Distorted Ring-Banded Spherulites in Partially Miscible Poly(L-actic acid)/Poly(ε-caprolactone) Blend

  • 何 貝安

Student thesis: Master's Thesis


Blend of poly(L-lactic acid) (PLLA)/poly(ε-caprolactone) (PCL) has been investigated by using polarized optical microscope (POM) and atomic force microscope (AFM) The two-step isothermal crystallization of PLLA/PCL=20/80 with various first crystallization temperatures and a fixed second crystallization temperature of 30 °C was investigated Wrinkle band encountered along with small concentric ring-banded were found in PLLAPCL=20/80 Wrinkle band and small concentric ring-banded spherulites formed at first crystallization temperature meanwhile at the second crystallization temperature the crystal PCL formed a ringless negative-sign where orange color filled for first and third quadrants Furthermore the two-step isothermal crystallization of PLLA/PCL=20/80 with a fixed first crystallization temperature of 117 °C and various second crystallization temperatures was also investigated In this term we can observe that the morphology of wrinkle band does not have any fixed pattern based on the morphology is similar for different samples treated by the same condition It happened due to the different diffused and inserted proportion of PCL below PLLA crystal which is attributed by phase separation Meanwhile ringless negative-sign spherulites lastly formed after suddenly cooled down or quenched to lower second crystallization temperatures without changing of wrinkle band morphology On the other hand at the higher second crystallization temperature the PCL crystal formed a ringless positive-sign as indicated with blue color filled for first and third quadrants and also the wrinkle band changed to branch-like band The branch-like band is attributed to the high chain mobility when reorganized crystal of PCL to pack at higher second crystallization temperature 47 °C Small concentric ring-banded spherulites which can be clearly observed in atomic force microscope were induced by rhythmic growth
Date of Award2014 Aug 20
Original languageEnglish
SupervisorEamor Woo (Supervisor)

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