1
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Streďanská A, Nečas D, Vrbka M, Suchánek J, Matonohová J, Toropitsyn E, Hartl M, Křupka I, Nešporová K. Understanding frictional behavior in fascia tissues through tribological modeling and material substitution. J Mech Behav Biomed Mater 2024; 155:106566. [PMID: 38729087 DOI: 10.1016/j.jmbbm.2024.106566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/12/2024] [Accepted: 05/03/2024] [Indexed: 05/12/2024]
Abstract
The objective of this study is to develop a reliable tribological model to enable a more thorough investigation of the frictional behavior of fascia tissues connected to non-specific lower back pain. Several models were designed and evaluated based on their coefficient of friction, using a low-frequency, low-load reciprocating motion. The study found that two technical elastomers, layered on PDMS to simulate the fascia and underlying muscle, are suitable substitutes for biological tissue in the model. The influence of tribopair geometry was also examined, and the results showed that greater conformity of contact leads to a lower COF, regardless of the material combination used. Finally, the friction properties of HA of various molecular weights and concentrations were tested.
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Affiliation(s)
- A Streďanská
- Biotribology Research Group, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
| | - D Nečas
- Biotribology Research Group, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic
| | - M Vrbka
- Biotribology Research Group, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic
| | - J Suchánek
- Faculty of Medicine in Hradec Králové, Charles University, Šimkova 870, 500 03, Hradec Králové, Czech Republic
| | - J Matonohová
- Contipro a.s., Dolní Dobrouč 401, 561 02, Dolní Dobrouč, Czech Republic
| | - E Toropitsyn
- Contipro a.s., Dolní Dobrouč 401, 561 02, Dolní Dobrouč, Czech Republic
| | - M Hartl
- Biotribology Research Group, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic
| | - I Křupka
- Biotribology Research Group, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic
| | - K Nešporová
- Contipro a.s., Dolní Dobrouč 401, 561 02, Dolní Dobrouč, Czech Republic
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2
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Xiao Y, Bai P, Guo Y. Modulus alteration of thin polystyrene films by their neighboring PDMS: Soft and hard confinement. J Chem Phys 2024; 160:211105. [PMID: 38832730 DOI: 10.1063/5.0209251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 05/17/2024] [Indexed: 06/05/2024] Open
Abstract
It is highly demanded to understand the confinement effect on nanoconfined polymers. Recent studies reported a strong perturbation of local dynamics and substantial alteration of glass transition temperature Tg at nanoscale. However, how confinement affects the mechanical properties of polymers is not fully understood. Here, we show that the modulus of thin polymer films could be remarkedly altered through a polymer-polymer interface. The modulus of a thin polystyrene (PS) film next to a polydimethylsiloxane (PDMS) was determined from the PS-PDMS bilayer bulging test. A series of experiments show that the modulus of PS can be increased up to 37%, when the modulus of the neighboring PDMS varies from 1.04 to 4.88 MPa. The results demonstrate a strong sensitivity of mechanical properties of thin polymers to the hard/soft environment, which we attribute to the change of high-mobility layer by the polymer-polymer interface.
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Affiliation(s)
- Yuhan Xiao
- University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Pei Bai
- University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yunlong Guo
- University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China
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3
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Roché M, Talini L, Verneuil E. Complexity in Wetting Dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 38294343 DOI: 10.1021/acs.langmuir.3c03292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
The spreading dynamics of a droplet of pure liquid deposited on a rigid, nonsoluble substrate has been extensively investigated. In a purely hydrodynamic description, the dynamics of the contact line is determined by a balance between the energy associated with the capillary driving force and the energy dissipated by the viscous shear in the liquid. This balance is expressed by the Cox-Voinov law, which relates the spreading velocity to the contact angle. More recently, complex situations have been examined in which dissipation and/or the driving force may be strongly modified, leading to sometimes spectacular changes in wetting dynamics. We review recent examples of effects at the origin of deviations from the hydrodynamic model, which may involve physical or chemical modifications of the substrate or of the wetting liquid, occurring at scales ranging from the molecular to the mesoscopic.
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Affiliation(s)
- Matthieu Roché
- Matière et Systèmes Complexes, Université Paris Cité, CNRS UMR 7057, 75013 Paris, France
- Department of Materials Physics, Research School of Physics, The Australian National University, Canberra ACT 2601, Australia
| | - Laurence Talini
- CNRS, Surface du Verre et Interfaces, Saint-Gobain, 93300 Aubervilliers, France
| | - Emilie Verneuil
- CNRS Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL Research University, Sorbonne Université, 75005 Paris, France
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4
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Oléron M, Limat L, Dervaux J, Roché M. Morphology and stability of droplets sliding on soft viscoelastic substrates. SOFT MATTER 2024; 20:762-772. [PMID: 38165773 DOI: 10.1039/d3sm01197f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
We show that energy dissipation partition between a liquid and a solid controls the shape and stability of droplets sliding on viscoelastic gels. When both phases dissipate energy equally, droplet dynamics is similar to that on rigid solids. When the solid is the major contributor to dissipation, we observe an apparent contact angle hysteresis of viscoelastic origin. We find excellent agreement between our data and a non-linear model of the wetting of gels of our own that also indicates the presence of significant slip. Our work opens general questions on the dynamics of curved contact lines on compliant substrates.
