1
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Zhang Y, Dong X, Zhang C, Wu X, Cheng J, Wu G, Sun R, Ni Z, Zhao G. Strengthen oriented poly (L-lactic acid) monofilaments via mechanical training. Int J Biol Macromol 2024; 263:129975. [PMID: 38418283 DOI: 10.1016/j.ijbiomac.2024.129975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 01/22/2024] [Accepted: 02/02/2024] [Indexed: 03/01/2024]
Abstract
Polymer materials have found extensive applications in the clinical and medical domains due to their exceptional biocompatibility and biodegradability. Compared to metallic counterparts, polymers, particularly Poly (L-lactic acid) (PLLA), are more suitable for fabricating biodegradable stents. As a viscoelastic material, PLLA monofilaments exhibit a creep phenomenon under sustained tensile stress. This study explores the use of creep to enhance the mechanical attributes of PLLA monofilaments. By subjecting the highly oriented monofilaments to controlled, constant force stretching, we achieved notable improvements in their mechanical characteristics. The results, as confirmed by tensile testing and dynamic mechanical analysis, revealed a remarkable 67 % increase in total elongation and over a 20 % rise in storage modulus post-mechanical training. Further microscopic analyses, including Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), revealed enhanced spacing and cavity formation. These mechanical advancements are attributed to the unraveling and a more orderly arrangement of molecular chains in the amorphous regions. This investigation offers a promising approach for augmenting the mechanical properties of PLLA monofilaments, potentially benefiting their application in biomedical engineering.
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Affiliation(s)
- Yan Zhang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Xuechun Dong
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Chen Zhang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Xiongyu Wu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Jie Cheng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Renhua Sun
- Department of Cardiology, Yancheng First Hospital, Affiliated Hospital of Nangjing University Medical School, Yancheng 224006, China
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
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2
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Chen Y, Yang W, Hu Z, Gao X, Ye J, Song X, Chen B, Li Z. Bionic structure and biocompatibilities of long chain branched poly(L-lactic acid) oriented microcellular foaming material. Int J Biol Macromol 2024; 263:130467. [PMID: 38423433 DOI: 10.1016/j.ijbiomac.2024.130467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/18/2024] [Accepted: 02/24/2024] [Indexed: 03/02/2024]
Abstract
In order to solve the problem of uneven microporous structure of Poly(L-lactic acid) (PLLA) bulk orientation by using biological safety multi-functional plant oil as chain extenders (CE), multi-armed flexible chains were introduced into PLLA through reactive processing to prepare long chain branched PLLA (LCB-PLLA). When the total content of the CE was 6.15 wt%, PLLA and the CE reacted most fully, while maintaining the tensile strength of PLLA and improving toughness. After introducing the LCB structure, the presence of multi-armed flexible chains increased the mobility of the molecular chains, resulting in a significantly lower degree of crystallinity. When the draw ratio up to 900 %, the crystallinity of LCB-PLLA-F-900 % was only 45.15 %, lower than that of PLLA-F-900 %. Thanks to the mobility of polymer chains can be enhanced, which reduces the degree of crystallinity while promoting the uniform growth of oriented microporous structures. Finally, an oriented micro-porous biomimetic LCB-PLLA material with an average cell diameter of 540 nm was prepared, and the results of in vitro cell culture showed that the oriented micro-porous LCB-PLLA biomimetic material was more conducive to cell proliferation.
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Affiliation(s)
- Yueling Chen
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Wenchao Yang
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Zikang Hu
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Xiaoyan Gao
- Sichuan Institute for Drug Control, Chengdu 610017, China
| | - Jingbiao Ye
- Hengdian Group TOSPO Engineering Plastics, Co., Ltd, Dongyang 322100, China
| | - Xiangqian Song
- Hengdian Group TOSPO Engineering Plastics, Co., Ltd, Dongyang 322100, China
| | - Baoshu Chen
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Zhengqiu Li
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China.
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3
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Mastalygina EE, Aleksanyan KV. Recent Approaches to the Plasticization of Poly(lactic Acid) (PLA) (A Review). Polymers (Basel) 2023; 16:87. [PMID: 38201752 PMCID: PMC10781029 DOI: 10.3390/polym16010087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Poly(lactic acid) (PLA) is a polyester attracting growing interest every year in different application fields, such as packaging, cosmetics, food, medicine, etc. Despite its significant advantages, it has low elasticity that may hinder further development and a corresponding rise in volume of consumption. This review opens a discussion of basic approaches to PLA plasticization. These considerations include copolymerization and blending with flexible polymers, introducing oligomers and low-molecular additives, as well as structural modification. It was demonstrated that each approach has its advantages, such as simplicity and low cost, but with disadvantages, including complex processing and the need for additional reagents. According to the analysis of different approaches, it was concluded that the optimal option is the application of copolymers as the additives obtained via reactive mixing to PLA and its blends with other polymers.
