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Chinga-Carrasco, GaryORCID iD iconorcid.org/0000-0002-6183-2017
Publications (10 of 97) Show all publications
Chiulan, I., Panaitescu, D. M., Radu, E.-R. -., Frone, A. N., Gabor, R. A., Nicolae, C. A., . . . Chinga-Carrasco, G. (2020). Comprehensive characterization of silica-modified silicon rubbers. Journal of The Mechanical Behavior of Biomedical Materials, 101, Article ID 103427.
Open this publication in new window or tab >>Comprehensive characterization of silica-modified silicon rubbers
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2020 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 101, article id 103427Article in journal (Refereed) Published
Abstract [en]

In this study a commercially liquid silicone rubber was filled with fumed silica particles in different concentrations and evaluated for medical applications. The thermal, morphological and mechanical properties of silicone/silica composite samples were studied before and after aging, flexural tests and immersion in saline environment. Understanding the effect of silica content, aging conditions and thickness (from 0.6 to 2 mm) of the samples on the behavior of these materials in different environments is crucial for applications as implantable devices. Before inducing any mechanical stress, tensile strength was found to increase for samples containing 3 or 5 wt% of fumed silica, depending on the thickness. A similar trend was observed after 106 flexes for tensile strength, storage modulus and hardness at room temperature, which increased with the concentration of fumed silica. Moreover, tensile strength decreased with increasing the thickness of the samples from 0.6 to 2 mm. The thermal degradation was found to start at higher temperature in the case of the composites as compared with neat silicone, however, the glass transition and melting temperatures were only slightly modified by the presence of the silica particles, regardless the mechanical aging. The MTT assay using L929 fibroblasts mouse cells showed a good short-time cytocompatibility for both silicone elastomer and the composite with 3 wt% fumed silica. Similarly, the measurement of the cytokine secretion revealed no inflammatory response.

Place, publisher, year, edition, pages
Elsevier Ltd, 2020
Keywords
Cell culture, Glass transition, Implants (surgical), Medical applications, Rubber, Rubber applications, Silica, Silicon, Silicon rubber, Silicone rubber, Cytokine secretions, Fumed silica particles, Implantable devices, Inflammatory response, Liquid silicone rubbers, Mechanical stress, Saline environment, Silicone elastomers, Tensile strength
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39984 (URN)10.1016/j.jmbbm.2019.103427 (DOI)
Note

Funding details: 283895, MNET17/NMCS-1204; Funding details: 33/2018, COFUND-MANUNET III-MedIn-1; Funding text 1: This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation , CCCDI – UEFISCDI, project number COFUND-MANUNET III-MedIn-1, within PNCDI III, contract no. 33/2018 , and by the Research Council of Norway , Grant: 283895 , through the MedIn project, MNET17/NMCS-1204 – “New functionalized medical devices for surgical interventions in the pelvic cavity”. Appendix A

Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-09Bibliographically approved
Kangas, H., Felissia, F. E., Filgueira, D., Ehman, N. V., Vallejos, M. E., Imlauer, C. M., . . . Chinga-Carrasco, G. (2019). 3D Printing High-Consistency Enzymatic Nanocellulose Obtained from a Soda-Ethanol-O2 Pine Sawdust Pulp.. Bioengineering (Basel, Switzerland), 6(3), Article ID E60.
Open this publication in new window or tab >>3D Printing High-Consistency Enzymatic Nanocellulose Obtained from a Soda-Ethanol-O2 Pine Sawdust Pulp.
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2019 (English)In: Bioengineering (Basel, Switzerland), ISSN 2306-5354, Vol. 6, no 3, article id E60Article in journal (Refereed) Published
Abstract [en]

Soda-ethanol pulps, prepared from a forestry residue pine sawdust, were treated according to high-consistency enzymatic fibrillation technology to manufacture nanocellulose. The obtained nanocellulose was characterized and used as ink for three-dimensional (3D) printing of various structures. It was also tested for its moisture sorption capacity and cytotoxicity, as preliminary tests for evaluating its suitability for wound dressing and similar applications. During the high-consistency enzymatic treatment it was found that only the treatment of the O2-delignified pine pulp resulted in fibrillation into nano-scale. For 3D printing trials, the material needed to be fluidized further. By 3D printing, it was possible to fabricate various structures from the high-consistency enzymatic nanocellulose. However, the water sorption capacity of the structures was lower than previously seen with porous nanocellulose structures, indicating that further optimization of the material is needed. The material was found not to be cytotoxic, thus showing potential as material, e.g., for wound dressings and for printing tissue models.