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Affiliation(s)
- Mathieu Oléron
- Matière et Systèmes Complexes, Université Paris Cité, CNRS UMR 7057, Paris, France.
| | - Laurent Limat
- Matière et Systèmes Complexes, Université Paris Cité, CNRS UMR 7057, Paris, France.
| | - Julien Dervaux
- Matière et Systèmes Complexes, Université Paris Cité, CNRS UMR 7057, Paris, France.
| | - Matthieu Roché
- Matière et Systèmes Complexes, Université Paris Cité, CNRS UMR 7057, Paris, France.
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5
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VanDonselaar KR, Bellido-Aguilar DA, Safaripour M, Kim H, Watkins JJ, Crosby AJ, Webster DC, Croll AB. Silicone elastomers and the Persson-Brener adhesion model. J Chem Phys 2023; 159:184708. [PMID: 37955325 DOI: 10.1063/5.0172415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 10/18/2023] [Indexed: 11/14/2023] Open
Abstract
Many modern anti-icing and anti-fouling coatings rely on soft, low surface energy elastomeric materials such as polydimethylsiloxane for their functionality. While the low surface energy is desirable for reducing adhesion, very little work considers the larger contribution to adhesive failure caused by the viscoelastic nature of elastomers. Here we examine several different siloxane elastomers using a JKR adhesion test, which was operated over a range of different speeds and temperatures. Additionally, we characterize the dynamic mechanical modulus over a large range of frequencies for each material. We note that surface energies of the materials are all similar, but variation in adhesion strength is clear in the data. The variation at low speeds is related to elastomer architecture but the speed dependence itself is independent of architecture. Qualitative correlations are noted between the JKR adhesion measurements and the dynamic moduli. Finally, an attempt is made to directly compare moduli and adhesion through the recent Persson-Brener model. Approximations of the model are shown to be inaccurate. The full model is found to be accurate at low speeds, although it fails to precisely capture higher speed behaviour.
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Affiliation(s)
- Kurt R VanDonselaar
- Department of Physics, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Daniel A Bellido-Aguilar
- Department of Coatings and Polymeric Materials, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Maryam Safaripour
- Department of Coatings and Polymeric Materials, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Hyemin Kim
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, Massachusetts 01002, USA
| | - James J Watkins
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, Massachusetts 01002, USA
| | - Alfred J Crosby
- Polymer Science and Engineering Department, University of Massachusetts Amherst, 120 Governors Drive, Amherst, Massachusetts 01002, USA
| | - Dean C Webster
- Department of Coatings and Polymeric Materials, North Dakota State University, Fargo, North Dakota 58102, USA
| | - Andrew B Croll
- Department of Physics, North Dakota State University, Fargo, North Dakota 58102, USA
- Materials and Nanotechnology, North Dakota State University, Fargo, North Dakota 58102, USA
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6
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Afferrante L, Violano G, Carbone G. Exploring the dynamics of viscoelastic adhesion in rough line contacts. Sci Rep 2023; 13:15060. [PMID: 37699918 PMCID: PMC10497551 DOI: 10.1038/s41598-023-39932-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/02/2023] [Indexed: 09/14/2023] Open
Abstract
Modeling the adhesion of viscoelastic rough surfaces is a recent challenge in contact mechanics. Existing models have primarily focused on simple systems with smooth topography or single roughness scale due to the co-action of roughness and viscoelasticity leading to elastic instabilities and rate-dependent behavior, resulting in complex adhesion dynamics. In this study, we propose a numerical model based on a finite element methodology to investigate the adhesion between a randomly rough profile and a viscoelastic half-plane. Approach-retraction simulations are performed under controlled displacement conditions of the rough indenter. The results demonstrate that viscous effects dampen the roughness-induced instabilities in both the approach and retraction phases. Interestingly, even when viscous effects are negligible, the pull-off stress, i.e., the maximum tensile stress required to detach the surfaces, is found to depend on the stiffness modulus and maximum load reached during the approach. Furthermore, when unloading is performed from a relaxed state of the viscoelastic half-plane, both adhesion hysteresis and pull-off stress are monotonic increasing functions of the speed. Conversely, when retraction begins from an unrelaxed state of the material, the maximum pull-off stress and hysteretic loss are obtained at intermediate velocities.
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Affiliation(s)
- Luciano Afferrante
- Department of Mechanics, Mathematics and Management, Polytechnic University of Bari, Via E. Orabona, 4, 70125, Bari, Italy
| | - Guido Violano
- Department of Materials Science and Engineering, Saarland University, Campus, Geb. C6.3, 66123, Saarbrücken, Germany.
| | - Giuseppe Carbone
- Department of Mechanics, Mathematics and Management, Polytechnic University of Bari, Via E. Orabona, 4, 70125, Bari, Italy
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7
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Huang J, Cao L, Xue CY, Zhou YZ, Cai YC, Zhao HY, Xing YH, Yu SH. Extremely Soft, Stretchable, and Self-Adhesive Silicone Conductive Elastomer Composites Enabled by a Molecular Lubricating Effect. NANO LETTERS 2022; 22:8966-8974. [PMID: 36374184 DOI: 10.1021/acs.nanolett.2c03173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Softness, adhesion, stretchability, and fast recovery from large deformations are essential properties for conductive elastomers that play an important role in the development of high-performance soft electronics. However, it remains an ongoing challenge to obtain conductive elastomers that combine these properties. We have fabricated a super soft (Young's modulus 2.3-12 kPa), highly stretchable (up to 1500% strain), and underwater adhesive silicone conductive elastomer composite (SF-C-PDMS) by incorporating dimethyl silicone oil as a lubricating agent in a cross-linked molecular network. The resultant SF-C-PDMS not only exhibits superior softness but also can readily recover after a strain of 1000%. The initial resistance only decreases by 8% after 100000 cycles of tensile fatigue test (100% strain, 0.5 Hz, 15 mm/s). This multifunctional silicone conductive elastomer composite is obtained in a one-step preparation at room temperature using commercially available materials. Moreover, we illustrate the capabilities of this composite in motion sensing.