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Affiliation(s)
- Elena E. Mastalygina
- Scientific Laboratory “Advanced Composite Materials and Technologies”, Plekhanov Russian University of Economics, 36 Stremyanny Ln., Moscow 117997, Russia
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygin St., Moscow 119991, Russia
| | - Kristine V. Aleksanyan
- Engineering Center, Plekhanov Russian University of Economics, 36 Stremyanny Ln., Moscow 117997, Russia
- Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 4 Kosygin St, Moscow 119991, Russia
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4
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Liu J, Wang B, Liu W, Hu X, Zhang C, Zhou Z, Lang J, Wu G, Zhang Y, Yang J, Ni Z, Zhao G. Regulating mechanical performance of poly (l-lactide acid) stent by the combined effects of heat and aqueous media. Int J Biol Macromol 2023:124987. [PMID: 37236565 DOI: 10.1016/j.ijbiomac.2023.124987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/08/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023]
Abstract
Annealing process has been applied to the development of thermoforming polymer braided stent and treating its basic constitute monofilaments, especially for Poly (l-lactide acid) (PLLA) condensed by lactic acid monomer made from the plant starch. In this work, high performance monofilaments were produced by melting spun and solid-state drawing methods. Inspired by the effects of water plasticization on semi-crystal polymer, PLLA monofilaments were annealed with and without constraint in vacuum and aqueous media. Then, the co-effects of water infestation and heat on the micro-structure and mechanical properties of these filaments were characterized. Furtherly, mechanical performance of PLLA braided stents shaped by different annealing methods was also compared. Results showed that annealing in aqueous media generated more obvious structure change of PLLA filaments. Interestingly, the combined effects of aqueous phase and thermal effectively increased the crystallinity, and decreased the molecular weight and orientation of PLLA filaments. Therefore, higher modulus, smaller strength, and elongation at the break for filaments could be obtained, which could furtherly realize better radial compression resistance of the braided stent. This annealing strategy could provide new perspectives between anneal and material properties of PLLA monofilaments, and provide more suitable manufacturing technics for polymer braided stent.
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Affiliation(s)
- Jinbo Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Bin Wang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Wentao Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Xue Hu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Chen Zhang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Zhiyuan Zhou
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Ji Lang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing, China
| | - Yi Zhang
- Center of Interventional Radiology & Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, Nanjing 210044, China
| | - Juekuan Yang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
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5
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A hazardous boundary of Poly(L-lactic acid) braided stent design: Limited elastic deformability of polymer materials. J Mech Behav Biomed Mater 2023; 138:105628. [PMID: 36543082 DOI: 10.1016/j.jmbbm.2022.105628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Poly (L-lactic acid) (PLLA) braided stents, which are expected to replace metal stents, are promising in peripheral vascular therapy due to their superior biocompatibility. Although various design ideas have been proposed and investigated on metal stents, few researches are related to the design theory of PLLA braided stent. In this article, mechanical performance of PLLA braided stents with different parameters was systematically evaluated, and a design theory based on material properties was proposed. Different from metal materials, the risk of filament deformation beyond elastic zone should be evaluated and controlled in PLLA stent design. The findings were obtained through combination study of experiments and simulations. Design parameters, including pitch angle and stent diameter, played a crucial role in mechanical performance of PLLA braided stent. The deformation of PLLA stents with larger pitch angles and stent diameters was in elastic zone and thus presented better mechanical performance with satisfactory resilience. This work could provide meaningful suggestions for preparing bioresorbable braided stents with suitable design parameters.
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6
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Yang W, Wu T, Chen Y, Huang Q, Ao J, Ming M, Gao X, Li Z, Chen B. Bionic structure and blood compatibility of highly oriented homo-epitaxially crystallized poly(l-lactic acid). Int J Biol Macromol 2023; 227:749-761. [PMID: 36563816 DOI: 10.1016/j.ijbiomac.2022.12.192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 12/09/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
A highly oriented poly(l-lactic acid) (PLLA), with a blood vessel-like biomimetic structure, was fabricated using solid-phase hot drawing technology and homo-epitaxial crystallization to improve the mechanical properties and biocompatibility of PLLA. Long chain branched PLLA (LCB-PLLA) was prepared through a two-step ring-opening reaction, and a consequent draw as high as 1000 % was achieved during the hot drawing. The modulus and tensile strength were found to have increased through the formation of oriented shish-kebab like crystals along the drawing direction during processing. Furthermore, PLLA nano-lamellae were formed on the surface of the oriented plates via the introduction of homo-epitaxial crystallization. The high degree of orientation and epitaxial crystallization substantially enhanced the biocompatibility of the PLLA by prolonging clotting time, decreasing the rate of hemolysis, and increasing the cell growth and reproduction of the osteoblasts.
