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Liparoti S, Pantani R. Opacification Kinetics of PLA during Liquid Water Sorption. Polymers (Basel) 2024; 16:2621. [PMID: 39339085 PMCID: PMC11435793 DOI: 10.3390/polym16182621] [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: 08/27/2024] [Revised: 09/12/2024] [Accepted: 09/15/2024] [Indexed: 09/30/2024] Open
Abstract
When in contact with water, poly(lactic acid), PLA, undergoes several physical changes. A very evident one is opacification, namely the change from the typical transparent appearance to a white opaque color. This phenomenon is particularly significant for many applications, including packaging, since opacity hinders the possibility of a clear look of the packed goods and also worsens the consumers' perceptions. In this work, we report an analysis of the time evolution of the phenomenon in different conditions of temperature and water concentration. The results allow us to define a time-scale of the phenomenon and to put it in relationship with the temperature and water content inside the material. In particular, opacification proceeds from the outer surface of the specimens toward the center. Both craze formation due to hydrolysis and crystallization contribute to the opacification phenomenon. Opacification becomes faster as temperature increases, whereas the increase in the solution density has the opposite effect. A model for describing the evolution of opacification was proposed and found to be consistent with the experimental data.
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Affiliation(s)
| | - Roberto Pantani
- Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy;
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2
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Malone LP, Best SM, Cameron RE. Accelerated degradation testing impacts the degradation processes in 3D printed amorphous PLLA. Front Bioeng Biotechnol 2024; 12:1419654. [PMID: 39036561 PMCID: PMC11257899 DOI: 10.3389/fbioe.2024.1419654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 06/18/2024] [Indexed: 07/23/2024] Open
Abstract
Additive manufacturing and electrospinning are widely used to create degradable biomedical components. This work presents important new data showing that the temperature used in accelerated tests has a significant impact on the degradation process in amorphous 3D printed poly-l-lactic acid (PLLA) fibres. Samples (c. 100 μ m diameter) were degraded in a fluid environment at37 ° C,50 ° C and80 ° C over a period of 6 months. Our findings suggest that across all three fluid temperatures, the fibres underwent bulk homogeneous degradation. A three-stage degradation process was identified by measuring changes in fluid pH, PLLA fibre mass, molecular weight and polydispersity index. At37 ° C, the fibres remained amorphous but, at elevated temperatures, the PLLA crystallised. A short-term hydration study revealed a reduction in glass transition (Tg), allowing the fibres to crystallise, even at temperatures below the dry Tg. The findings suggest that degradation testing of amorphous PLLA fibres at elevated temperatures changes the degradation pathway which, in turn, affects the sample crystallinity and microstructure. The implication is that, although higher temperatures might be suitable for testing bulk material, predictive testing of the degradation of amorphous PLLA fibres (such as those produced via 3D printing or electrospinning) should be conducted at37 ° C.
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Affiliation(s)
- Luke P. Malone
- Department of Materials Science and Metallurgy, Cambridge Centre for Medical Materials, University of Cambridge, Cambridge, United Kingdom
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3
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Reit M, Zarges JC, Heim HP. Correlation between the activation energy of PLA respectively PLA/starch composites and mechanical properties with regard to differ accelerated aging conditions. Biopolymers 2024; 115:e23571. [PMID: 38385628 DOI: 10.1002/bip.23571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/05/2024] [Accepted: 02/09/2024] [Indexed: 02/23/2024]
Abstract
Within this research semi-crystalline polylactide and composites with 50 wt.% native potato starch were compounded and injection molded. The material was mechanically characterized by tensile, three-point bending, and Charpy impact tests. These tests were carried out in the freshly molded state and after 332 and 792 h of storage at accelerated temperature or humidity. The respective activation energy was calculated by applying the Flynn-Wall-Ozawa method. The focus of the study was to investigate the correlation between the activation energy and the related mechanical and thermal properties. The results showed that the addition of native potato starch as a filler prevents the decrease in activation energy over the course of the experiments. Thus, the PLA/starch composite is more resistant to the two aging conditions than the pure PLA. When considering the mechanical properties, the pure PLA showed a large deviation of results compared to the initial value in a range of +63.88% to -33.96% with regard to the respective aging conditions, whereas the PLA/starch composite properties nearly always remained at the initial values. Through the investigation of the mechanical and thermal properties, it was shown that the steady activation energies are consistent with the mechanical properties, as these have shown only a small deviation of the mechanical properties during the duration of experiments for the PLA/starch composite.
