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Mu, Liwen
Publications (10 of 10) Show all publications
Dai, B., Zhu, W., Mu, L., Guo, X., Qian, H., Liang, X. & Kontogeorgis, G. (2019). Effect of the composition of biomass on the quality of syngas produced from thermochemical conversion based on thermochemical data prediction. Energy & Fuels, 33(6), 5253-5262
Open this publication in new window or tab >>Effect of the composition of biomass on the quality of syngas produced from thermochemical conversion based on thermochemical data prediction
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 33, no 6, p. 5253-5262Article in journal (Refereed) Published
Abstract [en]

Syngas produced from thermochemical conversion of biomass has been given more attention because it can be converted to a variety of fuels and chemicals as substitutes for petroleum-based chemicals via the Fischer–Tropsch process. In this study, one wheat straw and its element content fluctuation in the feasible range are selected as samples first to study the effect of the biomass composition on the quality of syngas produced. Then, the thermochemical data (standard molar enthalpy of formation, standard molar entropy, and heat capacity) of samples are predicted by highly accurate prediction models. Thermochemical conversions of the samples are simulated by the Gibbs energy minimization method based on the results of thermochemical data prediction. At last, the effect of the biomass composition on the resource index (amounts of CO and H2 and ratio of H2/CO) and energy index (lower heat value) of syngas is calculated and analyzed. This study provides a method to obtain the relationship between the composition of biomass and the quality of syngas produced.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-75269 (URN)10.1021/acs.energyfuels.9b00106 (DOI)000472800900054 ()2-s2.0-85067958903 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-09 (johcin)

Available from: 2019-07-09 Created: 2019-07-09 Last updated: 2019-08-22Bibliographically approved
Wu, J., Mu, L., Feng, X., Lu, X., Larsson, R. & Shi, Y. (2019). Poly(alkylimidazolium bis(trifluoromethylsulfonyl) imide)-Based Polymerized Ionic Liquids: A Potential  High-Performance Lubricating Grease. Advanced Materials Interfaces, 6(5), Article ID 1801796.
Open this publication in new window or tab >>Poly(alkylimidazolium bis(trifluoromethylsulfonyl) imide)-Based Polymerized Ionic Liquids: A Potential  High-Performance Lubricating Grease
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2019 (English)In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, no 5, article id 1801796Article in journal (Refereed) Published
Abstract [en]

Polymers prepared from ionic liquids are widely called polymerized ionic liquids (PILs). Compared to monocationic and dicationic ILs, PILs have higher molecular weights, charge, and greater intermolecular interactions, which make PILs have a higher possibility to generate better lubricity. PILs of poly‐alkylimidazolium bis(trifluoromethylsulfonyl)imide (PImC6NTf2) is studied herein. Dicationic ILs of 1,1′‐(pentane‐1,5‐diyl)‐bis(3‐butylimidazolium) bis(trifluoromethylsulfonyl)imide (BIm5‐(NTf2)2) is used as additive to decrease the crystallization temperature of PImC6NTf2. Lubricity of PImC6NTf2 and PImC6NTf2+BIm5‐(NTf2)2, as well as BIm5‐(NTf2)2 for comparison is evaluated under severe conditions, i.e., 3.0 to 3.5 GPa and 200 °C. The rheological study suggests that PImC6NTf2 can be classified into grease. Tribological test results show that PImC6NTf2 has much better antiwear property than BIm5‐(NTf2)2, especially at 3.5 GPa. Adding 4% BIm5‐(NTf2)2 to PImC6NTf2 is able to reduce friction under high pressure. At 200 °C, PImC6NTf2 exhibits excellent lubricity. The mixture of 96%PImC6NTf2+4%BIm5‐(NTf2)2 shows even better antiwear property than neat PImC6NTf2 and exhibits the highest friction reducing property among the ILs at 200 °C. It is speculated that the robust strength of PILs and strong adhesion between PILs and solids are key factors in achieving the excellent antiwear property.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
grease, high pressure and high temperature, lubricity, polymerized ionic liquids
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-72623 (URN)10.1002/admi.201801796 (DOI)000460657100002 ()
Note

