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Vadivel, H. S., Al-Maqdasi, Z., Pupure, L., Joffe, R., Kalin, M. & Emami, N. (2022). Time-dependent properties of newly developed multiscale UHMWPE composites. Polymer testing, 105, Article ID 107400.
Open this publication in new window or tab >>Time-dependent properties of newly developed multiscale UHMWPE composites
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2022 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 105, article id 107400Article in journal (Refereed) Published
Abstract [en]

Ultra-high molecular-weight polyethylene (UHMWPE) composites reinforced with Graphene Oxide (GO), Nanodiamonds (ND), and Short Carbon Fibres (SCF) are characterised for their mechanical performance in tensile and short-term creep tests. A methodology to separate and analyse the materials’ viscoelastic (VE) and viscoplastic (VP) responses is applied and evaluated. The results show a clear dependence of the performance on size scale/morphology of the reinforcements. All composites show time-dependent VP responses that can be expressed by Zapas model and fit the experimental data with high accuracy. The analysed VE strains and creep compliance curves reveal the nonlinear stress-dependent VE behaviour of all composites at all tested creep stresses. Combining multiscale reinforcements results in an improvement that surpasses that of individual reinforcements. The results of this work offer valuable input for the design and selection of polymer-based materials in demanding applications where prolonged use under service conditions is critical to their performance.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
UHMWPE, Multiscale, Nanocomposite, Creep, Tensile, Stiffness
National Category
Composite Science and Engineering
Research subject
Machine Elements; Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-87818 (URN)10.1016/j.polymertesting.2021.107400 (DOI)000724138000001 ()2-s2.0-85118901220 (Scopus ID)
Funder
The Kempe FoundationsEU, Horizon 2020
Note

Validerad;2021;Nivå 2;2021-11-24 (beamah)

Available from: 2021-11-08 Created: 2021-11-08 Last updated: 2023-09-04Bibliographically approved
Fonseca, E., da Silva, V. D., Amico, S. C., Pupure, L., Joffe, R. & Schrekker, H. S. (2021). Time-dependent properties of epoxy resin with imidazolium ionic liquid. Journal of Applied Polymer Science, 138(46), Article ID 51369.
Open this publication in new window or tab >>Time-dependent properties of epoxy resin with imidazolium ionic liquid
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2021 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 138, no 46, article id 51369Article in journal (Refereed) Published
Abstract [en]

This study investigates creep and viscoelastic behavior of the diglycidyl ether of bisphenol A (DGEBA) epoxy resin and triethylenetetramine (TETA) system containing an imidazolium ionic liquid (IL), the 1-n-butyl-3-methylimidazolium chloride (C4MImCl). Different time-dependent analysis methods are studied using data from tensile creep, tensile creep/recovery, and three-point and four-point flexural creep tests of epoxy with 1.0 or 4.0 phr of IL. From the results, the composition containing 1.0 phr of C4MImCl, cured at 60°C, presented greater viscoelasticity and crosslink density compared to compositions cured at 30 and 40°C, which was attributed to higher free volume and higher molecular mobility induced by the presence of the IL. In tensile creep tests using the stepped isostress method (SSM), no important degrading effects were found after the addition of 1.0 phr of IL over long time periods. This composition also showed the best overall performance in flexural SSM creep tests. 

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
Keywords
ionic liquids, resins, thermosets, viscosity and viscoelasticity
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-86465 (URN)10.1002/app.51369 (DOI)000671794700001 ()2-s2.0-85109404864 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-09-10 (beamah);

Forskningsfinansiärer: Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior – Brasil (CAPES) (Finance Code 001) & the joint CAPES/STINT project.

Available from: 2021-07-27 Created: 2021-07-27 Last updated: 2021-12-09Bibliographically approved
Al-Maqdasi, Z., Pupure, L., Gong, G., Emami, N. & Joffe, R. (2021). Time‐dependent properties of graphene nanoplatelets reinforced high‐density polyethylene. Journal of Applied Polymer Science, 138(30), Article ID 50783.
Open this publication in new window or tab >>Time‐dependent properties of graphene nanoplatelets reinforced high‐density polyethylene
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2021 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 138, no 30, article id 50783Article in journal (Refereed) Published
Abstract [en]

