1
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Zheng G, Han L, Zheng B, Bian J, Zhao Y, Pan H, Wang M, Zhang H. Enhanced strength, toughness and heat resistance of poly (lactic acid) with good transparency and biodegradability by uniaxial pre-stretching. Int J Biol Macromol 2024; 278:135222. [PMID: 39256127 DOI: 10.1016/j.ijbiomac.2024.135222] [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: 01/02/2024] [Revised: 07/20/2024] [Accepted: 08/29/2024] [Indexed: 09/12/2024]
Abstract
Sustainable poly (lactic acid) (PLA) with excellent strength, toughness, heat resistance, transparency, and biodegradability was achieved by uniaxial pre-stretching at 70 °C. The effect of pre-stretched ratio (PSR) on the microstructure and properties of the PLA was investigated. The undrawn PLA was brittle. However, after pre-stretching, the elongation at break was increased significantly. The maximum value of 161.2 % was obtained at pre-stretching ratio (PSR) of 1.0. With the increase of PSR, the modulus and strength were improved obviously (from 1601 MPa and 60.2 MPa for undrawn PLA to 2932 MPa and 106.3 MPa for the ps-PLA at PSR =3.0). Meanwhile, the heat resistance of PLA was improved obviously with the increase of PSR. For the ps-PLA3.0, there were almost no deformation and shrink at 140 °C. Interestingly, after pre-stretching, the PLA still maintained the good transparency and biodegradability. The brittleness for undrawn PLA was attributed to the network structure of cohesional entanglements. After pre-stretching, the destruction of the network structure and formation of the orientation, mesophase and oriented nanosized crystalline phase lead to the increased the toughness, strength and heat resistance without sacrificing the transparency and biodegradability. This work provides a significant guidance for the fabrication of PLA material with excellent comprehensive performance including strength, toughness, heat resistance, transparency, and biodegradability.
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Affiliation(s)
- Gaofei Zheng
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Lijing Han
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; School of Intelligent Manufacturing and Materials Engineering, Gannan University of science and technology, Ganzhou 341000, China.
| | - Bihuang Zheng
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Junjia Bian
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Yan Zhao
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Hongwei Pan
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Mingyu Wang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Huiliang Zhang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China; School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China
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2
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Liao Y, Lan Q. Understanding the Impact of Chain Mobility on Conformational Evolution and Kinetics of Mesophase Formation in Poly(ʟ-lactide) under Low-Pressure CO 2. Polymers (Basel) 2024; 16:1378. [PMID: 38794571 PMCID: PMC11124961 DOI: 10.3390/polym16101378] [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: 04/21/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Although the mesomorphic phase as an intermediate state has been introduced to understand polymer crystallization, the understanding of the mesomorphic phase is far from complete. Here, the effect of chain mobility on the mesophase structuring in melt-quenched poly(ʟ-lactide) (PLLA) treated in low-pressure CO2 at 1.6-2.0 MPa and 0 °C was investigated using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and atomic force microscopy (AFM). The IR and AFM results demonstrated that the final degree of order and the kinetics of structural evolution during the CO2-induced mesophase formation were critically dependent on the CO2 pressure. This was attributed to the distinct dynamics of conformational evolution (gg to gt conformer transition) due to the different CO2 pressures. The thermal behavior from the DSC results showed that CO2 pressure dominated both the scale and dynamics of the chain motion of PLLA. At a lower CO2 pressure of 1.6 MPa, smaller-scale segmental motion was not replaced by the larger-scale cooperative motion that occurred at a relatively higher CO2 pressure of 2 MPa, which was favorable for faster mesophase formation. Consequently, by inhibiting direct crystallization under limited mobility conditions, it was demonstrated that different chain mobility controlled by CO2 pressure and thus CO2 solubility impacted the dynamics of the mesophase formation of PLLA. The present results have implications for understanding the role of chain mobility in determining the intermediate structural phases in semicrystalline polymers.
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Affiliation(s)
| | - Qiaofeng Lan
- Biomaterials Research Center, School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China;
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3
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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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4
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Liu S, Chen W, Xiao L, Zhao Z, Liu F, Lu S, Chen C, Luo W, Jiang L, Li Y. Robust Osteoconductive β-Tricalcium Phosphate/L-poly(lactic acid) Membrane via Orientation-Strengthening Technology. ACS Biomater Sci Eng 2023; 9:5293-5303. [PMID: 37606611 DOI: 10.1021/acsbiomaterials.3c00617] [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] [Indexed: 08/23/2023]
Abstract
L-poly(lactic acid) (PLLA) is a biodegradable material with multiple biomedical application potentials, especially as a membrane for guided bone regeneration. In terms of its low strength and poor osteogenic activity, improving these two properties is the key to resolve the limitations of PLLA for bone-associated applications. Herein, an orientation-strengthening technology (OST) was developed to reinforce PLLA's mechanical strength by introducing biocompatible β-tricalcium phosphate (β-TCP) to improve the crystallinity of PLLA, allowing for the formation of a highly oriented architecture to acquire an advanced membrane with high mechanical property. Furthermore, the addition of β-TCP nanoparticles significantly promotes the osteogenic activity of the composites. The tensile strength of the membrane containing 5 wt % β-TCP was 220 MPa, which was 4-folds that of the native polylactic acid fabricated via the conventional method. The oriented microstructure enhanced both the mechanical strength and the osteogenic activity of the material. The parallel grooves on the material surface are similar to the mineralized collagen fibers on the bone surface, which promoted the growth and differentiation of osteoblasts, with β-TCP further contributing to the osteoconductive effect. The combination of β-TCP and orientation-strengthening effect endows the material with higher mechanical properties and bioactivities, which provides an advanced manufacturing strategy for the preparation of PLLA-based materials for bone repair.