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Affiliation(s)
- Jin Huang
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Lei Cao
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Cheng-Yuan Xue
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Zhe Zhou
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Yu-Chun Cai
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Hao-Yu Zhao
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Ye-Han Xing
- School of Chemistry and Chemical Engineering, Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, Hefei University of Technology, Hefei 230009, China
| | - Shu-Hong Yu
- Department of Chemistry, Institute of Biomimetic Materials & Chemistry, Anhui Engineering Laboratory of Biomimetic Materials, Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
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8
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Kelly M, Farhad S. Simplified mathematical modeling and parametric study on friction coefficient of rubber materials for vehicle's tire application. POLYM ENG SCI 2022. [DOI: 10.1002/pen.26164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Michael Kelly
- Department of Mechanical Engineering University of Akron Akron Ohio USA
- The Smithers Group, Inc Akron Ohio USA
| | - Siamak Farhad
- Department of Mechanical Engineering University of Akron Akron Ohio USA
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9
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Darby DR, Cai Z, Mason CR, Pham JT. Modulus and adhesion of Sylgard 184, Solaris, and Ecoflex 00‐30 silicone elastomers with varied mixing ratios. J Appl Polym Sci 2022. [DOI: 10.1002/app.52412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Daniel R. Darby
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Zhuoyun Cai
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Christopher R. Mason
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Jonathan T. Pham
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
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10
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Kim S, Lakshmanan S, Li J, Anthamatten M, Lambropoulos J, Shestopalov AA. Modulation of Interfacial Adhesion Using Semicrystalline Shape-Memory Polymers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3607-3616. [PMID: 35263106 PMCID: PMC8945391 DOI: 10.1021/acs.langmuir.2c00291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Semicrystalline shape-memory elastomers are molded into deformable geometrical features to control adhesive interactions between elastomers and a glass substrate. By mechanically and thermally controlling the deformation and phase-behavior of molded features, we can control the interfacial contact area and the interfacial adhesive force. Results indicate that elastic energy is stored in the semicrystalline state of deformed features and can be released to break attractive interfacial forces, automatically separating the glass substrate from the elastomer. Our findings suggest that the shape-memory elastomers can be applied in various contact printing applications to control adhesive forces and delamination mechanics during ink pickup and transfer.
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Affiliation(s)
- Soyoun Kim
- Department
of Chemical Engineering, University of Rochester, Rochester, New York 14627, United
States
| | - Sanjay Lakshmanan
- Department
of Mechanical Engineering, University of
Rochester, Rochester, New York 14627, United States
| | - Jinhai Li
- Department
of Chemical Engineering, University of Rochester, Rochester, New York 14627, United
States
| | - Mitchell Anthamatten
- Department
of Chemical Engineering, University of Rochester, Rochester, New York 14627, United
States
| | - John Lambropoulos
- Department
of Mechanical Engineering, University of
Rochester, Rochester, New York 14627, United States
| | - Alexander A. Shestopalov
- Department
of Chemical Engineering, University of Rochester, Rochester, New York 14627, United
States
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11
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Gagnon YJ, Burton JC, Roth CB. Physically intuitive continuum mechanics model for quartz crystal microbalance: Viscoelasticity of rubbery polymers at
MHz
frequencies. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - Connie B. Roth
- Department of Physics Emory University Atlanta Georgia USA
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12
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Persson BNJ. A simple model for viscoelastic crack propagation. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:3. [PMID: 33570714 PMCID: PMC7878232 DOI: 10.1140/epje/s10189-020-00001-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
When a crack propagates in a viscoelastic solid, energy dissipation can occur very far from the crack tip where the stress field may be very different from the [Formula: see text] singular form expected close to the crack tip. Most theories of crack propagation focus on the near crack tip region. Remarkable, here I show that a simple theory which does not account for the nature of the stress field in the near crack tip region results in a crack propagation energy in semiquantitative agreement with a theory based on the stress field in the near crack tip region. I consider both opening and closing crack propagation and show that for closing crack propagation in viscoelastic solids, some energy dissipation processes must occur in the crack tip process zone. The theory is illustrated by new experimental results for the adhesive interaction between a silica glass ball and a silicone rubber surface.
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13
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Liu L, Liu KK. Capillary force in adhesive contact between hydrogel microspheres. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2020.125828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Abstract
It is known that in the presence of surface roughness, adhesion can lead to distinct paths of loading and unloading for the area–load and penetration–load relationships, thus causing hysteretic loss. Here, we investigate the effects that the surface roughness parameters have on such adhesive hysteresis loss. We focus on the frictionless normal contact between soft elastic bodies and, for this reason, we model adhesion according to Johnson, Kendall, and Roberts (JKR) theory. Hysteretic energy loss is found to increase linearly with the true area of contact, while the detachment force is negligibly influenced by the maximum applied load reached at the end of the loading phase. Moreover, for the micrometric roughness amplitude hrms considered in the present work, adhesion hysteresis is found to be affected by the shorter wavelengths of roughness. Specifically, hysteresis losses decrease with increasing fractal dimension and cut-off frequency of the roughness spectrum. However, we stress that a different behavior could occur in other ranges of roughness amplitude.
