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Publications (9 of 9) Show all publications
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
Al-Maqdasi, Z., Gong, G., Nyström, B., Emami, N. & Joffe, R. (2020). Characterization of Wood and Graphene Nanoplatelets (GNPs) Reinforced Polymer Composites. Materials, 13(9), Article ID 2089.
Open this publication in new window or tab >>Characterization of Wood and Graphene Nanoplatelets (GNPs) Reinforced Polymer Composites
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2020 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 9, article id 2089Article in journal (Refereed) Published
Abstract [en]

This paper investigates the utilization of commercial masterbatches of graphene nanoplatelets to improve the properties of neat polymer and wood fiber composites manufactured by conventional processing methods. The effect of aspect ratio of the graphene platelets (represented by the different number of layers in the nanoplatelet) on the properties of high-density polyethylene (HDPE) is discussed. The composites were characterized for their mechanical properties (tensile, flexural, impact) and physical characteristics (morphology, crystallization, and thermal stability). The effect of the addition of nanoplatelets on the thermal conductivity and diffusivity of the reinforced polymer with different contents of reinforcement was also investigated. In general, the mechanical performance of the polymer was enhanced at the presence of either of the reinforcements (graphene or wood fiber). The improvement in mechanical properties of the nanocomposite was notable considering that no compatibilizer was used in the manufacturing. The use of a masterbatch can promote utilization of nano-modified polymer composites on an industrial scale without modification of the currently employed processing methods and facilities.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
graphene nanoplatelets (GNPs), nanocomposites masterbatch, wood polymer composites (WPC), energy transport, high density polyethylene (HDPE)
National Category
Composite Science and Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Polymeric Composite Materials; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-73740 (URN)10.3390/ma13092089 (DOI)000535941100083 ()32369956 (PubMedID)2-s2.0-85085253513 (Scopus ID)
Funder
Interreg NordNorrbotten County Council
Note

Validerad;2020;Nivå 2;2020-05-12 (alebob)

Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2022-10-31Bibliographically approved
Fernberg, P., Gong, G. & Mannberg, P. (2014). Processing and properties of new polyimide composites with high temperature ability (ed.). In: (Ed.), 16th European Conference on Composite Materials, ECCM 2014: Seville, Spain, 22 - 26 June 2014. Paper presented at European Conference on Composite Materials : 22/06/2014 - 26/06/2014. European Conference on Composite Materials, ECCM
Open this publication in new window or tab >>Processing and properties of new polyimide composites with high temperature ability
2014 (English)In: 16th European Conference on Composite Materials, ECCM 2014: Seville, Spain, 22 - 26 June 2014, European Conference on Composite Materials, ECCM , 2014Conference paper, Published paper (Refereed)
Abstract [en]

The communication present results from work on development and evaluation of new polymeric carbon fiber composites with extreme temperature performance: Tg up to 360°C is targeted. The anticipated use of such composites is found in aeroengine-applications. In the work we are exploring a new and tailored phenyl ethynyl terminated imide (PETI) formulation, specially developed for the program. The formulation utilizes crosslinkers of the Nexamide" type (from Nexam Chemical AB, Sweden). The resins are initially evaluated from a processing and property perspective. Both DSC-measurements and rheology characterization are utilized in the development. Suitable RTM-processing schemes are investigated from a viscosity point of view. The schemes are used in the composite sample manufacturing. Besides a processing perspective the study also present the first results on physical behavior of the polymers and their composites.

Place, publisher, year, edition, pages
European Conference on Composite Materials, ECCM, 2014
Keywords
Composite processing, Polyimides, Rheology
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-26830 (URN)2-s2.0-84915749357 (Scopus ID)015f1bc8-bcdd-4b5d-8e10-8043aef93079 (Local ID)9780000000002 (ISBN)015f1bc8-bcdd-4b5d-8e10-8043aef93079 (Archive number)015f1bc8-bcdd-4b5d-8e10-8043aef93079 (OAI)
Conference
European Conference on Composite Materials : 22/06/2014 - 26/06/2014
Note

Godkänd; 2014; 20141217 (andbra)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2022-10-31Bibliographically approved
Mathew, A. P., Gong, G., Björngrim, N., Wixe, D. & Oksman, K. (2011). Moisture absorption behaviour and its impact on the mechanical properties of polyvinyl acetate (PVAc) based cellulose nanocomposites (ed.). Polymer Engineering and Science, 51(11), 2136-2142
Open this publication in new window or tab >>Moisture absorption behaviour and its impact on the mechanical properties of polyvinyl acetate (PVAc) based cellulose nanocomposites
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2011 (English)In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 51, no 11, p. 2136-2142Article in journal (Refereed) Published
Abstract [en]

