Correlation between adhesion and

The dynamical adhesion process described in this section is also referred to as adhesion hysteresis. We will come back to this subject in later sections when discussing the correlation between adhesion and friction. 

To establish whether or not oligomerization affected adhesion, the adhesion data were least-squares-fitted to a line at each of the T H conditions (not shown). The slopes of such lines can statistically infer if a correlation between adhesion and degree of oligomerization existed. The slopes (in % relative to a reference of 99 g mm 1 as 100%) are -0.064, -0.031 and -0.043 for T(0), T(200) and T(500), respectively. The y-intercepts, or zero-oligomerized values of adhesions, of the T H conditions, (in % relative to a reference of 99 g mm"1 as... 

But this criterion for fracture is not easily translated into energy terms. Indeed, it is quite likely that an energy criterion would take a different form from Eq. (32). (We recall the fracture analysis of a simple lap shear test, and the failure of a shear stress criterion for fracture to hold in that case.) The reader is therefore recommended to treat Eq. 32 as an interesting correlation between adhesion and observable features of stiff fibers in a more extensible matrix, but one that will probably be superseded when an energy analysis has been carried out. 

The thickness of the coating also affects permeability, and in general, there is a correlation between thickness and life. However, with relatively thick coatings as obtained with some modern materials such as epoxies the relationship is not so well established. There may be a limiting thickness above which either little additional protection is obtained or the increase in cohesive strength reduces its adhesive strength. Coatings should always be applied as closely as possible to the manufacturer s recommended thickness. 

The friction from the repulsive pinning center is of particular interest because it is contrary to the common belief that friction must result from attractive interactions between sliding surfaces. The results presented in Fig. 17(a) demonstrate that friction can be created by purely repulsive interactions. What really matters is the instability of the sliding body and energy dissipation, rather than the attractive or repulsive nature of interactions. This may also shed a light on the efforts to explore the correlation between friction and adhesion. 

In previous work (30-321. it has been suggested that the adhesion between a carbon fibre and an epoxy matrix is essentially the result of physical bonds, either dispersive or polar. It is clear from the results in the last column of Table VI that there is no correlation between x and the reversible energy of adhesion WA, calculated as the sum of the dispersive and polar interactions at the fibre-matrix interface. 

A correlation between dispersive and acid/base properties of the fibers and the quality of the fiber matrix adhesion was then possible. 

Their results are shown In Figures 6 and 7. Figure 7 shows the correlation between f and adhesion of photo-... 

To analyze the oxidation level of the adhesive by fluorescence, the fluorescence of the two probes as a function of the CL-parameters, maximum intensity, and decay rate, for the polyurethane-acrylate-based adhesive, were plotted (Fig. 3.8). Quenching of fluorescence followed the same kinetics as the chemiluminescence increase during UV-exposure. The two fluorescent probes used were sensitive to the formation of oxidation products. Therefore, in this work, good correlations between fluorescence and chemiluminescence were established, which allow monitoring photodegradation by using extrinsic emission fluorescent probes and/or CL emission from bulk material. 

The issues of the correlation of adhesion and of viscoelastic relaxation with friction are currently being investigated using AFM and LFM. Although friction does not correlate with the adhesion energy between two... 

In future studies, we propose to add to the contact angle measurements (which probe only 5-10 A of the layer) XPS and FTIR spectroscopy analysis, in order to understand the kinetics of the reaction in the interior of the pulsed plasma polymer thin film. Once quantitative elucidation of the reactivity of the pulsed plasma polymer thin film has been fuUy accomplished, adhesion strength measurements will be performed and correlations between adhesion parameters and thermodynamic parameters wiU be explored. This wiU be the subject of a further paper. 

Recently, Chen has used microneedle-Kke posts made of polydimethylsiloxane (PDMS) to measure the mechanical forces that smooth muscle cells exert on each other at ceU adhesions (Figure 46.4) [28]. The researchers were also able to control the type of ceU-adhesion molecules present on the tip of each elastomeric post. Using this approach of geometric control combined with precisely defined surface chemistries, they were able to demonstrate correlations between mechanical and chemical signals in these cells. 

Accelerometers have been worn in many ways. They have been embedded in adhesive patches, belts, shirts, pants as well as in accessories such as straps, wristbands, bracelets, or balls. The integration of accelerometers in flexible wearable medical and sportswear has been explored with some interesting results. In the SensVest project, accelerometers were secured by Velcro straps connected to an adjustable vest and used in conjunction with a heart rate monitor to illustrate the correlation between activity and heart rate levels (Knight et al., 2005). In the SMASH project. Harms et al. (2008a) demonstrated with a small number of subjects that a loose-fitting... 

Ethylene-vinyl acetate copolymer, terpene-phenol resins, polyethylene oxide, PMMA and some of their blends were solution cast on basic (aluminium oxide) and acidic (hydroxylated glass) substrates. Fourier transform infrared reflection absorption spectroscopy (IRRAS) was used to determine both the nature and the free energy of interfacial adduct formation in the polymer/metal systems. A correlation between IRRAS and adhesive strength may be used to predict both the acid-base work of adhesion and the density of interfacial interacting sites. 14 refs. 

In our work presented below, free and bonded films of variable thicknesses were investigated using triblock copolymers. We were interested in this because other workers have cited data to indicate that adhesive joints often do not perform as predicted from properties of the bulk polymer adhesive. However, some researchers (17) have reported good correlation between situ and bulk properties. In our present investigation, the observations... 

To reconcile both precedent approaches, a tentative correlation between x and the work of adhesion W2 defined as the sum of dispersive and acid-base interactions (equation (8)) has been recently proposed [15]. For all the different fibre-matrix systems, whatever the nature and properties of both the fibre and the matrix. Figure 2 shows that a linear relationship, passing through the origin, can be established between x and W2. Therefore, it is possible to write ... 

The surfaces also become wettable by many adhesives. If there is an improvement in the wetting of the surface by the adhesive there is usually a reduction of voids in the bond line and much better bonding. However, there is not always a good correlation between wetting and bonding. 

Sinicki and Berg varied the Lewis acid-base interactions systematically and found a correlation between adhesion measured by peel testing and the calculated thermodynamic work of adhesion [118]. 

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