Mechanism of Lamellar Assembly in Janus-faced Spherulites of Poly(butylene succinate) Blended With Water-Soluble Poly(ethylene oxide)

Abstract

Morphology of semicrystalline poly(butylene succinate) (PBSu) revealed Janus-faced spherulites with fine banded spherulites The spherulitic morphology of neat PBSu showed banded spherulites with minor fibrous part at low crystallization temperature of 70 oC On the other hand morphology of neat PEO naturally exhibited fibrous pattern or coarse-grained morphology In brief the PBSu/PEO blend presented complex crystallization behaviours depending on the blend composition The band-spacing of neat PBSu became larger with the increasing of PEO content on the blend the optimum ring-band formation revealed at PBSu/PEO 70/30 Top cover confinement also had influenced on spherulite morphology in the blend PEO domains were found to nucleate and grow continuously in the blend 70/30 melted at Tmax 150 oC and after melted at 160 and 170 oC those small PEO segregations were increased and growth continuously after crystallized at room temperature for 30 minutes while in Tmax 190 and 200 oC PEO spherulite disappeared because homogeneous phase segregation (well distributed) From AFM observation the AFM images of PBSu/PEO blend before and after etching were found an amount of PEO crystallized on the top of PBSu making the surface of PBSu spherulites mostly covered by plat-like lamellae of PEO Thermal behaviour observation two melting endotherm peaks were observed by DSC for all blend system Blending PBSu with PEO did not generate any new endotherm peak of the blend By WAXD PBSu/PEO blend did not show any new crystal peak from DSC and WAXD indicated that both of PBSu and PEO were crystallized in their own crystal lattices From the FTIR result the usage of 190 oC melting temperature did not give any significant effect on PEO degradation The mechanism of Janus-faced spherulites of PBSu/PEO blend composed a ring-band and fibrous pattern The fibrous lamellae packed by wider lamellae in flat-on orientation The growth rate of fibrous lamellae had possibility to grow in all directions From top view by AFM and SEM images proved that the lamellae in the nuclei part composed by “tied” or sheaf-like lamellae bundled compactly The sheaf-like or tied lamellae were discerned to grow radially as a periodic ridge consist of edge-on orientation while the valley composed by narrow flat-on lamellae such phenomenon occured periodically It led to the formation of the ring-banded pattern The areas without sheaf-like lamellae was covered by plated lamellae that tent to grow as fibrous continuously The ring-banded and fibrous pattern were parallel with each other suggesting identical growth rates for these two regions The growth rates of both regions were quite similar From top view the lamellar arrangement in the fibrous pattern as flat-on orientation growth with small branches on the side part and growth continuously along radial direction and packed of long and wide lamellae From lateral view of fibrous region the lamellae orientation composed by flat-on lamellae resulting in the formation of a fibrous pattern On the other hand with the same view the center part was stood as the main ridge consisting of edge-on lamellae and bending to form flat-on lamellae on the valley composed by narrow lamellae in flat-on orientation From top view it was shown that the valley (darker region) packed by flat-on lamellae and ridge region packed with small edge-on lamellae resulting the formation of ring-banded pattern

Date of Award	2015 Aug 6
Original language	English
Supervisor	Eamor Woo (Supervisor)