Penetrating Spherulitic Growth in Poly(butylene adipate-co-butylene succinate)/Poly(ethylene oxide) Blends

Abstract

The spherulitic growth of poly(ethylene oxide) (PEO) was found to continue in the spherulites of poly(butylene adipate-co-butylene succinate) (PBAS) in the simultaneous spherulitic growth process of the two components in PBAS/PEO blends. This phenomenon, namely the formation of interpenetrating spherulites (IPS), was analyzed on the basis of birefringence observed by polarizing optical microscopy. The growth direction of PEO lamellae in the PBAS spherulites was found to be along the preexisting PBAS lamellae. PEO crystals also nucleated inside PBAS spherulites and showed spherulitic growth in them at relatively high crystallization temperatures. The conditions for realizing IPS were also discussed. Miscibility in these novel crystalline/crystalline polymer blends in the molten state was confirmed by differential scanning calorimetry and optical microscopy.

Crystalline and Spherulitic Morphology of Polymers Crystallized in Confined Systems

“…After cooling from 60 down to 40 • C, PBA began to nucleate inside the PBS spherulites (Figure 9b-d), leading to the enhanced brightness due to the birefringence of PBA spherulites. Similar phenomena have also been observed in the PBS/PEO [89] and PBAS/PEO blends [95]. As shown in Figure 9, PBA cannot form its own spherulites in crystallization, and the crystallization of PBA did not change the original shape of preexisting PBS spherulites, indicating that the PBA lamellae probably grew along the PBS ones.…”

“…Researchers have found that the binary miscible crystalline/crystalline polymers show the confined and fractional crystallization behavior because of the phase separation and segregation in different length scales during crystallization process. These crystalline/crystalline polymer blends included poly(ethylene terephthalate) (PET)/poly(butylene terephthalate) (PBT) [75], poly(3-hydroxybutyrate) (PHB)/poly(ethylene oxide) (PEO) [76,77], poly(vinylidene fluoride) (PVDF)/poly(butylene adipate) (PBA) [78][79][80], PVDF/poly(butylene succinate-co-butylene adipate) (PBSA) [81], PVDF/PHB [82], PVDF/poly(butylene succinate) (PBS) [83][84][85], PBS/PEO [86][87][88][89][90][91][92], PBS/PBA [93,94], poly(butylene adipate-co-butylene succinate) (PBAS)/PEO [95], poly(ethylene succinate) (PES)/PEO [96], PLLA/poly(oxymethylene) [97,98], and so on. Expect for the miscible blends with one or two crystalline homopolymers, the miscible copolymer/copolymer blends having crystalline components or blocks could also show the confined crystallization behavior [99,100].…”

“…These interlamellar, interfibrillar or interspherulitic environments will exert diversified confinement effects on the following crystallization of the low-T m component. The low-T m component will show the different crystallizabilities when segregated in different environments; this leads to the multistage and fractional crystallizations of the low-T m polymer component [78,79,81,84,87,88,90,91,[93][94][95]. Therefore, the crystalline/crystalline miscible…”

Micromorphology Memory in Amphiphilic Polypeptides

“…IR/ ATR spectra of the as-cast film (Figure 2b) show amide distinct peaks at 1657 cm À1 (s, amide I) and 1552 cm À1 (s, amide II) assigned to -helical conformations of PBLA blocks according to the literature, and beside that peak, very tiny amide shoulders at 1635 (amide I) and 1531 cm À1 (amide II) are assigned to -strands. 13 The -strand percentage to whole PBLA chains was estimated using peak fitting software (GRAMS/AI ver.7, Thermo Galactic) to be 5% for Dp ¼ 18, 3% for Dp ¼ 25, and 5% for Dp ¼ 32. Since PEG chains had a refractive index ellipsoid whose longitudinal axis was along the chain axis, 14 most of PEG chains might orient radially inside milli-spherulites while they oriented circularly inside micro-spherulites.…”

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.…”