The deformation of polymers at constant applied stress is one of their major drawbacks, limiting their use in advanced applications. The study of this property using classical techniques requires extensive testing over long periods of time. It is well known that reinforced polymers show improved behavior over time compared to their neat counterparts. In this study, the effect of adding different amounts of graphene nanoplatelets (GNPs) on the time‐dependent properties of high‐density polyethylene (HDPE) is investigated using short‐term creep tests and load/unload recovery tests. The results are discussed in terms of the test profile and the influence of loading history. Viscoplasticity/viscoelasticity analysis is performed using Zapas model and by comparing creep, creep compliance and pure viscoelasticity curves. The results show that the reinforcement of 15 wt% GNP have the most significant effect on the time‐dependent behavior, reducing the strain by more than 50%. The creep compliance curves show that nano‐reinforced HDPE behaves nonlinearly viscoelastically even at very low stresses. In addition to demonstrating the effect of nano‐reinforcement, the discussion of the results concludes that the influence of loading history can be quite significant and should not be neglected in the design and evaluation of material behavior.

Place, publisher, year, edition, pages
John Wiley & Sons, 2021
Keywords
graphene and fullerenes, mechanical properties, theory and modeling, thermoplastics, viscosity and viscoelasticity
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-83561 (URN)10.1002/app.50783 (DOI)000636776700001 ()2-s2.0-85103565338 (Scopus ID)
Funder
EU, Horizon 2020, 777810Interreg NordLuleå University of Technology
Note

Validerad;2021;Nivå 2;2021-06-10 (alebob);

An image from this article was selected for the cover image of the issue, it can be found here: https://doi.org/10.1002/app.50972

This article has previously appeared as a manuscript in a thesis.

Available from: 2021-04-09 Created: 2021-04-09 Last updated: 2023-03-16Bibliographically approved
Pupure, L., Varna, J., Joffe, R., Berthold, F. & Miettinen, A. (2020). Mechanical properties of natural fiber composites produced using dynamic sheet former. Wood Material Science & Engineering, 15(2), 76-86
Open this publication in new window or tab >>Mechanical properties of natural fiber composites produced using dynamic sheet former
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2020 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 15, no 2, p. 76-86Article in journal (Refereed) Published
Abstract [en]

Composites formed from wood fibers and man-made cellulosic fibers in PLA (polylactic acid) matrix, manufactured using sheet forming technique and hot pressing, are studied. The composites have very low density (due to high porosity) and rather good elastic modulus and tensile strength. As expected, these properties for the four types of wood fiber composites studied here improve with increasing weight fraction of fibers, even if porosity is also increasing. On the contrary, for man-made cellulosic fiber composites with circular fiber cross-section, the increasing fiber weight fraction (accompanied by increasing void content) has detrimental effect on stiffness and strength. The differences in behavior are discussed attributing them to fiber/ fiber interaction in wood fiber composites which does not happen in man-made fiber composites, and by rather weak fiber/matrix interface for man-made fibers leading to macro-crack formation in large porosity regions.

Place, publisher, year, edition, pages
Taylor & Francis, 2020
Keywords
Wood fiber composites, PLA, Tencel fibers, dynamic sheet former, stiffness, strength
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-69464 (URN)10.1080/17480272.2018.1482368 (DOI)000519990200002 ()2-s2.0-85048019947 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-03 (alebob)

Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2020-04-03Bibliographically approved
Varna, J. & Pupure, L. (2019). Characterization of viscoelasticity, viscoplasticity, and damage in composites (2ed.). In: Rui Miranda Guedes (Ed.), Creep and Fatigue in Polymer Matrix Composites: (pp. 497-530). Elsevier
Open this publication in new window or tab >>Characterization of viscoelasticity, viscoplasticity, and damage in composites
2019 (English)In: Creep and Fatigue in Polymer Matrix Composites / [ed] Rui Miranda Guedes, Elsevier, 2019, 2, p. 497-530Chapter in book (Refereed)
Abstract [en]

Empirical inelastic constitutive material models for composites and testing methodology for parameter determination in these models are analyzed. Short fiber as well as long unidirectional fiber reinforced composites are analyzed in situations when the main sources of inelastic behavior are a combination of (a) nonlinear viscoelasticity; (b) nonlinear viscoplasticity; and (c) microdamage-induced reduction of thermoelastic properties, all three evolving with time and stress. These phenomena are included in a common material model. The necessary tests for model identification are tensile quasistatic loading-unloading tests and creep tests at different stress levels with recorded strain recovery after load removal. The methodology is demonstrated presenting models for (a) shear in layers of [45/−45]s laminates; (b) response of short fiber composites (SMC with glass fiber bundles; composites with natural or man-made cellulosic fibers in bio-based resins).

