Adhesion, assessment

It is emphasized that the failure load of any adhesive joint is influenced by the joint geometry, rate of loading and test conditions. Therefore, lap shear tests should be used only for comparative purposes in adhesive assessment, selection and control. 

The optimum level of bonding between the phases of a composite is often not straightforward to determine or to achieve (see Fibre-matrix adhesion - assessment techniques). 

For measurement of adhesion, see Fibre-matrix adhesion - assessment techniques. 

The characteristics of interior paints that require testing and analysis include hiding and appearance, package stabiHty, adhesion, spatter resistance, flow and leveling, color and sheen uniformity, touch-up, stain removal, burnish resistance, and block and print resistance. A popular test that assesses the wet abrasion resistance of an interior paint is to measure its scmb resistance. A mechanical device is used to scmb a paint film of a specified thickness with a standard bmsh and abrasive cleanser suspension. The number of scmb cycles (back and forth movements of the weighted bmsh) at various end points (first cut through, or 50% removal of the film) is then recorded. Scmb resistance usually holds steady or decreases slightly as PVC is increased, but drops quickly once the CPVC is exceeded in a paint formulation. 

Most rubbers used in adhesives are not resistant to oxidation. Because the degree of unsaturation present in the polymer backbone of natural rubber, styrene-butadiene rubber, nitrile rubber and polychloroprene rubber, they can easily react with oxygen. Butyl rubber, however, possesses small degree of unsaturation and is quite resistant to oxidation. The effects of oxidation in rubber base adhesives after some years of service life can be assessed using FTIR spectroscopy. The ratio of the intensities of the absorption bands at 1740 cm" (carbonyl group) and at 2900 cm" (carbon-hydrogen bonds) significantly increases when the elastomer has been oxidized [50]. 

As with chemical etches, developing optimum conversion coatings requires assessment of the microstructure of the steel. Correlations have been found between the microstructure of the substrate material and the nature of the phosphate films formed. Aloru et al. demonstrated that the type of phosphate crystal formed varies with the orientation of the underlying steel crystal lattice [154]. Fig. 32 illustrates the different phosphate crystal morphologies that formed on two heat-treated surfaces. The fine flake structure formed on the tempered martensite surface promotes adhesion more effectively than the knobby protrusions formed on the cold-rolled steel. 

Adhesives and resins are one of the most important raw materials in wood-based panels. Thus, each question concerning the life cycle assessment and the recycling of bonded wood panels does bring into question the adhesive resins used. This includes, for example, the impact of the resin on various environmental aspects such as waste water and effluents, emission of noxious volatile chemicals during production and from the finished boards, or the reuse for energy generation of wood panels. The type of resin has also a crucial influence on feasibility and efficiency for several material recycling processes. 

The single filament pull out test, sometimes called the microdebond test, has received attention for some years as a way to assess the adhesion between fibers and matrices in fiber composite [90,91]. It provides a direct measure of interfacial adhesion and can be used with both brittle and ductile matrix resins. 

Strict control of the fusion process is imperative. In addition to thickness, hardness, continuity and adhesion checks, correct cure may be assessed by differential scanning calorimetry techniques, which are designed to measure any difference in the glass transition temperature of a laboratory-cured powder and the cured coating taken from the factory-coated pipe. 

There is no single test that will give a quantitative assessment of adhesion, and those which have been proposed all cause destruction of the test piece. It has already been stated that this property is dependent upon mechanical and chemical bonds between the enamel and the metal. One must, however, also consider the stresses set up at the interface and within the glass itself during cooling after fusion or after a delayed length of time. 

The authors of [99] proposed a calorimetric method for determining the degree of the polymer-filler interaction the exothermal effect manifests itself in the high energy of the polymer-filler adhesion, the endothermal effect is indicative of a poor, if any, adhesion. The method was used to assess the strength of the PVC-Aerosil interaction with Aerosil surface subjected to different pre-treatments... 

In a series of reviews [244-246] the models proposed for the assessment of the effect of fillers on the complex of PCM properties are discussed. Analysis of the models shows that, for a fixed filler content, the strength must be higher in compositions with fillers featuring the absolute adhesion to the matrix than in systems with little or no adhesion. The relative elongation and specific impact strength must, on the contrary, go up with the increasing adhesion. 

The above model has been successfully used to describe the thermomechanical behaviour of iron-particle reinforced resins. More precisely, the importance of this model is that it provides a quantitative means for assessing the adhesion efficiency between the phases and its effect on the thermomechanical properties of the composite. Moreover, by using this model the thermomechanical behaviour, as well as the extent of the mesophase developed in particulates could be described. The... 

In general these derivatives are safe, their chemical functions being the glycine moiety the same holds for AT,0-carboxymethyl chitosan, as demonstrated for instance by studies intended to assess the efficacy of W,0-carboxymethyl chitosan to limit adhesion formation in a rabbit abdominal surgery model. The inability of fibroblasts to adhere to N,0-carboxymethyl chitosan-coated surfaces suggests that it may act as a biophysical barrier [135]. 

You should do assessments on substances you use (eg adhesives, pants, cleanng agent, solvents) and substances generated from work activities (eg dust, fune, vapour). 

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