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Gonçalves LFFF, Reis RL, Fernandes EM. Forefront Research of Foaming Strategies on Biodegradable Polymers and Their Composites by Thermal or Melt-Based Processing Technologies: Advances and Perspectives. Polymers (Basel) 2024; 16:1286. [PMID: 38732755 PMCID: PMC11085284 DOI: 10.3390/polym16091286] [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: 01/12/2024] [Revised: 04/13/2024] [Accepted: 04/26/2024] [Indexed: 05/13/2024] Open
Abstract
The last few decades have witnessed significant advances in the development of polymeric-based foam materials. These materials find several practical applications in our daily lives due to their characteristic properties such as low density, thermal insulation, and porosity, which are important in packaging, in building construction, and in biomedical applications, respectively. The first foams with practical applications used polymeric materials of petrochemical origin. However, due to growing environmental concerns, considerable efforts have been made to replace some of these materials with biodegradable polymers. Foam processing has evolved greatly in recent years due to improvements in existing techniques, such as the use of supercritical fluids in extrusion foaming and foam injection moulding, as well as the advent or adaptation of existing techniques to produce foams, as in the case of the combination between additive manufacturing and foam technology. The use of supercritical CO2 is especially advantageous in the production of porous structures for biomedical applications, as CO2 is chemically inert and non-toxic; in addition, it allows for an easy tailoring of the pore structure through processing conditions. Biodegradable polymeric materials, despite their enormous advantages over petroleum-based materials, present some difficulties regarding their potential use in foaming, such as poor melt strength, slow crystallization rate, poor processability, low service temperature, low toughness, and high brittleness, which limits their field of application. Several strategies were developed to improve the melt strength, including the change in monomer composition and the use of chemical modifiers and chain extenders to extend the chain length or create a branched molecular structure, to increase the molecular weight and the viscosity of the polymer. The use of additives or fillers is also commonly used, as fillers can improve crystallization kinetics by acting as crystal-nucleating agents. Alternatively, biodegradable polymers can be blended with other biodegradable polymers to combine certain properties and to counteract certain limitations. This work therefore aims to provide the latest advances regarding the foaming of biodegradable polymers. It covers the main foaming techniques and their advances and reviews the uses of biodegradable polymers in foaming, focusing on the chemical changes of polymers that improve their foaming ability. Finally, the challenges as well as the main opportunities presented reinforce the market potential of the biodegradable polymer foam materials.
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Affiliation(s)
- Luis F. F. F. Gonçalves
- 3B’s Research Group, I3Bs–Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, Zona Industrial da Gandra, Barco, 4805-017 Guimarães, Portugal;
- ICVS/3B’s—PT Government Associate Laboratory, Barco, 4805-017 Guimarães, Portugal
| | - Rui L. Reis
- 3B’s Research Group, I3Bs–Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, Zona Industrial da Gandra, Barco, 4805-017 Guimarães, Portugal;
- ICVS/3B’s—PT Government Associate Laboratory, Barco, 4805-017 Guimarães, Portugal
| | - Emanuel M. Fernandes
- 3B’s Research Group, I3Bs–Research Institute on Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Parque de Ciência e Tecnologia, Zona Industrial da Gandra, Barco, 4805-017 Guimarães, Portugal;
- ICVS/3B’s—PT Government Associate Laboratory, Barco, 4805-017 Guimarães, Portugal
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Brütting C, Dreier J, Bonten C, Altstädt V, Ruckdäschel H. Glass transition of PLA-CO 2 mixtures after solid-state saturation. J CELL PLAST 2022. [DOI: 10.1177/0021955x221144543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Polymer foams offer high sustainable performance in terms of their lightweight potential, insulation and high specific mechanical properties. The foaming of polymers depends on the properties of gas-laden solids or liquids. For foaming in the solid state, the foaming temperature must be higher than the glass transition temperature of the saturated polymer system. Moreover, the knowledge of sorption conditions and thermal properties is crucial for foam formation. In this study, the correlation between the glass transition temperature and the sorption conditions was investigated. This comparison was made by determining the sorption behavior for different pressure levels and the corresponding glass transition temperature using a high-pressure differential scanning calorimetry. The time, pressure and CO2 content were varied. For the first time, the Chow model could be verified for PLA with a coordination number of 3.