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Affiliation(s)
- Wenchao Yang
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Ting Wu
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Yueling Chen
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Qingyi Huang
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Jinqing Ao
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China
| | - Mei Ming
- Dechang Jinfeng Rubber Co., Ltd., Dechang County, 615500, China
| | - Xiaoyan Gao
- Sichuan Institute for Drug Control, Chengdu 610017, China
| | - Zhengqiu Li
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China.
| | - Baoshu Chen
- School of Material Science and Engineering of Xihua University, Chengdu 610039, China.
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7
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Mechanical and barrier properties of simultaneous biaxially stretched polylactic acid/thermoplastic starch/poly(butylene adipate-co-terephthalate) films. Polym Bull (Berl) 2022. [DOI: 10.1007/s00289-022-04312-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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8
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Modeling of polymorphic composition development during isothermal crystallization of poly(l-lactide acid). POLYMER 2022. [DOI: 10.1016/j.polymer.2022.124618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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9
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Vozniak A, Bartczak Z. Deformation of Poly-l-lactid acid (PLLA) under Uniaxial Tension and Plane-Strain Compression. Polymers (Basel) 2021; 13:4432. [PMID: 34960984 PMCID: PMC8708863 DOI: 10.3390/polym13244432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/10/2021] [Accepted: 12/14/2021] [Indexed: 11/16/2022] Open
Abstract
The ability of PLLA, either amorphous or semicrystalline, to plastic deformation to large strain was investigated in a wide temperature range (Td = 70-140 °C). Active deformation mechanisms have been identified and compared for two different deformation modes-uniaxial drawing and plane-strain compression. The initially amorphous PLLA was capable of significant deformation in both tension and plane-strain compression. In contrast, the samples of crystallized PLLA were found brittle in tensile, whereas they proved to be ductile and capable of high-strain deformation when deformed in plane-strain compression. The main deformation mechanism identified in amorphous PLLA was the orientation of chains due to plastic flow, followed by strain-induced crystallization occurring at the true strain above e = 0.5. The oriented chains in amorphous phase were then transformed into oriented mesophase and/or oriented crystals. An upper temperature limit for mesophase formation was found below Td = 90 °C. The amount of mesophase formed in this process did not exceed 5 wt.%. An additional mesophase fraction was generated at high strains from crystals damaged by severe deformation. After the formation of the crystalline phase, further deformation followed the mechanisms characteristic for the semicrystalline polymer. Interlamellar slip supported by crystallographic chain slip has been identified as the major deformation mechanism in semicrystalline PLLA. It was found that the contribution of crystallographic slip increased notably with the increase in the deformation temperature. The most probable active crystallographic slip systems were (010)[001], (100)[001] or (110)[001] slip systems operating along the chain direction. At high temperatures (Td = 115-140 °C), the α→β crystal transformation was additionally observed, leading to the formation of a small fraction of β crystals.
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Affiliation(s)
| | - Zbigniew Bartczak
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź, Poland;
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10
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Li Z, Wu T, Chen Y, Gao X, Ye J, Jin Y, Chen B. Oriented homo-epitaxial crystallization of polylactic acid displaying a biomimetic structure and improved blood compatibility. J Biomed Mater Res A 2021; 110:684-695. [PMID: 34651453 DOI: 10.1002/jbm.a.37322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 09/23/2021] [Accepted: 10/06/2021] [Indexed: 11/06/2022]
Abstract
Epitaxial crystallization and solid hot-drawing technology were employed to fabricate oriented homo-epitaxial crystallization of polylactic acid (PLA) with nano-topography to enhance its blood compatibility and mechanical characteristics as blood-contacting medical devices. The process involved solid hot stretching the PLA plates. A PLA nutrient solution was then used to immerse the oriented plates to dissolve some of the PLA solutes, ensuring plate integrity. Consequently, the drawing process exponentially enhanced the modulus and tensile strength of the PLA. Orientation and epitaxial crystallization could substantially enhance blood compatibility of PLA by prolonging clotting time and decreasing hemolysis rate, protein adsorption, and platelet activation. The oriented homo-epitaxial crystallization of PLA exhibited a nano-topography and fibrous structure similar to the intimal layer of a blood vessel, and this biomimetic structure was advantageous in decreasing the activation and/or adhesion of platelets.