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Affiliation(s)
- Shengyang Liu
- Engineering Research Center for Biomedical Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Material Science & Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Weisin Chen
- Department of Orthopaedics, Zhongshan Hospital Fudan University, Shanghai 200032, China
| | - Lan Xiao
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane 4059, Australia
| | - Zheng Zhao
- Engineering Research Center for Biomedical Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Material Science & Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Fangrui Liu
- Engineering Research Center for Biomedical Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Material Science & Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Shunyi Lu
- Department of Orthopaedics, Zhongshan Hospital Fudan University, Shanghai 200032, China
| | - Can Chen
- Engineering Research Center for Biomedical Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Material Science & Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Wei Luo
- Wenzhou Institute of Shanghai University, Wenzhou 325000, China
| | - Libo Jiang
- Department of Orthopaedics, Zhongshan Hospital Fudan University, Shanghai 200032, China
| | - Yulin Li
- Engineering Research Center for Biomedical Materials of Ministry of Education, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Material Science & Engineering, East China University of Science and Technology, Shanghai 200237, China
- Wenzhou Institute of Shanghai University, Wenzhou 325000, China
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5
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Li D, Chen Y, Sun L, Zhou J, Dong L, Ren J. The Role of Interchain Force and/or Chain Entanglement in the Melt Strength and Ductility of PLA-Based Materials. Chem Asian J 2023; 18:e202300577. [PMID: 37466153 DOI: 10.1002/asia.202300577] [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: 07/02/2023] [Accepted: 07/18/2023] [Indexed: 07/20/2023]
Abstract
As an eco-friendly material, PLA was a desirable alternative to polyethylene and polypropylene films due to its biodegradability. The preferable melt strength of PLA-based materials was a key factor in ensuring its processing using extrusion blow. This paper focuses on the influence of interchain force and/or chain entanglement on the melt strength and ductility of PLA-based materials in recent years. In addition, the preparation of PLA-based materials via physical blending or reactive processing was also summarized. The blending of PLA with a flexible heteropolymer, driven by the interchain force and/or chain entanglements, were characterized as a practicable method for toughening PLA-based materials. Also, the restructuring of PLA chains, by branching based on chain entanglement, was suitable for increasing chain entanglements in PLA matrix, yielding satisfactory melt strength and ductility. This review aims to elucidate the relationship between interchain forces and/or entanglement with the melt strength and ductility of PLA-based materials. An essential and systematic understanding of the tailoring melt strength and rheological properties of PLA by interchain forces and/or entanglement was apt to improve and perfect the processing technology of the extrusion blow, and consequently improve the tensile strength and toughness of PLA films.
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Affiliation(s)
- Deling Li
- College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
| | - Ying Chen
- College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
| | - Limei Sun
- College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
| | - Jun Zhou
- College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
| | - Liming Dong
- College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
| | - Jizhen Ren
- College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou, Jiangsu, 221018, China
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6
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Li P, Jiang L, Lan L, Liu F, Liu Z, Huang Y, Dan Y. Sustainable polylactide materials with the function of blocking a specific wavelength of light based on aloe-emodin. Int J Biol Macromol 2023; 247:125744. [PMID: 37423438 DOI: 10.1016/j.ijbiomac.2023.125744] [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: 04/16/2023] [Revised: 06/18/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
Polylactide, a biodegradable polymer, can alleviate white pollution, but the use of polylactide in food packaging is limited by high transmittance to light with a specific wavelength, UV (185-400 nm) and short-wavelength visible (400-500 nm) light. Herein, the polylactide end-capped with renewable light absorber aloe-emodin (PLA-En), is blended with commercial polylactide (PLA) to fabricate the polylactide film with the function of blocking light with a specific wavelength, PLA/PLA-En film. Only 40 % of light around 287 and 430 nm transmits through PLA/PLA-En film incorporating 3 mass% of PLA-En, while the film still maintains good mechanical properties and high transparency more than 90 % at 660 nm because of the good compatibility with PLA. The PLA/PLA-En film exhibits stable light-blocking properties under light irradiation and anti-solvent migration under the immersion of fat simulant. Almost no PLA-En migrated out of the film with the molecular weight of PLA-En only 2.89 × 104 g/mol. Compared with PLA film and commercial PE plastic wrap, the designed PLA/PLA-En film exhibits a better preservative effect on riboflavin and milk for inhibiting the production of 1O2. This study offers a green strategy for developing UV and short-wavelength light protective food package film based on renewable resource.
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Affiliation(s)
- Pengfei Li
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Long Jiang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Lidan Lan
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Fei Liu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Zhi Liu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yun Huang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Yi Dan
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
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7
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Cai Y, Liu S, Fang C, Liu Z, He Y, Qu JP. Strengthening-toughening pure poly(lactic acid) with ultra-transparency through increasing mesophase promoted by elongational flow field. Int J Biol Macromol 2023:125091. [PMID: 37247709 DOI: 10.1016/j.ijbiomac.2023.125091] [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: 03/22/2023] [Revised: 05/15/2023] [Accepted: 05/23/2023] [Indexed: 05/31/2023]
Abstract
Poly(lactic acid) (PLA), as a biodegradable material, finds wide applications in packaging, automotive, and biological industries. However, achieving high strength, toughness, ultra-transparency, and heat resistance simultaneously in pure PLA through continuous one-step manufacturing remains a significant challenge. In this study, we addressed this challenge by utilizing the eccentric rotor extruder (ERE) in combination with cooling rolls to manufacture PLA sheets with outstanding mechanical performance. The ERE's elongational flow field combined with the cooling roller's weak stretching action induced orientation in the PLA molecular chains and promoted the formation of more mesophase, significantly improving mechanical properties. When the extrusion-stretch ratio (λ) value was 3.5, the tensile yield strength, Young's modulus, and elongation at break of ERE-fabricated samples ER-3.5 reached 86.2 MPa, 1777 MPa, and 57.9 %, respectively. Compared to the SE-3.5 samples manufactured with traditional methods, the increases were 38.8 %, 25.8 %, and 9.4 times, respectively. Additionally, the ERE manufactured samples maintained ultra-transparency and high heat resistance, making them suitable for food packaging, biomedicine, and other related fields. This methodology provides an efficient industrial-scale approach for manufacturing neat, biodegradable PLA with outstanding mechanical performance and ultra-transparency.
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Affiliation(s)
- Yu Cai
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Shuai Liu
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Cong Fang
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Zhihua Liu
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Yue He
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China.
| | - Jin-Ping Qu
- National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, PR China; Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, South China University of Technology, Guangzhou 510640, PR China; School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, PR China.