Cellulose nanowhisker (CNW) reinforced polyvinyl acetate (PVAc) nanocomposites were prepared by melt-extrusion using a master batch process. Microscopy images showed no visible aggregation of whiskers in the matrix. The influence of CNWs and moisture absorption on the mechanical behavior of the nanocomposites was studied. The water sorption studies indicated low water uptake (<10 wt%) for all the materials. However, higher moisture uptake was obtained in the nanocomposites compared to the matrix though the diffusion co-efficient of the nanocomposites was lower. The tensile strength and modulus were decreased with the addition of CNWs to PVAc, but the reduction is lower at higher CNW concentration indicating that the plasticizing effect of the moisture was counteracted to some extent by the reinforcing effect of CNWs. Higher tensile ductility and toughness, which were dependent on moisture absorption, were achieved in the nanocomposites than pure PVAc.

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-8574 (URN)10.1002/pen.22063 (DOI)000296254700004 ()2-s2.0-80054745063 (Scopus ID)716ff7b8-11b7-4610-a229-78582a435bdf (Local ID)716ff7b8-11b7-4610-a229-78582a435bdf (Archive number)716ff7b8-11b7-4610-a229-78582a435bdf (OAI)
Note

Validerad; 2011; 20110525 (krioks)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-09-05Bibliographically approved
Gong, G., Mathew, A. P. & Oksman, K. (2011). Strong aqueous gels of cellulose nanofibers and nanowhiskers isolated from softwood flour (ed.). TAPPI Journal, 10(2), 42565
Open this publication in new window or tab >>Strong aqueous gels of cellulose nanofibers and nanowhiskers isolated from softwood flour
2011 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 10, no 2, p. 42565-Article in journal (Refereed) Published
Abstract [en]

Two nanocelluloses (cellulose nanofibers [CNF] and nanowhiskers [CNW]) were extracted from softwood flour using chemical refining followed either by mechanical fibrillation or acid hydrolysis. The CNF slurry formed an opaque gel that exhibited highly coiled and entangled long fibers with widths between 10 and 20 nm when studied using atomic force microscopy (AFM). The aqueous suspension of the CNW formed a transparent gel with unique morphology of rigid and uniform, whiskerlike structures with widths as low as 1.5-3 nm and lengths in micrometer levels. The viscoelastic properties of these hydrogels with solids content of 0.2 wt% were measured using dynamic rheology experiments. The elastic modulus (G') and viscous modulus (G '') were frequency independent in the low-frequency region. Furthermore, G' was almost 10-fold higher than G '', showing a typical elastic gel behavior. The lower crystallinity obtained from X-ray analysis indicated that the unique structure of CNW from wood could be attributed to the native cellulose being partly dissolved and regenerated during acid hydrolysis.

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-14141 (URN)10.32964/tj10.2.7 (DOI)2-s2.0-79960014304 (Scopus ID)d7a1d520-082e-11e0-b767-000ea68e967b (Local ID)d7a1d520-082e-11e0-b767-000ea68e967b (Archive number)d7a1d520-082e-11e0-b767-000ea68e967b (OAI)
Note

Validerad; 2011; 20101215 (krioks);

Funders: The authors gratefully acknowledge Kempe Foundation in Sweden as well as VINNOVA under the nanofiber project and the European Commission for financial support under contract number 210037, FP7-NMP-2007 WOODY.

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-11-04Bibliographically approved
Gong, G., Pyo, J., Mathew, A. P. & Oksman, K. (2011). Tensile behavior, morphology and viscoelastic analysis of cellulose nanofiber-reinforced (CNF) polyvinyl acetate (PVAc) (ed.). Composites. Part A, Applied science and manufacturing, 42(9), 1275-1282
Open this publication in new window or tab >>Tensile behavior, morphology and viscoelastic analysis of cellulose nanofiber-reinforced (CNF) polyvinyl acetate (PVAc)
2011 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 42, no 9, p. 1275-1282Article in journal (Refereed) Published
Abstract [en]