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Affiliation(s)
| | - Julia Dreier
- Institut für Kunststofftechnik, University of Stuttgart, Germany
| | - Christian Bonten
- Institut für Kunststofftechnik, University of Stuttgart, Germany
| | - Volker Altstädt
- Department of Polymer Engineering, University Bayreuth, Germany
- Bavarian Polymer Institute and Bayreuth Institute of Macromolecular Research, University of Bayreuth, Germany
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Dippold M, Ruckdäschel H. Influence of pressure-induced temperature drop on the foaming behavior of amorphous polylactide (PLA) during autoclave foaming with supercritical CO2. J Supercrit Fluids 2022. [DOI: 10.1016/j.supflu.2022.105734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Peng K, Mubarak S, Diao X, Cai Z, Zhang C, Wang J, Wu L. Progress in the Preparation, Properties, and Applications of PLA and Its Composite Microporous Materials by Supercritical CO 2: A Review from 2020 to 2022. Polymers (Basel) 2022; 14:polym14204320. [PMID: 36297898 PMCID: PMC9611929 DOI: 10.3390/polym14204320] [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: 09/02/2022] [Revised: 09/22/2022] [Accepted: 10/11/2022] [Indexed: 11/16/2022] Open
Abstract
The development of degradable plastic foams is in line with the current development concept of being pollution free and sustainable. Poly(lactic acid) (PLA) microporous foam with biodegradability, good heat resistance, biocompatibility, and mechanical properties can be successfully applied in cushioning packaging, heat insulation, noise reduction, filtration and adsorption, tissue engineering, and other fields. This paper summarizes and critically evaluates the latest research on preparing PLA microporous materials by supercritical carbon dioxide (scCO2) physical foaming since 2020. This paper first introduces the scCO2 foaming technologies for PLA and its composite foams, discusses the CO2-assisted foaming processes, and analyzes the effects of process parameters on PLA foaming. After that, the paper reviews the effects of modification methods such as chemical modification, filler filling, and mixing on the rheological and crystallization behaviors of PLA and provides an in-depth analysis of the mechanism of PLA foaming behavior to provide theoretical guidance for future research on PLA foaming. Lastly, the development and applications of PLA microporous materials based on scCO2 foaming technologies are prospected.
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Affiliation(s)
- Kangming Peng
- CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007, China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Suhail Mubarak
- Department of Chemical and Biomolecular Engineering, Chonnam National University, Yeosu-si 59626, Jeonnam, Korea
| | - Xuefeng Diao
- Jinyoung (Xiamen) Advanced Materials Technology Co., Ltd., Xiamen 361028, China
| | - Zewei Cai
- CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- College of Chemistry, Fuzhou University, Fuzhou 350116, China
| | - Chen Zhang
- School of Materials and Chemistry Engineering, Minjiang University, Xiyuangong Road No. 200, Fuzhou 350108, China
- Industrial Design Institute, Minjiang University, Xiyuangong Road No. 200, Fuzhou 350108, China
- Correspondence: (C.Z.); (J.W.); (L.W.)
| | - Jianlei Wang
- CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Correspondence: (C.Z.); (J.W.); (L.W.)
| | - Lixin Wu
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
- Correspondence: (C.Z.); (J.W.); (L.W.)
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Investigation of Recycled and Coextruded PLA Filament for Additive Manufacturing. Polymers (Basel) 2022; 14:polym14122407. [PMID: 35745982 PMCID: PMC9227332 DOI: 10.3390/polym14122407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/03/2022] [Accepted: 06/04/2022] [Indexed: 02/04/2023] Open
Abstract
Polylactide acid (PLA) is one of the most used plastics in extrusion-based additive manufacturing (AM). Although it is bio-based and in theory biodegradable, its recyclability for fused filament fabrication (FFF) is limited due to material degradation. To better understand the material's recyclability, blends with different contents of recycled PLA (rPLA) are investigated alongside a coextruded filament comprised of a core layer with high rPLA content and a skin layer from virgin PLA. The goal was to determine whether this coextrusion approach is more efficient than blending rPLA with virgin PLA. Different filaments were extruded and subsequently used to manufacture samples using FFF. While the strength of the individual strands did not decrease significantly, layer adhesion decreased by up to 67%. The coextruded filament was found to be more brittle than its monoextruded counterparts. Additionally, no continuous weld line could be formed between the layers of coextruded material, leading to a decreased tensile strength. However, the coextruded filament proved to be able to save on master batch and colorants, as the outer layer of the filament has the most impact on the part's coloring. Therefore, switching to a coextruded filament could provide economical savings on master batch material.
