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Evaluating The Impact Of Surface Chemistry On Adhesion Of Polymeric Systems Underwater By Means Of Contact Mechanics
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Book Synopsis Evaluating the Impact of Surface Chemistry on Adhesion of Polymeric Systems Underwater by Means of Contact Mechanics by : Nasim Rahmani
Download or read book Evaluating the Impact of Surface Chemistry on Adhesion of Polymeric Systems Underwater by Means of Contact Mechanics written by Nasim Rahmani and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this study was to assess the effects of surface chemistry on adhesion of polymeric systems underwater. The adhesion is quantified by the thermodynamic work of adhesion (W) when two surfaces are approached and the energy release rate (G) when the surfaces are separated. For some polymeric systems there is a difference between W and G, referred to as adhesion hysteresis. For this study an experimental approach based upon Johnson-Kendall-Roberts (JKR) theory of contact mechanics was utilized to evaluate how surface chemistry affects the adhesion behavior (both W and adhesion hysteresis) in the presence of water. The interfacial interactions were also studied in air and contrasted to those obtained underwater. To accomplish the overall goal of this research, this study was divided into two phases where smooth model surfaces with disparate surface chemistries were used. The model surfaces in the first part included poly(dimethysiloxane) (PDMS), glass surfaces chemically functionalized to display hydrophilic to medium to hydrophobic characteristics, and thin films of wood-based biopolymers. The functionalities used to modify glass surfaces included polyethylene oxide (PEO) with hydrophilic nature; amine, carbomethoxy, and mercapto (thiol) with intermediate characteristics; cyclohexyl, fluorocarbon, and methyl with hydrophobic behavior. In addition to these surfaces, flat PDMS and clean glass surfaces were also used for means of comparison. The wood-derived polymers included two different cellulose types (natural cellulose and regenerated cellulose) as well as one lignin surface (from hardwood milled lignin). These surfaces were probed with native PDMS hemispheres, which are hydrophobic. The results showed that in air the value of W for all model surfaces was independent of the surface chemistry, except fluorocarbon which was lower. Underwater W was significantly affected by the surface hydrophilicity/ hydrophobicity. The adhesion hysteresis both in air and underwater was significantly dependent on the structure of the probed surface. For the second phase PDMS hemispheres were chemically modified with amine functionality to probe model surfaces with hydrophilic and intermediate behavior. These surfaces included glass surfaces functionalized with PEO and amine as well as PDMS sheets that were functionalized with amine. Native PDMS flat surfaces were also used for means of comparison. The results showed that for the selected surfaces both W and hysteresis were affected by the surface chemistry in both media.
Book Synopsis Adhesion and Adsorption of Polymers by : Lieng-Huang Lee
Download or read book Adhesion and Adsorption of Polymers written by Lieng-Huang Lee and published by Springer. This book was released on 1980-03 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Honolulu is a most beautiful place, suitable for all occa sions. Its choice as the meeting site for the first Joint Chemical Congress between the American Chemical SOCiety and the Chemical Society of Japan was praised by scientists from both sides. During this Congress, the International Conference on Adhesion and Adsorption of Polymers was held at the Hyatt Regency Hotel between April 2 and 5, 1979. We had speakers from ten nations presenting over forty papers related to the subject matter. It was a memorable event. Unlike our two previous adhesion symposia held in 1971 and 1975, this was the first time in the same conference that we discussed both adhesion and adsorption of polymers simultaneously. These two important phenomena are not only inter-related, but also equally important in adhesive technology as well as biochemical processes. The papers presented to this Conference deal with these two phenomena from both fundamental and practical viewpoints. Furthermore, with the advance of new surface analytical techniques, the actual, microscopic happenings at the interfaces can be pin pointed. Thus, characterization of interface became one of the major focuses of this Conference. As a result, a broad coverage of the subject matter includes statistical thermodynamics, surface physics, surface analysis, fracture mechaniCS, viscoelasticity, failure analysis, surface modification, adsorption kinetics, bio polymer adsorption, etc. Thanks to the diligence of our contri butors, we are now able to publish the final papers in these two volumes.
