A synchrotron SAXS study of PLLA crystallized at different temperatures: One-dimensional correlation functions

Díez‐Rodríguez, Tamara M.; Blázquez‐Blázquez, Enrique; Martínez, Juan Carlos; Cerrada, María L.; Pérez, Ernesto

doi:10.1016/j.polymer.2022.125232

Cited by 6 publications

(8 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, T 225 with low crystallinity and T 80 with an α′ crystal exhibited diffuse and broad scattering, which is an indication of the low electronic density difference between the crystalline and amorphous phases. The diffuse SAXS pattern of the α′ crystal, even with the periodic lamellae structure, has been observed in other studies as well. − For example, Díez-Rodríguez et al found that in samples annealed at 75 °C, which developed a primary α′ crystal, no long-spacing peak was detected. This diffuse SAXS pattern without the long-spacing maximum in the α′ crystal can be ascribed to the conformational disorder, ,, where partial chains in the unit cell of the α′ crystal may adopt the helix conformation other than 10 3 as the most do and distribute randomly in the unit cell. , Such a disorder could decrease the electronic density difference between the crystalline and amorphous phases, showing a diffuse SAXS pattern .…”

Section: Resultssupporting

confidence: 52%

“…45−47 For example, Di ́ez-Rodri ́guez et al 45 found that in samples annealed at 75 °C, which developed a primary α′ crystal, no long-spacing peak was detected. This diffuse SAXS pattern without the longspacing maximum in the α′ crystal can be ascribed to the conformational disorder, 18,46,48 where partial chains in the unit cell of the α′ crystal may adopt the helix conformation other than 10 3 as the most do and distribute randomly in the unit cell. 26,49 Such a disorder could decrease the electronic density difference between the crystalline and amorphous phases, showing a diffuse SAXS pattern.…”

Section: P Ds =mentioning

confidence: 97%

“…26,49 Such a disorder could decrease the electronic density difference between the crystalline and amorphous phases, showing a diffuse SAXS pattern. 46 Despite this disorder, the chain packing within the α′ crystal remains sufficiently compact to be impermeable to gas molecules. In fact, the α′ crystal possesses similar unit cell parameters (a = 10.80 Å, b = 6.20 Å, c = 28.80 Å) as the α crystal (a = 10.683 Å, b = 6.170 Å, c = 28.860 Å).…”

Section: P Ds =mentioning

confidence: 99%

See 2 more Smart Citations

Modulating Barrier Properties of Stereocomplex Polylactide: The Polymorphism Mechanism and Its Relationship with Rigid Amorphous Fraction

Chen,

Auras,

Kirkensgaard

et al. 2023

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

The barrier properties of semicrystalline polymers are crucial for their performance and their use as packaging materials. This work uncovers the mechanism of polymorphism modification (α, α′ and stereocomplex-crystals) and its combined effect on the oxygen and water vapor barrier properties of semicrystalline stereocomplex polylactide (SCPLA). A polymorphic selective filler-type nucleator was employed to eliminate the temperature effect on the development of polymorphism and rigid amorphous fraction (RAF), allowing correlations of barrier properties with different crystal forms and RAF combinations under the same amorphous composition (SCPLA). The oxygen and water vapor barrier performances strongly correlated with crystallinity and crystal form but were not monotonically related to the RAF quantity. The study proposes that the chain conformation of intermediate phases between the crystalline and amorphous phases differs with the associated crystal forms, thereby leading to different RAF “qualities” and contributing to different gas diffusion and solubility coefficients of the amorphous regions. RAF’s per unit excess free volume may be varied with crystal forms, for instance: α′ ≫ SC > α. Therefore, SCPLA with α′ crystals exhibited high oxygen and water vapor permeabilities. Those with high SC and α crystals showed similar barrier behaviors governed by Henry’s law dissolution and followed a linear “two-phase” relationship with total crystallinity.

show abstract

Section: Resultssupporting

confidence: 52%

Section: P Ds =mentioning

confidence: 97%

Section: P Ds =mentioning

confidence: 99%

See 1 more Smart Citation

Modulating Barrier Properties of Stereocomplex Polylactide: The Polymorphism Mechanism and Its Relationship with Rigid Amorphous Fraction

