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Publications (10 of 104) Show all publications
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)32369956 (PubMedID)
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: 2020-05-12Bibliographically approved
Bryant, M., Rituerto Sin, J., Emami, N. & Neville, A. (2020). Effect of proteins and phosphates on the degradation and repassivation of CoCrMo alloys under tribocorrosion conditions. Tribology - Materials, Surfaces & Interfaces
Open this publication in new window or tab >>Effect of proteins and phosphates on the degradation and repassivation of CoCrMo alloys under tribocorrosion conditions
2020 (English)In: Tribology - Materials, Surfaces & Interfaces, ISSN 1751-5831, E-ISSN 1751-584XArticle in journal (Refereed) Epub ahead of print
Abstract [en]

Cobalt-chromium-molybdenum alloys are commonly used for biomedical applications such as dental implants and joint implants. Once the material is implanted into the body it is exposed to the corrosiveness of biological fluids and, in some cases, to mechanical loading that can lead to the combined action of wear and corrosion; better known as tribocorrosion. The effect of four different simulated body fluids on the tribocorrosion behaviour of a CoCrMo alloy has been investigated. The degradation of the studied CoCrMo alloys due to tribocorrosion shows a great dependence on the chemical composition of the media. Phosphate-buffered saline (PBS)-based solutions tend to show higher mass loss than the solutions prepared with distilled water. Phosphates present in PBS tend to accumulate on the surface of the alloy and change its tribological performance. In addition, proteins show a lubricating effect reducing the coefficient of friction of the system in the boundary lubrication regime.

Place, publisher, year, edition, pages
Taylor & Francis, 2020
Keywords
Tribocorrosion, CoCrMo alloy, PBS, simulated body fluid
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-78392 (URN)10.1080/17515831.2020.1746012 (DOI)000525246700001 ()2-s2.0-85082869065 (Scopus ID)
Available from: 2020-04-08 Created: 2020-04-08 Last updated: 2020-04-22
Jain, A., Somberg, J. & Emami, N. (2019). Development and Characterisation of Multi-Scale Carbon Reinforced PPS Composites for Tribological Applications. Lubricants, 7(4), Article ID 34.
Open this publication in new window or tab >>Development and Characterisation of Multi-Scale Carbon Reinforced PPS Composites for Tribological Applications
2019 (English)In: Lubricants, E-ISSN 2075-4442, Vol. 7, no 4, article id 34Article in journal (Refereed) Published
Abstract [en]

 Polymer-based materials show to be of increasing interest in replacing metal based

materials in tribological applications due to their low weight, cost and easy manufacturability.

To further reduce the environmental impact of these bearing materials recyclability is becoming

more crucial, stimulating the need for high performing thermoplastic materials. In this study,

polyphenylene sulfide (PPS) composites were prepared in an effort to enhance the polymers’

tribological properties. Short carbon fibres (SCFs), graphene oxide (GO) and nano diamonds (NDs)

as well as polytetrafluoroethylene (PTFE) were used as micro and nano reinforcements. The addition

of SCFs especially decreased the linear coefficient of thermal expansions while enhancing the

micro hardness and wettability of the polymer. Under water lubricated conditions, a decrease

in friction up to 56% and a reduction of wear rate in the order of 103  was observed by the addition

of SCF. The reduction in friction and wear was further enhanced by the addition of NDs, providing

a synergistic effect of the reinforcements in micro and nano scale. By testing the individual

reinforcements under dry conditions, PTFE and SCFs were especially effective in reducing friction

while the release and consequent abrasion of NDs and SCFs increased the wear under a higher

contact pressure.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
PPS, short carbon fiber, nanocomposites, PTFE, wear, friction
National Category
Composite Science and Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-73529 (URN)10.3390/lubricants7040034 (DOI)000467292800006 ()2-s2.0-85066439713 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-17 (johcin)

Available from: 2019-04-09 Created: 2019-04-09 Last updated: 2019-06-17Bibliographically approved
Palmeira Belotti, L., Vadivel, H. S. & Emami, N. (2019). Tribological performance of hygrothermally aged UHMWPE hybrid composites. Tribology International, 138, 150-156
Open this publication in new window or tab >>Tribological performance of hygrothermally aged UHMWPE hybrid composites
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 138, p. 150-156Article in journal (Refereed) Published
Abstract [en]

In this work, the effect of hygrothermal aging on friction and wear of water lubricated, Ultra High Molecular Weight Polyethylene (UHMWPE) hybrid composites were evaluated. Graphene Oxide (GO), Nano Diamonds (ND) and Short Carbon Fibers (SCF) were used as reinforcements as they previously exhibited promising improvements in the tribological behavior of UHMWPE in water-lubricated sliding contacts. Hygrothermal aging and pin-on-disc tribological experiments were performed to evaluate the response of the UHMWPE composites. It was observed that the friction and wear of the composites were not significantly affected by the aging conditions, which was attributed to the structural integrity of the newly developed UHMWPE based hybrid composites.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
UHMWPE, Thermoplastics, Hybrid composites, Hygrothermal aging, Friction, Wear
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-75038 (URN)10.1016/j.triboint.2019.05.034 (DOI)000484647200015 ()2-s2.0-85066240520 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-26 (johcin)