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Affiliation(s)
- Margarita Reit
- Institute of Material Engineering, Polymer Engineering, University of Kassel, Kassel, Germany
| | - Jan-Christoph Zarges
- Institute of Material Engineering, Polymer Engineering, University of Kassel, Kassel, Germany
| | - Hans-Peter Heim
- Institute of Material Engineering, Polymer Engineering, University of Kassel, Kassel, Germany
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4
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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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5
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Larrañaga X, Sarasua JR, Zuza E. Role of Inorganic Fillers on the Physical Aging and Toughness Loss of PLLA/BaSO 4 Composites. ACS APPLIED POLYMER MATERIALS 2023; 5:9620-9631. [PMID: 38021210 PMCID: PMC10653123 DOI: 10.1021/acsapm.3c02112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 12/01/2023]
Abstract
The addition of inorganic fillers has been reported to increase the toughness of poly(l-lactide) (PLLA), but the effect of physical aging in such composites has been neglected. The present work discusses the effect of the still ongoing segmental relaxation in PLLA-based composites filled with BaSO4 inorganic particles in regard of the filler quantity. By means of differential scanning calorimetry, X-ray diffraction, and tensile testing of progressively aged PLLA filled with particles ranging from 0.5-10 wt %, we observed an increase in the mechanical energy required to activate the plastic flow of the primary structure in the PLLA matrix, which resulted in the embrittlement of the majority of composites upon enough aging. Results further clarify the role of debonding in the activation process of PLLA, and the behavior of the composite is described at the segmental level. Only an addition of 10% of particles has effectively preserved a ductile behavior of the samples beyond 150 aging days; therefore, we strongly remark the significance of studying the effect of physical aging in such composites.
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Affiliation(s)
- Xabier Larrañaga
- Department of Mining-Metallurgy
Engineering and Materials Science & POLYMAT, Faculty of Engineering, University
of the Basque Country (UPV/EHU), Alameda de Urquijo s/n, Bilbao 48013, Spain
| | - Jose R. Sarasua
- Department of Mining-Metallurgy
Engineering and Materials Science & POLYMAT, Faculty of Engineering, University
of the Basque Country (UPV/EHU), Alameda de Urquijo s/n, Bilbao 48013, Spain
| | - Ester Zuza
- Department of Mining-Metallurgy
Engineering and Materials Science & POLYMAT, Faculty of Engineering, University
of the Basque Country (UPV/EHU), Alameda de Urquijo s/n, Bilbao 48013, Spain
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6
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Skotnicki M, Drogoń A, Lulek J, Pyda M. Physical Ageing of Amorphous Poly(lactic acid)-Indapamide System Studied by Differential Scanning Calorimetry. Pharmaceutics 2023; 15:2341. [PMID: 37765312 PMCID: PMC10536509 DOI: 10.3390/pharmaceutics15092341] [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: 08/02/2023] [Revised: 09/05/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
The process of isothermal and non-isothermal physical ageing of amorphous polylactide (PLA) with the active pharmaceutical ingredient, indapamide (IND), was investigated. A PLA-IND system with a 50/50 weight ratio was obtained and characterized using differential scanning calorimetry (DSC). In the 50/50 (w/w) mixture, two glass transitions were observed: the first at 64.1 ± 0.3 °C corresponding to the glass transition temperature (Tg) of PLA, and the second at 102.6 ± 1.1 °C corresponding to the Tg of IND, indicating a lack of molecular mixing between the two ingredients. The PLA-IND system was subjected to the isothermal physical ageing process at different ageing temperatures (Ta) for 2 h. It was observed that the highest effect of physical ageing (enthalpy relaxation change) on IND in the PLA-IND system occurred at Ta = 85 °C. Furthermore, the system was annealed for various ageing times at 85 °C. The relaxation enthalpies were estimated for each experiment and fitted to the Kohlrausch-Williams-Watts (KWW) equation. The KWW equation allowed for the estimation of the relaxation time and the parameter describing the distribution of relaxation times of the isothermal physical ageing process of IND in the PLA-IND system. The physical ageing of the PLA-IND mixture (50/50) was also discussed in the context of heat capacity. Moreover, the activation energy and fragility parameters were determined for the PLA-IND (50/50) system.
