Correlations between growth regimes and unusual spherulite morphology in aliphatic versus aryl polyesters

• Main Authors: Yu Fan, 陳玉凡
• Other Authors: E. M. Woo
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/47094041509959528910

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 95 === Poly(octamethylene terephthalate) (POT) and poly(nonamethylene terephthalate) (PNT) with respectively eight and night methylene units between two terephthalates which were newly synthesized polyesters were under discussion about the crystal structures, growth kinetics, and spherulite morphology in this thesis. The crystalline morphology and polymorphism of polyesters were examined by means of polarized-optical microscopy (POM). The process of spherulite growth was photoed by Nikon charge-coupled-device CCD digital camera and the rates were measured from records using automatic image processing software. To analyze the regime behavior of spherulite growth, Lauritzen-Hoffman theory was introduced to fit the growth rate data, and resulted in two regimes with the increase of temperature. The change of morphologies not only depends on crystallization temperatures, but also relates to the growth regime behavior. It was also discovered that although the spherulites may be growing totally different, the crystal forms examined by wide-angle x-ray diffraction (WAXD) were the same. What deserved to be mentioned is that the ringed-spherulites of POT, which is unique under polarized or non-polarized optical microscopy. The band width of the ringed-spherulite under non-polarized optical microscopy is twice as that under polarized optical microscopy. To further probe into the ring pattern, scanning electron microscopy (SEM) was used. It was confirmed that the band width observed by SEM was corresponding to that observed by POM. There is the same situation about the band width of the second type of spherulites (the one that is more sparse than the other) of PNT. Difference in spherulite ring-band patterns between neat poly(��-caprolactone) (PCL) and miscible blends was probed to correlate with growth regimes. Spherulite growth in thin-film forms and transformation of spherulite patterns in different regimes were investigated by comparing neat PCL with its miscible blends. Blending of PCL with miscible amorphous polymers changes the spherulite patterns significantly. Effect of different diluent polymers varies. For neat PCL, in transition from regime III to regime II, the spherulites are patterned in ring-less to ring-banded types, respectively, in different regimes. Maltese-cross spherulites and dendritic spherulites (with highly irregular ring bands and no Maltese-cross) are featured in different growth regimes (low- and high-temperature regimes, respectively) for neat PCL.