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15
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Wang J, Tiwari A, Persson BNJ, Sivebaek IM. Cylinder-flat-surface contact mechanics during sliding. Phys Rev E 2020; 102:043002. [PMID: 33212665 DOI: 10.1103/physreve.102.043002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 09/16/2020] [Indexed: 11/07/2022]
Abstract
Using molecular dynamics we study the dependency of the contact mechanics on the sliding speed when an elastic block (cylinder) with a cos(q_{0}x) surface height profile is sliding in adhesive contact on a rigid flat substrate. The atoms on the block interact with the substrate atoms by Lennard-Jones potentials, and we consider both commensurate and (nearly) incommensurate contacts. For the incommensurate system the friction force fluctuates between positive and negative values, with an amplitude proportional to the sliding speed, but with the average close to zero. For the commensurate system the (time-averaged) friction force is much larger and nearly velocity independent. For both types of systems the width of the contact region is velocity independent even when, for the commensurate case, the frictional shear stress increases from zero (before sliding) to ≈0.1MPa during sliding. This frictional shear stress, and the elastic modulus used, are typical for polydimethylsiloxane rubber sliding on a glass surface, and we conclude that the reduction in the contact area observed in some experiments when increasing the tangential force must be due to effects not included in our model study, such as viscoelasticity or elastic nonlinearity.
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Affiliation(s)
- J Wang
- PGI-1, FZ Jülich, Germany, European Union and College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China
| | - A Tiwari
- PGI-1, FZ Jülich, Germany, European Union
| | | | - I M Sivebaek
- PGI-1, FZ Jülich, Germany, European Union; Department of Mechanical Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark, European Union; and Novo Nordisk Device R & D, DK-3400 Hillerød, Denmark, European Union
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16
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Gagnon YJ, Roth CB. Local Glass Transition Temperature Tg( z) Within Polystyrene Is Strongly Impacted by the Modulus of the Neighboring PDMS Domain. ACS Macro Lett 2020; 9:1625-1631. [PMID: 35617064 DOI: 10.1021/acsmacrolett.0c00659] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Profiles in the local glass transition temperature Tg(z) within polystyrene (PS) next to polydimethylsiloxane (PDMS) domains were determined using a localized fluorescence method. By changing the base to cross-linker ratio, we varied the cross-link density and, hence, the Young's modulus of PDMS (Sylgard 184). The local Tg(z) in PS at a distance of z = 50 nm away from the PS/PDMS interface was found to shift by 40 K as the PDMS modulus was varied from 0.9 to 2.6 MPa, demonstrating a strong sensitivity of this phenomenon to the rigidity of the neighboring domain. The extent the Tg(z) perturbation persists away from the PS/PDMS interface, z ≈ 65-90 nm before bulk Tg is recovered, is much shorter for this strongly immiscible system compared with the weakly immiscible systems studied previously, which we attribute to a smaller interfacial width, as the χ parameter for PS/PDMS is an order of magnitude larger.
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Affiliation(s)
- Yannic J. Gagnon
- Department of Physics, Emory University, Atlanta, Georgia 30322, United States
| | - Connie B. Roth
- Department of Physics, Emory University, Atlanta, Georgia 30322, United States
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17
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Tiwari A, Wang J, Persson BNJ. Adhesion paradox: Why adhesion is usually not observed for macroscopic solids. Phys Rev E 2020; 102:042803. [PMID: 33212630 DOI: 10.1103/physreve.102.042803] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/30/2020] [Indexed: 11/07/2022]
Abstract
The adhesion paradox refers to the observation that for most solid objects no adhesion can be detected when they are separated from a state of molecular contact. The adhesion paradox results from surface roughness, and we present experimental and theoretical results that show that adhesion in most cases is "killed" by the longest-wavelength roughness. In addition, adhesion experiments between a human finger and a clean glass plate were carried out, and for a dry finger no macroscopic adhesion occurred. We suggest that the observed decrease in the contact area with increasing shear force results from nonadhesive finger-glass contact mechanics, involving large deformations of complex layered material.
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Affiliation(s)
- A Tiwari
- PGI-1, FZ Jülich, Germany, Jülich 52428, European Union
| | - J Wang
- PGI-1, FZ Jülich, Germany, Jülich 52428, European Union.,College of Science, Zhongyuan University of Technology, Zhengzhou 450007, China
| | - B N J Persson
- PGI-1, FZ Jülich, Germany, Jülich 52428, European Union
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18
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Glover JD, Pham JT. Capillary-driven indentation of a microparticle into a soft, oil-coated substrate. SOFT MATTER 2020; 16:5812-5818. [PMID: 32412022 DOI: 10.1039/d0sm00296h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Small scale contact between a soft, liquid-coated layer and a stiff surface is common in many situations, from synovial fluid on articular cartilage to adhesives in humid environments. Moreover, many model studies on soft adhesive contacts are conducted with soft silicone elastomers, which possess uncrosslinked liquid molecules (i.e. silicone oil) when the modulus is low. We investigate how the thickness of a silicone oil layer on a soft substrate relates to the indentation depth of glass microspheres in contact with crosslinked PDMS, which have a modulus of <10 kPa. The particles indent into the underlying substrate more as a function of decreasing oil layer thickness. This is due to the presence of the liquid layer at the surface that causes capillary forces to pull down on the particle. A simple model that balances the capillary force of the oil layer and the minimal particle-substrate adhesion with the elastic and surface tension forces from the substrate is proposed to predict the particle indentation depth.