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8
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Li W, Zhang D, Qv C, Zhao R, Ma Z. Stretching-Induced Melting and Recrystallization Polymorphism Revealed in Polybutene-1. Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c02372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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9
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Brosset M, Herrmann L, Falher T, Brinkmann M. Preparation of oriented poly(lactic acid) thin films by a combination of high temperature rubbing and thermal annealing: Impact of annealing parameters on structure, polymorphism and morphology. JOURNAL OF POLYMER SCIENCE 2023. [DOI: 10.1002/pol.20220740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Marion Brosset
- Université de Strasbourg, CNRS Strasbourg France
- Centre Technique de la Plasturgie et des Composites Pôle universitaire d'Alençon, Campus de Damigny Damigny France
| | | | - Thierry Falher
- Centre Technique de la Plasturgie et des Composites Pôle universitaire d'Alençon, Campus de Damigny Damigny France
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10
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Brosset M, Herrmann L, Kiefer C, Falher T, Brinkmann M. Controlling orientation, polymorphism, and crystallinity in thin films of poly(lactic‐acid) homopolymer and stereocomplex aligned by high temperature rubbing. J Appl Polym Sci 2022. [DOI: 10.1002/app.53532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Marion Brosset
- Université de Strasbourg, CNRS, ICS UPR 22 Strasbourg France
- IPC – Pôle Universitaire d'Alençon Damigny France
| | | | - Céline Kiefer
- Université de Strasbourg, IPCMS, UMR 7504 Strasbourg France
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11
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Zhang J, Li JQ, Wei QY, Chen Y, Jia DZ, Lin H, Zhong GJ, Li ZM. Light weight, low dielectric constant, super-robust polylactide film based on stress-induced cavitation aided by crystallization. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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12
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Díez-Rodríguez TM, Blázquez-Blázquez E, Martínez JC, Cerrada ML, Pérez E. A synchrotron SAXS study of PLLA crystallized at different temperatures: One-dimensional correlation functions. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Jia S, Han L, Chen Y, Pan H, Wang X, Zhang H, Dong L, Zhang H. Effect of initial crystallization on microstructure and mechanical properties of uniaxially pre-stretched poly(L-lactic acid). POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Nematic-to-Isotropic Phase Transition in Poly(L-Lactide) with Addition of Cyclodextrin during Abiotic Degradation Study. Int J Mol Sci 2022; 23:ijms23147693. [PMID: 35887040 PMCID: PMC9319020 DOI: 10.3390/ijms23147693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/28/2022] [Accepted: 07/08/2022] [Indexed: 12/04/2022] Open
Abstract
Poly(L-lactide) is capable of self-assembly into a nematic mesophase under the influence of temperature and mechanical stresses. Therefore, subsequent poly(L-lactide) films were obtained and characterized, showing nematic liquid crystal properties both before and after degradation. Herein, we present that, by introducing β-cyclodextrin into the polymer matrix, it is possible to obtain a chiral nematic mesophase during pressing, regardless of temperature and time. The obtained poly(L-lactide) films exhibiting liquid crystal properties were subjected to degradation tests and the influence of degradation on these properties was determined. Thermotropic phase behavior was investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The degradation process demonstrated an influence on the liquid crystal properties of pressed polymer films. The colored planar texture of the chiral nematic mesophase, which was not observed prior to degradation in films without the addition of β-cyclodextrin, appeared after incubation in water as a result of the entrapment of degradation products in the polymer matrix. These unusual tailor-made properties, obtained in liquid crystals in (bio)degradable polymers using a simple method, demonstrate the potential for advanced photonic applications.
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15
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Zhou L, Xu PP, Ni SH, Xu L, Lin H, Zhong GJ, Huang HD, Li ZM. Superior Ductile and High-barrier Poly(lactic acid) Films by Constructing Oriented Nanocrystals as Efficient Reinforcement of Chain Entanglement Network and Promising Barrier Wall. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-022-2723-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Mechanical Behavior of Thermoplastic Starch: Rationale for the Temperature-Relative Humidity Equivalence. Polymers (Basel) 2022; 14:polym14132531. [PMID: 35808576 PMCID: PMC9269158 DOI: 10.3390/polym14132531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 06/17/2022] [Accepted: 06/17/2022] [Indexed: 12/10/2022] Open
Abstract
This paper aimed at understanding and rationalizing the influence of both temperature and relative humidity on the mechanical behavior of thermoplastic starch (TPS). DMA experiments revealed that water molecules impact the crosslinking network by reducing the intermolecular hydrogen bond density, resulting in a less dense entanglement network. In addition, the in-situ X-ray characterization during hydration of starch revealed structural changes, which were ascribed to conformational changes in the starch chain, due to their interaction with the uptake water molecules. Finally, the study of TPS uniaxially stretched at different temperatures and humidity showed that the mechanical behavior of TPS could be rationalized by considering the ΔT parameter, which corresponds to the temperature difference between the drawing temperature and the glass transition temperature of TPS.
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17
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Marano S, Laudadio E, Minnelli C, Stipa P. Tailoring the Barrier Properties of PLA: A State-of-the-Art Review for Food Packaging Applications. Polymers (Basel) 2022; 14:1626. [PMID: 35458376 PMCID: PMC9029979 DOI: 10.3390/polym14081626] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 02/01/2023] Open
Abstract
It is now well recognized that the production of petroleum-based packaging materials has created serious ecological problems for the environment due to their resistance to biodegradation. In this context, substantial research efforts have been made to promote the use of biodegradable films as sustainable alternatives to conventionally used packaging materials. Among several biopolymers, poly(lactide) (PLA) has found early application in the food industry thanks to its promising properties and is currently one of the most industrially produced bioplastics. However, more efforts are needed to enhance its performance and expand its applicability in this field, as packaging materials need to meet precise functional requirements such as suitable thermal, mechanical, and gas barrier properties. In particular, improving the mass transfer properties of materials to water vapor, oxygen, and/or carbon dioxide plays a very important role in maintaining food quality and safety, as the rate of typical food degradation reactions (i.e., oxidation, microbial development, and physical reactions) can be greatly reduced. Since most reviews dealing with the properties of PLA have mainly focused on strategies to improve its thermal and mechanical properties, this work aims to review relevant strategies to tailor the barrier properties of PLA-based materials, with the ultimate goal of providing a general guide for the design of PLA-based packaging materials with the desired mass transfer properties.
