Deformation of Poly-l-lactid acid (PLLA) under Uniaxial Tension and Plane-Strain Compression

Vozniak, Alina; Bartczak, Z.

doi:10.3390/polym13244432

Cited by 5 publications

(2 citation statements)

References 59 publications

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“…While PLLA has a high compressive and tensile strength, it is brittle and not amenable to deformation and recovery at the macro (defect), micro (pore), and nano (nanofiber) scales ( 13 ). Various groups have described curable resin materials injected into a defect and then polymerized in situ within the defect site ( 14 , 15 ).…”

Section: Introductionmentioning

confidence: 99%

Temperature-responsive PCL-PLLA nanofibrous tissue engineering scaffolds with memorized porous microstructure recovery

Woodbury,

Swanson,

Douglas

et al. 2023

Front. Dent. Med

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Biomaterial scaffolds in tissue engineering facilitate tissue regeneration and integration with the host. Poor healing outcomes arise from lack of cell and tissue infiltration, and ill-fitting interfaces between matrices or grafts, resulting in fibrous tissue formation, inflammation, and resorption. Existing tissue engineering scaffolds struggle to recover from deformation to fit irregularly shaped defects encountered in clinical settings without compromising their mechanical properties and favorable internal architecture. This study introduces a synthetic biomaterial scaffold composed of high molecular weight poly (L-lactic acid) (PLLA) and an interpenetrating network of poly (ε-caprolactone) (PCL), in a composition aiming to address the need for conformal fitting synthetic matrices which retain and recover their advantageous morphologies. The scaffold, known as thermosensitive memorized microstructure (TS-MMS), forms nanofibrous materials with memorized microstructures capable of recovery after deformation, including macropores and nanofibers. TS-MMS nanofibers, with 50–500 nm diameters, are formed via thermally induced phase separation (TIPS) of PLLA after in situ polymerization of PCL-diacrylate. A critical partial-melting temperature of TS-MMS at 52°C enables bulk deformation above this temperature, while retaining the nanofibrous and macroporous structures upon cooling to 37°C. Incorporation of drug-loaded poly (lactide-co-glycolide) (PLGA) nanoparticles directly into TS-MMS nanofibers during fabrication allows sustained release of a model drug for up to 40 days. Subcutaneous implantation in vivo using LysM-Cre;td-Tomato; Col1eGFP mice demonstrates successful cellularization and integration of deformed/recovered TS-MMS materials, surpassing the limitations of deformed PLLA scaffolds, to facilitate cell and vasculature infiltration requisite for successful bone regeneration. Additionally we demonstrated a method for embedding controlled release vehicles directly into the scaffold nanofibers; controlled release of simvastatin enhances vascularization and tissue maturation. TS-MMS scaffolds offer promising improvements in clinical handling and performance compared to existing biomaterial scaffolds.

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Section: Introductionmentioning

confidence: 99%

Temperature-responsive PCL-PLLA nanofibrous tissue engineering scaffolds with memorized porous microstructure recovery

Woodbury,

Swanson,

Douglas

et al. 2023

Front. Dent. Med

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“…For this reason, many researchers have focused on approaches to increase the toughness of PLA such as plasticization, copolymerization, blending with other tough polymers, and adding elastomers [ 3 ]. Nonetheless, different opinions have emerged on the definitions and testing methods for toughness [ 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

The Use of Various Measurement Methods for Estimating the Fracture Energy of PLA (Polylactic Acid)

Gao

Drozdov

2022

Materials

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The essential work of fracture (EWF) and Izod/Charpy impact tests have been used to investigate the fracture toughness in the plane stress of brittle polymers. In this paper, we had three goals: first, we aimed to employ how to estimate PLA toughness in different geometries; then, we proposed to compare Izod and Charpy Impact toughness in the same geometry; finally, we intended to determine the difference between EWF toughness and dynamic toughness. The results showed that the EWF method could be applied to evaluate PLA fracture behavior with small ligaments (2–4 mm), while the dynamic test could be employed with larger ligaments (5–7 mm). A comparison of the two impact test results obtained the following conclusions: Charpy impact toughness was higher than Izod impact toughness in the same geometry, and the impact toughness under a notch angle of 90° was larger than that of an angle of 45°. Both EWF and dynamic tests can be used to explore PLA toughness with small ligaments. The fracture energy decreases with ligament size in the EWF test, but it increases in the dynamic test.

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Crystal Evolution of Amorphous Poly(lactic acid) During Simultaneous Multi‐step Tensile Deformation and Annealing

Kajornprai,

Sringam,

Seejuntuek

et al. 2024

Journal of Polymer Science

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The cold‐crystallization and crystal evolution of amorphous poly(lactic acid) (PLA) are analyzed during multistep tensile deformation and annealing at 70°C using in situ synchrotron wide‐angle X‐ray scattering (WAXS) measurements. The 2D‐WAXS diffraction pattern reveals that the PLA crystalline structure forms perpendicular to the draw direction. The annealing process lets to a rearrangement of the crystalline structure, while the stretching causes crystal contraction. Both WAXS and FTIR analyses confirm that the crystals developed through stretching and annealing are in the α′‐form. The crystallinity of PLA increases with higher deformation strains and longer annealing times. The orientation degree of both crystalline and amorphous phases of PLA, as indicated by the Hermans orientation factor and dichroic ratio of 956 cm−1 band (evaluated by WAXS and polarized FTIR analysis, respectively) also increase. The enhanced cold‐crystallization ability of PLA is attributed to the synergistic effect of tensile deformation and annealing, rather than either technique alone. The unusual crystallization phenomenon observed during multistep tensile deformation coupled with annealing provides valuable insights into the crystallization and crystal evolution of PLA.

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Deformation of Poly-l-lactid acid (PLLA) under Uniaxial Tension and Plane-Strain Compression

Cited by 5 publications

References 59 publications

Temperature-responsive PCL-PLLA nanofibrous tissue engineering scaffolds with memorized porous microstructure recovery

Temperature-responsive PCL-PLLA nanofibrous tissue engineering scaffolds with memorized porous microstructure recovery

The Use of Various Measurement Methods for Estimating the Fracture Energy of PLA (Polylactic Acid)

Crystal Evolution of Amorphous Poly(lactic acid) During Simultaneous Multi‐step Tensile Deformation and Annealing

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