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Kuhnigk J, Standau T, Dörr D, Brütting C, Altstädt V, Ruckdäschel H. Progress in the development of bead foams – A review. J CELL PLAST 2022. [DOI: 10.1177/0021955x221087603] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
For a long time, the number of available bead foam variants limited to standard polymers which restricted their functionality mainly to packaging, thermal insulation (e.g. in construction) and shock absorption (e.g. in transportation). In particular, standard polymers such as expanded polystyrene, expanded polyethylene and expanded polypropylene were used for components requiring good insulating properties and high energy absorption at low cost. Mainly since the last two decades, new polymer variants have found their way into the world of bead foams and are currently adding further functionalities, such as sustainability, flame retardancy, increased thermal stability and enhanced mechanical performance (e.g. improvements in energy absorption and impact resistance). Versatile fields of application open up, revolutionizing both industry and design sectors. This review article emphasizes the special development progress of new bead foam variants and their processing technologies. Upcoming opportunities of digital methods for modelling and simulation are highlighted.
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Affiliation(s)
- Justus Kuhnigk
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Tobias Standau
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Dominik Dörr
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Christian Brütting
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Volker Altstädt
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
- Bavarian Polymer Institute and Bayreuth Institute of Macromolecular Research, University of Bayreuth, Bayreuth, Germany
| | - Holger Ruckdäschel
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
- Bavarian Polymer Institute and Bayreuth Institute of Macromolecular Research, University of Bayreuth, Bayreuth, Germany
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Albuquerque RQ, Brütting C, Standau T, Ruckdäschel H. A machine learning investigation of low-density polylactide batch foams. E-POLYMERS 2022. [DOI: 10.1515/epoly-2022-0031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Abstract
Developing novel foams with tailored properties is a challenge. If properly addressed, efficient screening can potentially accelerate material discovery and reduce material waste, improving sustainability and efficiency in the development phase. In this work, we address this problem using a hybrid experimental and theoretical approach. Machine learning (ML) models were trained to predict the density of polylactide (PLA) foams based on their processing parameters. The final ML ensemble model was a linear combination of gradient boosting, random forest, kernel ridge, and support vector regression models. Comparison of the actual and predicted densities of PLA systems resulted in a mean absolute error of 30 kg·m−3 and a coefficient of determination (R
2) of 0.94. The final ensemble model was then used to explore the ranges of predicted density in the space of processing parameters (temperature, pressure, and time) and to suggest some parameter sets that could lead to low-density PLA foams. The new PLA foams were produced and showed experimental densities in the range of 36–48 kg·m−3, which agreed well with the corresponding predicted values, which ranged between 38 and 54 kg·m−3. The experimental–theoretical procedure described here could be applied to other materials and pave the way to more sustainable and efficient foam development processes.
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Affiliation(s)
- Rodrigo Q. Albuquerque
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30 , 95447 Bayreuth , Germany
- Neue Materialien Bayreuth GmbH, Gottlieb-Keim-Straße 60 , 95448 Bayreuth , Germany
| | - Christian Brütting
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30 , 95447 Bayreuth , Germany
| | - Tobias Standau
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30 , 95447 Bayreuth , Germany
| | - Holger Ruckdäschel
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30 , 95447 Bayreuth , Germany
- Neue Materialien Bayreuth GmbH, Gottlieb-Keim-Straße 60 , 95448 Bayreuth , Germany
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Jia LJ, Phule AD, Yu Z, Zhang X, Zhang ZX. Ultra-light poly(lactic acid)/SiO 2 aerogel composite foam: A fully biodegradable and full life-cycle sustainable insulation material. Int J Biol Macromol 2021; 192:1029-1039. [PMID: 34673099 DOI: 10.1016/j.ijbiomac.2021.10.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 10/20/2022]
Abstract
In this study, a fully biodegradable ultra-light poly(lactic acid)/silicon dioxide (PLA/SiO2) aerogel nanocomposite with ultra-low thermal conductivity was successfully fabricated. PLA used was a produced from lactic acid, where the lactic acid has been produced from carbohydrates. The rheological properties of PLA were enhanced by diphenylmethane diisocyanate (MDI). The foaming properties, cell density, cell size uniformity, mechanical properties and thermal conductivity and thermal diffusivity of PLA were further improved by SiO2 aerogel, and finally the ultra-low density foamed material was prepared by supercritical CO2. The density of PLA foam can be as low as 0.02 g/cm3 and the thermal conductivity as low as 0.02628 W/m·K. The PLA-based composites can be used in many fields such as thermal insulation, vibration damping and packaging, and can be fully biodegradable and sustainable throughout their life cycle, which meets the global trend of energy saving and emission reduction.
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Affiliation(s)
- Li Jiang Jia
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Ajit Dattatray Phule
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Zhen Yu
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Xin Zhang
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Zhen Xiu Zhang
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science and Technology, Qingdao 266042, China.