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Affiliation(s)
- Stefania Marano
- Department of Science and Engineering of Matter, Environment and Urban Planning, Marche Polytechnic University, 60131 Ancona, Italy; (E.L.); (P.S.)
| | - Emiliano Laudadio
- Department of Science and Engineering of Matter, Environment and Urban Planning, Marche Polytechnic University, 60131 Ancona, Italy; (E.L.); (P.S.)
| | - Cristina Minnelli
- Department of Life and Environmental Sciences, Marche Polytechnic University, 60131 Ancona, Italy;
| | - Pierluigi Stipa
- Department of Science and Engineering of Matter, Environment and Urban Planning, Marche Polytechnic University, 60131 Ancona, Italy; (E.L.); (P.S.)
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18
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Nucleating Agents to Enhance Poly(l-Lactide) Fiber Crystallization during Industrial-Scale Melt Spinning. Polymers (Basel) 2022; 14:polym14071395. [PMID: 35406268 PMCID: PMC9002846 DOI: 10.3390/polym14071395] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/19/2022] [Accepted: 03/25/2022] [Indexed: 01/27/2023] Open
Abstract
The nucleating agent N,N′-bis(2-hydroxyethyl)-terephthalamide (BHET) has promising effects on poly(l-lactide) (PLA) under quiescent conditions and for injection molding applications, but its suitability for industrial-scale fiber melt spinning is unclear. We therefore determined the effects of 1% and 2% (w/w) BHET on the crystallinity, tenacity, and elongation at break of PLA fibers compared to pure PLA and PLA plus talc as a reference nucleating agent. Fibers were spun at take-up velocities of 800, 1400 and 2000 m/min and at drawing at ratios of 1.1–4.0, reaching a final winding speed of 3600 m/min. The fibers were analyzed by differential scanning calorimetry, wide-angle X-ray diffraction, gel permeation chromatography and tensile testing. Statistical analysis of variance was used to determine the combined effects of the spin-line parameters on the material properties. We found that the fiber draw ratio and take-up velocity were the most important factors affecting tenacity and elongation, but the addition of BHET reduced the mechanical performance of the fibers. The self-organizing properties of BHET were not expressed due to the rapid quenching of the fibers, leading to the formation of α′-crystals. Understanding the behavior of BHET in the PLA matrix provides information on the performance of nucleation agents during high-speed processing that will allow processing improvements in the future.
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19
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Díez-Rodríguez TM, Blázquez-Blázquez E, Pérez E, Cerrada ML. Influence of Content in D Isomer and Incorporation of SBA-15 Silica on the Crystallization Ability and Mechanical Properties in PLLA Based Materials. Polymers (Basel) 2022; 14:polym14061237. [PMID: 35335567 PMCID: PMC8949796 DOI: 10.3390/polym14061237] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 12/10/2022] Open
Abstract
Two L-rich polylactides (PLLA) with distinct contents in D isomer and their composites with an intermediate amount of mesoporous Santa Barbara Amorphous-15 (SBA-15) (about 9 wt.%) particles were attained by melt extrusion for the evaluation of the effect of content in D isomer and incorporation of mesoporous silica on the structural PLLA features and on their ultimate mechanical performance. For that, samples have been crystallized under dynamic and isothermal tests (from the melt and from the glassy states). The results from DSC and X-ray diffraction show obtainment of the pure α’ and α modifications at different intervals of crystallization temperature depending on the D steroisomer amount of the PLLA used. Furthermore, several phase transitions are observed depending on the crystallinity reached and the polymorphs developed during the isothermal crystallization from the glass: an additional cold crystallization, the α’/α transformation and the subsequent melting process, appearing all of them at temperatures clearly dependent on the D content. Rigidity, measured through microhardness in amorphous samples, is also affected by the D isomer and the presence of SBA-15 particles. Reinforcement effect of mesoporous silica is relatively more important in the matrix with the highest D content.
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20
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Díez-Rodríguez TM, Blázquez-Blázquez E, Martínez JC, Pérez E, Cerrada ML. Composites of a PLA with SBA-15 mesoporous silica: Polymorphism and properties after isothermal cold crystallization. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.124515] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Infrared bands to distinguish amorphous, meso and crystalline phases of poly(lactide)s: Crystallization and phase transition pathways of amorphous, meso and co-crystal phases of poly(ʟ-lactide) in the heating process. POLYMER 2022. [DOI: 10.1016/j.polymer.2021.124495] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Zhou J, Xu S, Zheng Y, Yu C, Shan G, Bao Y, Pan P. Multistage Structural Ordering and Crystallization of Poly(trimethylene terephthalate) during Sub-Tg Stretching: Synergetic Effects of Chain Orientation and Conformational Transition. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c02056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jian Zhou
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
- Institute of Zhejiang University-Quzhou, 78 Jiuhua Boulevard North, Quzhou 324000, China
| | - Shanshan Xu
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
| | - Ying Zheng
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
- Institute of Zhejiang University-Quzhou, 78 Jiuhua Boulevard North, Quzhou 324000, China
| | - Chengtao Yu
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
- Institute of Zhejiang University-Quzhou, 78 Jiuhua Boulevard North, Quzhou 324000, China
| | - Guorong Shan
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
- Institute of Zhejiang University-Quzhou, 78 Jiuhua Boulevard North, Quzhou 324000, China
| | - Yongzhong Bao
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
- Institute of Zhejiang University-Quzhou, 78 Jiuhua Boulevard North, Quzhou 324000, China
| | - Pengju Pan
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China
- Institute of Zhejiang University-Quzhou, 78 Jiuhua Boulevard North, Quzhou 324000, China
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23
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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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24
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Xu S, Zhou J, Pan P. Structural Evolutions of Initially Amorphous Polymers during Near‐
T
g
Stretching: A Minireview of Recent Progresses. MACROMOL CHEM PHYS 2021. [DOI: 10.1002/macp.202100427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Shanshan Xu
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University 38 Zheda Road Hangzhou 310027 China
| | - Jian Zhou
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University 38 Zheda Road Hangzhou 310027 China
- Institute of Zhejiang University‐Quzhou 78 Jiuhua Boulevard North Quzhou 324000 China
| | - Pengju Pan
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University 38 Zheda Road Hangzhou 310027 China
- Institute of Zhejiang University‐Quzhou 78 Jiuhua Boulevard North Quzhou 324000 China
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25