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Affiliation(s)
- Marcin Skotnicki
- Chair and Department of Pharmaceutical Technology, Poznan University of Medical Sciences, 60-780 Poznan, Poland;
| | - Agata Drogoń
- Department of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Poland
| | - Janina Lulek
- Chair and Department of Pharmaceutical Technology, Poznan University of Medical Sciences, 60-780 Poznan, Poland;
| | - Marek Pyda
- Department of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Poland
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7
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Pregi E, Romsics I, Várdai R, Pukánszky B. Interactions, Structure and Properties of PLA/lignin/PBAT Hybrid Blends. Polymers (Basel) 2023; 15:3237. [PMID: 37571133 PMCID: PMC10422597 DOI: 10.3390/polym15153237] [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: 06/07/2023] [Revised: 07/11/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023] Open
Abstract
Poly(butylene adipate-co-terephthalate) (PBAT) was added to poly(lactic acid) (PLA)/lignin blends to decrease the considerable stiffness and brittleness of the blends. Two- and three-component blends were prepared in a wide composition range through homogenization in an internal mixer followed by compression molding. Interactions among the components were estimated by comparing the solubility parameters of the materials used and through thermal analysis. Mechanical properties were characterized by tensile testing. The structure of the blends was studied using scanning electron (SEM) and digital optical (DOM) microscopy. The results showed that the interactions between PBAT and lignin are somewhat stronger than those between PLA and the other two components. The maleic anhydride grafted PLA added as a coupling agent proved completely ineffective; it does not modify the interactions. The structural analysis confirmed the immiscibility of the components; the structure of the blends was heterogeneous at each composition. A dispersed structure formed when the concentration of one of the components was small, while, depending on lignin content, an interpenetrating network-like structure developed and phase inversion took place in the range of 30-60 vol% PBAT content. Lignin was located mainly in the PBAT phase. Properties were determined by the relative amount of PBAT and PLA; the addition of lignin deteriorated properties, mainly the deformability of the blends. Other means, such as reactive processing, must be used to improve compatibility and blend properties. The results contribute considerably to a better understanding of structure-property correlations in lignin-based hybrid blends.
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Affiliation(s)
- Emese Pregi
- Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary (B.P.)
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
| | - Imre Romsics
- Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary (B.P.)
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
| | - Róbert Várdai
- Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary (B.P.)
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
| | - Béla Pukánszky
- Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary (B.P.)
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
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8
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Preparation of Biocomposites with Natural Reinforcements: The Effect of Native Starch and Sugarcane Bagasse Fibers. Molecules 2022; 27:molecules27196423. [PMID: 36234960 PMCID: PMC9571990 DOI: 10.3390/molecules27196423] [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: 08/25/2022] [Revised: 09/15/2022] [Accepted: 09/23/2022] [Indexed: 11/16/2022] Open
Abstract
Biocomposites were prepared from poly(lactic acid) and two natural reinforcements, a native starch and sugarcane bagasse fibers. The strength of interfacial adhesion was estimated by model calculations, and local deformation processes were followed by acoustic emission testing. The results showed that the two additives influence properties differently. The strength of interfacial adhesion and thus the extent of reinforcement are similar because of similarities in chemical structure, the large number of OH groups in both reinforcements. Relatively strong interfacial adhesion develops between the components, which renders coupling inefficient. Dissimilar particle characteristics influence local deformation processes considerably. The smaller particle size of starch results in larger debonding stress and thus larger composite strength. The fracture of the bagasse fibers leads to larger energy consumption and to increased impact resistance. Although the environmental benefit of the prepared biocomposites is similar, the overall performance of the bagasse fiber reinforced PLA composites is better than that offered by the PLA/starch composites.
