Structural evolution of the amorphous phase during crystallization of poly(l-lactic acid): A synchrotron wide-angle X-ray scattering study

Mano, João F.

doi:10.1016/j.jnoncrysol.2007.04.022

Cited by 31 publications

(29 citation statements)

References 31 publications

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“…A similar crystallinity of 35% was measured by XRD for a PLLA with a mass-average molar mass of 120,000 g mol -1 , cold-crystallized at 80°C [35]. Table 1, together with the crystal fractions determined by XRD, X c (XRD) (T c ).…”

Section: Resultssupporting

confidence: 69%

Enthalpy of melting of α′- and α-crystals of poly(l-lactic acid)

Righetti

Gazzano

Lorenzo

et al. 2015

European Polymer Journal

166

127

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Section: Resultssupporting

confidence: 69%

Enthalpy of melting of α′- and α-crystals of poly(l-lactic acid)

Righetti

Gazzano

Lorenzo

et al. 2015

European Polymer Journal

166

127

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“…A numerical measure is the glass transition temperature (T g ), which increased with crystallization temperature increase ( Table 1). Broadening of the glass transition was described by different authors, in most cases for PLLA [15,21,22,24]. In the case of long annealing times at 85°C, an important T g shift of approximately 6°C was found for both grades of PLA.…”

Section: Pla Sample Morphologymentioning

confidence: 73%

“…This effect causes the glass transition to shift to higher temperatures [40], which is also observed in our case and in the case of Drieskens' publication for PLA. In the case of PLA the shift of the T g was attributed to the confinement of the MAF, though [21][22][23][24], as the RAF is not able to relax in the region of the glass transition. In our data, we cannot observe an increase in S with increasing crystallinity degree.…”

Section: Gas Barrier Propertiesmentioning

confidence: 95%

“…The latter does not relax at the glass transition temperature, because molecules are partially trapped in the crystalline lamellae [20]. In addition, some authors show a confinement effect on the mobile amorphous phase between crystalline lamellae, which develops during crystallization [21][22][23][24]. The confined MAF shows a glass transition temperature which is shifted to higher temperatures compared to a fully amorphous sample.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Impact of crystallinity of poly(lactide) on helium and oxygen barrier properties

Guinault¹,

Sollogoub²,

Ducruet³

et al. 2012

European Polymer Journal

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible.This is an author-deposited version published in: http://sam.ensam.eu Handle ID: .http://hdl.handle.net/10985/10118 To cite this version :A GUINAULT, C SOLLOGOUB, Violette DUCRUET, Sandra DOMENEK -Impact of crystallinity of poly(lactide) on helium and oxygen barrier properties -European Polymer Journal -Vol. 48, p.779-788 -2012 Any correspondence concerning this service should be sent to the repository The helium and oxygen gas barrier properties of poly(lactide) were investigated as a function of stereochemistry and crystallinity degree. Poly(L-lactide) and poly(D,L-lactide) films were obtained by extrusion and thermally cold crystallized in either a 0 -or a-crystalline form with increasing crystallinity degree. Annealing of the films at low temperatures yielded to a 0 -crystals as well as the creation of a rigid amorphous fraction in the amorphous phase. Unexpectedly, the quantity of the rigid amorphous fraction was highest in poly(L-lactide) crystallized under a 0 -form. Unexpectedly, the gas permeability increased with increasing quantity of a 0 -crystals in poly(L-lactide) and remained constant with increasing quantity of a 0 -crystals in poly(D,L-lactide). A gain in gas barrier properties was obtained upon crystallization at higher temperatures yielding a-crystals. The analysis of the oxygen transport parameters, in particular the diffusion and the solubility coefficient showed that the diffusion was accelerated upon crystallization, while the solubility coefficient decreased in an expected manner which led to conclude that it remained constant in the amorphous phase. The acceleration of the diffusion seems to be correlated to the occurrence of the rigid amorphous fraction, which holds larger free volume. To conclude, for optimization of poly(lactide) gas barrier properties by focussing on the decrease of the diffusion coefficient it can be suggested to work with poly(D,L-lactide) and to aim a crystallization in a-form avoiding the formation of a rigid amorphous fraction.

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“…As a result, PLLA has been used as an implant material, surgical suture, drug carrier, and as a material for disposable products such as baby diapers and packagings [6,[9][10][11][12]. In one of the applications, PLLA has been studied for possible use as a biodegradable shape memory stent material [7,[13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%