Validerad;2019;Nivå 2;2019-03-11 (johcin)

Available from: 2019-01-18 Created: 2019-01-18 Last updated: 2019-06-14Bibliographically approved
Shetty, P., Mu, L. & Shi, Y. (2019). Polyelectrolyte Cellulose Gel with PEG/Water: Toward Fully Green Lubricating Grease. Carbohydrate Polymers
Open this publication in new window or tab >>Polyelectrolyte Cellulose Gel with PEG/Water: Toward Fully Green Lubricating Grease
2019 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344Article in journal (Refereed) Epub ahead of print
Abstract [en]

Developing a fully green lubricant is an urgent need due to the growing consciousness of environmental protection and dwindling resources. In this work, fully green gel lubricants were developed out of cellulose derivatives as gelator and mixture of water and poly(ethylene glycol) 200 (PEG 200) as the base fluid. The non-ionic hydroxyethyl cellulose (HEC) and anionic sodium carboxymethyl cellulose (NaCMC) were chosen to understand the effect of ionic and non-ionic gelators on the thermal, rheological and the tribological properties of the gel lubricant. HEC or NaCMC is demonstrated as effective additive to reduce wear, stabilize friction coefficient and enhance the thermal stability of developed lubricants. It is shown that anionic gelator will result in producing lower friction and wear in comparison to non-ionic gelator, which may be attributed to the possible tribo-film formation due to the negative charge in the NaCMC molecules and its larger molecular weight.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Cellulose, Green, lubricant, PEG/Water, Gel
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76921 (URN)10.1016/j.carbpol.2019.115670 (DOI)
Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2019-11-28
Mu, L., Ma, X., Guo, X., Chen, M., Ji, T., Hua, J., . . . Shi, Y. (2019). Structural strategies to design bio-ionic liquid: Tuning molecular interaction with lignin for enhanced lubrication. Journal of Molecular Liquids, 280, 49-57
Open this publication in new window or tab >>Structural strategies to design bio-ionic liquid: Tuning molecular interaction with lignin for enhanced lubrication
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2019 (English)In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 280, p. 49-57Article in journal (Refereed) Published
Abstract [en]

Lignin strengthened ionic liquids (ILs) have shown high potential to be used as high performance green lubricants. Strengthened lignin-ILs molecular interaction is an effective approach to improve their lubrication properties. The molecular interactions of ILs’ cation and anion containing different functional groups with lignin and efficiency on the lubricating properties have rarely been studied yet. In this work, a series of novel green lubricants with dissolved lignin in [Choline][Amino Acid] ([CH][AA]), [Tetramethylammonium][Glycine] ([N 1111 ][Gly]) and [Tetrabutylammonium][Glycine] ([N 4444 ][Gly]) ILs have been synthesized and their tribological properties were systematically investigated. The longer alkyl chain in cation without reciprocal H-bond interaction between ILs’ cation and anion has the positive effect on the anti-wear properties. In addition, the less steric effect and more negative natural charges of amino acid anion synergistically contribute to the stronger H-bond interaction between lignin and choline base ILs, which enhances lubrication film strength and thus resulting in the better tribological property of ILs/lignin green lubricants. Specifically, the wear volume loss of the steel disc lubricated by [N 4444 ][Gly] with the addition of 15% lignin is only 12% of the one lubricated by pure [N 4444 ][Gly]. This work presents a method to tune molecular interaction between lignin and ILs via the structural design of ILs’ cation and anion, which are revealed as the key factor that bridges the individual components and improves overall lubricating properties. 