Chen,

Auras,

Kirkensgaard

et al. 2023

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

show abstract

“…SAXS was used to analyze the crystal structure, and the Lorentz‐correction curves of the samples after isothermal crystallization at desired temperatures are shown in Figure 7. Crystal structure parameters such as the long period ( L ) can be obtained from the Lorentz‐corrected SAXS curves 55,56 . It could be found that unimodal curves were observed for the neat PLLA, PLLA/Sc‐fibers, and PLLA/g‐CNCs after isothermal crystallization at different temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…period (L) can be obtained from the Lorentz-corrected SAXS curves. 55,56 It could be found that unimodal curves were observed for the neat PLLA, PLLA/Sc-fibers, and PLLA/g-CNCs after isothermal crystallization at different temperatures. However, for PLLA/g-CNCs/Sc-fibers sample, it showed distinct bimodal curves at the q values about 0.3 and 0.4 nm À1 after isothermal crystallization (90-120 C, Figure 7d).…”

Section: Isothermal Crystallizationmentioning

confidence: 98%

Effect of electrospun stereocomplex PLA fibers and modified cellulose nanocrystals on crystallization of poly(L‐lactic acid)

Wan

Zhuang

et al. 2023

J of Applied Polymer Sci

View full text Add to dashboard Cite

Poly(L-lactic acid) (PLLA) is a biodegradable polymer that has attracted increasing attention due to its fantastic properties. Nevertheless, the disadvantages of PLLA, such as low crystallization rate and brittleness, limit its wide commercial applications. In the present work, electrospun stereocomplex PLA fibers (Sc-fibers) and PLLA grafted cellulose nanocrystals (g-CNCs) are prepared as nano-fillers and then blended with PLLA matrix to prepare different nanocomposites. Both of nano-fillers would accelerate the crystallization rate of PLLA, and as expected, g-CNCs have much stronger nucleation ability towards PLLA than Sc-fibers. Nevertheless, the crystallization of PLLA will decrease to some extent in the presence of both nano-fillers of g-CNCs and Scfibers due to the preferential formation of stereocomplex crystals on the surfaces of CNCs. Moreover, the presence of nano-fillers would enhance the mechanical properties of PLLA, such as the elongation at break can increase by four times after incorporating both g-CNCs and Sc-fibers. This work provides a new consideration for designing different nano-fillers, especially for polymer matrices with low crystallization ability and brittleness.

show abstract

Significantly enhanced crystallization of poly(L‐lactide) by incorporation of poly(D‐lactide) grafted cellulose nanocrystals

Li,

Meng,

Tong

2024

J of Applied Polymer Sci

View full text Add to dashboard Cite

Poly(L‐lactic acid) (PLLA), as a green, biodegradable polymer material, has garnered considerable attention due to its ease of processing and exceptional properties. However, the inherent slow crystallization rate and brittleness of PLLA substantially restrict its extensive applications across various domains. In present work, PLLA and poly(D‐lactide) (PDLA)‐modified cellulose nanocrystals (CNCs), referred as CNC‐g‐L and CNC‐g‐D, are serving as nano‐fillers to enhance the crystallization rate of PLLA. Our findings demonstrate that both nano‐fillers could enhance the crystallization rate of PLLA, but the CNC‐g‐D shows a more efficient nucleation agent compared with its counterpart, CNC‐g‐L. Isothermal crystallization analysis indicates that CNC‐g‐D substantially increases nucleation density of PLLA, with pronounced crystallization at an elevated temperature of 155°C as confirmed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Wide‐angle x‐ray diffraction (WAXD) analysis shows the preformation of stereocomplex crystals on the CNC‐g‐D surface may result in a fast crystallization rate. Meanwhile, after incorporation of different nano‐fillers, the toughness property of PLLA has also been significantly enhanced. Our result has shown the CNC‐g‐D could serve as an efficient nucleation agent toward PLLA and also facilitate to aiding in establishing comprehensive structure–property relationships of polymer materials.

show abstract

A synchrotron SAXS study of PLLA crystallized at different temperatures: One-dimensional correlation functions

Cited by 6 publications

References 37 publications

Modulating Barrier Properties of Stereocomplex Polylactide: The Polymorphism Mechanism and Its Relationship with Rigid Amorphous Fraction

Modulating Barrier Properties of Stereocomplex Polylactide: The Polymorphism Mechanism and Its Relationship with Rigid Amorphous Fraction

Effect of electrospun stereocomplex PLA fibers and modified cellulose nanocrystals on crystallization of poly(L‐lactic acid)

Significantly enhanced crystallization of poly(L‐lactide) by incorporation of poly(D‐lactide) grafted cellulose nanocrystals

Contact Info

Product

Resources

About