Polymorphic and miscibility behavior in crystalline/crystalline blends of poly(pentamethylene terephthalate) with poly(heptamethylene terephthalate)

Yen, Kai Cheng; Woo, Eamor M.

doi:10.1002/pi.2673

Cited by 7 publications

(4 citation statements)

References 25 publications

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“…Poly(dodecamethylene terephthalate) (P12T) was not commercially available; thus it was synthesized in-house using two-step polymerization from dimethyl terephthalate (DMT) and 50% excess 1,12-dodecanediol with 0.1% butyl titanate as a catalyst following the procedure published previously. 33,34 Typical condensation polymerization procedures were followed to ensure high-enough molecular weights, containing at least 30 repeat units. The weight-average molecular weight (M n ) and the polydispersity index (PDI) as determined by gel permeation chromatography (GPC, Waters) were 9224 g mol 21 and 1.91, respectively.…”

Section: Methodsmentioning

confidence: 99%

Periodic extinction bands composed of all flat‐on lamellae in poly(dodecamethylene terephthalate) thin films crystallized at high temperatures

Lugito

Woo

Chang

2017

J Polym Sci B Polym Phys

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Using in‐house synthesized poly(dodecamethylene terephthalate) (P12T) as a model, periodic extinction‐banded spherulites melt‐crystallized at high Tcs (100–115 °C) are expounded in terms of growth mechanism. The extinction‐banded spherulites wildly differing from the usual blue/orange double ring‐banded spherulites are composed of all flat‐on discrete single‐crystalline lamellae packed like roof shingles (or fish scales) along the circularly curved bands and the lamellae in the extinction bands are flat with a lozenge shape with no continuous twisting at all. For P12T films of more than 10 µm crystallized at Tc = 105–115 °C, no periodic bands were seen, and all spherulites were ringless, where periodic growth precipitation of crystals to extinction does not occur until impingement. Extinction bands in the P12T spherulites with the inter‐ring spacing steadily decrease with decreasing film thickness, because for thinner films (submicrons to 2 µm), draining or depletion of available molten species takes place more frequently, leading to bands of smaller inter‐ring spacing. The petal‐like extinction bands are discussed and analyzed in detail using 3D AFM imaging. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 601–611

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Section: Methodsmentioning

confidence: 99%

Periodic extinction bands composed of all flat‐on lamellae in poly(dodecamethylene terephthalate) thin films crystallized at high temperatures

Lugito

Woo

Chang

2017

J Polym Sci B Polym Phys

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“…The usual-type lamellae also have a higher T m than the unusual ones. There are ample literature reports that also found unusual-type spherulites in polymers containing terephthalate group, such as poly(pentamethylene terephthalate) (PPT), poly(hexamethylene terephthalate) (PHT), poly(heptamethylene terephthalate) (PHepT), , poly(octamethylene terephthalate) (POT), poly(nonamethylene terephthalate) (PNT), , etc.…”

Section: Introductionmentioning

confidence: 99%

Phase-Separation Induced Lamellar Re-Assembly and Spherulite Optical Birefringence Reversion

2014

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By using atomic-force and scanning electron microscopies (AFM, SEM), wide-angle and small-angle X-ray diffraction (WAXD and SAXS), and thermal and infrared spectroscopy characterization, mechanisms and correlations between lamellar reassembly, phase separation domains, and birefringence patterns in crystallized spherulites in poly(hydroxyl butyrate) (PHB) were probed in detail. Crystallization-induced phase separation in PHB blended with amorphous poly(methyl acrylate) (PMA) produces pebble-like PMA domains, which influence the birefringence types (positive vs negative types) of spherulites in crystallized blends with respect to composition and temperature. Extents of crystallization-induced phase separation were dependent on temperature and composition; for a fixed PHB/PMA (60/40) blend composition the phase separation extent was inversely proportional to temperature of crystallization (T c ). Correspondingly, depending on the extents of phase separation (counted as quantitative ratio of pebble-like PMA domains divided by entire area of the blend samples), the Maltese cross in spherulite patterns of PHB in the blend may rotate from the original positive-type spherulites at T c = 90°C to negative-type spherulites at T c = 60°C. The SAXS analyses showed the thickness variation of PHB lamellae (or PHB + amorphous polymer long periods) with T c was not an influencing factor, but that the formation of grains in the PMA domains from the crystallizationinduced phase separation could majorly influence the optical birefringence. Correlations among the phase domains, lamellae assembly, transitions from positive-type, unusual-type, and negative-types of crystallized spherulites in polymers have been expounded upon.

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“…This result suggests that the dominant lamellae are oriented to different directions in the PBT spherulites of different optical types. There are ample literature reports that have found unusual-type spherulites in other polymers containing a terephthalate group, such as poly(pentamethylene terephthalate) (PPT), 16 poly-(hexamethylene terephthalate) (PHT), 17 poly(heptamethylene terephthalate) (PHepT), 18 poly(octamethylene terephthalate) (POT), 19 or poly(nonamethylene terephthalate) (PNT), 20 etc.…”

Section: ■ Introductionmentioning

confidence: 99%

Interior Dissection on Domain-Dependent Birefringence Types of Poly(3-hydroxybutyrate) Spherulites in Blends

2016

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The mechanisms and correlations between the rotation of Maltese cross axis, optical birefringence types, and lamellar reassembly induced by phase-separation domains, in poly(3-hydroxybutyrate) (PHB)/poly(1,4-butylene adipate) (PBA). In this work, a novel approach via interior dissection into spherulites in correlations with the top-surface morphology of the PHB/PBA (50/50) blend crystallized at a series of T c 's with various domain sizes. The PHB/PBA blend is used as the model system in comparison to alternative blends of PHB with other polyesters of various extents of phase-separated domains. Domains of optimal sizes were found to be essential in lamellar reassembly, which strongly affects the birefringence types of spherulites. Via the proven approaches, this work expounds how domain sizes and lamellar reorientation in partially miscible blends cause changes in the birefringence types of PHB spherulites, while, in contrast, complete miscibility or extreme phase separation with large domains does not.

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Polymorphic and miscibility behavior in crystalline/crystalline blends of poly(pentamethylene terephthalate) with poly(heptamethylene terephthalate)

Cited by 7 publications

References 25 publications

Periodic extinction bands composed of all flat‐on lamellae in poly(dodecamethylene terephthalate) thin films crystallized at high temperatures

Periodic extinction bands composed of all flat‐on lamellae in poly(dodecamethylene terephthalate) thin films crystallized at high temperatures

Phase-Separation Induced Lamellar Re-Assembly and Spherulite Optical Birefringence Reversion

Interior Dissection on Domain-Dependent Birefringence Types of Poly(3-hydroxybutyrate) Spherulites in Blends

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