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Oliver-Ortega H, Vandemoortele V, Bala A, Julian F, Méndez JA, Espinach FX. Nanoclay Effect into the Biodegradation and Processability of Poly(lactic acid) Nanocomposites for Food Packaging. Polymers (Basel) 2021; 13:2741. [PMID: 34451280 PMCID: PMC8399732 DOI: 10.3390/polym13162741] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/10/2021] [Accepted: 08/13/2021] [Indexed: 11/16/2022] Open
Abstract
One of the most promising expectations in the design of new materials for food packaging is focused on the development of biodegradable systems with improved barrier character. In this sense PLA reinforced with nanoclay is a potential alternative to the use of conventional oil-derivative polymers due to the synergetic effect of the biodegradable character of PLA and the barrier-induced effect derived from the dispersion of nanoparticles. In this work, composite materials based on PLA and reinforced with bentonite nanoparticles (up to 4% w/w) (NC) have been prepared to produce films with improved barrier character against water vapor transportation. Additionally, the biodegradable character of the composites depending on the crystallinity of the polymer and percentage of NC have been evaluated in the presence of an enzymatic active medium (proteinase K). Finally, a study of the capacity to film production of the composites has been performed to determine the viability of the proposals. The dispersion of the nanoparticles induced a tortuous pathway of water vapor crossing, reducing this diffusion by more than 22%. Moreover, the nanoclays materials were in all the cases acceptable for food packing in terms of migration. A migration lower than 1 mg/m2 was obtained in all the materials. Nonetheless, the presence of the nanoclays in decreased biodegradable capacity was observed. The time was enlarged to more than 15 days for the maximum content (4% w/w). On the other hand, the incorporation of NC does not avoid the processability of the material to obtain film-shaped processed materials.
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Affiliation(s)
- Helena Oliver-Ortega
- Group LEPAMAP-PRODIS, Department of Chemical Engineering, University of Girona, c. M. Aurèlia Capmany, 61, 17003 Girona, Spain; (F.J.); (J.A.M.); (F.X.E.)
| | | | - Alba Bala
- UNESCO Chair in Life Cycle and Climate Change ESCI-UPF, Universitat Pompeu Fabra, Passeig Pujades 1, 08003 Barcelona, Spain;
| | - Fernando Julian
- Group LEPAMAP-PRODIS, Department of Chemical Engineering, University of Girona, c. M. Aurèlia Capmany, 61, 17003 Girona, Spain; (F.J.); (J.A.M.); (F.X.E.)
| | - José Alberto Méndez
- Group LEPAMAP-PRODIS, Department of Chemical Engineering, University of Girona, c. M. Aurèlia Capmany, 61, 17003 Girona, Spain; (F.J.); (J.A.M.); (F.X.E.)
| | - Francesc Xavier Espinach
- Group LEPAMAP-PRODIS, Department of Chemical Engineering, University of Girona, c. M. Aurèlia Capmany, 61, 17003 Girona, Spain; (F.J.); (J.A.M.); (F.X.E.)
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26
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Nagendra B, Rizzo P, Daniel C, Guerra G. Planar Orientation and Transparency of Nanoporous-Crystalline Polymer Films. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00925] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Baku Nagendra
- Dipartimento di Chimica e Biologia, INSTM Research Unit, Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
| | - Paola Rizzo
- Dipartimento di Chimica e Biologia, INSTM Research Unit, Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
| | - Christophe Daniel
- Dipartimento di Chimica e Biologia, INSTM Research Unit, Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
| | - Gaetano Guerra
- Dipartimento di Chimica e Biologia, INSTM Research Unit, Università di Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy
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27
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28
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Wei H, Yan S, Menary G. Modelling Stretch Blow Moulding of Poly (l-lactic acid) for the Manufacture of Bioresorbable Vascular Scaffold. Polymers (Basel) 2021; 13:polym13060967. [PMID: 33809921 PMCID: PMC8004264 DOI: 10.3390/polym13060967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 03/09/2021] [Accepted: 03/16/2021] [Indexed: 11/25/2022] Open
Abstract
Stretch blow moulding (SBM) has been employed to manufacture bioresorbable vascular scaffold (BVS) from poly (l-lactic acid) (PLLA), whilst an experience-based method is used to develop the suitable processing conditions by trial-and-error. FEA modelling can be used to predict the forming process by the scientific understanding on the mechanical behaviour of PLLA materials above the glass transition temperature (Tg). The applicability of a constitutive model, the ‘glass-rubber’ (GR) model with material parameters from biaxial stretch was examined on PLLA sheets replicating the biaxial strain history of PLLA tubes during stretch blow moulding. The different stress–strain relationship of tubes and sheets under equivalent deformation suggested the need of re-calibration of the GR model for tubes. A FEA model was developed for PLLA tubes under different operation conditions, incorporating a virtual cap and rod to capture the suppression of axial stretch. The reliability of the FEA modelling on tube blowing was validated by comparing the shape evolution, strain history and stress–strain relationship from modelling to the results from the free stretch blow test.
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Affiliation(s)
- Huidong Wei
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK;
| | - Shiyong Yan
- School of Mechanical and Aerospace Engineering, Queen’s University Belfast, Belfast BT9 5AH, UK;
| | - Gary Menary
- School of Mechanical and Aerospace Engineering, Queen’s University Belfast, Belfast BT9 5AH, UK;
- Correspondence:
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29
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Water-responsive shape memory PLLA via incorporating PCL-(PMVS-s-PAA)-PCL-PTMG-PCL-(PMVS-s-PAA)-PCL. Eur Polym J 2021. [DOI: 10.1016/j.eurpolymj.2020.110252] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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30
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Wei H. Optimisation on Thermoforming of Biodegradable Poly (Lactic Acid) (PLA) by Numerical Modelling. Polymers (Basel) 2021; 13:654. [PMID: 33671769 PMCID: PMC7926767 DOI: 10.3390/polym13040654] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/12/2021] [Accepted: 02/17/2021] [Indexed: 11/16/2022] Open
Abstract
Poly (lactic acid) (PLA) has a broad perspective for manufacturing green thermoplastic products by thermoforming for its biodegradable properties. The mechanical behaviour of PLA has been demonstrated by its strong dependence on temperature and strain rate at biaxial deformation. A nonlinear viscoelastic model by the previous study was employed in a thermoforming process used for food packaging. An optimisation approach was developed by achieving the optimal temperature profile of specimens by defining multiple heating zones based on numerical modelling with finite element analysis (FEA). The forming process of a PLA product was illustrated by modelling results on shape evolution and biaxial strain history. The optimal temperature profile was suggested in scalloped zones to achieve more even thickness distribution. The sensitivity of the optimal results was addressed by checking the robustness under perturbation.