Book Synopsis Adhesion to Fluoropolymers by : Derek Brewis
Download or read book Adhesion to Fluoropolymers written by Derek Brewis and published by iSmithers Rapra Publishing. This book was released on 2006 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Contact Mechanics Studies of Polymer Thin Film Adhesion by : Rachel Lynn McSwain
Download or read book Contact Mechanics Studies of Polymer Thin Film Adhesion written by Rachel Lynn McSwain and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this dissertation focuses on using the unique abilities of the JKR technique to probe the interfacial interactions of two independent polymer systems. To perform these studies, modifications were made to the JKR technique, including the integration of a thermal cycle to enable testing of thermally initiated interfacial interactions between two materials. Another enhancement of the JKR technique involved incorporation of cyclic testing to study crack growth under fatigue conditions.
Book Synopsis Contact and Adhesion Between Solids by : John McKenzie Levins
Download or read book Contact and Adhesion Between Solids written by John McKenzie Levins and published by . This book was released on 1994 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Investigation of Polymer Adhesion Mechanics Using a Blister Contact Test by : Nathan Ip
Download or read book Experimental Investigation of Polymer Adhesion Mechanics Using a Blister Contact Test written by Nathan Ip and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The adhesion of thin layers of soft polymers is important in many applications, such as tapes, microtransfer printing, and bioinspired adhesives. Traditional adhesion tests based on probe contacts are not suitable for characterizing thin layers and common separation-based specimens, such as the peel test, have well-known limitations. The blister contact test (BCT) was developed in this dissertation to overcome the limitations of current methods and was used to investigate the adhesion and separation of several technologically relevant adhesive systems. In the BCT, a thin sheet was elastically deformed into adhesive contact with a reference substrate and the contact area was optically imaged. Modulated pressure was applied to generate both advancing and receding adhesive contact. Digital image correlation was used to measure the displacements of the specimen. The strain energy release rate at the interface was determined from the measured contact radius, applied pressure, system geometry, and elastic properties of the specimen using a mechanics model. An analytical mechanics model based on von Kármán plate theory was developed and used for analysis of the BCT data. Finite element analysis was used to validate and identify the range of applicability of the analytical model. The BCT was used to investigate the adhesion and separation behaviors of three different polymer adhesive systems. First, experiments between a silicone elastomer (polydimethylsiloxane--PDMS) and a stiff substrate were performed to investigate rate effects in adhesion and separation. For the first time, the rate dependence during advancing contact was characterized. Second, the effect of acid-base interactions on performance of pressure sensitive adhesives (PSAs) was examined via a series of BCTs in which adhesion between different formulations of adhesives and multiple substrates was investigated. Viscoelastic contributions to PSA adhesion were also studied. Finally, the effect of layer thickness on rate dependence was investigated through experiments between polyethylene terephthalate (PET) sheets and PDMS films of different thicknesses. The work in this dissertation demonstrates the flexibility and capability of the BCT as a method to characterize adhesion of flat polymer sheets and provides new understanding of several types of polymer adhesive contacts.
Book Synopsis Scaling Down for a Broader Understanding of Underwater Adhesion by : Alex Nyarko
Download or read book Scaling Down for a Broader Understanding of Underwater Adhesion written by Alex Nyarko and published by . This book was released on 2018 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of synthetic adhesives that function efficiently in the presence of water is one of the challenging ventures in the field of adhesion. In underwater conditions, water is persistently present at the adhesive-adherend interface leading to a reduction in interfacial strength and consequent adhesive failure. The Caulobacter crescentus bacterium is known to attach irreversibly to surfaces underwater by utilizing an adhesive structure called the holdfast, which exhibits the highest adhesive energy known for any organism. Despite the impressive characteristics of the holdfast, its chemical properties still remain poorly understood. In the first work, I employ spectroscopic techniques, including attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and sum frequency generation spectroscopy (SFG) to identify the presence of a proteinaceous component of the holdfast chemistry in addition to possible surface molecules responsible for mediating adhesion at the interface. By comparing the IR spectra of the holdfast to peptidoglycan extracts from other species, I demonstrate the similarity of the holdfast chemistry to the peptidoglycan. Knowledge of the holdfast chemistry will provide ideas for designing synthetic underwater adhesives, which are needed in medicine and engineering.Even though our understanding of the holdfast chemistry has improved with these findings, the fundamental role of water in adhesion and friction remains unclear. My work therefore investigates the effect of water on friction and adhesion at contacts between surfaces having opposite surface energies, using substrates with a gradient of wettability. We bridge macroscopic measurements with surface sensitive investigations to provide a better understanding of the effect of water on adhesion and friction. This study can serve as a guide for making surfaces which exhibit specific friction and adhesion characteristics underwater. The final study examines the chemistry of the tree frog mucus used in wet adhesion. Employing ATR-IR analysis, we indicate the presence of a proteinaceous content with a close similarity in spectral profile of the toe pad and ventral skin mucus. Surface sensitive investigation shows the presence of surfactant-like molecules at the interface as well as evidence of additional moieties in the toe pad mucus as indicated by its strong surface interaction. Together, my work provides insights for the fabrication of adhesives and surfaces which are effective in underwater conditions.
