Adhesion to skin

May be disposable Impervious Not resistant to hot splashes Low melting point could cause adhesion to skin gloves or headgear... 

Incompatibilities between the adhesive system and other formulation excipients may be circumvented by designs in which the adhesive is remote from the drug delivery area of the system (Figure 14.15d). Three critical considerations in system selection are adhesion to skin, compatibility with skin and physical/chemical stability of the total formulation and components. 

This chapter provides a summary of the generalized theory and a discussion of the parameters which appear in its equations. The use of the theory is illustrated for several different adhesion situations, including the peeling of rubberlike and pressure-sensitive adhesives, adhesion to skin, and the moisture resistance of structural adhesives bonded to metals and glass. 

Japanese researchers have disclosed that additives such as long-chain aliphatic alcohols, carboxylic acids and esters can give adhesives that produce less adhesion to skin without compromising normal adhesive properties [51]. 

This miracle glue was introduced in 1959. It took about 10-15 years for the adhesive to enter the steep growth stage of its life cycle. The Consumer Product Safety Commission considered suspending its distribution to the consumer market because of the material s excellent adhesion to skin but the Commission finally decided that a warning label as required under the Hazardous Substances Act would be sufficient. Since 1975, consumption has jumped six-fold, and consumer applications have swelled from less than 20% of the total volume to over 40%. Other major outlets include electronics, toys and hobbies. Cyanoacrylates are now reaching maturity, and future growth will be more moderate (Table 10). 

Various types of pearlescent materials are used in decorative cosmetic products, such as bismuth oxychloride (BiOCl), which is a synthetic pearlescent in the form of octagonal platelets giving a very shiny metallic pearlescent effect. It offers strong covering effects and good adhesion to skin surface. It is soft and silky to the touch. However, due to its poor stability to light, it has a tendency to darken after prolonged exposure. 

Current usage is almost entirely associated with the good adhesion to aluminium. Specific applications include the bonding of aluminium foil to plastics films, as the adhesive layer between aluminium foil and polyethylene in multilayer extrusion-laminated non-lead toothpaste tubes and in coated aluminium foil pouches. Grades have more recently become available for manufacture by blown film processes designed for use in skin packaging applications. Such materials are said to comply with FDA regulations. 

Some applications, such as incise drapes require loading of the PSA matrix with anti-bacterial agents. Proper selection of the monomers allows the PSA to be compatible with compounds like iodine, while maintaining the adhesion to the skin. 

Apply a skin adhesive to the area around the gauze dressing. 

In addition, chemical product properties can be classified into structural and functional. Examples of structural properties are density, viscosity, size, and shapes, whereas examples of functional properties are safety, smooth, skin protection, and adhesion to surface. It is clear that the structural properties will depend on the structure and components of the chemical products, whereas the functional properties are more related to the interaction product-environment. 

The LLNA is the preferred method when compared to the GPMT because (a) it can equivalently predict human contact dermatitis, (b) a dose-response can be obtained, and (c) it is in line with current animal welfare efforts. Nevertheless, several situations exist where the GPMT is advantageous, depending predominantly on the choice of test substances. The LLNA is known for less powerful detection of the sensitization potential of metallic compounds, high molecular weight proteins, strong irritants, and for substances with low adhesion to the skin surface (skin wettability is a prerequisite for the successful application of LLNA) [136-140],... 

Carbon tetrachloride is absorbed through the skin of humans, although much less readily than from the lung. After use as a shampoo or as a solvent for removal of adhesives from skin, a number of fatal or near-fatal cases have been reported. It has been noted that these exposures must have also involved high levels of inhalation exposure as well as dermal exposure. It has been estimated that immersion of both hands in the liquid for 30 minutes would yield an exposure equivalent to breathing 100-500 ppm for 30 minutes. 

When transdermal estrogens are used there can be problems with poor adhesion and skin irritation. The latter occurs more often in hot humid weather and can rarely proceed to edema, induration, a vesicular rash, residual pigmentation, itching, and erythema (59). 

The rabbit-skin glue or the cottage cheese provide adhesives to bind the whiting compounds into a thick, creamy solution that can be applied to a masonite board and built up layer by layer to form a solid ground. Calcium sulfate and calcium hydroxide dehydrate as the gesso dries and solidify to form a cement ground. They also provide a white solution that is made more brilliant with the addition of titanium dioxide. 

The S ACD can be employed to sample and quantify loose corneocytes and squames from the skin surface. Such a procedure is only valid for conditions where the intercorneocyte bonds are weaker than the SACD adhesion to the SC.14 In fact, tiny scales found in the common type of facial dry skin, dandruff, and seborrheic dermatitis come off quite easily.31-42 By contrast, thick compact adherent scales found in ichthyosis and severe winter xerosis of the lower legs12 31 are not reliably harvested using SACD. This represents a classical pitfall of the method.14... 

The gastrointestinal (GI) microflora plays an important role in the health status of people and animals. The GI tract represents a much larger contact area with the environment, compared to the 2 m2 skin surface of our body (van Dijk 1997). The mucosal surface of the small intestine is increased by forming folds, intestinal villi, and the formation of microvilli in the enterocyte resorptive luminal membrane. The resulting surface of GI system is calculated to be 150-200m2, therefore it provides enough space for the interactions related to digestion and for the adhesion to the mucosal wall. 

Monomers are primarily used to lower the viscosity of the uncured material to facilitate application. The monomer must be matched with the resin to give the desired set of properties with respect to adhesion to the substrate and bulk properties such as flexibility, stiffness, cure behavior, and durability. Early radiation curable monomers had problems associated with toxicity and skin sensitivity newly developed monomers have been significantly improved in this respect. 

Note that there are closed-cell and open-cell foams. Adhesives may spread or wick deeply into the open-cell variety, thereby affecting the resulting mechanical properties of the foam and perhaps even weakening the foam. When foam is bonded to another less porous substrate, the adhesive could be applied to the nonfoam substrate to minimize the wicking and ingress of the adhesive into the body of the foam. With the closed-cell variety, the adhesive cannot wick deeply into the foam, but usually the foam s skin must be machined or abraded to allow for some surface roughness for the adhesive to mechanically attach. 

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