increase the molecular weight of the blend mixture, the phase morphology becomes partial miscible, even immiscible (in some conditions). For the PCHMA/PMS system, there exists a single Tg which will be different when the molecular weight is changed. There is a single homogeneous phase in POM and SEM. Because the change of molecular weight won't change its phase morphology. PCHMA/PMS system has a very good miscibility. The fourier-transition infrared spectrometer (FTIR) shows that the interactions between PCHMA and PMS are very weak. In this research, no matter what behavior the three blend systems have, LCST or UCST, the curve will move with the change of molecular weight which can be described by Flory-Huggins equations.
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