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Affiliation(s)
- Zhengqiu Li
- School of Material Science and Engineering, Xihua University, Chengdu, China
| | - Ting Wu
- School of Material Science and Engineering, Xihua University, Chengdu, China
| | - Yueling Chen
- School of Material Science and Engineering, Xihua University, Chengdu, China
| | - Xiaoyan Gao
- Institute of Passive Medical Device Testing, Sichuan Institute for Drug Control, Chengdu, China
| | - Jingbiao Ye
- Research and Development Department, Hengdian Group TOSPO Engineering Plastics, Co., Ltd, Dongyang, China
| | - Ying Jin
- Research and Development Department, Hengdian Group TOSPO Engineering Plastics, Co., Ltd, Dongyang, China
| | - Baoshu Chen
- School of Material Science and Engineering, Xihua University, Chengdu, China
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11
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Li X, Tian Y, Zhang J, Cheng J, Wu G, Zhang Y, Zhao G, Ni Z. Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5266] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Xin Li
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Yuan Tian
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Jing Zhang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Jie Cheng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering Nanjing Forestry University Nanjing China
| | - Yi Zhang
- Center of Interventional Radiology & Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School Southeast University Nanjing China
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
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12
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Zheng Y, Pan P. Crystallization of biodegradable and biobased polyesters: Polymorphism, cocrystallization, and structure-property relationship. Prog Polym Sci 2020. [DOI: 10.1016/j.progpolymsci.2020.101291] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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13
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Aliotta L, Gazzano M, Lazzeri A, Righetti MC. Constrained Amorphous Interphase in Poly(l-lactic acid): Estimation of the Tensile Elastic Modulus. ACS OMEGA 2020; 5:20890-20902. [PMID: 32875224 PMCID: PMC7450648 DOI: 10.1021/acsomega.0c02330] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
The mechanical properties of semicrystalline PLLA containing exclusively α'- or α-crystals have been investigated. The connection between experimental elastic moduli and phase composition has been analyzed as a function of the polymorphic crystalline form. For a complete interpretation of the mechanical properties, the contribution of the crystalline regions and the constrained amorphous interphase or rigid amorphous fraction (RAF) has been quantified by a three-phase mechanical model. The mathematical approach allowed the simultaneous quantification of the elastic moduli of (i) the α'- and α-phases (11.2 and 14.8 GPa, respectively, in excellent agreement with experimental and theoretical data reported in the literature) and (ii) the rigid amorphous fractions linked to the α'- and α-forms (5.4 and 6.1 GPa, respectively). In parallel, the densities of the RAF connected with α'- and α-crystals have been measured (1.17 and 1.11 g/cm3, respectively). The slightly higher value of the elastic modulus of the RAF connected to the α-crystals and its lower density have been associated to a stronger chain coupling at the amorphous/crystal interface. Thus, the elastic moduli at T room of the crystalline (E C), mobile amorphous (E MAF), and rigid amorphous (E RAF) fractions of PLLA turned out to be quantitatively in the order of E MAF < E RAF < E C, with the experimental E MAF value equal to 3.6 GPa. These findings can allow a better tailoring of the properties of PLLA materials in relation to specific applications.
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Affiliation(s)
- Laura Aliotta
- Department
of Civil and Industrial Engineering, University
of Pisa, Largo L. Lazzarino 1, Pisa 56122, Italy
| | - Massimo Gazzano
- CNR-ISOF,
National Research Council−Institute of Organic Synthesis and
Photoreactivity, Via P. Gobetti 101, Bologna 40129, Italy
| | - Andrea Lazzeri
- Department
of Civil and Industrial Engineering, University
of Pisa, Largo L. Lazzarino 1, Pisa 56122, Italy
- CNR-IPCF,
National Research Council−Institute for Chemical and Physical
Processes, Via G. Moruzzi
1, Pisa 56124, Italy
| | - Maria Cristina Righetti
- CNR-IPCF,
National Research Council−Institute for Chemical and Physical
Processes, Via G. Moruzzi
1, Pisa 56124, Italy
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14
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Heeley EL, Billimoria K, Parsons N, Figiel Ł, Keating EM, Cafolla CT, Crabb EM, Hughes DJ. In-situ uniaxial drawing of poly-L-lactic acid (PLLA): Following the crystalline morphology development using time-resolved SAXS/WAXS. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Glagolev MK, Vasilevskaya VV. Coarse-grained simulation of molecular ordering in polylactic blends under uniaxial strain. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122232] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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16
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Liu Y, Cao H, Ye L, Coates P, Caton-Rose F, Zhao X. Long-Chain Branched Poly(lactic acid)-b-poly(lactide-co-caprolactone): Structure, Viscoelastic Behavior, and Triple-Shape Memory Effect as Smart Bone Fixation Material. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.9b06514] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Yalong Liu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Huijie Cao
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Lin Ye
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Phil Coates
- School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K
| | - Fin Caton-Rose
- School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K
| | - Xiaowen Zhao
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
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