Adhesion quality

It is interesting to point out the small variation of the average value of the variable Ef(r)-modulus of the mesophase, which reflects the uniformity of the adhesion quality of these series of composites, which is also indicated by the almost linear variation of the composite modulus, versus the volume content. 

It was shown that these adhesion-coefficients depend on the ratio of the logarithms of the ratios of the moduli of phases and those of the radii of mesophase and inclusion. Thus, for a certain average size of inclusions, the thinner the mesophase, the better the adhesion quality of the composite. 

The glass polyalkenoate cement uniquely combines translucency with the ability to bond to untreated tooth material and bone. Indeed, the only other cement to possess translucency is the dental silicate cement, while the zinc polycarboxylate cement is the only other adhesive cement. It is also an agent for the sustained release of fluoride. For these reasons the glass polyalkenoate cement has many applications in dentistry as well as being a candidate bone cement. Its translucency makes it a favoured material both for the restoration of front teeth and to cement translucent porcelain teeth and veneers. Its adhesive quality reduces and sometimes eliminates the need for the use of the dental drill. The release of fluoride from this cement protects neighbouring tooth material from the ravages of dental decay. New clinical techniques have been devised to exploit the unique characteristics of the material (McLean Wilson, 1977a,b,c Wilson McLean, 1988 Mount, 1990). 

The glass-ionomer cement is the most versatile of all the dental cements and has been developed for a variety of applications (McLean Wilson, 1974, 1977a,b,c Swift, 1988b van de Voorde, 1988 Wilson McLean, 1988 Mount, 1990). Many of its applications depend on its adhesive quality which means that, unlike the non-adhesive traditional filling materials, it does not require the preparation of mechanical undercuts for retention and the consequent loss of sound tooth material. 

Another important use for the glass polyalkenoate cement is in preventive dentistry where it can be used to fill and seal naturally occurring pits and fissures in molar teeth which are sites for the initiation of caries (McLean Wilson, 1974, 1977b Komatsu, 1981 Wilson McLean, 1988). Its adhesive quality and ability to act as a long-term fluoridereleasing gel make it particularly suitable for this purpose. Special formulations for this application have been placed on the market. 

The cylindrical-type sealing process for strip packaging does not usually have a cooling cycle or quench surface, hence any pull on the seal ply will tend to weaken the seal while the sealant is still pliable. Therefore, it is desirable that the sealant have good hot tack or a high melt viscosity at processing temperatures. Hot tack is generally accepted to mean the adhesion quality of the sealant from the moment it leaves the seal head and the time it returns to its set or permanent condition. 

Estimating the Adhesive Quality of Lignins for Internal Bond Strength... 

Table II. Lignin parameters for assessing adhesive quality...

Adhesive quality of lignins—Continued experimental procedures, 373 GPC, 375,378/ interactive sites, 373 lignin parameters for assessing quality, 375,3791... 

Tin—Zinc, Baths for tin—zinc alloys stem from work done after World War II in efforts to find a substitute for cadmium. Although alloys of all concentrations are possible, 80% tin—20% zinc gives the best combination of properties. This alloy has a low coefficient of friction, low electrical contact resistance, is solderable, slightly anodic to steel, and does not form voluminous corrosion products. In addition, the tin—zinc alloy has good paint adhesion qualities, good ductility, and is easily spotwelded. 

The employed liquid can also be used to electroplate A1 on an uneven surface or even a screw, as shown in Figure 12.4. The in situ etching leads to A1 layers all showing satisfactory adhesive qualities. 

Exact proportions of resin and hardener must be weighed out on an accurate balance or in a measuring container for best adhesive quality and reproducibility. Possible problems that can occur by not adhering to the proper mixing proportions can include incomplete polymerization (too little catalyst), brittleness (excessive catalyst), and corrosion of metallic adherends (excessive catalyst). 

Historically, several adhesives have been derived from natural carbohydrate polymers (1,4-6). In a few cases, they have been utilized because of their own particular adhesive quality. However, natural carbohydrate polymers are usually utilized as modifiers for more costly synthetic resins, especially as thickeners, collodial stabilizers, and flow controllers. Table II lists examples of the use of natural gums in adhesives (7-40). 

Silk is the only natural fibre which exists as a continuous filament. Each Bombyx mori cocoon can yield up to 1600 meters of filament. These can be easily joined together using the adhesive qualities of seriein to form a theoretically endless filament. 

Within the three STARAMIC "families" 300, 600, and 700— a broad, controlled range of viscosities, particle sizes, and cold water solubilities are available. Individually, each starch exhibits outstanding film-forming characteristics and exceptional adhesive qualities. 

Acrylics exhibit excellent adhesion to substrates such as concrete, masonry and wood. The majority of acrylic products are applied without using primer and give satisfactory adhesion. The more flexible resins give superior adhesion within the family of acrylic resins. The adhesive qualities of individual resins vary both with flexibility and with functionality. 

With the exception of the epoxies, the adhesive quality of the cements and mortars is not high. They will develop hair cracks at interface with the masonry units consider these joints not watertight. The membrane is the major line of defense and is the watertight element in this construction. 

This pheonomena, if present in the molded part, will usually be self-evident. Adhesive qualities to materials such as scotch tape and paint, for example, will be very poor. For the most part, however, this undesirable feature can be controlled or avoided. Raw material manufactures will usually select only those IMR compounds which are either (1) isocyanate reactive, or (2) have polymer solubility characteristics which are free of this problem. 

Preparation and Properties of Dextrin (section 377).— Heat about 5 grams of starch for one-half hour at 220°-225° in an oil-bath or air-bath. Pour the product into a mortar, add 2 cc. of water, and notice the adhesive quality of the mixture. Add 25 cc. of water and grind with a pestle. If there is a residue of starch which has not been converted into dextrin, filter through a folded filter. Use 2 cc. of the solution to determine whether the product reduces Fehling s solution. Test 2 cc. of the solution with a drop of iodine solution and note the color. 

In ocular delivery to the cul-de-sac of the eye, nanoparticles in suspension can prolong the action of the drug both by slow release and their slower escape by way of the punctae compared to a solution, and perhaps the adhesive qualities of some nanosystems (66) also assist. 

Other electrodes such as gold can be used, but films formed on platinlum generally have good adhesion qualities. 

Nitroxyl radicals can also be used to improve the mechanical properties of filled polymers, resins in particular, by increasing the adhesive quality of the fillers by treating their surfaces with solutions of nitroxyl radicals. The efficiency of nitroxyl radicals as modifiers is higher than that of well-known modifiers e.g., 4-toluene isocyanate. 

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