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Affiliation(s)
- Huidong Wei
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK;
- Rayner Intraocular Lenses Limited, Worthing BN14 8AQ, UK
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31
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Effect of d-isomer content on strain-induced crystallization behaviour of Poly(lactic acid) polymer under high speed uniaxial drawing. POLYMER 2021. [DOI: 10.1016/j.polymer.2021.123422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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32
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Wang F, Liu H, Li Y, Li Y, Ma Q, Zhang J, Hu X. Tunable Biodegradable Polylactide-Silk Fibroin Scaffolds Fabricated by a Solvent-Free Pressure-Controllable Foaming Technology. ACS APPLIED BIO MATERIALS 2020; 3:8795-8807. [PMID: 35019555 DOI: 10.1021/acsabm.0c01157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Polylactide (PLA) and silk fibroin (SF) are biocompatible green macromolecular materials with tunable structures and properties. In this study, microporous PLA/SF composites were fabricated under different pressures by a green solid solvent-free foaming technology. Scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetric (TG) analysis, and Fourier transform infrared (FTIR) spectroscopy were used to analyze the morphology, structure, and mechanical properties of the PLA/SF scaffolds. The crystalline, mobile amorphous phases and rigid amorphous phases in PLA/SF composites were calculated to further understand their structure-property relations. It was found that an increase in pore density and a decrease in pore size can be achieved by increasing the saturation pressure during the foaming process. In addition, changes in the microcellular structure provided PLA/SF scaffolds with better thermal stability, tunable biodegradation rates, and mechanical properties. FTIR and XRD analysis indicated strong hydrogen bonds were formed between PLA and SF molecules, which can be tuned by changing the foaming pressure. The composite scaffolds have good cell compatibility and are conducive to cell adhesion and growth, suggesting that PLA/SF microporous scaffolds could be used as three-dimensional (3-D) biomaterials with a wide range of applications.
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Affiliation(s)
- Fang Wang
- Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, P. R. China.,School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Hao Liu
- Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, P. R. China.,School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Yingying Li
- Center of Analysis and Testing, Nanjing Normal University, Nanjing 210023, P. R. China.,School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Yajuan Li
- School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Qingyu Ma
- School of Physics and Technology, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Jun Zhang
- School of Chemistry and Materials Science, Nanjing Normal University Jiangsu, Nanjing 210023, P. R. China
| | - Xiao Hu
- Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey 08028, United States.,Department of Biomedical Engineering, Rowan University, Glassboro, New Jersey 08028, United States.,Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, New Jersey 08028, United States
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33
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Zhou H, Song Z, Cai S. Toughening of poly(lactide acid) with low crystallinity through biaxial poststretching. JOURNAL OF POLYMER SCIENCE 2020. [DOI: 10.1002/pol.20200526] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Hongwei Zhou
- Department of Mechanical and Aerospace Engineering University of California San Diego California USA
| | - Zhaoqiang Song
- Department of Mechanical and Aerospace Engineering University of California San Diego California USA
| | - Shengqiang Cai
- Department of Mechanical and Aerospace Engineering University of California San Diego California USA
- Materials Science and Engineering Program University of California San Diego California USA
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34
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Dynamic Mechanical Analysis Investigations of PLA-Based Renewable Materials: How Are They Useful? MATERIALS 2020; 13:ma13225302. [PMID: 33238537 PMCID: PMC7700632 DOI: 10.3390/ma13225302] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/04/2020] [Accepted: 11/12/2020] [Indexed: 02/04/2023]
Abstract
Interest in renewable polymers increased exponentially in the last decade and in this context poly(lactic acid) (PLA) became the leader mainly for practical reasons. Nevertheless, it is outstanding also from a scientific point of view, because its thermal and morphological properties are offering challenging new insights. With regard to dynamic mechanical analysis (DMA), PLA does not have the classical behavior of a thermoplastic polymer. Often, overlapping events (enthalpic relaxation, glass transition and crystallization) that occur as the temperature increases make the DMA result of a PLA look inexplicable even for polymer scientists. This review offers a perspective of the main phenomena that can be revealed in a DMA experiment and systematizes the information that can be obtained for every region (glassy, glass transition, rubbery, cold-crystallization and melting). Also, some unusual patterns registered in some cases will be commented upon. The review intends to offer indices that one should pay attention to in the interpretation of a DMA experiment, even if the investigator has only basic skills with DMA investigations.
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35
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Díez-Rodríguez TM, Blázquez-Blázquez E, Pérez E, Cerrada ML. Composites Based on Poly(Lactic Acid) (PLA) and SBA-15: Effect of Mesoporous Silica on Thermal Stability and on Isothermal Crystallization from Either Glass or Molten State. Polymers (Basel) 2020; 12:polym12112743. [PMID: 33227923 PMCID: PMC7699165 DOI: 10.3390/polym12112743] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/11/2020] [Accepted: 11/16/2020] [Indexed: 11/29/2022] Open
Abstract
Several composites based on an L-rich poly(lactic acid) (PLA) with different contents of mesoporous Santa Barbara Amorphous (SBA-15) silica were prepared in order to evaluate the effect of the mesoporous silica on the resultant PLA materials by examining morphological aspects, changes in PLA phases and their transitions, and, primarily, the influence on some final properties. Melt extrusion was chosen for the obtainment of the composites, followed by quenching from the melt to prepare films. Completely amorphous samples were then attained, as deduced from X-ray diffraction and differential scanning calorimetry (DSC) analyses. Thermogravimetric analysis (TGA) results demonstrated that the presence of SBA-15 particles in the PLA matrix did not exert any significant influence on the thermal decomposition of these composites. An important nucleation effect of the silica was found in PLA, especially under isothermal crystallization either from the melt or from its glassy state. As expected, isothermal crystallization from the glass was considerably faster than from the molten state, and these high differences were also responsible for a more considerable nucleating role of SBA-15 when crystallizing from the melt. It is remarkable that the PLA under analysis showed very close temperatures for cold crystallization and its subsequent melting. Moreover, the type of developed polymorphs did not accomplish the common rules previously described in the literature. Thus, all the isothermal experiments led to exclusive formation of the α modification, and the observation of the α’ crystals required the annealing for long times at temperatures below 80 °C, as ascertained by both DSC and X-ray diffraction experiments. Finally, microhardness (MH) measurements indicated a competition between the PLA physical aging and the silica reinforcement effect in the as-processed amorphous films. Physical aging in the neat PLA was much more important than in the PLA matrix that constituted the composites. Accordingly, the MH trend with SBA-15 content was strongly dependent on aging times.
