Shear effects on crystalline structures of poly(l-lactide)

Xiao, Peitao; Li, Hongfei; Huang, Shaoyong; Wen, Huiying; Yu, Donghong; Shang, Yingrui; Li, Jingqing; Wu, Zhonghua; An, Lijia; Jiang, Shichun

doi:10.1039/c3ce40466h

Cited by 14 publications

(18 citation statements)

References 49 publications

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“…The occurrence of a second order peak suggest that the crystalline repeat structure is well developed and highly ordered. Similar, observations were made by Xiao et al [62], however this was found during crystallization at 150 o C, post shear from the melt at high shear rates (20 -30 s -1 ). The PLLA samples when Td = 70 and 90 o C ( Figure 9B and C), show a similar trend in the development of the SAXS peak(s) from 90 o C, and again the emergence of the second order peak at higher annealing temperatures.…”

Section: Development Of Molecular Orientation Post-drawsupporting

confidence: 87%

An investigation into the crystalline morphology transitions in poly-L-lactic acid (PLLA) under uniaxial deformation in the quasi-solid-state regime

Billimoria

Heeley

Parsons

et al. 2018

European Polymer Journal

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A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.For more information, please contact the WRAP AbstractThe mechanical behaviour, crystalline and macromorphology structure development during uniaxial deformation and annealing of poly-L-lactic acid (PLLA), with varying strain rate and draw temperatures (Td) above Tg, have been investigated using small-and wide-angle Xray scattering (SAXS/WAXS), microscopy, thermal and mechanical techniques. The mechanical behaviour of PLLA, was strongly dependent on Td where embrittlement and eventual failure were observed as Td was increased, during uniaxial drawing of the amorphous polymer. This was mirrored in the bulk surface morphology where crazing, microvoiding and cavitation occurred with increasing Td. SAXS/WAXS data showed that strain-induced crystallization occurs on drawing, but crystallite orientation decreased with increasing Td, due to chain relaxation at temperatures ≥30 o C above Tg. However, no longrange oriented lamellar macromorphology was observed post-draw directly and only developed in the samples that were step annealed at temperatures above Td. Also, the disordered α' crystal form was observed post-draw at Td between 60 -80 o C, whereas Td ≥ 90 o C, resulted in the ordered α crystal form directly. However, on annealing at temperatures of ≥110 o C, the α'-α crystal transition ensued and in all samples, an oriented lamellar macromorphology developed. Therefore, Td and post-draw annealing, have a significant influence on the mechanical properties, crystallinity and crystalline phase transformation in PLLA, which in-turn, affects the polymers medical and industrial applications.

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Section: Development Of Molecular Orientation Post-drawsupporting

confidence: 87%

An investigation into the crystalline morphology transitions in poly-L-lactic acid (PLLA) under uniaxial deformation in the quasi-solid-state regime

Billimoria

Heeley

Parsons

et al. 2018

European Polymer Journal

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“…To understand the crystallization behaviors and crystallization mechanism of polymers, a crystallization theory of Hoffman-Lauritzen with the popular expression given by eqn (1) has been developed and widely used to describe the temperature dependence of the growth rate u near the melting temperature. 12 Within such a temperature range, the growth rates are considered to be controlled by an activation step.…”

Section: Introductionmentioning

confidence: 99%

Crystalline structures and crystallization behaviors of poly(l-lactide) in poly(l-lactide)/graphene nanosheet composites

Xiao

et al. 2015

Polym. Chem.

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“…When the shear rate exceeded 50 s À1 , the orientation stayed nearly the same. As reported by Xiao [34], the orientation of a crystals was hardly observed for neat PLLA sheared at temperatures higher than 175 C (20 s À1 , 5 s). In our case, the orientation may have two possible origins.…”

Section: In-situ Waxs Under Different Shear Ratesmentioning

confidence: 64%

“…The final SC content with shearing at 150 C was almost twice of that at 200 C. The change of nucleation density and the SC content with shear temperatures can be interpreted in terms of the competition between shear-induced orientation and relaxation at different temperatures. The shear-induced crystallization depends not only on the shear rate but also on the shear temperature [30,34,47]. The relationship between the supercooling degree and the shear-induced crystallization has been studied.…”

Section: Effect Of Shear Temperaturementioning

confidence: 99%

Enhancement of stereocomplex formation in poly(l-lactide)/poly(d-lactide) mixture by shear

Song

Zhang

Yin

et al. 2015

Polymer

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Shear effects on crystalline structures of poly(l-lactide)

Cited by 14 publications

References 49 publications

An investigation into the crystalline morphology transitions in poly-L-lactic acid (PLLA) under uniaxial deformation in the quasi-solid-state regime

An investigation into the crystalline morphology transitions in poly-L-lactic acid (PLLA) under uniaxial deformation in the quasi-solid-state regime

Crystalline structures and crystallization behaviors of poly(l-lactide) in poly(l-lactide)/graphene nanosheet composites

Enhancement of stereocomplex formation in poly(l-lactide)/poly(d-lactide) mixture by shear

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