Download or read book Underwater Adhesion written by and published by . This book was released on 2020 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Micro- and Nano-scale Surface Adhesion and Contact Mechanics Studies by : Wentao Yan
Download or read book Micro- and Nano-scale Surface Adhesion and Contact Mechanics Studies written by Wentao Yan and published by . This book was released on 1997 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Assessment of Surface Contamination with Contact Mechanics by :
Download or read book Assessment of Surface Contamination with Contact Mechanics written by and published by . This book was released on 2000 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors are particularly interested in the work of adhesion measurements as a means to facilitate the understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. Of the several issues under investigation, one is the effect of organic contamination on the adhesive strength for several types of polymer/metal interface combinations. The specific question that the authors are trying to address is at what level of contamination does adhesive strength decrease. The use of contact mechanics, the JKR method, is a good approach for studying this question. Another approach being studied is the use of interracial fracture mechanics. The model contaminant is hexadecane--non-polar, medium molecular weight hydrocarbon fluid. They choose hexadecane because it replicates typical machining fluids, is nonreactive with Al surfaces, and should not dissolve readily into the adhesive systems of interest. The application of a uniform, controllable and reproducible hexadecane layer on Al surfaces has proven to be difficult. A primary concern is whether studies of model systems can be extended to systems of technological interest. The JKR theory is a continuum mechanics model of contact between two solid spheres that was developed by Johnson, Kendall and Roberts. The JKR theory is an extension of Hertzian contact theory and attributes the additional increase in the contact area between a soft elastomeric hemisphere to adhesive forces between the two surfaces. The JKR theory allows a direct estimate of the surface free energy of interface as well as the work of adhesion (Wa) between solids. Early studies performed in this laboratory involved the determination of Wa between silicone (PDMS) and Al surfaces in order to establish the potential adhesive failure mechanisms. However, the JKR studies using commercial based PDMS [poly(dimethylsiloxane)] was fraught with difficulty that were attributed to the additives used in commercial PDMS systems. The authors could not discriminate hydrogen-bonding effects between Al2O3 and hydroxyl groups in the PDMS, and other possible bonding mechanisms. A model PDMS elastomer and polymer treatments were developed for studying solid surfaces by measuring the degree of self-adhesion hysteresis as indicator of surface properties. The goal of this work is to measure the adhesion between PDMS/Al surfaces -- contaminated and two cleaning techniques. A custom-made JKR apparatus is used to determine the amount of hysteresis and Wa.
Book Synopsis Investigation of Adhesion and Fracture of the Polymer-oxide Interfaces Using Rolling Contact Mechanics by : Honquan She
Download or read book Investigation of Adhesion and Fracture of the Polymer-oxide Interfaces Using Rolling Contact Mechanics written by Honquan She and published by . This book was released on 2002 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the very basic origin, the adhesion strength or fracture resistance of contacting interfaces results from intermolecular forces. When interface is separated, external energy is provided to the system, which eventually is dissipated in the form of mechanical deformation of the bulk material and cleavage of the interfacial bonds. The objective of this study is to understand the energy dissipation mechanism of interfacial fracture. It particularly includes polymer molecular weight and rate dependent properties of fracture. The model system consists of an oxidized polydimethylsiloxane(PDMS)-made hemicylinder and a PDMS thin films substrate, in which system energy is mainly dissipated at the interface layer. A unique experimental methodology---rolling contact mechanics method is developed by rolling the hemi-cylinder on the test substrate at a uniform velocity, the contact deformation of which is used to estimate the energy dissipation governed by non-equilibrium processes occurred at the interface. The strong molecular weight dependent fracture energy can be explained in terms of polymer chain extension and relaxation, which has its origins in the classic Lake-Thomas theory. The fracture energy is amplified by the molecular weights of polymers which bridge the open interface. The rate effect can be explained using the kinetic theory of thermally activated bond rupture, the results of which point out that this molecular weight dependent Lake-Thomas effect is purely a non-equilibrium effect and isn't compatible with the traditional notion of equilibrium fracture. The energy dissipation occurred at the interface can now be understood under the framework which combined chain elasticity and interfacial kinetics.