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36
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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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37
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Wang Z, Zhang C, Zhang Z, Chen X, Wang X, Wen M, Chen B, Cao W, Liu C. Polyethylene oxide enhances the ductility and toughness of polylactic acid: the role of mesophase. SOFT MATTER 2020; 16:7018-7032. [PMID: 32648874 DOI: 10.1039/d0sm00671h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A lack of understanding of the structure-property relationship of the polylactic acid (PLA)-based polymer composite system makes it a challenge to manufacture products with optimized mechanical performance by precisely regulating the microscopic structure and morphology. Herein, we chose the PLA/polyethylene oxide (PEO) blend as a model to investigate the structural reason for the enhanced ductility and toughness of this kind of material. We have demonstrated that a considerable amount of the PLA mesophases exist in the melt quenched films that display high ductility and toughness, in contrast to the PLA crystals in their counterparts of slowly cooled films that are dominated by brittle fracture. The mesophase formed by melt quenching is attributed to a moderate acceleration of PLA chain mobility due to the plasticizing effect of the flexible PEO. In situ experiments have revealed the further formation of oriented mesophases induced by tensile deformation, which presents a high consistency between the content increase and the tensile stress intensification. We illustrate that the mesophases directly develop into a microfibrillar morphology to transmit the external stress and prevent crack propagation under deformation. This work emphasizes the essential role of the PLA mesophase in acquiring the enhanced ductility and toughness of the PLA/PEO composite films, which may be generalized to other similar PLA-based polymer composite materials.
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Affiliation(s)
- Zhen Wang
- National Engineering Research Center for Advanced Polymer Processing Technology, Key Laboratory of Materials Processing and Mold (Zhengzhou University), Ministry of Education, Zhengzhou University, Zhengzhou, 450002, China.
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38
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Wang X, Yan H, Shen Y, Tang H, Yi B, Qin C, Zhang Y. Shape Memory and Osteogenesis Capabilities of the Electrospun Poly(3-Hydroxybutyrate- co-3-Hydroxyvalerate) Modified Poly(l-Lactide) Fibrous Mats. Tissue Eng Part A 2020; 27:142-152. [PMID: 32524903 DOI: 10.1089/ten.tea.2020.0086] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Poly(l-lactide) (PLLA) as one of the most well-known biodegradable polyesters has been studied extensively for bone tissue engineering. If being properly programmed, scaffolds from PLLA can also be endowed with the capability of shape memory. However, several noted issues, for example, mechanical brittleness, high glass transition temperature Tg, and relatively poor shape retention and recovery properties, necessitate modification of the PLLA to improve its application efficacy in physiological conditions. This study is proposed to modify PLLA by having the biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) incorporated to form ultrafine composite fibers (i.e., PLLA-PHBV) through electrospinning. Different pairs of PLLA-PHBV at the varying mass ratios of 10:0, 9:1, 8:2, 7:3, 6:4, and 0:10 can be successfully electrospun into fibrous form with the fineness of 2-3 μm. Incorporation of PHBV enables to give rise to desired Tg decreases and also, interestingly, increases in the Young's modulus of the PLLA-PHBV blends, while gradually increasing the PHBV mass ratios up to 30%. The PLLA-PHBV (7:3) formulation is identified to present excellent shape memory properties with high shape fixing ratio (>98%) and shape recovery ratio (>96%) compared to the unmodified PLLA fiber counterpart. Moreover, the PLLA-PHBV (7:3) fibers also show enhanced osteogenesis-inducing ability in the mouse bone mesenchymal stem cells, even under nonosteoinductive conditions. Collectively, for the first time this study demonstrates the enhanced shape memory and osteogenesis capabilities of the electrospun PLLA-PHBV composite fibers, and the researched PLLA-PHBV (7:3) fiber system could be potentially applied as a multifunctional scaffolding material for applications in bone tissue repair and regeneration. Impact statement By first converting the poly(l-lactide) (PLLA)-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) hybrids into fibrous form at varied mass ratios followed by a thorough characterization, we reasonably demonstrated that incorporation of an appropriate amount of PHBV (i.e., 30%) into the PLLA fibers could give rise to significant improvement on the shape memory capability of the PLLA, along with the desired decreases in the transition temperature (Tg). Moreover, the fibrous PLLA-PHBV (7:3) scaffold was also found to significantly promote the osteogenic commitment in bone mesenchymal stem cells with osteoinductive factors in a synergistic manner. Our biomimicking and shape memory enabled fibrous scaffold of PLLA-PHBV could be used to construct multifunctional three-dimensional scaffold with shape memory effect for bone regeneration.