Keywords
3D printing, cytotoxicity, nanocellulose, pine sawdust, soda ethanol pulping
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39716 (URN)10.3390/bioengineering6030060 (DOI)31315280 (PubMedID)
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-12Bibliographically approved
Silva, F., Gracia, N., McDonagh, B., Domingues, F., Nerín, C. & Chinga-Carrasco, G. (2019). Antimicrobial activity of biocomposite films containing cellulose nanofibrils and ethyl lauroyl arginate. Journal of Materials Science, 54(18), 12159-70
Open this publication in new window or tab >>Antimicrobial activity of biocomposite films containing cellulose nanofibrils and ethyl lauroyl arginate
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2019 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 18, p. 12159-70Article in journal (Refereed) Published
Abstract [en]

Food packaging is tailored to keep food fresh by increasing shelf life and preventing microbial deterioration. However, traditional food packaging is commonly made from non-degradable polymers without antimicrobial properties and that pose an environmental threat if not disposed properly. To address this issue, here we describe the preparation of cellulose nanofibril (CNF) films and hydrogels with antimicrobial activity against common foodborne pathogens such as verotoxigenic E. coli, L. monocytogenes and S. Typhimurium. Furthermore, two grades of negatively charged CNFs with different fibrillation degrees were modified with ethyl lauroyl arginate (LAE), which is an antimicrobial agent. CNF films were able to bind LAE molecules up to a maximum concentration of 145–160 ppm. LAE–CNF biocomposite films exerted a bactericidal activity against a major foodborne pathogen present in ready-to-eat food (L. monocytogenes) even at 1% LAE. Our work describes a novel biopolymer-based strategy that overcomes the current hurdles with LAE incorporation into packaging materials, offering a green and antimicrobial alternative for packaging of ready-to-eat (RTE) meat products. .

Place, publisher, year, edition, pages
Springer New York LLC, 2019
Keywords
Antimicrobial agents, Cellulose, Cellulose films, Composite materials, Deterioration, Escherichia coli, Film preparation, Nanofibers, Packaging, Packaging machines, Packaging materials, Anti-microbial activity, Anti-microbial properties, Bactericidal activity, Cellulose nanofibrils, Environmental threats, Food-borne pathogens, Maximum concentrations, Microbial deterioration, Food microbiology
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39283 (URN)10.1007/s10853-019-03759-3 (DOI)2-s2.0-85067416376 (Scopus ID)
Available from: 2019-06-28 Created: 2019-06-28 Last updated: 2019-07-05Bibliographically approved
Chinga-Carrasco, G., Ehman, N., Filgueira, D., Johansson, J., Vallejos, M., Felissia, F., . . . Area, M. (2019). Bagasse—A major agro-industrial residue as potential resource for nanocellulose inks for 3D printing of wound dressing devices. Additive Manufacturing, 28, 267-274
Open this publication in new window or tab >>Bagasse—A major agro-industrial residue as potential resource for nanocellulose inks for 3D printing of wound dressing devices
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2019 (English)In: Additive Manufacturing, ISSN 2214-8604, Vol. 28, p. 267-274Article in journal (Refereed) Published
Abstract [en]

Sugarcane bagasse, an abundant residue, is usually burned as an energy source. However, provided that appropriate and sustainable pulping and fractionation processes are applied, bagasse can be utilized as a main source of cellulose nanofibrils (CNF). We explored in this study the production of CNF inks for 3D printing by direct-ink-writing technology. The CNF were tested against L929 fibroblasts cell line and we confirmed that the CNF from soda bagasse fibers were found not to have a cytotoxic potential. Additionally, we demonstrated that the alginate and Ca 2+ caused significant dimensional changes to the 3D printed constructs. The CNF-alginate grids exhibited a lateral expansion after printing and then shrank due to the cross-linking with the Ca 2+ . The release of Ca 2+ from the CNF and CNF-alginate constructs was quantified thus providing more insight about the CNF as carrier for Ca 2+ . This, combined with 3D printing, offers potential for personalized wound dressing devices, i.e. tailor-made constructs that can be adapted to a specific shape, depending on the characteristics of the wound healing treatment.