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Ferràs-Tarragó J, Sabalza-Baztán O, Sahuquillo-Arce JM, Angulo-Sánchez MÁ, De-La-Calva Ceinos C, Amaya-Valero JV, Baixauli-García F. Autoclave sterilization of an in-house 3D-printed polylactic acid piece: biological safety and heat-induced deformation. Eur J Trauma Emerg Surg 2021; 48:3901-3910. [PMID: 33959787 DOI: 10.1007/s00068-021-01672-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/12/2021] [Indexed: 12/17/2022]
Abstract
AIMS Fused filament fabrication 3D printing with polylactic acid filaments is the most widely used method to generate biomodels at hospitals throughout the world. The main limitation of this manufacturing system is related to the biomodels' temperature sensitivity, which all but prevents them to be sterilized using conventional methods. The purpose of this study is to define an autoclave temperature-resistant FFF-PLA 3D printing protocol to print 3D fractures biomodels during preoperative planning. METHODS AND RESULTS Six different printing protocols were established, each with a different infill percentage. Ten distal radius biomodels were printed with each protocol and each biomodel was subject to 3D scanning. The biomodels were subsequently autoclave-sterilized at 134 °C and subjected to a new scanning process, which was followed by a calculation of changes in area, volume and deformity using the Hausdorff-Besicovitch method. Finally, 192 polylactic acid models were produced using the printing protocol offering the greatest resistance and were contaminated with 31 common nosocomial pathogens to evaluate the effectiveness of sterilizing the model printed using the said protocol. Sterilization resulted in a mean deformation of the biomodel of 0.14 mm, a maximum deformity of 0.75 mm, and a 1% area and a 3.6% volume reduction. Sterilization of the pieces printed using the analyzed protocol was 100% effective. CONCLUSIONS The analyzed 3D printing protocol may be applied with any FFF-PLA 3D printer, it is safe and does not significantly alter the morphology of biomodels. These results indicate that 3D printing is associated with significant advantages for health centers as it increases their autonomy, allowing them to easily produce 3D biomodels that can be used for the treatment of fractures.
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Affiliation(s)
- Joan Ferràs-Tarragó
- Orthopaedic Surgery and Traumatology, Hospital La Fe, Av Fernando Abril Martorell 106, Valencia, Spain.
| | | | | | | | | | - Jose Vicente Amaya-Valero
- Orthopaedic Surgery and Traumatology, Hospital La Fe, Av Fernando Abril Martorell 106, Valencia, Spain
| | - Francisco Baixauli-García
- Orthopaedic Surgery and Traumatology, Hospital La Fe, Av Fernando Abril Martorell 106, Valencia, Spain
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Standau T, Nofar M, Dörr D, Ruckdäschel H, Altstädt V. A Review on Multifunctional Epoxy-Based Joncryl® ADR Chain Extended Thermoplastics. POLYM REV 2021. [DOI: 10.1080/15583724.2021.1918710] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Tobias Standau
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Mohammadreza Nofar
- Metallurgical and Materials Engineering, Department Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, Maslak, Istanbul, Turkey
- Polymer Science and Technology Program, Institute of Science and Technology, Istanbul Technical University, Maslak, Istanbul, Turkey
| | - Dominik Dörr
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Holger Ruckdäschel
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
| | - Volker Altstädt
- Department of Polymer Engineering, University of Bayreuth, Bayreuth, Germany
- Bavarian Polymer Institute and Bayreuth Institute of Macromolecular Research, University of Bayreuth, Bayreuth, Germany
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Special Issue: Structure, Properties and Applications of Polymeric Foams. MATERIALS 2021; 14:ma14061474. [PMID: 33802980 PMCID: PMC8002667 DOI: 10.3390/ma14061474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 03/16/2021] [Indexed: 11/30/2022]
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12
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Ferràs-Tarragó J, Sabalza-Baztán O, Sahuquillo-Arce JM, Angulo-Sánchez MÁ, Amaya-Valero J, De-La-Calva Ceinos C, Baixauli-García F. Security of 3D-printed polylactide acid piece sterilization in the operating room: a sterility test. Eur J Trauma Emerg Surg 2021; 48:3895-3900. [PMID: 33452547 DOI: 10.1007/s00068-020-01564-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022]
Abstract
INTRODUCTION 3D-printing technology has become very popular the last 10 years, and their advantages have been widely proved. However, its safety in the operating room after sterilization has not been evaluated. Thus, the use of 3D printing is still questioned. The aim of this work is to evaluate the security of polylactic acid (PLA) to print surgical models after its sterilization. MATERIALS AND METHODS One hundred and eighty-six PLA plates and 6 negative controls without microorganisms were seeded. After 10 days of culture, the PLA plates were randomized into three groups: A, B, and C. Group A underwent a sterilization process using an autoclave program at 134 °C. Group B was seeded in different culture media and group C was used to make crystal violet stains on the biofilms formed on the PLA. Mechanical properties of PLA after autoclave sterilization including, the breaking load, deformation and breaking load per surface were calculated. RESULTS Hundred percent of the group B showed monomicrobial growth. Stains performed on group C PLA showed biofilms in all PLA pieces. After sterilization, no pathogen growth was observed in group A during the culture observation period showing 100% sterilization effectiveness. A filling percentage of 5% obtained a breaking load of 6.36 MPa, and its elastic limit occurred after an elongation of 167.4%. A 10% infill was mechanically safe. CONCLUSIONS Autoclave sterilization of PLA-printed pieces is safe for the patient and mechanically strong for the surgeon. This is the first 3D-printing protocol described and evaluated to implement 3D-printing technology safely in the operating room. SIGNIFICANCE AND IMPACT OF STUDY This is the first 3D-printing protocol described to print and sterilize 3D biomodels using an autoclave showing its biological safety and its mechanical resistance.