Book Synopsis Evaluation of Macroscopic Adhesion and Interfacial Interactions of Mussel-inspired Hydrophobic Adhesives by : Sukhmanjot Kaur
Download or read book Evaluation of Macroscopic Adhesion and Interfacial Interactions of Mussel-inspired Hydrophobic Adhesives written by Sukhmanjot Kaur and published by . This book was released on 2020 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nature has been a source of inspiration for designing many new materials. A prevalent example is of mussel which has inspired the synthesis of adhesive polymers for biomedical application. The most common strategy is to incorporate the catechol groups present in the mussel foot proteins into the polymer adhesives. However, the role of individual chemical units such as aromatic group and two hydroxyl groups of the catechol molecule toward the adhesion of the polymers is not clearly understood. Thus, in order to explore the capabilities of mussel-based catechol moieties incorporated into the polymers in enhancing the polymer interfacial adhesion to a hydroxylated surface in dry and wet environments, we designed the polymers using controlled chemistry to vary the side groups selectively. Direct adhesion measurements of the polymers were done using the JKR adhesion test to minimize the contribution from the bulk as compared to commonly used lap-shear measurements. Attempts were made to connect the macroscopic adhesion of the polymers with the interfacial interaction strength of the model molecules or the polymers with the surface hydroxyl groups using surface sensitive sum-frequency generation spectroscopy (SFG). Additionally, molecular dynamics (MD) simulation were utilized to shed light on the physical picture of the interactions of molecules with the substrate. In the first study, polymers containing the functional groups with either only hydroxyl, only aromatic, or a combination of hydroxyl and aromatic groups representing four amino acids (Serine, Phenylalanine, Tyrosine, and Dihydroxyphenylanaline (DOPA)) were tested. The macroscopic JKR adhesion results of polymers were explained with the combination of SFG Spectroscopy and MD simulations results. The study helped to identify the contribution of hydroxyl and aromatic groups toward the interfacial adhesion in catechol based adhesives in dry conditions. In the second study, we tested catechol and protected catechol containing polymers to identify the role of catechol in interfacial adhesion in wet conditions. The macroscopic wet adhesion of the polymers was connected to information gained from SFG experiment, where we probed the contact interface between the polymer and sapphire substrate in the presence of water. This study explored the question of whether catechol can displace water and bond with hydrophilic surfaces.In the third study, we performed SFG along with MD simulations of liquid molecules in contact with sapphire to better understand the physical picture of interfacial interactions. The parameters affecting the interaction strength and their effect on the spectroscopic features were also investigated in this study. Thus, in this dissertation, we looked at the interfacial interactions using SFG and MD simulations to understand the macroscopic adhesion of mussel inspired hydrophobic adhesives. The work provides an understanding of the molecular interactions of the side groups and the correlation to the macroscopic adhesion. Additionally, in the context of mussel inspired adhesives, the role of hydrophobicity is signified as the critical component to remove the interfacial water. The work advances the understanding of nature-inspired adhesives and provides a framework for designing new adhesive materials.