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9
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Wang BW, Liu H, Ying J, Liu CT, Shen CY, Wang YM. Effect of Physical Aging on Heterogeneity of Poly(ε-caprolactone) Toughening Poly(lactic acid) Probed by Nanomechanical Mapping. CHINESE JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1007/s10118-022-2806-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Orellana-Barrasa J, Ferrández-Montero A, Ferrari B, Pastor JY. Natural Ageing of PLA Filaments, Can It Be Frozen? Polymers (Basel) 2022; 14:polym14163361. [PMID: 36015618 PMCID: PMC9416607 DOI: 10.3390/polym14163361] [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: 05/25/2022] [Revised: 07/08/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
The physical ageing of polylactic acid (PLA) is a phenomenon that changes the material’s properties over time. This ageing process is highly dependent on ambient variables, such as temperature and humidity. For PLA, the ageing is noticeable even at room temperatures, a process commonly referred to as natural ageing. Stopping the ageing by freezing the material can be helpful to preserve the properties of the PLA and stabilise it at any time during its storage until it is required for testing. However, it is essential to demonstrate that the PLA’s mechanical properties are not degraded after defrosting the samples. Four different methods for stopping the ageing (anti-ageing processes) are analysed in this paper—all based on freezing and defrosting the PLA samples. We determine the temperature and ambient water vapor influence during the freezing and defrosting process using desiccant and zip bags. The material form selected is PLA filaments (no bulk material or scaffold structures) printed at 190 °C with diameters between 400 and 550 µm and frozen at −24 °C in the presence or absence of a desiccant. The impact of the anti-ageing processes on PLA’s ageing and mechanical integrity is studied regarding the thermal, mechanical and fractographical properties. In conclusion, an anti-ageing process is defined to successfully stop the natural ageing of the PLA for an indefinite length of time. This process does not affect the mechanical properties or the structural integrity of the PLA. As a result, large quantities of this material can be produced in a single batch and be safely stored to be later characterised under the same manufacturing and ageing conditions, which is currently a limiting factor from an experimental point of view as polymeric filament properties can show significant variety from batch to batch.
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Affiliation(s)
- Jaime Orellana-Barrasa
- Centro de Investigación en Materiales Estructurales (CIME), Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Correspondence:
| | | | - Begoña Ferrari
- Instituto de Cerámica y Vidrio (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - José Ygnacio Pastor
- Centro de Investigación en Materiales Estructurales (CIME), Universidad Politécnica de Madrid, 28040 Madrid, Spain
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11
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Bayart M, Dubus M, Charlon S, Kerdjoudj H, Baleine N, Benali S, Raquez JM, Soulestin J. Pellet-Based Fused Filament Fabrication (FFF)-Derived Process for the Development of Polylactic Acid/Hydroxyapatite Scaffolds Dedicated to Bone Regeneration. MATERIALS (BASEL, SWITZERLAND) 2022; 15:ma15165615. [PMID: 36013752 PMCID: PMC9415795 DOI: 10.3390/ma15165615] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/29/2022] [Accepted: 08/08/2022] [Indexed: 05/10/2023]
Abstract
Scaffolds can be defined as 3D architectures with specific features (surface properties, porosity, rigidity, biodegradability, etc.) that help cells to attach, proliferate, and to differentiate into specific lineage. For bone regeneration, rather high mechanical properties are required. That is why polylactic acid (PLA) and PLA/hydroxyapatite (HA) scaffolds (10 wt.%) were produced by a peculiar fused filament fabrication (FFF)-derived process. The effect of the addition of HA particles in the scaffolds was investigated in terms of morphology, biological properties, and biodegradation behavior. It was found that the scaffolds were biocompatible and that cells managed to attach and proliferate. Biodegradability was assessed over a 5-month period (according to the ISO 13781-Biodegradability norm) through gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and compression tests. The results revealed that the presence of HA in the scaffolds induced a faster and more complete polymer biodegradation, with a gradual decrease in the molar mass (Mn) and compressive mechanical properties over time. In contrast, the Mn of PLA only decreased during the processing steps to obtain scaffolds (extrusion + 3D-printing) but PLA scaffolds did not degrade during conditioning, which was highlighted by a high retention of the mechanical properties of the scaffolds after conditioning.