Place, publisher, year, edition, pages
Elsevier, 2019 Edition: 2
Series
Woodhead Publishing Series in Composites Science and Engineering
Keywords
Fiber composites, Stiffness reduction, Viscoelasticity, Viscoplasticity, Creep
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-73438 (URN)10.1016/B978-0-08-102601-4.00016-3 (DOI)2-s2.0-85080806881 (Scopus ID)978-0-08-102601-4 (ISBN)
Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2020-08-26Bibliographically approved
Basso, M., Piselli, A., Simonato, M., Furlanetto, R., Pupure, L., Joffe, R. & De Nardo, L. (2019). Effect of food chemicals and temperature on mechanical reliability of bio-based glass fibers reinforced polyamide. Composites Part B: Engineering, 157, 140-149
Open this publication in new window or tab >>Effect of food chemicals and temperature on mechanical reliability of bio-based glass fibers reinforced polyamide
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2019 (English)In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 157, p. 140-149Article in journal (Refereed) Published
Abstract [en]

This paper presents an experimental study to assess the effects of food chemicals and temperature on the mechanical performance of glass fiber reinforced bio-based polyamide. The diffusion of food chemicals was mainly driven by thermal energy, following Arrhenius law in all tested environments. Degradation of mechanical properties and decrease in reliability were assessed, due to the plasticization of polymer matrix. Secondary but not negligible effect on flexural strength degradation is given by the different chemical interaction between polymeric chains and molecules of food chemicals. Colour change was measured and resulted to be positively correlated to diffusion.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-70638 (URN)10.1016/j.compositesb.2018.08.078 (DOI)000452939900014 ()2-s2.0-85052484539 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-31 (andbra)

Available from: 2018-08-29 Created: 2018-08-29 Last updated: 2019-03-27Bibliographically approved
Basso, M., Pupure, L., Simonato, M., Furlanetto, R., De Nardo, L. & Joffe, R. (2019). Nonlinear creep behaviour of glass fiber reinforced polypropylene: Impact of aging on stiffness degradation. Composites Part B: Engineering, 163, 702-709
Open this publication in new window or tab >>Nonlinear creep behaviour of glass fiber reinforced polypropylene: Impact of aging on stiffness degradation
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2019 (English)In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 163, p. 702-709Article in journal (Refereed) Published
Abstract [en]

Nonlinear creep behavior of one commercial short glass fiber reinforced polypropylene was investigated using tensile creep tests and stiffness degradation measurements. The impact of thermal aging and following quenching was evaluated on the latter mechanical property. Experimental results were modeled applying nonlinear viscoelastic model used by Pupure et al. (2013) and developed by Lou and Schapery [1,2]. Results showed that this model can describe nonlinear behavior of short glass fiber reinforced polymer composites, where microdamage is given by debonding of fiber-matrix interfaces already at low strains, where cracks propagate and lead to tensile creep fracture.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Polymer-matrix composites (PMCs), Creep, Analytical modelling, Mechanical testing
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-72884 (URN)10.1016/j.compositesb.2019.01.052 (DOI)000461262500069 ()2-s2.0-85060028172 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-13 (johcin)

Available from: 2019-02-13 Created: 2019-02-13 Last updated: 2019-04-12Bibliographically approved
Al-Maqdasi, Z., Pupure, L., Emami, N. & Joffe, R. (2019). Time-dependent properties of graphene reinforced HDPE. In: R. Joffe; L. Pupure; J. Varna; L. Wallström (Ed.), Proceedings of 9th International Conference on Composite Testing and Model Identification: Book of Abstracts. Paper presented at 9th International Conference on Composites Testing and Model Identification (CompTest 2019), May 27-29, 2019, Luleå, Sweden. , Article ID 163.
Open this publication in new window or tab >>Time-dependent properties of graphene reinforced HDPE
2019 (English)In: Proceedings of 9th International Conference on Composite Testing and Model Identification: Book of Abstracts / [ed] R. Joffe; L. Pupure; J. Varna; L. Wallström, 2019, article id 163Conference paper, Oral presentation with published abstract (Other academic)
Keywords
Graphene nano-platelets, Polymer nano-composites, Viscoplasticity, Modelling
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-96171 (URN)
Conference
9th International Conference on Composites Testing and Model Identification (CompTest 2019), May 27-29, 2019, Luleå, Sweden
Funder
Interreg Nord
Available from: 2023-03-16 Created: 2023-03-16 Last updated: 2024-01-12Bibliographically approved
Gong, G., Nyström, B., Sandlund, E., Eklund, D., Noël, M., Westerlund, R., . . . Joffe, R. (2018). Development of Electrophoretic Deposition Prototype for Continuous Production of Carbon Nanotube-Modified Carbon Fiber Fabrics Used in High-Performance Multifunctional Composites. Fibers, 6(4), Article ID 71.
Open this publication in new window or tab >>Development of Electrophoretic Deposition Prototype for Continuous Production of Carbon Nanotube-Modified Carbon Fiber Fabrics Used in High-Performance Multifunctional Composites
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2018 (English)In: Fibers, ISSN 2079-6439, Vol. 6, no 4, article id 71Article in journal (Refereed) Published
Abstract [en]