Place, publisher, year, edition, pages
Elsevier B.V., 2019
Keywords
3D printing, Alginate, Bagasse, Biomaterials, Nanocellulose, Scaffolds, Calcium compounds, Cell culture, Cellulose, Scaffolds (biology), 3-D printing, Agro-industrial residue, Cellulose nanofibrils, Dimensional changes, Fractionation process, Potential resources, Sugar-cane bagasse, Wound-healing treatment, 3D printers
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38888 (URN)10.1016/j.addma.2019.05.014 (DOI)2-s2.0-85065648577 (Scopus ID)
Note

Funding details: Universidad Nacional de Asunción; Funding details: Consejo Nacional de Investigaciones Científicas y Técnicas; Funding details: Norges Forskningsråd, 271054; Funding text 1: This work has been funded by the ValBio-3D project (Grant ELAC2015/T03-0715 Valorization of residual biomass for advanced 3D materials; Research Council of Norway , Grant no. 271054). The authors acknowledge the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and the Universidad Nacional de Misiones (Argentina) for the financial support. Thanks to Mirjana Filipovic, Ingebjørg Leirset and Anne Marie Reitan (RISE PFI) for laboratory analyses.

Available from: 2019-06-03 Created: 2019-06-03 Last updated: 2019-06-03Bibliographically approved
Jack, A. A., Nordli, H. R., Powell, L. C., Farnell, D. J., Pukstad, B., Rye, P. D., . . . Hill, K. E. (2019). Cellulose Nanofibril Formulations Incorporating a Low-Molecular-Weight Alginate Oligosaccharide Modify Bacterial Biofilm Development.. Biomacromolecules
Open this publication in new window or tab >>Cellulose Nanofibril Formulations Incorporating a Low-Molecular-Weight Alginate Oligosaccharide Modify Bacterial Biofilm Development.
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2019 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed) Epub ahead of print
Abstract [en]

Cellulose nanofibrils (CNFs) from wood pulp are a renewable material possessing advantages for biomedical applications because of their customizable porosity, mechanical strength, translucency, and environmental biodegradability. Here, we investigated the growth of multispecies wound biofilms on CNF formulated as aerogels and films incorporating the low-molecular-weight alginate oligosaccharide OligoG CF-5/20 to evaluate their structural and antimicrobial properties. Overnight microbial cultures were adjusted to 2.8 × 109 colony-forming units (cfu) mL-1 in Mueller Hinton broth and growth rates of Pseudomonas aeruginosa PAO1 and Staphylococcus aureus 1061A monitored for 24 h in CNF dispersions sterilized by γ-irradiation. Two CNF formulations were prepared (20 g m-2) with CNF as air-dried films or freeze-dried aerogels, with or without incorporation of an antimicrobial alginate oligosaccharide (OligoG CF-5/20) as a surface coating or bionanocomposite, respectively. The materials were structurally characterized by scanning electron microscopy (SEM) and laser profilometry (LP). The antimicrobial properties of the formulations were assessed using single- and mixed-species biofilms grown on the materials and analyzed using LIVE/DEAD staining with confocal laser scanning microscopy (CLSM) and COMSTAT software. OligoG-CNF suspensions significantly decreased the growth of both bacterial strains at OligoG concentrations >2.58% (P < 0.05). SEM showed that aerogel-OligoG bionanocomposite formulations had a more open three-dimensional structure, whereas LP showed that film formulations coated with OligoG were significantly smoother than untreated films or films incorporating PEG400 as a plasticizer (P < 0.05). CLSM of biofilms grown on films incorporating OligoG demonstrated altered biofilm architecture, with reduced biomass and decreased cell viability. The OligoG-CNF formulations as aerogels or films both inhibited pyocyanin production (P < 0.05). These novel CNF formulations or bionanocomposites were able to modify bacterial growth, biofilm development, and virulence factor production in vitro. These data support the potential of OligoG and CNF bionanocomposites for use in biomedical applications where prevention of infection or biofilm growth is required.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39720 (URN)10.1021/acs.biomac.9b00522 (DOI)31251598 (PubMedID)
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-12Bibliographically approved
Opedal, M. T., Espinosa, E., Rodríguez, A. & Chinga-Carrasco, G. (2019). Lignin: A biopolymer from forestry biomass for biocomposites and 3D printing. Materials, 12(18), Article ID 3006.
Open this publication in new window or tab >>Lignin: A biopolymer from forestry biomass for biocomposites and 3D printing
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 18, article id 3006Article in journal (Refereed) Published
Abstract [en]