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Affiliation(s)
- Justin D Glover
- Department of Chemical and Material Engineering, University of Kentucky, Lexington, KY 40506, USA.
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19
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Shui L, Jia L, Li H, Guo J, Guo Z, Liu Y, Liu Z, Chen X. Rapid and continuous regulating adhesion strength by mechanical micro-vibration. Nat Commun 2020; 11:1583. [PMID: 32221304 PMCID: PMC7101336 DOI: 10.1038/s41467-020-15447-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 03/12/2020] [Indexed: 02/01/2023] Open
Abstract
Controlled tuning of interface adhesion is crucial to a broad range of applications, such as space technology, micro-fabrication, flexible electronics, robotics, and bio-integrated devices. Here, we show a robust and predictable method to continuously regulate interface adhesion by exciting the mechanical micro-vibration in the adhesive system perpendicular to the contact plane. An analytic model reveals the underlying mechanism of adhesion hysteresis and dynamic instability. For a typical PDMS-glass adhesion system, the apparent adhesion strength can be enhanced by 77 times or weakened to 0. Notably, the resulting adhesion switching timescale is comparable to that of geckos (15 ms), and such rapid adhesion switching can be repeated for more than 2 × 107 vibration cycles without any noticeable degradation in the adhesion performance. Our method is independent of surface microstructures and does not require a preload, representing a simple and practical way to design and control surface adhesion in relevant applications.
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Affiliation(s)
- Langquan Shui
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, 430072, Wuhan, People's Republic of China
| | - Laibing Jia
- Department of Naval Architecture, Ocean and Marine Engineering, University of Strathclyde, G4 0LZ, Glasgow, UK
- School of Marine Science and Technology, Northwestern Polytechnical University, 710072, Xi'an, People's Republic of China
| | - Hangbo Li
- School of Marine Science and Technology, Northwestern Polytechnical University, 710072, Xi'an, People's Republic of China
| | - Jiaojiao Guo
- Department of Engineering Mechanics, School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, 710072, Xi'an, People's Republic of China
| | - Ziyu Guo
- Department of Engineering Mechanics, School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, 710072, Xi'an, People's Republic of China
| | - Yilun Liu
- State Key Laboratory for Strength and Vibration of Mechanical Structure, School of Aerospace Engineering, Xi'an Jiaotong University, 710048, Xi'an, People's Republic of China
| | - Ze Liu
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, 430072, Wuhan, People's Republic of China.
| | - Xi Chen
- Department of Earth and Environmental Engineering, Earth Engineering Center, Center for Advanced Materials for Energy and Environment, Columbia University, New York, 10027, NY, USA.
- School of Chemical Engineering, Northwest University, 710069, Xi'an, People's Republic of China.
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20
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Glover JD, McLaughlin CE, McFarland MK, Pham JT. Extracting uncrosslinked material from low modulus sylgard 184 and the effect on mechanical properties. JOURNAL OF POLYMER SCIENCE 2020. [DOI: 10.1002/pol.20190032] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Justin D. Glover
- Department of Chemical and Materials EngineeringUniversity of Kentucky, 177 F. Paul Anderson Tower Lexington Kentucky 40506
| | - Colbi E. McLaughlin
- Department of Chemical and Materials EngineeringUniversity of Kentucky, 177 F. Paul Anderson Tower Lexington Kentucky 40506
| | - Mary K. McFarland
- Department of Chemical and Materials EngineeringUniversity of Kentucky, 177 F. Paul Anderson Tower Lexington Kentucky 40506
| | - Jonathan T. Pham
- Department of Chemical and Materials EngineeringUniversity of Kentucky, 177 F. Paul Anderson Tower Lexington Kentucky 40506
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21
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Dalvi S, Gujrati A, Khanal SR, Pastewka L, Dhinojwala A, Jacobs TDB. Linking energy loss in soft adhesion to surface roughness. Proc Natl Acad Sci U S A 2019; 116:25484-25490. [PMID: 31772024 PMCID: PMC6925979 DOI: 10.1073/pnas.1913126116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A mechanistic understanding of adhesion in soft materials is critical in the fields of transportation (tires, gaskets, and seals), biomaterials, microcontact printing, and soft robotics. Measurements have long demonstrated that the apparent work of adhesion coming into contact is consistently lower than the intrinsic work of adhesion for the materials, and that there is adhesion hysteresis during separation, commonly explained by viscoelastic dissipation. Still lacking is a quantitative experimentally validated link between adhesion and measured topography. Here, we used in situ measurements of contact size to investigate the adhesion behavior of soft elastic polydimethylsiloxane hemispheres (modulus ranging from 0.7 to 10 MPa) on 4 different polycrystalline diamond substrates with topography characterized across 8 orders of magnitude, including down to the angstrom scale. The results show that the reduction in apparent work of adhesion is equal to the energy required to achieve conformal contact. Further, the energy loss during contact and removal is equal to the product of the intrinsic work of adhesion and the true contact area. These findings provide a simple mechanism to quantitatively link the widely observed adhesion hysteresis to roughness rather than viscoelastic dissipation.
