Tablets adhesivity

The two major forces that have been found to affect polymer-tablet adhesion include the strength of the interfacial bond and the internal stresses within the coating. For pharmaceutical products, hydrogen bond formation is the primary type of interfacial contact... 

The initial ejection peak force required to break the tablet adhesion to the die wall. This force is the highest force encountered during ejection and occurs over a very short period of time. 

Adhesion between the polymeric film and substrate is a major concern. Poor adhesion could result in flaking or peeling of the coating from the substrate core. Moisture could accmnulate at the film-substrate interface and compromise the mechanical protection provided by the coating. Polymer adhesion is related to both film-substrate interfacial interactions and internal stresses within the film. Polymer adhesion can be evaluated by peel tests or butt joint tests. Apart from the specific properties of the polymers, excipients used in tablet formulations can influence film-tablet adhesion. Since adhesion between a polymer and the tablet smface is due primarily to hydrogen bond formation, hydrophobic agents may decrease adhesion by... 

Formulation. Compressed tablet formulations contain several types of inert, adjuvant ingredients necessary for proper preparation and therapeutic performance. Tablets designed to be swallowed need diluent, disintegrating, binding (adhesive), and lubricating inert ingredients, whereas... 

Vinyl acetate [108-05-4] (VAc), CH2=CHOOCCH2, the ethenyl ester of acetic acid, is primarily use for the manufacture of poly(vinyl acetate) [9003-20-7] (PVAc) and vinyl acetate copolymers. Poly(vinyl acetate) homo- and copolymers are found as components in coatings, paints and sealants, binders (adhesives, nonwovens, constmction products, and carpet-backing), and miscellaneous uses such as chewing gum and tablet coatings. AppHcations have grown over the years in a number of areas (1 4). 

Other apphcations for VP/VA copolymers are uses as water-soluble or remoistenable hot melt adhesives (140), pharmaceutical tablet coatings, binders, and controUed-release substrates. 

EthylceUulose [9004-57-3], a cellulose either (qv), as prepared commercially, ie, of high DS, is thermoplastic and has alow density (1.14 g/cm ). It forms films of good thermostabiUty and excellent flexibiUty and toughness. EthylceUulose is used in lacquers, inks, and adhesives and is combined with waxes and resins in the preparation of hot-melt plastics. It is also used as a pharmaceutical tablet binder. 

Cellulose is also commercially modified by acetylation to produce a material suitable for X-ray and cine film. Commercially cellulose ethers are also prepared, such as methylcellulose. This material is water-soluble and gives a highly viscous solution at very low concentrations. Hence it is widely used as a thickener in latex paints and adhesives, in cosmetics and for coating pharmaceutical tablets. 

There are a number of industrial and technological areas in which nanoscale adhesion is important. One of the earliest fields concerned with adhesion on this scale was colloid science. Colloid particles lie in the intermediate region between macro and nano, with dimensions typically of the order of hundreds of nanometers up to a few microns. This means that their true contact areas he well within the nano-domain and are influenced by interactions on this length scale. Adhesion between such particles is important, due to its influence on mineral separation processes and on the aggregation of powders, for example, on the walls of machinery or in the forming of medical tablets. In an extraterrestrial context, such... 

Glucose syrups 25-50 Strong adhesive tablets may soften in high humidity... 

Ishida et al. were some of the first investigators to propose a method for investigating the adhesive properties of tablets [151]. Their method involved placing a tablet onto a membrane under constant pressure for one minute and then measuring the force required to remove it. Most methods published since that time involve essentially the same principle, with variations in the type of membrane used and the... 

Jimenez-Castellanos et al. developed a method to measure both the adhesional and frictional forces involved in the attachment of such tablets to mucosa. These researchers found that a good correlation existed between the maximal adhesion strength and polymer content of the tablets tested [155]. 

Capsule formulations usually require lubricants just as do tablet formulations. Lubricants ease the ejection of plugs, reduce filming on pistons and adhesion of powder to metal surfaces, and reduce friction between sliding surfaces in contact with powder. The same lubricants are used in both tablet and capsule formulations. 

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