The characteristic length of cooperative rearranging region for uniaxial drawn poly(ethylene terephthalate) films

Furushima, Yoshitomo; Ishikiriyama, Kazuhiko; Higashioji, Takuji

doi:10.1016/j.polymer.2013.06.030

Cited by 18 publications

(21 citation statements)

References 23 publications

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“…45,54,55,56 Similar results are obtained after UCW and SEQ drawings even if the cooperativity length is slightly higher ( T = 2.0 nm). These results are supported by previous ones obtained with drawn PET, 49,57,58,59 showing that drawing can also induce high heterogeneities in molecular dynamics. The decrease of the cooperativity length in drawn materials is mainly associated to two phenomena: the complexity of the environment that causes heterogeneities in the relaxation process so creates an effect close to confinement conditions, and the orientation of the macromolecules that causes the breaking of weak energy intermolecular bonds.…”

Section: Thermal Analysis and Molecular Mobilitysupporting

confidence: 89%

Structural Dependence of the Molecular Mobility in the Amorphous Fractions of Polylactide

et al. 2014

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Fragilityindex and cooperativity length characterizing the molecular mobility in the amorphous phase are for the first time calculated in drawn polylactide (PLA). The microstructure of the samples is investigated from wide-angle X-ray scattering (WAXS) whereas the amorphous phase dynamics are revealed from broadband dielectric spectroscopy (BDS) and temperature-modulated differential scanning calorimetry (TMDSC). The drawing processes induce the decrease of both cooperativity and fragility with the orientation of the macromolecules. Post-drawing annealing reveals an unusual absence of correlation between the evolutions of cooperativity length and fragility. The cooperativity length remains the same compared to the drawn sample while a huge increase of the fragility index is recorded. By splitting the fragility index in a volume contribution and an energetic contribution, it is revealed that the amorphous phase in annealed samples exhibits a high energetic parameter, even exceeding the amorphous matrix value. It is assumed that the relaxation process is driven in such a way that the volume hindrance caused by the thermomechanical constraint is compensated by the acceleration of segmental motions linked to the increase of degrees of freedom. This result should also contribute to the understanding of the constraint slackening in the amorphous phase during annealing of drawn PLA, which causes among others the decrease of its barrier properties.

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Section: Thermal Analysis and Molecular Mobilitysupporting

confidence: 89%

Structural Dependence of the Molecular Mobility in the Amorphous Fractions of Polylactide

et al. 2014

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“…and given in Table . The volume of a CRR ( ξ 3 ) varies in the same range than those calculated for other glass‐formers . It decreases of about 60% as the percentage of TA or ATBC reached 10 %wt.…”

Section: Resultsmentioning

confidence: 60%

Molecular mobility and physical ageing of plasticized poly(lactide)

Dobircau

Delpouve

Herbinet

et al. 2014

Polymer Engineering & Sci

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Molecular mobility and physical ageing of amorphous plasticized polylactide (PLA) with two different contents of mesolactide are studied with the help of thermal analysis. Used plasticizers are acetyl tributyl citrate (ATBC) and triacetin (TA), two molecules with established miscibility and plasticizing efficiency. Lower plasticizer permanence of TA compared with ATBC is found. The plasticizer molecules decreased the size of the cooperativity domains at the glass transition temperature Tg and likely in the glassy state by decreasing intermacromolecular interactions and notwithstanding the mesolactide content of PLA and the chemical identity of the plasticizer. The recovery function is given and shows a significant effect of the plasticizer on the physical ageing. The supplementary free volume brought by the plasticizer enhances molecular mobility in the glassy state and increases structural relaxation at one order of magnitude. The comparison between different plasticizers reveals that the structural relaxation is however independent from the type of plasticizer and the percentage of mesolactide in PLA. POLYM. ENG. SCI., 55:858–865, 2015. © 2014 Society of Plastics Engineers

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“…To explain this result, we should first consider that despite the orientation of the macromolecules, the material is non-crystalline which means that the amorphous phase is not confined in any way. That makes a big difference compare to semi-crystalline drawn materials that typically exhibit lower cooperativity motions at the glass transition [5,14]. In this latter case, the decrease of cooperativity induced by the drawing should not be attributed to the induced orientation of the macromolecules but to the presence of crystallites confining the amorphous phase.…”

Section: Tablementioning

confidence: 98%

“…External hindrances are related to geometrical restrictions like the confinement between nanolayers [7,8] or the addition of additives such as fillers [9,10] or plasticizer [11]. On the other hand, internal hindrances are related to the materials itself, in other words its microstructural modifications such as spherulitic crystallization [12,13] or orientation/crystallization of the amorphous phase induced by drawing [5,14].…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics in electrospun amorphous plasticized polylactide fibers

Monnier

Delpouve

Basson

et al. 2015

Polymer

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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. The molecular dynamics in the amorphous phase of electrospun fibers of polylactide (PLA) has been investigated using the cooperative rearranging region concept. An unusual and significant increase of the cooperativity length at the glass transition induced by the electrospinning has been observed. This behavior is attributed to the singularity of the amorphous phase organization. Electrospun PLA fibers rearrange in a pre-ordered metastable state which is characterized by highly oriented but non-crystalline polymer chains, and the presence of highly cohesive mesophase which plays the role of an anchoring point in the amorphous phase. The successful processing of electrospun fibers of plasticized polylactide is also demonstrated. It is shown that the plasticizer remains in the polymer matrix of the nanofiber after electrospinning. When PLA is plasticized, the loosening of the macromolecules prevails over the preferential orientation of the chains; therefore no mesophase is formed during the electrospinning and the cooperativity length remains the same. When the content of plasticizer increases, the inter-chain characteristic distances estimated from wide angle X-ray scattering (WAXS) are redistributed, suggesting a change in the level of interactions between macromolecules. It is assumed that the resulting decrease of the cooperativity length is driven by the progressive reduction of the number of inter-chain weak bonds. It is shown that in a non-confined environment, the number of structural entities involved in the alpha relaxation is strongly dependent on the level of physical interactions in the amorphous phase.

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The characteristic length of cooperative rearranging region for uniaxial drawn poly(ethylene terephthalate) films

Cited by 18 publications

References 23 publications

Structural Dependence of the Molecular Mobility in the Amorphous Fractions of Polylactide

Structural Dependence of the Molecular Mobility in the Amorphous Fractions of Polylactide

Molecular mobility and physical ageing of plasticized poly(lactide)

Molecular dynamics in electrospun amorphous plasticized polylactide fibers

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