In-situ SAXS study of the plastic deformation behavior of polylactide upon cold-drawing

Stoclet, Grégory; Lefebvre, Jean‐Marc; Séguéla, Roland; Vanmansart, Claude

doi:10.1016/j.polymer.2014.02.010

Cited by 62 publications

(77 citation statements)

References 49 publications

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“…Engineering stress-strain curves and selected 2D SAXS and WAXS patterns collected during the uniaxial tensile deformation of PLA at 50 and 60°C are illustrated in Fig. 49 Moreover, both streaks are normal to each other, similar to the characteristic of shear banding of amorphous polymers during cold drawing. Both the SAXS and WAXS patterns of the undrawn PLA samples are isotropic, proving that there are no oriented structures in the undrawn samples.…”

Section: In Situ Saxs and Waxs Analysis Of Pla Stretched At Differentmentioning

confidence: 79%

“…3. 49 Therefore, we are convinced that these streaks originated from the scattering of sheared voids inclined to the draw direction. When the sample was subjected to stretching at 50°C, a strong streak in the SAXS pattern inclined to the draw axis with an angle of about 30°firstly appeared before the yield point, as shown in Fig.…”

Section: In Situ Saxs and Waxs Analysis Of Pla Stretched At Differentmentioning

confidence: 83%

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Deformation and structure evolution of glassy poly(lactic acid) below the glass transition temperature

Zhou

Zhang

et al. 2015

CrystEngComm

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Poly(lactic acid) (PLA) is a bio-based and compostable thermoplastic polyester that has rapidly evolved into a competitive commodity material over the last decade. One key bottleneck in expanding the field of application of PLA is the control of its structure and properties. Therefore, in situ investigations under cooling are necessary for understanding the relationship between them. The most intriguing feature of a supercooled liquid is its dramatic rise in viscosity as it is cooled toward the glass transition temperature (T g ) though accompanied by very little change in the structural features observable by typical X-ray experiments. The deformation behaviors and structure evolution of glassy PLA during uniaxially stretching below T g were investigated in situ by synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques. The stretched samples were measured by differential scanning calorimetry (DSC). The obtained results showed that the deformation and yield stress of glassy PLA are strongly dependent on the stretching temperatures together with the transition from mesophase to mesocrystal and the formation of cavities. With the increase in drawing temperature, the onset of the mesocrystal formation is delayed to a higher strain value, whereas corresponding to the same critical orientation degree of amorphous chains (f am ≈ 0.45). The DSC results indicated that the post-T g endothermic peak corresponding to the melting of mesocrystal appears and shifts to a higher temperature with increasing stretching temperature, followed by the down-shifts (to a lower temperature) of the exothermic peak of cold crystallization of PLA. The appearance of a small exothermic peak just before the melting peak related to the transition of the α′ to α crystal implies the formation of an α′ crystal during cold crystallization in the drawn PLA samples. The structure evolution of glassy PLA stretched below T g was discussed in details.

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Section: In Situ Saxs and Waxs Analysis Of Pla Stretched At Differentmentioning

confidence: 79%

Section: In Situ Saxs and Waxs Analysis Of Pla Stretched At Differentmentioning

confidence: 83%

Deformation and structure evolution of glassy poly(lactic acid) below the glass transition temperature

Zhou

Zhang

et al. 2015

CrystEngComm

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“…From the literature, rubber-toughening of polymers is extensively described based on toughening and fracture mechanisms, as called crazing, shear yielding, cavitation or debonding. [52][53][54][55][56] In this respect, Stoclet et al 57 characterized the complex plastic deformation behavior exhibited by PLA, considering both the elementary mechanisms and the drawing kinetics. As expected, the crazing mechanism is responsible for the brittle character of PLA.…”

Section: Discussionmentioning

confidence: 99%

Mechanistic insights on nanosilica self-networking inducing ultra-toughness of rubber-modified polylactide-based materials

et al. 2015

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“…In the case of semicrystalline PLA, deformation was controlled by chain orientation mechanisms engendering a progressive transformation of the lamella morphology into microfibrills . Later, Stoclet et al reported new fundamental insights on the plastic deformation mechanisms of amorphous and semicrystalline PLA. In the case of amorphous PLA, WAXS investigation showed that drawing above glass transition temperature ( T g ) involved an orientation of amorphous chains leading to a mesomorphic phase and/or a strain‐induced α′ crystalline phase, depending on the drawing temperature .…”

Section: Introductionmentioning

confidence: 99%

In situ multiscale study of deformation heterogeneities in polylactide‐based materials upon drawing: Influence of initial crystallinity and plasticization

Brüster

Martin

Bardon

et al. 2018

J Polym Sci B Polym Phys

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This work aims at identifying defects called deformation heterogeneities developing in polylactide (PLA)‐based materials upon drawing at room temperature. The influence of the initial crystallinity and of the plasticization methodology (physical blending vs. reactive blending) on the type of defect is also investigated. Defects are characterized in situ by (a) calculating the volume strain from digital image correlation (DIC), (b) measuring their surface density from optical microscopy, and (c) assessing their scattering invariant from small‐angle X‐ray scattering. Complementary structural analyses are done by microcomputed X‐ray tomography and atomic force microscopy. Drawing is accompanied by crazing in the case of low‐crystalline PLA, cracking in the case of annealed PLA, no defect in the case of plasticized PLA by physical blending, and shear bands and cracking in the case of plasticized PLA by reactive blending. These observations are discussed based on the initial structural features of the materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1452–1468

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In-situ SAXS study of the plastic deformation behavior of polylactide upon cold-drawing

Cited by 62 publications

References 49 publications

Deformation and structure evolution of glassy poly(lactic acid) below the glass transition temperature

Deformation and structure evolution of glassy poly(lactic acid) below the glass transition temperature

Mechanistic insights on nanosilica self-networking inducing ultra-toughness of rubber-modified polylactide-based materials

In situ multiscale study of deformation heterogeneities in polylactide‐based materials upon drawing: Influence of initial crystallinity and plasticization

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