Available from: 2019-06-26 Created: 2019-06-26 Last updated: 2019-09-27Bibliographically approved
Emami, N. (2018). Biocompatibility, Mechanical and Tribological properties of GO reinforced thermoplastic polymer”. Flow Process Composite Materials Conference. In: : . Paper presented at 14th-Flow Process Composite Materials Conference.
Open this publication in new window or tab >>Biocompatibility, Mechanical and Tribological properties of GO reinforced thermoplastic polymer”. Flow Process Composite Materials Conference
2018 (English)Conference paper, Oral presentation only (Refereed)
National Category
Materials Engineering Composite Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-71922 (URN)
Conference
14th-Flow Process Composite Materials Conference
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06
Emami, N. (2018). Design and manufacturing of Graphene Oxide reinforced high performing thermoplastics hybrid composites for Tribological applications. In: : . Paper presented at SIO-grafen National expert meeting-graphene as polymer composite reinforcement.
Open this publication in new window or tab >>Design and manufacturing of Graphene Oxide reinforced high performing thermoplastics hybrid composites for Tribological applications
2018 (English)Conference paper, Oral presentation only (Other academic)
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-71911 (URN)
Conference
SIO-grafen National expert meeting-graphene as polymer composite reinforcement
Funder
VINNOVA
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06
Homayoun, M.-R., Golchin, A. & Emami, N. (2018). Effect of Hygrothermal Ageing on Tribological Behaviour of PTFE-Based Composites. Lubricants, 6(4), Article ID 103.
Open this publication in new window or tab >>Effect of Hygrothermal Ageing on Tribological Behaviour of PTFE-Based Composites
2018 (English)In: Lubricants, E-ISSN 2075-4442, Vol. 6, no 4, article id 103Article in journal (Refereed) Published
Abstract [en]

The present study investigates the influence of hygrothermal ageing on the tribological behaviour of polytetrafluoroethylene (PTFE) polymer composites. Three PTFE composites along with unfilled PTFE were tested in sliding contact against Inconel 625 (a Ni-based alloy) plates in both dry and water-lubricated conditions, utilising a unidirectional pin-on-disc tribometer. The tribo-tests were performed at a constant sliding speed of 0.13 m/s with a normal load of 84N providing an apparent contact pressure of 5 MPa. Hygrothermal conditioning was carried out at two different temperatures, and the water absorption evolution and kinetic parameters were estimated. Various characterisation methods were used to identify the wear mechanisms and influence of hygrothermal ageing on the degradation of the filler/matrix. The different tribological behaviour for different PTFE composites was observed within the ageing timeframe. The wear resistance of the fibre-filled samples was reduced compared to the non-aged ones over the ageing timeframe. However, the friction and wear resistance of the bronze-filled PTFE were enhanced by hygrothermal ageing.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
hygrothermal ageing, PTFE, friction, wear
National Category
Mechanical Engineering Materials Engineering Composite Science and Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-71930 (URN)10.3390/lubricants6040103 (DOI)000455618500019 ()2-s2.0-85059383793 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-01 (inah)

Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2019-02-01Bibliographically approved
Emami, N. & Belotti, L. (2018). Effect of surface roughness and hygrothermal aging of multiscale carbon reinforced UHMWPE composites. In: : . Paper presented at 14th-Flow Process Composite Materials Conference.
Open this publication in new window or tab >>Effect of surface roughness and hygrothermal aging of multiscale carbon reinforced UHMWPE composites
2018 (English)Conference paper, Oral presentation only (Refereed)
National Category
Materials Engineering Composite Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-71923 (URN)
Conference
14th-Flow Process Composite Materials Conference
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06
Emami, N. & Melk, L. (2018). Fracture toughness and thermal characterisation of GO based UHMWPE composites. In: : . Paper presented at 14th-Flow Process Composite Materials Conference.
Open this publication in new window or tab >>Fracture toughness and thermal characterisation of GO based UHMWPE composites
2018 (English)Conference paper, Oral presentation only (Refereed)
National Category
Materials Engineering Manufacturing, Surface and Joining Technology Composite Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-71925 (URN)
Conference
14th-Flow Process Composite Materials Conference
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06
Belotti, L., Vadivel, H. & Emami, N. (2018). Influence of counter surface topography on the tribological behavior  of  hybrid UHMWPE composites. In: : . Paper presented at Nordtrib-2018.
Open this publication in new window or tab >>Influence of counter surface topography on the tribological behavior  of  hybrid UHMWPE composites
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Composite Science and Engineering Mechanical Engineering
Identifiers
urn:nbn:se:ltu:diva-71927 (URN)
Conference
Nordtrib-2018
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8676-8819

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