Contact-Mechanics-Based Studies of Adhesion between Polymers

1998 ◽  
Vol 71 (3) ◽  
pp. 407-448 ◽  
Author(s):  
V. S. Mangipudi ◽  
M. Tirrell
Keyword(s):  
Contact Mechanics ◽  
Interfacial Adhesion ◽  
Molecular Level ◽  
Work Of Adhesion ◽  
Recent Developments ◽  
Thermodynamic Work Of Adhesion ◽  
New Applications ◽  
Solid Bodies ◽  
Interfacial Force ◽  
Theoretical Developments

Abstract Contact mechanics deals with the deformation of solid bodies in contact. In recent years, significant advances have been made both in the theoretical and experimental areas of contact mechanics, especially in the area of soft solids, in relating the contact deformation to interfacial adhesion. On the theoretical front, new theories of contact mechanics have been developed to relate the interfacial force induced deformation to the thermodynamic work of adhesion both for elastic and viscoelastic solids. On the experimental front, several new techniques have been developed to measure the interfacial forces and the interfacial-force-induced deformations. These techniques have been used, with the aid of the theories of contact mechanics, to measure directly the surface and interfacial energies of a variety of polymers and other model surfaces. These experimental and theoretical developments have also been exploited to measure quantitatively the effect of interfacial chain diffusion on the adhesion of polymer interfaces. We summarize the recent developments in the theories of contact mechanics, and their applications in the design and interpretation of experimental measurement of molecular level adhesion between elastomers, glassy and viscoelastic polymers. We also review the experimental and theoretical developments related to the role of chain diffusion on interfacial adhesion. Finally, we identify some potential new applications of contact-mechanics-based techniques in such emerging area of adhesion science as molecular level studies of adhesion of viscoelastic materials and biomaterials.

scholarly journals Adhesion Assessment of Copper Thin Films

1997 ◽  
Vol 473 ◽  
Author(s):  
M. D. Kriese ◽  
N. R. Moody ◽  
W. W. Gerberich
Keyword(s):  
Residual Stress ◽  
Interfacial Adhesion ◽  
Work Of Adhesion ◽  
Copper Films ◽  
Cathode Sputtering ◽  
Interfacial Toughness ◽  
Si Substrates ◽  
Thermodynamic Work ◽  
High Residual Stress ◽  
Thermodynamic Work Of Adhesion

ABSTRACTNano-indentation testing has been used to quantitatively assess the adhesion of thin copper films, sputtered to thicknesses of 150 nm to 1500 nm. Copper films of low residual stress were deposited via RF diode cathode sputtering onto SiO2/Si substrates. Overlayers of DC magnetron sputtered high residual stress tungsten, 850 nm thick, were additionally used to provide a driving force for delamination. All films tested exhibited buckle-driven delamination, from which the interfacial toughness was estimated to be 0.2 – 2 J/m2, which is comparable to the thermodynamic work of adhesion. The use of an overlayer requires extensions of existing models, but otherwise does not change the interfacial adhesion, allowing measurements of films that would not otherwise delaminate.

Shot-noise simulations of HREM images of polymer crystals

1989 ◽  
Vol 47 ◽  
pp. 342-343
Author(s):  
Philippe Pradère ◽  
Edwin L. Thomas
Keyword(s):  
Low Dose ◽  
Molecular Level ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
Inorganic Materials ◽  
Photographic Emulsion ◽  
Polymer Crystals ◽  
Resolution Electron ◽  
Recent Developments ◽  
Lattice Images

High Resolution Electron Microscopy (HREM) is a very powerful technique for the study of crystal defects at the molecular level. Unfortunately polymer crystals are beam sensitive and are destroyed almost instantly under the typical HREM imaging conditions used for inorganic materials. Recent developments of low dose imaging at low magnification have nevertheless permitted the attainment of lattice images of very radiation sensitive polymers such as poly-4-methylpentene-1 and enabled molecular level studies of crystal defects in somewhat more resistant ones such as polyparaxylylene (PPX) [2].With low dose conditions the images obtained are very noisy. Noise arises from the support film, photographic emulsion granularity and in particular, the statistical distribution of electrons at the typical doses of only few electrons per unit resolution area. Figure 1 shows the shapes of electron distribution, according to the Poisson formula :

New Developments in the Plasma Transferred Arc Process

1997 ◽  
Author(s):  
R.J. DuMola ◽  
G.R. Heath
Keyword(s):  
High Performance ◽  
Power Utility ◽  
Small Areas ◽  
Powder Alloys ◽  
Plasma Transferred Arc ◽  
Transferred Arc ◽  
Recent Developments ◽  
Coating Method ◽  
And Performance ◽  
New Applications

