Effects of Blend Composition and Crystallization Temperature on Unique Crystalline Morphologies of Miscible Poly(ethylene succinate)/Poly(ethylene oxide) Blends

Abstract

In a previous short communication (Macromolecules 2002, 35, 8251-8254), we reported a unique morphology in binary miscible crystalline poly(ethylene succinate) (PES)/poly(ethylene oxide) (PEO) polymer blends, in which two kinds of spherulites, corresponding to each component, respectively, grew simultaneously and PEO spherulites continued to crystallize inside PES spherulites on contact, forming interpenetrated spherulites. In the present work the effects of blend composition and crystallization temperature on the crystalline morphologies of PES/PEO blends were studied by optical microscopy in detail. The unique morphology of PES spherulites penetrated by PEO spherulites was observed for the blends with PEO content ranging from 50 to 90% in a wide crystallization temperature range. Furthermore, three novel and interesting crystalline morphologies were found depending on blend composition and crystallization temperature. First, new boundaries were formed by the growth of a single PEO spherulite itself after penetrating into PES spherulites because of the change in the growth direction. Second, both components penetrated each other and formed interpenetrated spherulites. Third, PES and PEO formed a special kind of blended spherulite that nucleated from the same site and showed two growth fronts with PEO growing faster than PES. The growth rates of both components were studied; furthermore, much more attention has been directed to the study of the observed growth rates of both types of spherulites when they developed freely in the undercooled melt and when they were forced to penetrate each other. The blend composition and crystallization temperature effects on the various crystalline morphologies were summarized in PES/PEO polymer blends, which should be of great interest and importance for a better understanding of the crystallization and morphology in miscible crystalline/crystalline polymer blends.

The crystallization and morphology of melt-miscible polymer blends

“…We now consider the case in which the two species crystallize isothermally at the same temperature, forming two distinct spherulite types. Nishi, Qiu, Ikehara and colleagues have reported on the morphology of a number of such systems [19][20][21][22][23][24][25][26][27][28][29]. A common theme through these reports is that, despite separate nucleation events, where possible, fibrils of the individual components tend to intermingle within spherulites.…”

“…A common theme through these reports is that, despite separate nucleation events, where possible, fibrils of the individual components tend to intermingle within spherulites. Figure 6 is a polarized light micrograph of 50/50 poly (ethylene succinate)/poly(ethylene oxide) (PES/PEO) blend crystallizing at 47.5°C [29]. In (a) a rapidly growing PEO spherulite and a slower growing PES succinate spherulite are about to impinge.…”

Flow‐Induced Orientation in Miscible Crystalline Polymer Blends of Poly(vinylidene fluoride) and Poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyvalerate)]

“…The spherulitic morphologies of miscible blends of crystalline polymers have been extensively studied by optical microscopy and atomic force microscopy, with particular attention paid to the interpenetrating crystallization and interlocking spherulitic crystallization. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Two types of lamellar structures, interlamellar inclusion and interlamellar exclusion, are induced in miscible polymer blends constituted of two crystalline polymers. If the fractional crystallization of components occurs in the range of lamellae crystals, one component is included in the interlamellar region of another component.…”

Crystallization Kinetics and Hydrophilicity Improvement of Biodegradable Poly(butylene succinate) in its Miscible Blends with Poly(ethylene oxide)

“…However, miscible polymer blends involving two crystalline components have received much less attention than fully amorphous or amorphous/crystalline blends. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] It is of great importance, from both academic and technological viewpoints, to investigate this special kind of blend, in which both components are able to crystallize with different conditions leading to varied crystallization behavior and morphology. Recently, Jungnickel reviewed the crystallization kinetic and morphological peculiarities in binary crystalline/crystalline polymer blends.…”

“…Furthermore, interpenetrated spherulites are found in a few miscible pairs of two crystalline polymers when the two components crystallize simultaneously. [11][12][13][14][15][16][17][18][19][20] Moreover, of particular interest and importance is that most of the reported miscible binary crystalline blends, such as poly(3-hydroxybutyrate) (PHB)/PEO, [4] PHB/poly (ethylene succinate) (PES), [8] poly(vinylidene fluoride) (PVDF)/PHB, [10] poly(L-lactic acid) (PLLA)/poly(ester carbonate) (PEC) [11,12] and PLLA/PHB blends, [16] consist of biodegradable aliphatic polyesters. PBSU/PEO blends are typical miscible crystalline/crystalline blends with PBSU being the high-T m component and PEO the low-T m component.…”