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Affiliation(s)
- Xianliu Wang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China
| | - Hongyu Yan
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China
| | - Yanbing Shen
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China
| | - Han Tang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China
| | - Bingcheng Yi
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China
| | - Chunping Qin
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China
| | - Yanzhong Zhang
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai, P.R. China.,Key Lab of Science and Technology of Eco-Textiles, Ministry of Education, Donghua University, Shanghai, P.R. China
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39
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Louisy E, Fontaine G, Gaucher V, Bonnet F, Stoclet G. Comparative studies of thermal and mechanical properties of macrocyclic versus linear polylactide. Polym Bull (Berl) 2020. [DOI: 10.1007/s00289-020-03290-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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40
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Sun ZB, Wei QY, Xie XL, Xu L, Ji X, Zhou L, Zhong GJ, Li ZM. Spatial dependence of ordering process in bulk materials of polylactide and its multiple system during hygrothermal aging. Polym Degrad Stab 2020. [DOI: 10.1016/j.polymdegradstab.2020.109107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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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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42
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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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43
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Guo H, Li J, Wang J, Meng Y, Wu Z, Jiang S. Direct Observations on Structure Evolutions in Polyamide 6 during Deformation at High Temperatures with WAXS and SAXS. POLYM ENG SCI 2020. [DOI: 10.1002/pen.25316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Huilong Guo
- Global Energy Interconnection Group Co., LtdSTATE GRID Corporation of China Beijing 100031 China
- School of Materials Science and EngineeringTianjin University Tianjin 300072 China
| | - Jingqing Li
- School of Materials Science and EngineeringTianjin University Tianjin 300072 China
| | - Jiayi Wang
- Institute of High Energy PhysicsChinese Academy of Sciences, and University of Chinese Academy of Sciences Beijing 100049 China
| | - Yanfeng Meng
- School of Chemistry and Materials ScienceLudong University Yantai 264025 China
| | - Zhonghua Wu
- Institute of High Energy PhysicsChinese Academy of Sciences, and University of Chinese Academy of Sciences Beijing 100049 China
| | - Shichun Jiang
- School of Materials Science and EngineeringTianjin University Tianjin 300072 China
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44
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45
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Chen Y, Zhao L, Pan H, Jia S, Han L, Dong L. Impact of -isomer content on the microstructure and mechanical properties of uniaxially pre-stretched poly(lactic acid). POLYMER 2020. [DOI: 10.1016/j.polymer.2019.122022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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46
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Li Y, Han C, Yu Y, Huang D. Structure variation and properties enhancement of uniaxial stretching poly(
l
‐lactic acid)/eggshell powder composites. J Appl Polym Sci 2019. [DOI: 10.1002/app.48158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Yi Li
- School of Materials Science and EngineeringJilin Jianzhu University Changchun 130118 China
- Key Laboratory of Polymer EcomaterialsChangchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun 130022 China
| | - Changyu Han
- Key Laboratory of Polymer EcomaterialsChangchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun 130022 China
| | - Yancun Yu
- Key Laboratory of Polymer EcomaterialsChangchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun 130022 China
| | - Dexin Huang
- School of Materials Science and EngineeringJilin Jianzhu University Changchun 130118 China
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47
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Morel A, Oberle SC, Ulrich S, Yazgan G, Spano F, Ferguson SJ, Fortunato G, Rossi RM. Revealing non-crystalline polymer superstructures within electrospun fibers through solvent-induced phase rearrangements. NANOSCALE 2019; 11:16788-16800. [PMID: 31465059 DOI: 10.1039/c9nr04432a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The design of nanofibers for biomedical applications requires a deep understanding of the fiber formation process and the resulting internal structure. In this regard, non-crystalline, mesomorphic structures play a central role in the processing of many polymers as precursors in the formation of crystalline superstructures (e.g. shish-kebab) and influence strongly the physical properties of polymers with a low degree of crystallinity. Yet, our ability to probe these relevant features is often greatly limited by their low contrast differences with the amorphous phase. We present an approach to reveal the organization of the mesomorphic superstructures within such polymeric materials, on the example of electrospun poly(l-lactide) nanofibers. Based on solvent-induced crystallization, this method employs fine-tuned solvent/non-solvent systems to enhance the contrast of these structural features by selectively triggering and controlling reorganization of the phases. Hereby, the mesomorphic regions are transformed into an α-crystalline phase, while the nanoscale spatial arrangement of the underlying superstructures is preserved. Combined with X-ray analytical techniques and electron microscopy, our approach provides detailed insights into the nanofiber's inner architecture, allowing for its direct visualization. Thereby, the influence of electrospinning parameters on the fiber formation process is explained as well as the impact of the resulting non-crystalline superstructures on single fiber mechanical properties. The method can be applied to comparable polymers for the development of materials with controlled, tailored properties.
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Affiliation(s)
- Alexandre Morel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, 9014 St Gallen, Switzerland.
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48
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Affiliation(s)
- Masoud Razavi
- College of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Shi-Qing Wang
- College of Polymer Science and Engineering, University of Akron, Akron, Ohio 44325, United States
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49
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Influence of Annealing and Biaxial Expansion on the Properties of Poly(l-Lactic Acid) Medical Tubing. Polymers (Basel) 2019; 11:polym11071172. [PMID: 31373323 PMCID: PMC6680782 DOI: 10.3390/polym11071172] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/04/2019] [Accepted: 07/05/2019] [Indexed: 01/30/2023] Open
Abstract
Poly-l-lactic acid (PLLA) is one of the most common bioabsorbable materials in the medical device field. However, its use in load-bearing applications is limited due to its inferior mechanical properties when compared to many of the competing metal-based permanent and bioabsorbable materials. The objective of this study was to directly compare the influence of both annealing and biaxial expansion processes to improve the material properties of PLLA. Results showed that both annealing and biaxial expansion led to an overall increase in crystallinity and that the crystallites formed during both processes were in the α’ and α forms. 2D-WAXS patterns showed that the preferred orientation of crystallites formed during annealing was parallel to the circumferential direction. While biaxial expansion resulted in orientation in both axial and circumferential directions, with relatively equal sized crystals in both directions, Da (112 Å) and Dc (97 Å). The expansion process had the most profound effect on mechanical performance, with a 65% increase in Young’s modulus, a 45% increase in maximum tensile stress and an 18-fold increase in strain at maximum load. These results indicate that biaxially expanding PLLA at a temperature above Tcc is possible, due to the high strain rates associated with stretch blow moulding.
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50
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Gao XR, Li Y, Huang HD, Xu JZ, Xu L, Ji X, Zhong GJ, Li ZM. Extensional Stress-Induced Orientation and Crystallization can Regulate the Balance of Toughness and Stiffness of Polylactide Films: Interplay of Oriented Amorphous Chains and Crystallites. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00932] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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