Book Synopsis Contact Mechanics Modeling of Homogeneous and Layered Elastic-Plastic Media by : Zhichao Song
Download or read book Contact Mechanics Modeling of Homogeneous and Layered Elastic-Plastic Media written by Zhichao Song and published by . This book was released on 2012 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this dissertation was to analyze surface contact interaction at different length scales and to elucidate the effects of material properties (e.g., adhesion and mechanical properties), normal and shear (friction) surface tractions, and topography parameters (e.g., roughness) on contact deformation. To accomplish this objective, a surface adhesion model based on an interatomic potential was incorporated into finite element contact models of rough surfaces exhibiting multi-scale roughness described by statistical and fractal geometry models. The problem of a rigid sphere in contact with an elastic-plastic half-space was first examined in the light of finite element simulations. Four post-yield deformation regimes were identified and the boundaries of neighboring regimes were obtained by curve-fitting of finite element results. Material hardness was shown to significantly deviate from the similarity solution with decreasing elastic modulus-to-yield strength ratio and the logarithmic dependence of the mean contact pressure on the indentation depth was found to hold only when the plastic zone was completely surrounded by elastic material. Constitutive equations were first derived for elastic-perfectly plastic half-spaces from curve-fitting finite element results and were then extended to isotropic, power-law hardening half-spaces, using the concept of the effective strain, which correlates the indentation depth with the indenter size. Finite element simulations of unloading process and repetitive normal contact were used to correlate the residual indentation depth and the dissipated plastic energy with the maximum indentation depth. Elastic shakedown, plastic shakedown, and ratcheting were identified by tracking the accumulation of plasticity for different values of maximum contact load and elastic modulus-to-yield strength ratio. The semi-infinite half-space was characterized by three different regions, named ratcheting region, shakedown region and elastic region, as the distance to contact surface increases. The obtained results have direct implication in material property measurements obtained with indentation method, particularly for materials exhibiting strain hardening behavior, and provide insight into the accumulation of plasticity due to repetitive contact loading, which is important in the understanding of the contact fatigue life of contact-mode devices. Sliding contact between a rigid fractal surface exhibiting multi-scale roughness and an elastic-plastic half-space was examined to elucidate rough-surface deformation due to small-amplitude reciprocating sliding (fretting). Stick-slip at the asperity scale was analyzed based on Mindlin's theory and a friction model that accounts for both adhesion and plowing effects. Numerical results yield insight into the effects of surface roughness, contact pressure, oscillation amplitude, elastic modulus-to-yield strength ratio, and interfacial adhesion on the friction force, slip index, and energy dissipation. The results of this study illustrate the important role of the contact load and surface topography on the energy dissipation and fretting wear of small-amplitude oscillatory contacts. Surface adhesion modeled as surface traction obeying the Lennard-Jones (LJ) potential was incorporated into the contact analysis of a rigid sphere indenting an elastic half-space to study contact instabilities associated with instantaneous surface contact (jump-in) and detachment (jump-out). This surface traction was introduced into a finite element contact model in the form of nonlinear spring elements and the jump-in/jump-out condition obtained analytically was confirmed by finite element results. Then, adhesive contact between a rigid sphere and an elastic-plastic half-space was analyzed and the effect of plasticity on the pull-off force and the commencement of contact instabilities was interpreted in terms of a modified Tabor parameter. The developed finite element model with nonlinear spring elements representing adhesive surface interaction provides a physics-based, computationally-efficient technique for studying adhesive contacts. The obtained results provide explanation for the contact instabilities encountered during surface probing with microprobe tips and stiction (permanent adhesion) in contact-mode microdevices. Adhesive contact between a rigid sphere and a layered medium analyzed with the finite element method shed light into adhesion-induced contact deformation. Two modes of surface detachment were observed for perfect bonding of the film to the substrate - brittle- and ductile-like surface detachment. Simulation results illustrate the effects of the maximum surface separation, film thickness, film-to-substrate elastic property mismatch, and substrate yield strength on the mode of surface detachment and residual deformation. Introducing a cohesive model that allows for crack formation and growth along the film/substrate interface in the previous finite element model, a residual cohesive zone was found at the crack tip after complete unloading. Contact instabilities and interface delamination were interpreted by the competing effects of surface adhesion and interfacial cohesion. Crack closure and crack-tip opening displacement (CTOD) were studied by performing a parametric study of the cohesive strength, interfacial energy, surface energy, surface adhesive strength, substrate yield strength, and initial defect size. The obtained results can be used to explain thin-film failure in contact systems due to the effect of adhesion and to improve the endurance of thin-film media subjected to surface tractions. Adhesive contact of two elastic rough surfaces was analyzed by integrating asperity-scale constitutive equations into the model of Greenwood and Williamson (1966) to account for the effect of contact instabilities at asperity level on the macroscopic contact response. The strength of adhesion was found to be mostly affected by the Tabor parameter and the surface roughness. The widely used adhesion parameter of Fuller and Tabor (1977) was shown to be appropriate only for contact systems characterized by a high Tabor parameter. Therefore, a new adhesion parameter that governs the strength of adhesion of contact systems with a low Tabor parameter was introduced. Finally, a generalized adhesion parameter was derived by using the concept of the effective interatomic separation, defined as the ratio of the elastic stretch due to adhesion and the equilibrium interatomic distance. The research carried out in this dissertation provides fundamental understanding of the evolution of the stress and strain fields in contacting surfaces, the evolution of plasticity in indentation, the development of friction and dissipation of energy in fretting contacts, the occurrence of adhesion-induced contact instabilities and interfacial delamination, and the factors affecting the strength of adhesion for rough surfaces in normal contact. The results of this thesis have direct implications in various technologies, including high-efficiency gas turbines, magnetic storage devices, and microelectromechanical systems.