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Affiliation(s)
- Marie Bayart
- Centre for Materials and Processes, IMT Nord Europe, Institut Mines-Télécom, University of Lille, F-59000 Lille, France
| | - Marie Dubus
- Biomatériaux et Inflammation en Site Osseux (BIOS) EA 4691 & UFR d’Odontologie, Université de Reims Champagne-Ardenne, F-51100 Reims, France
| | - Sébastien Charlon
- Centre for Materials and Processes, IMT Nord Europe, Institut Mines-Télécom, University of Lille, F-59000 Lille, France
- Correspondence:
| | - Halima Kerdjoudj
- Biomatériaux et Inflammation en Site Osseux (BIOS) EA 4691 & UFR d’Odontologie, Université de Reims Champagne-Ardenne, F-51100 Reims, France
| | - Nicolas Baleine
- Center of Innovation and Research in Materials and Polymers (CIRMAP), Laboratory of Polymeric and Composite Materials, University of Mons (UMons), Place du Parc 20, 7000 Mons, Belgium
| | - Samira Benali
- Center of Innovation and Research in Materials and Polymers (CIRMAP), Laboratory of Polymeric and Composite Materials, University of Mons (UMons), Place du Parc 20, 7000 Mons, Belgium
| | - Jean-Marie Raquez
- Center of Innovation and Research in Materials and Polymers (CIRMAP), Laboratory of Polymeric and Composite Materials, University of Mons (UMons), Place du Parc 20, 7000 Mons, Belgium
| | - Jérémie Soulestin
- Centre for Materials and Processes, IMT Nord Europe, Institut Mines-Télécom, University of Lille, F-59000 Lille, France
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A facile strategy for preparation of strong tough poly(lactic acid) foam with a unique microfibrillated bimodal micro/nano cellular structure. Int J Biol Macromol 2022; 199:264-274. [PMID: 34999040 DOI: 10.1016/j.ijbiomac.2021.12.187] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/12/2021] [Accepted: 12/29/2021] [Indexed: 12/13/2022]
Abstract
This work reports the design and fabrication of strong tough poly(lactic acid) (PLA) foam by combining pressure-induced-flow (PIF) processing with supercritical CO2 foaming. PIF processing widened the foaming window of PLA to 40-120 °C, while supercritical CO2 foaming released the undesired internal stress of PLA samples with PIF processing (P-PLA). The prepared PLA foams displayed a unique microfibrillated bimodal micro/nano cellular structure which is strongly affected by saturation temperature (Ts). Both micron and nano cells showed decreasing cells size and increasing cell density as Ts elevated. The orientation factor as well as internal stress of PLA foams decreased with increased Ts. Compared with P-PLA samples, PLA foam prepared at Ts of 40 °C showed negligible reduction of orientation from 0.45 to 0.41 and release of internal stress characterized by the rightward shift of Raman peak (stretching vibration of CO bond from 1763 to 1766 cm-1). Furthermore, PLA foam prepared at Ts of 40 °C presented excellent impact strength (32.3 kJ/m2), tensile strength (42.0 MPa), and ductility (14.2%). The combination of PIF processing and supercritical CO2 foaming provides a facile and effective method to prepare strong tough PLA foam that has immense potential in biomedical, aerospace, automotive, and other structural applications.