Cellulose nanofiber-reinforced (CNF) polyvinyl acetate (PVAc) composites were prepared using the twin-screw extrusion technique. The influence of CNF content on nanocomposites morphology, tensile, and viscoelastic properties was studied. The tensile modulus and strength increased with increasing CNF content, being 59% and 21% higher in 10 wt% CNF composite compared to neat PVAc. The activation volume at yielding of PVAc was decreased by CNFs, indicating restricted chain mobility. The fracture surfaces of nanocomposites showed bridging of CNFs inside the micro-cracks. The storage modulus increased for all nanocomposites compared to the matrix, being more significant in the rubbery state. Also, the activation energy for the transition increased with increased CNF content. A slight shift and broadening was observed in the tan delta peak for 10 wt% CNFs composite. The creep strain of PVAc was reduced, whereas the creep elasticity and viscosity calculated from Burger’s model were increased by the addition of CNFs.Keywords: A. Polymer-matrix composites (PMCs); B. Creep, Mechanical properties; E. Extrusion

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-3353 (URN)10.1016/j.compositesa.2011.05.009 (DOI)000293313900022 ()2-s2.0-79959997011 (Scopus ID)12b6eb91-6e99-40a6-ac2a-7a08aa078f83 (Local ID)12b6eb91-6e99-40a6-ac2a-7a08aa078f83 (Archive number)12b6eb91-6e99-40a6-ac2a-7a08aa078f83 (OAI)
Note

Validerad; 2011; 20110525 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-09-05Bibliographically approved
Gong, G., Mathew, A. P. & Oksman, K. (2011). Toughening effect of cellulose nanowhiskers on polyvinyl acetate: Fracture toughness and viscoelastic analysis (ed.). Polymer Composites, 32(10), 1492-1498
Open this publication in new window or tab >>Toughening effect of cellulose nanowhiskers on polyvinyl acetate: Fracture toughness and viscoelastic analysis
2011 (English)In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 32, no 10, p. 1492-1498Article in journal (Refereed) Published
Abstract [en]

The toughening effect of cellulose nanowhiskers (CNWs) on modified polyvinyl acetate (PVAc) was analyzed with the help of morphology, relaxation, and creep behavior. The CNWs together with bound moisture at the matrix/whisker interfaces resulted in significant improvement in resistance to crack initiation and propagation. The magnitude of plastic deformation of the nanocomposites was higher than that of the neat PVAc. The relaxation temperature decreased, while the width of the damping peak increased with increasing CNW and moisture contents. The results from creep modeling showed that the instantaneous elastic modulus first increased and then decreased with the addition of CNWs, while the time-dependent elasticity and viscosity decreased. The results suggested that the reinforcing effect of the CNWs was overwhelmed by the plasticizing effect of the bound moisture. Furthermore, low concentrations of CNWs significantly improved the fracture toughness of PVAc at the minor cost of strength, stiffness, and creep resistance. In this article, we present a novel approach to studying the toughening effect of CNWs on polymers using fracture tests and viscoelastic modeling

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-15279 (URN)10.1002/pc.21170 (DOI)000295453700002 ()2-s2.0-80052970592 (Scopus ID)ec745d70-c053-48fa-b714-922631872232 (Local ID)ec745d70-c053-48fa-b714-922631872232 (Archive number)ec745d70-c053-48fa-b714-922631872232 (OAI)
Note

Validerad; 2011; 20110525 (krioks)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-09-05Bibliographically approved
Pupure, L., Al-Maqdasi, Z., Gong, G., Emami, N. & Joffe, R.Effect of Nano-reinforcement on the Time-dependent Properties of Graphene Modified High Density Polyethylene.
Open this publication in new window or tab >>Effect of Nano-reinforcement on the Time-dependent Properties of Graphene Modified High Density Polyethylene
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(English)Manuscript (preprint) (Other academic)
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-73741 (URN)
Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2023-03-16
Al-Maqdasi, Z., Gong, G., Emami, N. & Joffe, R.Mechanical Performance of PE Reinforced with Graphene Nanoplatelets (GNPs): Effect of Composition and Processing Parameters.
Open this publication in new window or tab >>Mechanical Performance of PE Reinforced with Graphene Nanoplatelets (GNPs): Effect of Composition and Processing Parameters
(English)Manuscript (preprint) (Other academic)
National Category
Composite Science and Engineering
Research subject
Machine Elements; Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-90136 (URN)
Projects
Smart-WPC
Funder
Interreg NordNorrbotten County CouncilLuleå University of Technology, Smart Machine and Materials (SMM)
Available from: 2022-04-08 Created: 2022-04-08 Last updated: 2022-04-08
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3449-8233

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