Biopolymers from forestry biomass are promising for the sustainable development of new biobased materials. As such, lignin and fiber-based biocomposites are plausible renewable alternatives to petrochemical-based products. In this study, we have obtained lignin from Spruce biomass through a soda pulping process. The lignin was used for manufacturing biocomposite filaments containing 20% and 40% lignin and using polylactic acid (PLA) as matrix material. Dogbones for mechanical testing were 3D printed by fused deposition modelling. The lignin and the corresponding biocomposites were characterized in detail, including thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis (XRD), antioxidant capacity, mechanical properties, and scanning electron microscopy (SEM). Although lignin led to a reduction of the tensile strength and modulus, the reduction could be counteracted to some extent by adjusting the 3D printing temperature. The results showed that lignin acted as a nucleating agent and thus led to further crystallization of PLA. The radical scavenging activity of the biocomposites increased to roughly 50% antioxidant potential/cm2, for the biocomposite containing 40 wt % lignin. The results demonstrate the potential of lignin as a component in biocomposite materials, which we show are adequate for 3D printing operations. © 2019 by the authors.

Place, publisher, year, edition, pages
MDPI AG, 2019
Keywords
3D printing, Biocomposites, Biopolymers, Lignin, Polylactic acid (PLA), Antioxidants, Biomass, Biomolecules, Composite materials, Differential scanning calorimetry, Forestry, Fourier transform infrared spectroscopy, Fused Deposition Modeling, Gravimetric analysis, Mechanical testing, Petrochemicals, Polyesters, Scanning electron microscopy, Tensile strength, Thermogravimetric analysis, Timber, X ray powder diffraction, 3-D printing, Antioxidant capacity, Antioxidant potential, Bio-composites, Biocomposite materials, Fused deposition modelling, Poly lactic acid, Radical scavenging activity
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39986 (URN)10.3390/ma12183006 (DOI)
Note

 Funding details: 282310; Funding details: FPU14/02278; Funding details: Population Foundation of India, PFI; Funding details: CA17128; Funding details: Ministerio de Ciencia e Innovación, MICINN, CTQ2016-78729-R; Funding text 1: Johnny Kvakland Melb?, Kenneth Aasar?d, Ingebj?rg Leirset and Cornelis van derWijst at RISE PFI are acknowledged for valuable assistance in the laboratory work. Part of this work was funded by the Research Council of Norway through the ALLOC project (grant 282310). The authors thank the COST Action LignoCOST (CA17128) for funding the short-term scientific mission of E.E. at RISE PFI and Spain's DGICyT, MICINN for supporting this research within the framework of the Projects CTQ2016-78729-R and the Spanish Ministry of Science and Education through the National Program FPU (Grant Number FPU14/02278).

Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-09Bibliographically approved
Ottesen, V., Larsson, P. T., Chinga-Carrasco, G., Syverud, K. & Gregersen, Ö. (2019). Mechanical properties of cellulose nanofibril films: effects of crystallinity and its modification by treatment with liquid anhydrous ammonia. Cellulose (London), 26(11), 6615-27
Open this publication in new window or tab >>Mechanical properties of cellulose nanofibril films: effects of crystallinity and its modification by treatment with liquid anhydrous ammonia
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2019 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 11, p. 6615-27Article in journal (Refereed) Published
Abstract [en]