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13
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Starkova O, Gagani AI, Karl CW, Rocha IBCM, Burlakovs J, Krauklis AE. Modelling of Environmental Ageing of Polymers and Polymer Composites—Durability Prediction Methods. Polymers (Basel) 2022; 14:polym14050907. [PMID: 35267730 PMCID: PMC8912441 DOI: 10.3390/polym14050907] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/15/2022] [Accepted: 02/21/2022] [Indexed: 02/07/2023] Open
Abstract
Polymers and polymer composites are negatively impacted by environmental ageing, reducing their service lifetimes. The uncertainty of the material interaction with the environment compromises their superior strength and stiffness. Validation of new composite materials and structures often involves lengthy and expensive testing programs. Therefore, modelling is an affordable alternative that can partly replace extensive testing and thus reduce validation costs. Durability prediction models are often subject to conflicting requirements of versatility and minimum experimental efforts required for their validation. Based on physical observations of composite macroproperties, engineering and phenomenological models provide manageable representations of complex mechanistic models. This review offers a systematised overview of the state-of-the-art models and accelerated testing methodologies for predicting the long-term mechanical performance of polymers and polymer composites. Accelerated testing methods for predicting static, creep, and fatig ue lifetime of various polymers and polymer composites under environmental factors’ single or coupled influence are overviewed. Service lifetimes are predicted by means of degradation rate models, superposition principles, and parametrisation techniques. This review is a continuation of the authors’ work on modelling environmental ageing of polymer composites: the first part of the review covered multiscale and modular modelling methods of environmental degradation. The present work is focused on modelling engineering mechanical properties.
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Affiliation(s)
- Olesja Starkova
- Institute for Mechanics of Materials, University of Latvia, Jelgavas 3, LV-1004 Riga, Latvia;
- Correspondence:
| | - Abedin I. Gagani
- Siemens Digital Industries Software, Via Werner von Siemens 1, 20128 Milan, Italy;
| | | | - Iuri B. C. M. Rocha
- Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands;
| | - Juris Burlakovs
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 5 Kreutzwaldi St., 51014 Tartu, Estonia;
| | - Andrey E. Krauklis
- Institute for Mechanics of Materials, University of Latvia, Jelgavas 3, LV-1004 Riga, Latvia;
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14
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Beltrán FR, Arrieta MP, Elena Antón D, Lozano-Pérez AA, Cenis JL, Gaspar G, de la Orden MU, Martínez Urreaga J. Effect of Yerba Mate and Silk Fibroin Nanoparticles on the Migration Properties in Ethanolic Food Simulants and Composting Disintegrability of Recycled PLA Nanocomposites. Polymers (Basel) 2021; 13:polym13121925. [PMID: 34200571 PMCID: PMC8230047 DOI: 10.3390/polym13121925] [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: 05/16/2021] [Revised: 05/28/2021] [Accepted: 06/05/2021] [Indexed: 11/29/2022] Open
Abstract
The main objective of the present research is to study the effect of the incorporation of low amounts of silk fibroin nanoparticles (SFNs) and yerba mate nanoparticles (YMNs) on the migration phenomenon into ethanolic food simulants as well as on the disintegrability under composting conditions of mechanically recycled polylactic acid (PLA). Recycled PLA was obtained under simulated recycling conditions by melt processing virgin PLA into films and further subjecting them to an accelerated aging process, which involved photochemical, thermal, and hydrothermal aging steps followed by an intense washing step. SFNs were extracted from Bombyx mori cocoons and YMNs from yerba mate waste. Then, recycled PLA was melted, reprocessed, and reinforced with either 1%wt. of SFNs or YMNs, by melt extrusion, and further processed into films by compression molding. The obtained nanocomposites were exposed to ethanolic food simulants (ethanol 10% v/v, simulant A and ethanol 50% v/v, simulant D1) and the structural, thermal, and mechanical properties were studied before and after the exposure to the food simulants. The migration levels in both food simulants were below the overall migration limits required for food contact materials. The materials were disintegrated under simulated composting conditions at the laboratory scale level and it was observed that the nanoparticles delayed the disintegration rate of the recycled PLA matrix, but nanocomposites were fully disintegrated in less than one month.
