Microscopic and Microbeam X-ray Studies on Lamellar Assembly in Biodegradable Polymers Copolymers and Blends

  • 謝 雅婷

Student thesis: Doctoral Thesis

Abstract

This study has been focused on the spherulitic morphology of biodegradable polyesters copolymer and blends by using microscopic and microbeam X-ray techniques Double ring-banded spherulites of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV with 12 wt% 3HV) blending with 30 wt% amorphous poly(vinyl acetate) (PVAc) were examined using polarized light optical microscopy (POM) scanning electron microscopy (SEM) atomic-force microscopy (AFM) and micro-beam X-ray diffraction A ring-banded spherulite of PHBV/PVAc 70/30 blend was linearly scanned across the bands in 5 μm steps by means of microbeam X-ray diffraction Solvent-etching and fracturing were utilized for probing the interior lamellar textures of the blend samples Detail interior lamellar orientations in bulk film of PHBV three-dimensional ring-banded spherulites were revealed SEM and micro-beam X-ray diffraction results suggest that the PHBV lamellar orientation gradually change along the radial growth direction with right-handed rotation sense The blending effect in band pattern (width and regularity) of PHBV/PVAc blend was also discussed Subsequently the spherulitic morphology of poly(ethylene adipate) (PEA) poly(1 4-butylene adipate) (PBA) poly(1 6-hexamethylene adipate) (PHA) and poly(epsilon-caprolactone) (PCL) thin films on different glass substrates were investigated by using POM and AFM Polyester films were prepared by spin coating technique onto unmodified and two types of polymethacrylate (poly(benzyl methacrylate) PBzMA and poly(methyl methacrylate) PMMA) grafted glass slides Melt-crystallized PEA PBA and PHA thin films on modified substrates exhibited the same spherulitic morphologies with their film samples on unmodified glass slides However two types of newfound spherulitic morphologies (negative- and non-birefringence mixed pattern and positive-type water lettuce-like pattern) were observed in PCL film samples AFM observation shows that the negative-type birefringence crystals of PCL are composed of edge-on lamellae and the positive-type or non-birefringence crystals are composed of tilted flat-on lamellae (forward or backward along their radial direction) Furthermore the melting and crystallization behaviors of PCL in PCL/PBzMA and PCL/PMMA blends have investigated in this study by using differential scanning calorimetry (DSC) DSC results suggest that the crystallinity of PCL on polymethacrylate grafted glass slides can be maintained at nearly 50% still
Date of Award2014 Jul 28
Original languageEnglish
SupervisorEamor Woo (Supervisor)

Cite this

Microscopic and Microbeam X-ray Studies on Lamellar Assembly in Biodegradable Polymers Copolymers and Blends
雅婷, 謝. (Author). 2014 Jul 28

Student thesis: Doctoral Thesis