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Affiliation(s)
- Siddhesh Dalvi
- Department of Polymer Science, The University of Akron, Akron, OH 44325
| | - Abhijeet Gujrati
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261
| | - Subarna R Khanal
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261
| | - Lars Pastewka
- Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany
| | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron, Akron, OH 44325;
| | - Tevis D B Jacobs
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261;
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22
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Experimental synthesis and characterization of rough particles for colloidal and granular rheology. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.04.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Simaite A, Spenko M. Evaluation of silicone elastomers as structural materials for microstructured adhesives. BIOINSPIRATION & BIOMIMETICS 2019; 14:046005. [PMID: 31075783 DOI: 10.1088/1748-3190/ab20e6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Microstructured (sometimes referred to as gecko-like) adhesives have numerous advantages over flat films, especially for practical applications on non-ideal surfaces that may be uneven or contaminated with dust. However, due to interdependence among material surface and bulk properties, the best material to fabricate such adhesives is still unknown. In this work, we analyzed eleven commercially available silicone elastomers to evaluate their use as flat and microstructured adhesives to address multiple material related questions that may impact the choice of the 'best' material for microstructured dry adhesives. To illustrate the applicability of the measured properties to modeling microstructured surfaces, we use stalk-shaped microstructures, whose contact mechanics are well understood. We demonstrate that there is no correlation between the adhesion strength of flat and microstructured adhesives; while bulk dissipation is the most important factor influencing the adhesion strength of flat elastomers, after microstructurization, interface toughness becomes more important. Therefore, microstructured elastomers loaded with high surface energy additives may demonstrate higher adhesion than their flat counterparts. We also compare the adhesion of flat and microstructured silicone elastomers on rough substrates. In this case, we show that while flat elastomer adhesion decreases with increasing substrate roughness, microstructured silicone adhesion actually increases with increasing roughness up to 0.19 [Formula: see text]m. This is the first time an increase in adhesion strength on rough surfaces is reported for materials stiffer than 1.0 MPa.
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Affiliation(s)
- Aiva Simaite
- Illinois Institute of Technology, Mechanical, Materials and Aerospace Engineering, Chicago, IL 60616, United States of America
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24
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Abstract
We study the adhesion and friction for three tire tread rubber compounds. The adhesion study is for a smooth silica glass ball in contact with smooth sheets of the rubber in dry condition and in water. The friction studies are for rubber sliding on smooth glass, concrete, and asphalt road surfaces. We have performed the Leonardo da Vinci-type friction experiments and experiments using a linear friction tester. On the asphalt road, we also performed vehicle breaking distance measurements. The linear and non-linear viscoelastic properties of the rubber compounds were measured in shear and tension modes using two different Dynamic Mechanical Analysis (DMA) instruments. The surface topography of all surfaces was determined using stylus measurements and scanned-in silicon rubber replicas. The experimental data were analyzed using the Persson contact mechanics and rubber friction theory.
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25
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Dhong C, Kayser LV, Arroyo R, Shin A, Finn M, Kleinschmidt AT, Lipomi DJ. Role of fingerprint-inspired relief structures in elastomeric slabs for detecting frictional differences arising from surface monolayers. SOFT MATTER 2018; 14:7483-7491. [PMID: 30152497 PMCID: PMC6146067 DOI: 10.1039/c8sm01233d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The perception of fine texture of an object is influenced by its microscopic topography and surface chemistry-i.e., the topmost layer of atoms and molecules responsible for its surface energy, adhesion, and friction generated when probed by a fingertip. Recently, it has been shown that human subjects can discriminate high-energy (i.e., hydrophilic), oxidized silicon from low-energy (i.e., hydrophobic), fluorinated alkylsilane-coated silicon. The basis of discrimination was consistent with differences between stick-slip friction frequencies generated when sliding the fingertip across the two surfaces. One aspect that was not examined was the presence of surface relief structures on the fingertip. Indeed, papillary ridges-fingerprints-may be involved in enhanced discrimination of fine textures arising from surface roughness, but how (or whether) fingerprints may also be involved in the discrimination of surface chemistry-through its effect on friction-is unknown. Here, using a mock finger made from a slab of silicone rubber shows that relief structures amplify differences in stick-slip friction when slid across either a hydrophilic oxide or a hydrophobic monolayer on silicon. We quantify the similarity between the friction traces of the mock fingers sliding across hydrophilic and hydrophobic surfaces under varying velocities and applied masses using a cross-correlation analysis. We then convert the cross-correlational data into convenient "discriminability matrices." These matrices identify combinations of downward forces and sliding velocities that enhance differences in friction between hydrophilic and hydrophobic monolayers. In addition, a computational model of macroscopic, "rate-and-state" friction confirms that frictional differences in chemistry are amplified when elastic slabs bear a patterned interface. This biomimetic approach to engineering sliding interfaces may inform the development of improved electronic skin and haptic devices and may contribute to understanding the role of relief structure in tactile perception.
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Affiliation(s)
- Charles Dhong
- Department of NanoEngineering, University of California, San Diego, La Jolla, CA, USA.