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Affiliation(s)
- Freddys R. Beltrán
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Universidad Politécnica de Madrid, E.T.S.I. Industriales, 28006 Madrid, Spain; (F.R.B.); (D.E.A.); (G.G.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), Madrid, Spain;
| | - Marina P. Arrieta
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Universidad Politécnica de Madrid, E.T.S.I. Industriales, 28006 Madrid, Spain; (F.R.B.); (D.E.A.); (G.G.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), Madrid, Spain;
- Correspondence: ; Tel.: +34-910-677-301
| | - Diego Elena Antón
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Universidad Politécnica de Madrid, E.T.S.I. Industriales, 28006 Madrid, Spain; (F.R.B.); (D.E.A.); (G.G.); (J.M.U.)
| | - Antonio A. Lozano-Pérez
- Depertamento de Biotecnología, Genómica y Mejora Vegetal, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), 30150 Murcia, Spain; (A.A.L.-P.); (J.L.C.)
| | - José L. Cenis
- Depertamento de Biotecnología, Genómica y Mejora Vegetal, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), 30150 Murcia, Spain; (A.A.L.-P.); (J.L.C.)
| | - Gerald Gaspar
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Universidad Politécnica de Madrid, E.T.S.I. Industriales, 28006 Madrid, Spain; (F.R.B.); (D.E.A.); (G.G.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), Madrid, Spain;
| | - María U. de la Orden
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), Madrid, Spain;
- Deparamento de Química Orgánica, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - Joaquín Martínez Urreaga
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Universidad Politécnica de Madrid, E.T.S.I. Industriales, 28006 Madrid, Spain; (F.R.B.); (D.E.A.); (G.G.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), Madrid, Spain;
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Beltrán FR, Arrieta MP, Moreno E, Gaspar G, Muneta LM, Carrasco-Gallego R, Yáñez S, Hidalgo-Carvajal D, de la Orden MU, Martínez Urreaga J. Evaluation of the Technical Viability of Distributed Mechanical Recycling of PLA 3D Printing Wastes. Polymers (Basel) 2021; 13:1247. [PMID: 33921369 PMCID: PMC8069463 DOI: 10.3390/polym13081247] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 02/07/2023] Open
Abstract
3D printing PLA wastes were recovered from a well-known reference grade and from different sources. The recovered wastes were subjected to an energic washing step and then reprocessed into films by melt-extrusion, followed by compression molding to simulate the industrial processing conditions. The obtained materials were characterized and the optical, structural, thermal and crystallization behavior are reported. The mechanical recycling process leads to an increase of the crystallinity and a decrease of the intrinsic viscosity of the formulations, particularly in the sample based on blends of different 3D-PLA wastes. Moreover, the obtained films were disintegrated under composting conditions in less than one month and it was observed that recycled materials degrade somewhat faster than the starting 3D-PLA filament, as a consequence of the presence of shorter polymer chains. Finally, to increase the molecular weight of the recycled materials, the 3D-PLA wastes were submitted to a solid-state polymerization process at 110, 120, and 130 °C, observing that the recycled 3D-wastes materials based on a well-known reference grade experiences an improvement of the intrinsic viscosity, while that coming from different sources showed no significant changes. Thus, the results show that 3D printing PLA products provides an ideal environment for the implementation of distributed recycling program, in which wastes coming from well-known PLA grades can successfully be processed in films with good overall performance.
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Affiliation(s)
- Freddys R. Beltrán
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), 28012 Madrid, Spain;
| | - Marina P. Arrieta
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), 28012 Madrid, Spain;
| | - Eduardo Moreno
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
| | - Gerald Gaspar
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
| | - Luisa M. Muneta
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
| | - Ruth Carrasco-Gallego
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
| | - Susana Yáñez
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
| | - David Hidalgo-Carvajal
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
| | - María U. de la Orden
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), 28012 Madrid, Spain;
- Facultad de Óptica y Optometría, Universidad Complutense de Madrid, 28037 Madrid, Spain
| | - Joaquín Martínez Urreaga
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain; (F.R.B.); (E.M.); (G.G.); (L.M.M.); (R.C.-G.); (S.Y.); (D.H.-C.); (J.M.U.)