Book Synopsis Understanding Contact Mechanics and Friction on Rough Surfaces by : Siddhesh Narayan Dalvi
Download or read book Understanding Contact Mechanics and Friction on Rough Surfaces written by Siddhesh Narayan Dalvi and published by . This book was released on 2020 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the mechanism of adhesion and friction in soft materials is critical to the fields of transportation (tires, wiper blades, seals etc.), prosthetics and soft robotics. Most surfaces are inherently rough and the interfacial area between two contacting bodies depends largely on the material properties and surface topography of the contacting bodies. Johnson, Kendall and Roberts (JKR) derived an equilibrium energy balance for the behavior of smooth elastic spherical bodies in adhesive contact that predicts a thermodynamic work of adhesion for two surfaces in contact. The JKR equation gives a reversible work of adhesion value during approach and retraction. However, viscoelastic dissipation, surface roughness and chemical bonding result in different work of adhesion values for approach and retraction. This discrepancy is termed adhesion hysteresis. Roughness is undermined as a cause of hysteresis in adhesion studies. Recently, a continuum mechanics model has been developed that predicts the work of adhesion on rough surfaces with known roughness in the form of power spectral density (PSD) function. To test the above mentioned theoretical model, we have conducted JKR experiments between highly cross-linked smooth polydimethylsiloxane (PDMS) of four different elastic moduli and diamond surfaces of four different crystal sizes and roughness.The rough diamond surfaces are characterized for topography using stylus profilometry, atomic force microscopy and in-situ transmission electron microscopy combined to give a comprehensive PSD. Results suggest that the observed work of adhesion during approach is equivalent to energy required to stretch the PDMS network at the surface and in the bulk to form the real rough contact area. However, in retraction work of adhesion is found to be proportional to the ratio of excess energy spent in the loading-unloading cycle and the true contact area obtained from topography indicating conformal contact matching fracture mechanics behavior. Thus, the study resolves adhesion hysteresis discrepancy on rough surfaces.It is known that adhesion hysteresis increases interfacial friction on rough surfaces. However, an experimentally proven quantitative model is still missing. Previous studies on smooth surfaces have shown that shear stress increases with velocity initially, reaching a maximum and then either plateaus out or decreases depending upon the modulus of the sliding elastomer. We have performed shear measurements with velocities ranging from nm/sec to cm/sec between PDMS elastomers and diamond surfaces. Data suggests higher shear stresses at lower velocities for rough surfaces and thus a shift for the peak previously observed on smooth surfaces. Additionally, there are states such as steady-state sliding, stick-slip and detachment waves with increasing stress in the same order. These states are found to occur at a critical stress and their onset is linearly proportional to the elastic modulus of the sliding rubber. The stress predictions using existing theories do not decouple adhesion and deformation energy losses during friction observed ex- perimentally on rough surfaces and further investigation is required in order to obtain a better friction model.
Book Synopsis Polymer Interface and Adhesion by : Wu
Download or read book Polymer Interface and Adhesion written by Wu and published by CRC Press. This book was released on 1982-03-31 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: Poly mer Interface and Adhesion provides the critical basis for further advancement in thisfield. Combining the principles of interfacial science, rheology, stress analysis, and fracturemechanics, the book teaches a new approach to the analysis of long standing problemssuch as: how is the interface formed; what are its physical and mechanical properties;and how does the interface modify the stress field and fracture strength of the material.The book offers many outstanding features, including extensive listings of pertinent references, exhaustive tabulations of the interfacial properties of polymers, critical reviews ofthe many conflicting theories, and complete discussions of coupling agents, adhesion promotion, and surface modifications. Emphasis is placed on physical concepts and mechanisms, using clear, understandable mathematics.Polymer Interface and Adhesion promotes a more thorough understanding of the physical, mechanical, and adhesive properties of multiphase, polymer systems. Polymer scientistsand engineers, surface chemists, materials scientists, rheologists, as well as chemical andmechanical engineers interested in the research, development or industrial applications ofpolymers, plastics, fibers, coatings, adhesives, and composites need this important newsource b
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1987 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