The influence of cellulose crystallinity on mechanical properties of cellulose nano-fibrils (CNF) was investigated. Degree of crystallinity (DoC) was modified using liquid anhydrous ammonia. Such treatment changes crystal allomorph from cellulose I to cellulose III, a change which was reversed by subsequent boiling in water. DoC was measured using solid state nuclear magnetic resonance (NMR). Crystalline index (CI) was also measured using wide angle X-ray scattering (WAXS). Cotton linters were used as the raw material. The cotton linter was ammonia treated prior to fibrillation. Reduced DoC is seen to associate with an increased yield point and decreased Young modulus. Young modulus is here defined as the maximal slope of the stress–strain curves. The association between DoC and Young modulus or DoC and yield point are both statistically significant. We cannot conclude there has been an effect on strainability. While mechanical properties were affected, we found no indication that ammonia treatment affected degree of fibrillation. CNF was also studied in air and liquid using atomic force microscopy (AFM). Swelling of the nanofibers was observed, with a mean diameter increase of 48.9%.

Place, publisher, year, edition, pages
Springer Netherlands, 2019
Keywords
Cellulose nanofibrils, Degree of crystallinity, Mechanical properties, Swelling, Ammonia, Atomic force microscopy, Cellulose, Cellulose films, Chromium compounds, Cotton, Crystallinity, Liquids, Nanofibers, Nuclear magnetic resonance, X ray scattering, Ammonia treatment, Anhydrous ammonia, Cellulose crystallinity, Cotton linters, Crystalline index, Solid-state nuclear magnetic resonance
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39277 (URN)10.1007/s10570-019-02546-2 (DOI)2-s2.0-85067190175 (Scopus ID)
Available from: 2019-07-03 Created: 2019-07-03 Last updated: 2019-07-03Bibliographically approved
Espinosa, E., Filgueira, D., Rodríguez, A. & Chinga-Carrasco, G. (2019). Nanocellulose-Based Inks-Effect of Alginate Content on the Water Absorption of 3D Printed Constructs.. Bioengineering (Basel, Switzerland), 6(3), Article ID E65.
Open this publication in new window or tab >>Nanocellulose-Based Inks-Effect of Alginate Content on the Water Absorption of 3D Printed Constructs.
2019 (English)In: Bioengineering (Basel, Switzerland), ISSN 2306-5354, Vol. 6, no 3, article id E65Article in journal (Refereed) Published
Abstract [en]

2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl2). The effect of two different concentrations of CaCl2 (50 and 100 mM) was studied. The 3D printed hydrogels were freeze-dried to produce aerogels which were tested for water absorption. Scanning Electronic Microscopy (SEM) pictures demonstrated that the higher the concentration of the cross-linker the higher the definition of the printed tracks. CNF-based aerogels showed a remarkable water absorption capability. Although the incorporation of alginate and the cross-linking with CaCl2 led to shrinkage of the 3D printed constructs, the approach yielded suitable porous structures for water and moisture absorption. It is concluded that the 3D printed biocomposite structures developed in this study have characteristics that are promising for wound dressings devices.

Keywords
3D printing, absorption, nanocellulose, wound dressings
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39712 (URN)10.3390/bioengineering6030065 (DOI)31366050 (PubMedID)
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-12Bibliographically approved
Espinosa, E., Bascón-Villegas, I., Rosal, A., Pérez-Rodríguez, F., Chinga-Carrasco, G. & Rodríguez, A. (2019). PVA/(ligno)nanocellulose biocomposite films. Effect of residual lignin content on structural, mechanical, barrier and antioxidant properties. International Journal of Biological Macromolecules, 141, 197-206
Open this publication in new window or tab >>PVA/(ligno)nanocellulose biocomposite films. Effect of residual lignin content on structural, mechanical, barrier and antioxidant properties
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2019 (English)In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 141, p. 197-206Article in journal (Refereed) Published
Abstract [en]

Nanocelluloses with and without residual lignin were isolated from wheat straw. In addition, the effect of TEMPO-mediated oxidation on the production of lignin-containing nanocellulose was studied. The different nanocelluloses were used as reinforcing agent in Poly(vinyl alcohol) films. The morphology, crystallinity, surface microstructure, barrier properties, light transmittance, mechanical and antioxidant properties were evaluated. The translucency of films was reduced by the addition of nanocellulose, however, the ability to block UV-light increased from 10% for PVA to >50% using lignin-containing nanocellulose, and 30% for lignin-free samples. The mechanical properties increased considerably, however, for loads higher than 5% a negative trend was observed presumptively due to a clustering of nanocellulose components in PVA matrix. The barrier properties of the films were improved with the use of nanocellulose, especially at small amounts (1–3%). The antioxidant capacity of films was increased up to 10% using lignin-containing nanocellulose compared to 4.7% using PVA. © 2019 Elsevier B.V.