- Grupo de Investigación Polímeros Caracterización y Aplicaciones (POLCA), 28012 Madrid, Spain;
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Jariyavidyanont K, Zhuravlev E, Schick C, Androsch R. Kinetics of homogeneous crystal nucleation of polyamide 11 near the glass transition temperature. POLYMER CRYSTALLIZATION 2020. [DOI: 10.1002/pcr2.10149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Katalee Jariyavidyanont
- Interdisciplinary Center for Transfer‐oriented Research in Natural Sciences Martin Luther University Halle‐Wittenberg Halle/Saale Germany
| | | | - Christoph Schick
- Institute of Physics University of Rostock Rostock Germany
- Department of Physical Chemistry Kazan Federal University Kazan Russia
| | - René Androsch
- Interdisciplinary Center for Transfer‐oriented Research in Natural Sciences Martin Luther University Halle‐Wittenberg Halle/Saale Germany
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Impacts of cellulose nanofibril and physical aging on the enthalpy relaxation behavior and dynamic mechanical thermal properties of Poly(lactic acid) composite films. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122677] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Atreya M, Dikshit K, Marinick G, Nielson J, Bruns C, Whiting GL. Poly(lactic acid)-Based Ink for Biodegradable Printed Electronics With Conductivity Enhanced through Solvent Aging. ACS APPLIED MATERIALS & INTERFACES 2020; 12:23494-23501. [PMID: 32326695 DOI: 10.1021/acsami.0c05196] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Biodegradable electronics is a rapidly growing field, and the development of controllably biodegradable, high-conductivity materials suitable for additive manufacturing under ambient conditions remains a challenge. In this report, printable conductive pastes that employ poly(lactic acid) (PLA) as a binder and tungsten as a conductor are demonstrated. These composite conductors can provide enhanced stability in applications where moisture may be present, such as environmental monitoring or agriculture. Post-processing the printed traces using a solvent-aging technique increases their conductivity by up to 2 orders of magnitude, with final conductivities approaching 5000 S/m. Such techniques could prove useful when thermal processes including heating or laser sintering are limited by the temperature constraints of typical biodegradable substrates. Both accelerated oxidative and hydrolytic degradation of the printed composite conductors are examined, and a fully biodegradable capacitive soil moisture sensor is fabricated and tested.
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Affiliation(s)
- Madhur Atreya
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Karan Dikshit
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309 United States
| | - Gabrielle Marinick
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Jenna Nielson
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Carson Bruns
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gregory L Whiting
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309 United States
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Monnier X, Delpouve N, Saiter-Fourcin A. Distinct dynamics of structural relaxation in the amorphous phase of poly(l-lactic acid) revealed by quiescent crystallization. SOFT MATTER 2020; 16:3224-3233. [PMID: 32162627 DOI: 10.1039/c9sm02541c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Fast scanning calorimetry (FSC) experiments were performed to investigate physical aging in amorphous and semi-crystalline poly(l-lactic acid)s (PLLAs) that were thermally crystallized under conditions leading to the α'- or α-crystalline form, and either favouring or inhibiting the development of a rigid amorphous fraction (RAF). The enthalpy of recovery was calculated after two procedures of rescaling to the content of the whole amorphous phase and also to the only content of the mobile amorphous fraction (MAF), which helped in clarifying the contribution of the RAF. From the dependence of the structural relaxation rate on the aging temperature, two regimes were evidenced for all samples. In the aging temperature domain situated close to the glass transition, the structural relaxation occurs significantly faster in the MAF. Its rate is independent of the aging temperature and is not influenced by the microstructure. However, the distance to equilibrium is higher in samples for which the coupling is strong between crystal and amorphous, implying that the time to reach equilibrium is also higher. In contrast, at low aging temperatures, for which the whole amorphous phase can be considered as solid, MAF and RAF exhibit the same structrural relaxation rate. This convergence in the relaxation kinetics by decreasing the temperature of physical aging was interpreted as the evolution of relaxation dynamics in the MAF from segmental to local. This change is highlighted by the comparison between MAF and RAF relaxation kinetics, but it occurs similarly in a pure amorphous system.
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Affiliation(s)
- Xavier Monnier
- Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux, 76000 Rouen, France.
| | - Nicolas Delpouve
- Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux, 76000 Rouen, France.
| | - Allisson Saiter-Fourcin
- Normandie Univ, UNIROUEN Normandie, INSA Rouen, CNRS, Groupe de Physique des Matériaux, 76000 Rouen, France.
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