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Affiliation(s)
- Joan Ferràs-Tarragó
- Orthopaedic Surgery and Traumatology. Hospital La Fe, Av Fernando Abril Martorell 106, Valencia, Spain.
| | | | | | | | - Jose Amaya-Valero
- Orthopaedic Surgery and Traumatology. Hospital La Fe, Av Fernando Abril Martorell 106, Valencia, Spain
| | | | - Francisco Baixauli-García
- Orthopaedic Surgery and Traumatology. Hospital La Fe, Av Fernando Abril Martorell 106, Valencia, Spain
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Dörr D, Standau T, Murillo Castellón S, Bonten C, Altstädt V. Rheology in the Presence of Carbon Dioxide (CO 2) to Study the Melt Behavior of Chemically Modified Polylactide (PLA). Polymers (Basel) 2020; 12:polym12051108. [PMID: 32414010 PMCID: PMC7285241 DOI: 10.3390/polym12051108] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/06/2020] [Accepted: 05/12/2020] [Indexed: 11/21/2022] Open
Abstract
For the preparation of polylactide (PLA)-based foams, it is commonly necessary to increase the melt strength of the polymer. Additives such as chain extenders (CE) or peroxides are often used to build up the molecular weight by branching or even crosslinking during reactive extrusion. Furthermore, a blowing agent with a low molecular weight, such as carbon dioxide (CO2), is introduced in the foaming process, which might affect the reactivity during extrusion. Offline rheological tests can help to measure and better understand the kinetics of the reaction, especially the reaction between the polymer and the chemical modifier. However, rheological measurements are mostly done in an inert nitrogen atmosphere without an equivalent gas loading of the polymer melt, like during the corresponding reactive extrusion process. Therefore, the influence of the blowing agent itself is not considered within these standard rheological measurements. Thus, in this study, a rheometer equipped with a pressure cell is used to conduct rheological measurements of neat and chemical-modified polymers in the presence of CO2 at pressures up to 40 bar. The specific effects of CO2 at elevated pressure on the reactivity between the polymer and the chemical modifiers (an organic peroxide and as second choice, an epoxy-based CE) were investigated and compared. It could be shown in the rheological experiments that the reactivity of the chain extender is reduced in the presence of CO2, while the peroxide is less affected. Finally, it was possible to detect the recrystallization temperature Trc of the unmodified and unbranched sample by the torque maximum in the rheometer, representing the tear off of the stamp from the sample. Trc was about 13 K lower in the CO2-loaded sample. Furthermore, it was possible to detect the influences of branching and gas loading simultaneously. Here the influence of the branching on Trc was much higher in comparison to a gas loading.
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Affiliation(s)
- Dominik Dörr
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany; (D.D.); (T.S.)
| | - Tobias Standau
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany; (D.D.); (T.S.)
| | - Svenja Murillo Castellón
- Institut für Kunststofftechnik, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany; (S.M.C.); (C.B.)
| | - Christian Bonten
- Institut für Kunststofftechnik, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany; (S.M.C.); (C.B.)
| | - Volker Altstädt
- Department of Polymer Engineering, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany; (D.D.); (T.S.)
- Bavarian Polymer Institute, Universitätsstraße 30, 95447 Bayreuth, Germany
- Correspondence: ; Tel.: +49-921-55-7471
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