Place, publisher, year, edition, pages
Elsevier B.V., 2019
Keywords
Biocomposite films, Lignin effect, Nanocellulose
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39937 (URN)10.1016/j.ijbiomac.2019.08.262 (DOI)2-s2.0-85071834076 (Scopus ID)
Note

Funding details: FPU14/02278; Funding details: Universidad de Córdoba; Funding details: Ministerio de Ciencia e Innovación, MICINN, CTQ2016-78729-R; Funding text 1: The authors are grateful to Spain's DGICyT, MICINN for funding this research within the framework of the Projects CTQ2016-78729-R and supported by the Spanish Ministry of Science and Education through the National Program FPU (Grant Number FPU14/02278 ), and also to the staff of the Central Service for Research Support (SCAI) at the University of Córdoba. Appendix A

Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19Bibliographically approved
Heggset, E. B., Strand, B. L., Sundby, K. W., Simon, S., Chinga-Carrasco, G. & Syverud, K. (2019). Viscoelastic properties of nanocellulose based inks for 3D printing and mechanical properties of CNF/alginate biocomposite gels. Cellulose (London) (1), 581-595
Open this publication in new window or tab >>Viscoelastic properties of nanocellulose based inks for 3D printing and mechanical properties of CNF/alginate biocomposite gels
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2019 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 1, p. 581-595Article in journal (Refereed) Published
Abstract [en]

Inks for 3D printing based on cellulose nanofibrils (CNFs) or mixtures of CNFs and either cellulose nanocrystals (CNCs) or alginate were assessed by determining their viscoelastic properties i.e. complex viscosity and storage and loss moduli (G′ and G″). Two types of alginates were used, i.e. from Laminaria hyperborea stipe and Macrocystis pyrifera. Shape fidelity of 3D printed grids were qualitatively evaluated and compared to the viscoelastic properties of the inks. The biocomposite gels containing alginate were post stabilized by crosslinking with Ca2+. Mechanical properties of the crosslinked biocomposite gels were assessed. The complex viscosity, G′ and G″ of CNF suspensions increased when the solid content was increased from 3.5 to 4.0 wt%, but levelled off by further increase in CNF solid content. The complex viscosity at low angular frequency at 4 wt% was as high as 104 Pa·s. This seemed to be the necessary viscosity level for obtaining good shape fidelity of the printed structures for the studied systems. By replacing part of the CNFs with CNCs, the complex viscosity, G′ and G″ were reduced and so was also the shape fidelity of the printed grids. The changes in complex viscosity and moduli when CNFs was replaced with alginate depended on the relative amounts of CNFs/alginate. The type of alginate (from either L. hyp. stipe or M. pyr.) did not play a role for the viscoelastic properties of the inks, nor for the printed grids before post stabilization. Replacing CNFs with up to 1.5 wt% alginate gave satisfactory shape fidelity. The effect of adding alginate and subsequent crosslinking with Ca2+, strongly affected the strength properties of the gels. By appropriate choice of relative amounts of CNFs and alginate and type of alginate, the Young’s modulus and rupture strength could be controlled within the range of 30–150 kPa and 1.5–6 kg, respectively. The deformation at rupture was around 55%. The alginate from L. hyp. stipe yields higher Young’s modulus and lower syneresis compared to M. pyr. This shows that the choice of alginate plays a significant role for the mechanical properties of the final product, although it does not influence on the viscoelastic properties of the ink. The choice of alginate should be L. hyp. stipe if high strength is desired.

Keywords
Alginate, Cellulose, Cellulose derivatives, Composite materials, Hydrogels, Mechanical properties, Nanocellulose, Rheology, Suspensions, Viscoelasticity, Viscosity, 3-D printing
National Category
Nano Technology Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:ri:diva-36660 (URN)10.1007/s10570-018-2142-3 (DOI)2-s2.0-85057032463 (Scopus ID)
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2019-03-06Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6183-2017

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