Abstract The plasma transferred arc process continues to be the coating method of choice for the application of cobalt base alloys onto valve and valve trim. Although new applications have been developed over the years, the process remains largely associated with the application of high performance, highly alloyed powders for relatively small parts or small areas of large parts. The use of the plasma transferred arc process for large volume application has been limited by the robustness and performance characteristics of the equipment and the use of cobalt. A new plasma transferred arc system (power source, torch and process controller) has been developed which allows the application of powder metal alloys at deposition rates of up to 40 pounds per hour. In addition, there has been a development of new non-cobalt powder alloys with excellent mixed corrosion and wear resistance properties. These capabilities have rendered the process technically and economically viable for large and demanding applications in the mining, power utility and steel industries. The new PTA system and the recent developments in powder alloys will be discussed. Reference will be made to specific applications in target industries.

scholarly journals Molecular Dynamic Investigations on the Adhesion Behaviors of Asphalt Mastic–Aggregate Interface

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5061
Author(s):  
Wenyi Xu ◽  
Xin Qiu ◽  
Shanglin Xiao ◽  
Ganghua Hu ◽  
Feng Wang ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Molecular Dynamic ◽  
Interfacial Adhesion ◽  
Silica Particles ◽  
Work Of Adhesion ◽  
Electrostatic Energy ◽  
Adsorption Effect ◽  
Asphalt Mastic ◽  
Polar Components ◽  
Molecular Arrangement

The asphalt mastic–aggregate interface plays an essential role in determining the service performance of asphalt mixtures. The objective of this paper was to investigate the adhesion behaviors and mechanism between asphalt mastic and aggregate based on molecular dynamic (MD) simulations. First, the asphalt mastic model considering the actual mass ratio of filler to asphalt (F/A) condition was established and validated in terms of thermodynamic properties. Second, the molecular arrangement characteristics of polar components on the aggregate substrate were analyzed by radial distribution function (RDF), relative concentration (RC), and mean square displacement (MSD). Third, the interfacial adhesion ability between asphalt and aggregate was quantitively evaluated based on the work of adhesion. Finally, the coupling effect of moisture and temperature on interfacial adhesion behaviors was investigated to explore the adhesion failure characteristics of the asphalt–aggregate interface. The results demonstrate that the thermodynamic properties could be employed to validate the reliability of the asphalt mastic model. The self-aggregation degree of polar components in base asphalt could be significantly increased with the addition of silica particles, exhibiting a change of configuration from “parallel arrangement” into “stack distribution” due to the high polarity of silica particles. The polar components in asphalt mastic exhibit a more uniform distribution state and lower mobility capability than base asphalt owing to the adsorption effect of silica particles. Silica particles with amounts of residual charges could significantly increase the electrostatic energy of the asphalt mastic–aggregate interface, contributing to an improvement of the adhesion between asphalt mastic and aggregate. The increase of temperature enhances the work of adhesion of the asphalt mastic–aggregate interface, which is opposite to that of the base asphalt–aggregate interface. The asphalt mastic exhibits a greater sensitivity to interfacial moisture damage than base asphalt. The findings would provide insights into a better understanding on the micro adhesion mechanism of the asphalt mastic–aggregate interface.

scholarly journals Significance of 5-S-Cysteinyldopa as a Marker for Melanoma

2020 ◽  
Vol 21 (2) ◽  
pp. 432 ◽  
Author(s):  
Kazumasa Wakamatsu ◽  
Satoshi Fukushima ◽  
Akane Minagawa ◽  
Toshikazu Omodaka ◽  
Tokimasa Hida ◽  
...  
Keyword(s):  
Early Detection ◽  
Imaging Techniques ◽  
Primary Melanoma ◽  
Urinary Biomarkers ◽  
Prognostic Indicators ◽  
Main Concern ◽  
Sample Collection ◽  
Diagnosis And Prognosis ◽  
Recent Developments ◽  
New Applications