An electrophoretic deposition (EPD) prototype was developed aiming at the continuous production of carbon nanotube (CNT) deposited carbon fiber fabric. Such multi-scale reinforcement was used to manufacture carbon fiber-reinforced polymer (CFRP) composites. The overall objective was to improve the mechanical performance and functionalities of CFRP composites. In the current study, the design concept and practical limit of the continuous EPD prototype, as well as the flexural strength and interlaminar shear strength, were the focus. Initial mechanical tests showed that the flexural stiffness and strength of composites with the developed reinforcement were significantly reduced with respect to the composites with pristine reinforcement. However, optical microscopy study revealed that geometrical imperfections, such as waviness and misalignment, had been introduced into the reinforcement fibers and/or bundles when being pulled through the EPD bath, collected on a roll, and dried. These defects are likely to partly or completely shadow any enhancement of the mechanical properties due to the CNT deposit. In order to eliminate the effect of the discovered defects, the pristine reinforcement was subjected to the same EPD treatment, but without the addition of CNT in the EPD bath. When compared with such water-treated reinforcement, the CNT-deposited reinforcement clearly showed a positive effect on the flexural properties and interlaminar shear strength of the composites. It was also discovered that CNTs agglomerate with time under the electric field due to the change of ionic density, which is possibly due to the electrolysis of water (for carboxylated CNT aqueous suspension without surfactant) or the deposition of ionic surfactant along with CNT deposition (for non-functionalized CNT aqueous suspension with surfactant). Currently, this sets time limits for the continuous deposition.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
electrophoretic deposition, carbon nanotube, multi-scale carbon reinforcement, multifunctional composites
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-72826 (URN)10.3390/fib6040071 (DOI)000455068600004 ()2-s2.0-85058692640 (Scopus ID)
Available from: 2019-02-08 Created: 2019-02-08 Last updated: 2022-10-27Bibliographically approved
Pupure, L., Varna, J. & Joffe, R. (2018). Methodology for macro-modeling of bio-based composites with inelastic constituents. Composites Science And Technology, 163, 41-48
Open this publication in new window or tab >>Methodology for macro-modeling of bio-based composites with inelastic constituents
2018 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 163, p. 41-48Article in journal (Refereed) Published
Abstract [en]

Methodology for development of a macro-scale model (with strain as an input) for Regenerated Cellulose fiber (RCF) composites with highly non-linear (viscoelastic (VE) and viscoplastic (VP)) constituents is presented and demonstrated. The VE is described by Schapery's models and Zapas' model is used for VP. For a purely VE constituent the model can be identified from stress relaxation in constant strain tests. In the presence of VP the constant strain test does not render VE stress relaxation functions, because part of the applied strain is VP and the VE strain is changing. As an alternative creep and strain recovery tests are suggested to find the plasticity law and also the nonlinear creep compliances to identify the VE model where stress is an input. The incremental form of this model is then inverted and used to simulate the VE relaxation tests and the simulated relaxation functions are used to identify the VE model with VE strain as an input.

Models for constituents are used in micromechanics simulations of the composite behavior in arbitrary ramps including the composite VE relaxation test. Using the latter, a macro-model is developed and its validity and accuracy are demonstrated.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-68687 (URN)10.1016/j.compscitech.2018.05.015 (DOI)000438323000006 ()2-s2.0-85046756325 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-15 (rokbeg)

Available from: 2018-05-09 Created: 2018-05-09 Last updated: 2018-08-07Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-8050-2294

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