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26
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Kim JH, Kim SR, Kil HJ, Kim YC, Park JW. Highly Conformable, Transparent Electrodes for Epidermal Electronics. NANO LETTERS 2018; 18:4531-4540. [PMID: 29923729 DOI: 10.1021/acs.nanolett.8b01743] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We present a highly conformable, stretchable, and transparent electrode for application in epidermal electronics based on polydimethylsiloxane (PDMS) and Ag nanowire (AgNW) networks. With the addition of a small amount of a commercially available nonionic surfactant, Triton X, PDMS became highly adhesive and mechanically compliant, key factors for the development of conformable and stretchable substrates. The polar functional groups present in Triton X interacted with the Pt catalyst present in the PDMS curing agent, thereby hindering the cross-linking reaction of PDMS and modulating the mechanical properties of the polymer. Due to the strong interactions that occur between the polar functional groups of Triton X and AgNWs, AgNWs were effectively embedded in the adhesive PDMS (a-PDMS) matrix, and the highly enhanced conformability, mechanical stretchability, and transparency of the a-PDMS matrix were maintained in the resulting AgNW-embedded a-PDMS matrix. Finally, wearable strain and electrocardiogram (ECG) sensors were fabricated from the AgNW-embedded a-PDMS. The a-PDMS-based strain and ECG sensors exhibited significantly improved sensing performances compared with those of the bare PDMS-based sensors because of the better stretchability and conformability to the skin of the former sensors.
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Affiliation(s)
- Jin-Hoon Kim
- Department of Materials Science and Engineering , Yonsei University , Seoul 03722 , Korea
| | - Seung-Rok Kim
- Department of Materials Science and Engineering , Yonsei University , Seoul 03722 , Korea
| | - Hye-Jun Kil
- Biomedical Research Institute, Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Yu-Chan Kim
- Biomedical Research Institute, Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Jin-Woo Park
- Department of Materials Science and Engineering , Yonsei University , Seoul 03722 , Korea
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27
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Dorogin L, Tiwari A, Rotella C, Mangiagalli P, Persson BNJ. Adhesion between rubber and glass in dry and lubricated condition. J Chem Phys 2018; 148:234702. [PMID: 29935497 DOI: 10.1063/1.5025605] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We study the adhesion between differently processed glass and filled bromobutyl rubber in dry conditions, in water, and in silicone oil. The boundary line between contact and non-contact in adhesion experiments can be considered as a mode I crack, and we show that viscoelastic energy dissipation, close to the opening (or closing) crack tip and surface roughness, strongly affects the work of adhesion. We observe strong adhesion hysteresis and, in contrast to the Johnson-Kendall-Roberts theory prediction for elastic solids, this results in a pull-off force (and work of adhesion) which depends on the loading force and contact time. In particular, for the system immersed in water and silicone oil, we register very weak adhesive bonding. For glass ball with baked-on silicone oil, the pull-off force is nearly independent of the contact time, but this is not observed for the unprocessed glass surface.
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Affiliation(s)
- L Dorogin
- Leibniz Institute for Polymer Research Dresden, P.O. Box 120 411, D-01005 Dresden, Germany
| | - A Tiwari
- PGI-1, FZ Jülich, Jülich, Germany
| | - C Rotella
- Sanofi, 13, quai Jules Guesde, BP 14, 94403 Vitry sur Seine Cedex, France
| | - P Mangiagalli
- Sanofi, 13, quai Jules Guesde, BP 14, 94403 Vitry sur Seine Cedex, France
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28
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Dorogin L, Persson BNJ. Contact mechanics for polydimethylsiloxane: from liquid to solid. SOFT MATTER 2018; 14:1142-1148. [PMID: 29345705 DOI: 10.1039/c7sm02216f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Adhesion between a glass ball and a polydimethylsiloxane (PDMS) sample is dependent on the PDMS cross-link density, and the transformation of the material from the uncrosslinked liquid state to the fully crosslinked solid state is investigated in this study. The physical picture reflected a gradual transition from capillary forces driven contact mechanics to the classical Johnson-Kendall-Roberts (JKR)-type contact mechanics. PDMS was produced by mixing the base fluid and a cross-linker at a ratio of 10 : 1 and allowed to slowly cross-link at room temperature with simultaneous measurement of the ball-PDMS interaction force. The PDMS sample was in the liquid state during the first ≈16 hours, and in this case the ball-PDMS interaction was purely adhesive, i.e., no repulsive interaction was observed. Later at the PDMS gel-point the cross-linked PDMS clusters percolate, converting the fluid into a soft (fluid-filled) poroelastic solid. In the transition period, PDMS appears similar to pressure-sensitive adhesives. There we observe so-called "stringing" and permanent deformation of the material impacted by the ball. At room temperature, it takes more than ∼100 hours for PDMS to fully cross-link that can be confirmed by the comparison with the earlier-studied reference PDMS produced at elevated temperatures.
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29
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Das A, Sallat A, Böhme F, Sarlin E, Vuorinen J, Vennemann N, Heinrich G, Stöckelhuber KW. Temperature Scanning Stress Relaxation of an Autonomous Self-Healing Elastomer Containing Non-Covalent Reversible Network Junctions. Polymers (Basel) 2018; 10:E94. [PMID: 30966129 PMCID: PMC6414832 DOI: 10.3390/polym10010094] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/08/2018] [Accepted: 01/16/2018] [Indexed: 11/17/2022] Open
Abstract
In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.
