| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 105 === Dual types of ring-banded morphology of PNT, which are single ring-banded morphology (Type-1) and double ring-banded morphology (Type-2), are investigated by polarized optical microscopy (POM) and scanning electron microscopy (SEM) to understand the exact crystallization mechanisms. We exploit POM to not only determine the Tmax effects on the number proportion and volume fraction of Type-1 and Type-2 spherulites over the entire sample, but also record the growth rates of both and the beginning nuclei morphology plus the subsequent spherulitic morphology captured at different time of crystallization. However, the kinetic aspects cannot explain why PNT could form the dual types of ring-banded morphology under the same thermal condition; instead, while capturing the entire crystallization process, we clearly clarify the reason. Then we take advantage of SEM to observe the interior lamellar arrangement of Type-1 and Type-2 spherulites, and to see whether any differences inside the bulk. Under such analyses, we first understand the only same characteristic existing in Type-1 and Type-2 spherulites: 2 kinds of discontinuities in lamellar arrangement. And the following examination show that the lamellae of Type-1 spherulites demonstrate the different arrangement while being observed from different dissection angle, in addition, the nuclei positions either near the top surface or more inside the spherulite also influences the arrangement and complexity of interior lamellae. As for Type-2 spherulites of PNT, we observe the strong correlation between the topography and interior lamellar assembly, that is to say, both the lamellar arrangement in top surface and inside the bulk display the tilted characteristics. More interestingly, the lamellar arrangements of Type-2 spherulites clearly demonstrate the twisting structure with enough growing space. Consequently, under the combination of POM and SEM analyses, we exactly illustrate the different crystallization mechanisms of Type-1 and Type-2 spherulites of PNT.
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