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Amino acid, Hydrogen bond, Ionic liquids, Lignin, Lubrication, Structure
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-72933 (URN)10.1016/j.molliq.2019.02.022 (DOI)000464089800007 ()2-s2.0-85061426516 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-18 (svasva)

Available from: 2019-02-18 Created: 2019-02-18 Last updated: 2019-04-29Bibliographically approved
Mu, L., Wu, J., Matsakas, L., Chen, M., Rova, U., Christakopoulos, P., . . . Shi, Y. (2019). Two important factors of selecting lignin as efficient lubricating additives in poly (ethylene glycol): Hydrogen bond and molecular weight. International Journal of Biological Macromolecules, 129, 564-570
Open this publication in new window or tab >>Two important factors of selecting lignin as efficient lubricating additives in poly (ethylene glycol): Hydrogen bond and molecular weight
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2019 (English)In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 129, p. 564-570Article in journal (Refereed) Published
Abstract [en]

Lignin, one of the most abundant natural polymers, has been successfully used as an effective lubricant additive with high value. The chemical structure of lignin is very diverse and strongly affected by both the source of lignin (i.e. plant species) and the lignin extraction process. In this work, a series of lignin from different biomass sources (hard or soft wood) and extraction process (organosolv with or without acid catalyst) has been successfully incorporated into poly(ethylene glycol) (PEG) and fortified lubricating properties were achieved. The effects of different lignin on the rheological, thermal and tribological properties of the lignin/EG lubricants were systematically investigated by different characterization techniques. Lignin in PEG significantly improves the lubricating property, where a wear reduction of 93.8% was observed. The thermal and lubrication properties of the PEG lubricants filled with different kinds of lignin are tightly related to the synergistic state of hydrogen bonding and molecular weight distribution. Lignin with broader molecular weight distribution and higher hydroxyl content shows better adhesion on metal surfaces and strengthened lubricating film, which could be used as the efficient lubricating additives. This work provides a criterion for selecting appropriate lignin as the efficient lubricant additive and accelerates the application of lignin.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Lignin, Lubrication, Poly (ethylene glycol), Hydrogen bonding, Molecular weight
National Category
Bioprocess Technology Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements; Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-72899 (URN)10.1016/j.ijbiomac.2019.01.175 (DOI)000466621200058 ()2-s2.0-85061540788 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-20 (svasva)

Available from: 2019-02-14 Created: 2019-02-14 Last updated: 2019-06-18Bibliographically approved
Mu, L., Wu, J., Matsakas, L., Chen, M., Vahidi, A., Grahn, M., . . . Shi, Y. (2018). Lignin from Hardwood and Softwood Biomass as a Lubricating Additive to Ethylene Glycol. Molecules, 23(3), Article ID 537.
Open this publication in new window or tab >>Lignin from Hardwood and Softwood Biomass as a Lubricating Additive to Ethylene Glycol
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2018 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 23, no 3, article id 537Article in journal (Refereed) Published
Abstract [en]

Ethylene glycol (EG)-based lubricant was prepared with dissolved organosolv lignin from birch wood (BL) and softwood (SL) biomass. The effects of different lignin types on the rheological, thermal, and tribological properties of the lignin/EG lubricants were comprehensively investigated by various characterization techniques. Dissolving organosolv lignin in EG results in outstanding lubricating properties. Specifically, the wear volume of the disc by EG-44BL is only 8.9% of that lubricated by pure EG. The enhanced anti-wear property of the EG/lignin system could be attributed to the formation of a robust lubrication film and the strong adhesion of the lubricant on the contacting metal surface due to the presence of a dense hydrogen bonding (H-bonding) network. The lubricating performance of EG-BL outperforms EG-SL, which could be attributed to the denser H-bonding sites in BL and its broader molecular weight distribution. The disc wear loss of EG-44BL is only 45.7% of that lubricated by EG-44SL. Overall, H-bonding is the major contributor to the different tribological properties of BL and SL in EG-based lubricants.

