Fractionated crystallization in semicrystalline polymers

Sangroniz, Leire; Wang, Bao; Su, Yunlan; Liu, Guoming; Cavallo, Dario; Wang, Dujin; Müller, Alejandro J.

doi:10.1016/j.progpolymsci.2021.101376

Cited by 54 publications

(67 citation statements)

References 337 publications

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Section: Resultsmentioning

confidence: 99%

“…The first effect is expected, given the extremely limited size of the PGA domains, and it is almost not resolvable with FE-SEM. As a consequence, a very small number of nucleating impurities is present in the PGA domains, leading to vanishing crystallization kinetics [44]. As a matter of fact, PGA can only crystallize upon the subsequent heating, as evidenced by the cold-crystallization peak observed above the melting temperature of PCL, at around 70 • C. On the other hand, the increase of the crystallization temperature of PCL can be ascribed to a nucleating effect of PGA domains themselves, or to an effective transfer of nucleating impurities from the PGA to the matrix polymer.…”

Section: Study Of the Thermal Propertiesmentioning

confidence: 99%

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The Blending of Poly(glycolic acid) with Polycaprolactone and Poly(l-lactide): Promising Combinations

et al. 2021

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Poly(glycolic acid) (PGA) holds unique properties, including high gas barrier properties, high tensile strength, high resistance to common organic solvents, high heat distortion temperature, high stiffness, as well as fast biodegradability and compostability. Nevertheless, this polymer has not been exploited at a large scale due to its relatively high production cost. As such, the combination of PGA with other bioplastics on one hand could reduce the material final cost and on the other disclose new properties while maintaining its “green” features. With this in mind, in this work, PGA was combined with two of the most widely applied bioplastics, namely poly(l-lactide) (PLLA) and poycaprolactone (PCL), using the melt blending technique, which is an easily scalable method. FE-SEM measurements demonstrated the formation of PGA domains whose dimensions depended on the polymer matrix and which turned out to decrease by diminishing the PGA content in the mixture. Although there was scarce compatibility between the blend components, interestingly, PGA was found to affect both the thermal properties and the degradation behavior of the polymer matrices. In particular, concerning the latter property, the presence of PGA in the blends turned out to accelerate the hydrolysis process, particularly in the case of the PLLA-based systems.

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Section: Resultsmentioning

confidence: 99%

Section: Study Of the Thermal Propertiesmentioning

confidence: 99%

The Blending of Poly(glycolic acid) with Polycaprolactone and Poly(l-lactide): Promising Combinations

et al. 2021

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“…The 20/80 PEO/PHD blend exhibits two crystallization peaks during cooling from the melt that according to WAXS are both due to PHD crystals. This is an uncommon behavior as fractionated crystallization is normally associated with the minor component in blends [ 29 ]. Therefore, this peculiar behavior merits future studies that are outside the scope of the present contribution.…”

Section: Resultsmentioning

confidence: 99%

Polyether Single and Double Crystalline Blends and the Effect of Lithium Salt on Their Crystallinity and Ionic Conductivity

et al. 2021

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In this work, blends of Poly(ethylene oxide), PEO, and poly(1,6-hexanediol), PHD, were prepared in a wide composition range. They were examined by Differential Scanning Calorimetry (DSC), Polarized Light Optical Microscopy (PLOM) and Wide Angle X-ray Scattering (WAXS). Based on the results obtained, the blends were partially miscible in the melt and their crystallization was a function of miscibility and composition. Crystallization triggered phase separation. In blends with higher PEO contents both phases were able to crystallize due to the limited miscibility in this composition range. On the other hand, the blends with higher PHD contents display higher miscibility and therefore, only the PHD phase could crystallize in them. A nucleation effect of the PHD phase on the PEO phase was detected, probably caused by a transference of impurities mechanism. Since PEO is widely used as electrolyte in lithium batteries, the PEO/PHD blends were studied with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI), and the effect of Li-salt concentration was studied. We found that the lithium salt preferentially dissolves in the PEO phase without significantly affecting the PHD component. While the Li-salt reduced the spherulite growth rate of the PEO phase within the blends, the overall crystallization rate was enhanced because of the strong nucleating effect of the PHD component. The ionic conductivity was also determined for the blends with Li-salt. At high temperatures (>70 °C), the conductivity is in the order of ~10−3 S cm−1, and as the temperature decreases, the crystallization of PHD was detected. This improved the self-standing character of the blend films at high temperatures as compared to the one of neat PEO.

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“…Given the fact that droplets are typically small (i.e., few micrometers or less), nucleation can be considered as the rate-determining step in the overall crystallization process. 6 − 8 …”

Section: Introductionmentioning

confidence: 99%

Surface Roughness Enhances Self-Nucleation of High-Density Polyethylene Droplets Dispersed within Immiscible Blends

et al. 2022

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Highly linear or high-density polyethylenes (HDPEs) have an intrinsically high nucleation density compared to other polyolefins. Enhancing their nucleation density by self-nucleation is therefore difficult, leading to a narrow self-nucleation Domain (i.e., the so-called Domain II or the temperature Domain where self-nuclei can be injected into the material without the occurrence of annealing). In this work, we report that when HDPE is blended (up to 50%) with immiscible matrices, such as atactic polystyrene (PS) or Nylon 6, its self-nucleation capacity can be greatly increased. In addition, temperatures higher than the equilibrium melting temperature of the HDPE phase are needed to erase the significantly enhanced crystalline memory in the blends. Morphological evidence gathered by Scanning and Transmission Electron Microscopies (SEM and TEM) indicates that these unexpected results can be explained by the modification of the interface between blend components. The filling of the solid HDPE surface asperities by the low viscosity polystyrene during heating to the self-nucleation temperature, or the crystallization of the matrix in the case of Nylon 6, enhances the interface roughness between the two polymers in the blends. Such rougher interfaces can remarkably increase the self-nucleation capacity of the HDPE phase via surface nucleation.

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Fractionated crystallization in semicrystalline polymers

Cited by 54 publications

References 337 publications

The Blending of Poly(glycolic acid) with Polycaprolactone and Poly(l-lactide): Promising Combinations

The Blending of Poly(glycolic acid) with Polycaprolactone and Poly(l-lactide): Promising Combinations

Polyether Single and Double Crystalline Blends and the Effect of Lithium Salt on Their Crystallinity and Ionic Conductivity

Surface Roughness Enhances Self-Nucleation of High-Density Polyethylene Droplets Dispersed within Immiscible Blends

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