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Affiliation(s)
- Amit Das
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany.
- Laboratory of Materials Science, Tampere University of Technology, P.O. Box 589, 33101 Tampere, Finland.
| | - Aladdin Sallat
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany.
- Faculty of Chemistry and Food Chemistry, Department of macromolecular Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
| | - Frank Böhme
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany.
| | - Essi Sarlin
- Laboratory of Materials Science, Tampere University of Technology, P.O. Box 589, 33101 Tampere, Finland.
| | - Jyrki Vuorinen
- Laboratory of Materials Science, Tampere University of Technology, P.O. Box 589, 33101 Tampere, Finland.
| | - Norbert Vennemann
- Faculty of Engineering and Computer Science, University of Applied Sciences Osnabrück, 49076 Osnabrück, Germany.
| | - Gert Heinrich
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany.
- Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik, Technische Universität Dresden, D-01062 Dresden, Germany.
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30
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Tiwari A, Dorogin L, Tahir M, Stöckelhuber KW, Heinrich G, Espallargas N, Persson BNJ. Rubber contact mechanics: adhesion, friction and leakage of seals. SOFT MATTER 2017; 13:9103-9121. [PMID: 29177290 DOI: 10.1039/c7sm02038d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We study the adhesion, friction and leak rate of seals for four different elastomers: Acrylonitrile Butadiene Rubber (NBR), Ethylene Propylene Diene (EPDM), Polyepichlorohydrin (GECO) and Polydimethylsiloxane (PDMS). Adhesion between smooth clean glass balls and all the elastomers is studied both in the dry state and in water. In water, adhesion is observed for the NBR and PDMS elastomers, but not for the EPDM and GECO elastomers, which we attribute to the differences in surface energy and dewetting. The leakage of water is studied with rubber square-ring seals squeezed against sandblasted glass surfaces. Here we observe a strongly non-linear dependence of the leak rate on the water pressure ΔP for the elastomers exhibiting adhesion in water, while the leak rate depends nearly linearly on ΔP for the other elastomers. We attribute the non-linearity to some adhesion-related phenomena, such as dewetting or the (time-dependent) formation of gas bubbles, which blocks fluid flow channels. Finally, rubber friction is studied at low sliding speeds using smooth glass and sandblasted glass as substrates, both in the dry state and in water. The measured friction coefficients are compared to theory, and the origin of the frictional shear stress acting in the area of real contact is discussed. The NBR rubber, which exhibits the strongest adhesion both in the dry state and in water, also shows the highest friction both in the dry state and in water.
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Affiliation(s)
- A Tiwari
- Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology, Richard Birkelandsvei 2B, N-7491 Trondheim, Norway
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31
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Emerson JA, Garabedian NT, Moore AC, Burris DL, Furst EM, Epps TH. Unexpected Tribological Synergy in Polymer Blend Coatings: Leveraging Phase Separation to Isolate Domain Size Effects and Reduce Friction. ACS APPLIED MATERIALS & INTERFACES 2017; 9:34480-34488. [PMID: 28945331 DOI: 10.1021/acsami.7b10170] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We employed a systematic processing approach to control phase separation in polymer blend thin films and significantly reduce dynamic friction coefficients (μ)s. We leveraged this modulation of phase separation to generate composite surfaces with dynamic friction coefficients that were substantially lower than expected on the basis of simple mixing rules, and in several cases, these friction coefficients were lower than those of both pure components. Using a model polyisoprene [PI]/polystyrene [PS] composite system, a minimum μ was found in films with PS mass fractions between 0.60 and 0.80 (μblend = 0.11 ± 0.03); that value was significantly lower than the friction coefficient of PS (μPS = 0.52 ± 0.01) or PI (μPI = 1.3 ± 0.09) homopolymers and was comparable to the friction coefficient of poly(tetrafluoroethylene) [PTFE] (μPTFE = 0.09 ± 0.01) measured under similar conditions. Additionally, through experiments in which the domain size was systematically varied at constant composition (through an annealing process), we demonstrated that μ decreased with decreasing characteristic domain size. Thus, the tribological synergy between PS and PI domains (discrete size, physical domain isolation, and overall film composition) was shown to play an integral role in the friction and wear of these PS/PI composites. Overall, our results suggest that even high friction polymers can be used to create low friction polymer blends by following appropriate design rules and demonstrate that engineering microstructure is critical for controlling the friction and adhesion properties of composite films for tribologically relevant coatings.
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Affiliation(s)
- Jillian A Emerson
- Department of Chemical & Biomolecular Engineering, University of Delaware , Newark, Delaware 19716, United States
| | - Nikolay T Garabedian
- Department of Mechanical Engineering, University of Delaware , Newark, Delaware 19716, United States
| | - Axel C Moore
- Department of Biomedical Engineering, University of Delaware , Newark, Delaware 19716, United States
| | - David L Burris
- Department of Mechanical Engineering, University of Delaware , Newark, Delaware 19716, United States
| | - Eric M Furst
- Department of Chemical & Biomolecular Engineering, University of Delaware , Newark, Delaware 19716, United States
| | - Thomas H Epps
- Department of Chemical & Biomolecular Engineering, University of Delaware , Newark, Delaware 19716, United States
- Department of Materials Science & Engineering, University of Delaware , Newark, Delaware 19716, United States
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