Place, publisher, year, edition, pages
MDPI, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Bioprocess Technology Chemical Process Engineering
Research subject
Machine Elements; Biochemical Process Engineering; Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-67800 (URN)10.3390/molecules23030537 (DOI)000428514100028 ()29495559 (PubMedID)2-s2.0-85043353975 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-03-01 (andbra)

Available from: 2018-03-01 Created: 2018-03-01 Last updated: 2019-04-02Bibliographically approved
Mu, L., Shi, Y., Guo, X., Zhuang, W., Chen, L., Ji, T., . . . Zhu, J. (2017). Grafting Heteroelement-Rich Groups on Graphene Oxide: Tuning Polarity and Molecular Interaction with Bio-Ionic Liquid for Enhanced Lubrication. Journal of Colloid and Interface Science, 498, 47-54
Open this publication in new window or tab >>Grafting Heteroelement-Rich Groups on Graphene Oxide: Tuning Polarity and Molecular Interaction with Bio-Ionic Liquid for Enhanced Lubrication
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2017 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 498, p. 47-54Article in journal (Refereed) Published
Abstract [en]

Two different heteroelement-rich molecules have been successfully grafted on graphene oxide (GO) sheets which were then used as lubricant additives in bio-ionic liquid. The grafting was processed with reactions between GO sheets and synthesized heteroelement-rich molecules (Imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, respectively). The modified GO (m-GO) was added into [Choline][Proline] ([CH][P]) bio-ionic liquid, and has been demonstrated effective additive in promoting lubrication. Different characterization techniques have been utilized to study the reaction between GO and the two modifiers. The effect of molecular structure of the modifiers on the rheological and tribological properties of m-GO/[CH][P] lubricants was systematically investigated. Both theoretical calculation and experimental results demonstrated that the introduced heteroelement-rich groups are beneficial to increase the robustness of lubrication film by intensified hydrogen bonding and enhance the lubricant/friction surface adhesion by increased polarity of the m-GO. As a result, the interfacial lubrication could be significantly improved by these newly developed m-GO/[CH][P] lubricants.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-62450 (URN)10.1016/j.jcis.2017.03.044 (DOI)000399855600005 ()28319840 (PubMedID)2-s2.0-85015699247 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-03-23 (andbra)

Available from: 2017-03-13 Created: 2017-03-13 Last updated: 2019-02-22Bibliographically approved
Mu, L., He, J., Li, Y., Ji, T., Mehra, N., Shi, Y. & Zhu, J. (2017). Molecular Origin of Efficient Phonon Transfer in Modulated Polymer Blends: Effect of Hydrogen Bonding on Polymer Coil Size and Assembled Microstructure. The Journal of Physical Chemistry C, 121(26), 14204-14212
Open this publication in new window or tab >>Molecular Origin of Efficient Phonon Transfer in Modulated Polymer Blends: Effect of Hydrogen Bonding on Polymer Coil Size and Assembled Microstructure
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2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 26, p. 14204-14212Article in journal (Refereed) Published
Abstract [en]

Molecular level engineering of polymer or polymer blends has been recently demonstrated effective strategy to regulate thermal conductivity. Such materials are of great interest to meet critical requirements of transparent, light weight, flexible, etc for thermal management in electronic applications. In this work, modulated polymer blends with poly(vinyl alcohol) (PVA) and biopolymers (lignin, gelatin) were designed and significantly enhanced thermal conductivity was achieved by tuning the intermolecular interaction among polymer components. The hydrogen bond interaction has been revealed as the major driving force that affects the polymer coil dimension in aqueous solution, the microstructure of coil-coil interaction in solid film and thus the thermal conduction. A solid relationship across molecular level interaction to macro-scale thermal conduction is constructed via careful characterization of the coil size in liquid phase and assembled microstructure in solid phase. Appropriate integration of biopolymers and PVA is essential to achieve synergistic effect. Specifically, thermal conductivity of polymer blend with 10% lignin and 10% G90 in PVA reaches 0.71 W/m·K, which is 184% enhancement as compared to pure PVA. This work reveals the fundamental molecular origin of polymer blends in association with thermal conductivity and has great potential to guide molecular engineering for superior physicochemical properties.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-64060 (URN)10.1021/acs.jpcc.7b03726 (DOI)000405252800026 ()2-s2.0-85024504405 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-08-08 (rokbeg)

Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2019-02-22Bibliographically approved
Mu, L., Shi, Y., Guo, X., Wu, J., Ji, T., Chen, L., . . . Zhu, J. (2016). Enriching Heteroelements in Lignin as Lubricating Additives for Bioionic Liquids (ed.). A C S Sustainable Chemistry & Engineering, 4(7), 3877-3887
Open this publication in new window or tab >>Enriching Heteroelements in Lignin as Lubricating Additives for Bioionic Liquids
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2016 (English)In: A C S Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 4, no 7, p. 3877-3887Article in journal (Refereed) Published
Abstract [en]

Depolymerization and modification of lignin have been achieved simultaneously in a one-pot chemical reaction. Two heteroelement-rich modifiers, imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, were selected to react with lignin in this work. The modified lignin (m-lignin) is demonstrated as an effective lubricating additive for [choline][amino acid] ([CH][AA]) bioionic liquids. Different characterization techniques have been utilized to study the lignin depolymerization, reaction between lignin and modifiers and m-lignin/[CH][AA] interaction. The effect of the molecular structure of the modifiers on the rheological and tribological properties of m-lignin/[CH][AA] lubricants was systematically investigated. Density function theory is used to calculate the electronic structure of lignin, m-lignin, and [CH][AA]. The atomic natural charge analysis revealed the most negative charge on nitrogen bonded to a phosphorus atom and the strongest capability of forming hydrogen bonding with [CH][AA]. The introduced nitrogen and phosphorus elements not only increase the hydrogen bonding density in m-lignin/[CH][AA] but also enhance the polarity of the m-lignin, both of which facilitate a strong adhesion of lubricant on a metal surface and thus promote lubrication. A larger fraction of heteroatom groups in m-lignin contributes to a better lubrication property of these lubricants

Keywords
Depolymerization, Heteroelement, Hydrogen bonding, Lignin, Lubrication
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-14572 (URN)10.1021/acssuschemeng.6b00669 (DOI)000380291200036 ()2-s2.0-84979076065 (Scopus ID)df69cea5-8ec2-4d4c-8898-0d25356410d0 (Local ID)df69cea5-8ec2-4d4c-8898-0d25356410d0 (Archive number)df69cea5-8ec2-4d4c-8898-0d25356410d0 (OAI)
Note

Validerad; 2016; Nivå 2; 20160627 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-02-22Bibliographically approved
Mu, L., Ji, T., Chen, L., Mehra, N., Shi, Y. & Zhu, J. (2016). Paving the Thermal Highway with Self-Organized Nanocrystals in Transparent Polymer Composites. ACS Applied Materials and Interfaces, 8(42), 29080-29087
Open this publication in new window or tab >>Paving the Thermal Highway with Self-Organized Nanocrystals in Transparent Polymer Composites
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2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 42, p. 29080-29087Article in journal (Refereed) Published
Abstract [en]

Phonon transfer is greatly scattered in traditional polymer composites due to the unpaired phonon frequency at the polymer/filler interface. A key innovation of this work is to build continuous crystal network by self-organization and utilize it as “thermal highway” that circumvents the long-existing interfacial thermal barrier issue in traditional composites. By tuning the molecular diffusion rate of dicarboxylic acids (oxalic acid, malonic acid, and succinic acid), different crystal structures including skeletal, dendrite, diffusion-limited aggregates, and spherulite were synthesized in PVA film. These continuous crystal structures benefit the efficient phonon transfer in the composites with minimized interfacial scattering and lead to a significant thermal conductivity enhancement of up to 180% compared to that of pure polymer. Moreover, the transparent feature of these composite films provides additional benefits in display applications. The post heat treatment effect on the thermal conductivity of the composite films shows a time-dependent behavior. These uniquely structured polymer/crystal composites are expected to generate significant impacts in thermal management applications.

Keywords
crystal network, phonon, polymer composites, thermal conductivity, transparent
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-60506 (URN)10.1021/acsami.6b10451 (DOI)000386540300091 ()2-s2.0-84993982660 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-11-17 (andbra)

Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2019-02-22Bibliographically approved
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