Melanoma is one of the most lethal and malignant cancers and its incidence is increasing worldwide, and Japan is not an exception. Although there are numerous therapeutic options for melanoma, the prognosis is still poor once it has metastasized. The main concern after removal of a primary melanoma is whether it has metastasized, and early detection of metastatic melanoma would be effective in improving the prognosis of patients. Thus, it is very important to identify reliable methods to detect metastases as early as possible. Although many prognostic biomarkers (mainly for metastases) of melanoma have been reported, there are very few effective for an early diagnosis. Serum and urinary biomarkers for melanoma diagnosis have especially received great interest because of the relative ease of sample collection and handling. Several serum and urinary biomarkers appear to have significant potential both as prognostic indicators and as targets for future therapeutic methods, but still there are no efficient serum and urinary biomarkers for early detection, accurate diagnosis and prognosis, efficient monitoring of the disease and reliable prediction of survival and recurrence. Levels of 5-S-cysteinyldopa (5SCD) in the serum or urine as biomarkers of melanoma have been found to be significantly elevated earlier and to reflect melanoma progression better than physical examinations, laboratory tests and imaging techniques, such as scintigraphy and echography. With recent developments in the treatment of melanoma, studies reporting combinations of 5SCD levels and new applications for the treatment of melanoma are gradually increasing. This review summarizes the usefulness of 5SCD, the most widely used and well-known melanoma marker in the serum and urine, compares 5SCD and other useful markers, and finally its application to other fields.

scholarly journals Beyond switches: Rotaxane- and catenane-based synthetic molecular motors

2008 ◽  
Vol 80 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Euan R. Kay ◽  
David A. Leigh
Keyword(s):  
Molecular Motors ◽  
Physical Science ◽  
Statistical Physics ◽  
Biological Process ◽  
Molecular Level ◽  
Molecular Machines ◽  
Interlocked Molecules ◽  
Recent Developments ◽  
New Generation ◽  
First Time

Nature uses molecular motors and machines in virtually every significant biological process, but learning how to design and assemble simpler artificial structures that function through controlled molecular-level motion is a major challenge for contemporary physical science. The established engineering principles of the macroscopic world can offer little more than inspiration to the molecular engineer who creates devices for an environment where everything is constantly moving and being buffeted by other atoms and molecules. Rather, experimental designs for working molecular machines must follow principles derived from chemical kinetics, thermodynamics, and nonequilibrium statistical physics. The remarkable characteristics of interlocked molecules make them particularly useful for investigating the control of motion at the molecular level. Yet, the vast majority of synthetic molecular machines studied to date are simple two-state switches. Here we outline recent developments from our laboratory that demonstrate more complex molecular machine functions. This new generation of synthetic molecular machines can move continuously and progressively away from equilibrium, and they may be considered true prototypical molecular motors. The examples discussed exemplify two, fundamentally different, "Brownian ratchet" mechanisms previously developed in theoretical statistical physics and realized experimentally in molecular-level devices for the first time in these systems.

The Effect of Environment on Adhesion of Shrink-Resist Polymers on Wool

1976 ◽  
Vol 46 (11) ◽  
pp. 796-801 ◽  
Author(s):  
Brett O. Bateup ◽  
John R. Cook ◽  
H. Douglas Feldtman ◽  
Barry E. Fleischfresser
Keyword(s):  
Surface Tension ◽  
Adhesive Joints ◽  
Work Of Adhesion ◽  
Polymer Interface ◽  
Thermodynamic Work ◽  
Polymer Adhesive ◽  
Thermodynamic Work Of Adhesion ◽  
Secondary Bonding

The durability of wool/polymer adhesive Joints in wash liquors of different surface tension was determined by measuring the rate of felting shrinkage of polymer-treated wool sliver and fabric in each liquor. The rate of felting shrinkage increased as the surface tension of the liquor decreased. This trend in the rate of felting shrinkage of polymer-treated wool agreed well with the trend in the magnitude of the thermodynamic work of adhesion of a wool/polymer “adhint” in different liquids, calculated assuming only secondary bonding forces across the wool/polymer interface. Limitations of the theory are discussed

WirePATH Rapid Tooling Process and Supporting Software Development

2003 ◽  
Author(s):  
Alexander Lee ◽  
James Brink ◽  
David Anderson ◽  
Karthik Ramani
Keyword(s):  
Computer Aided Design ◽  
Electrical Discharge Machining ◽  
Computer Software ◽  
Wire Edm ◽  
Overall Design ◽  
Design Changes ◽  
Mold Making ◽  
Recent Developments ◽  
New Applications ◽  
Aided Design

Recent developments in Computer Aided Design (CAD) have drastically reduced overall design cycle time and cost. In this paper, wirePATH, a new method for rapid direct tooling, is presented. By using specialized interactive segmentation computer software and wire electrical discharge machining (wire EDM), wirePATH can reduce manufacturing time and cost for injection molds, casting patterns, and dies. Compared to other conventional-mold making methods, wirePATH can reduce fabrication time by as much as 40 to 70%. Wirepath can use a combination of wire EDM and other processes. Our method provides a new means to produce a greater variety in products by changing only portions of the tooling. Segments allow a part of a mold to be replaced to accommodate design changes and repair. WirePATH enables new applications of wire EDM to more complex shapes by bridging the gaps between CAD, our method, wire EDM and conventional manufacturing processes.

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