Debonding agents

Moisture acts as a debonding agent through one of or a combination of the following mechanisms 1) attack of the metallic surface to form a weak, hydrated oxide interface, 2) moisture assisted chemical bond breakdown, or 3) attack of the adhesive. (2 ) A primary drawback to good durability of metal/adhesive bonds in wet environments is the ever present substrate surface oxide. Under normal circumstances, the oxide layer can be altered, but not entirely removed. Since both metal oxides and water are relatively polar, water will preferentially adsorb onto the oxide surface, and so create a weak boundary layer at the adhesive/metal interface. For the purposes of this work, the detrimental effects of moisture upon the adhesive itself will be neglected. The nitrile rubber modified adhesive used here contains few hydrolyzable ester linkages and therefore will be considered to remain essentially stable. 

This was a very important debunking of the myth that increased cationicity in starch leads to enhanced paper strength (extension of this logic would be that anionic starches are debonding agents). 

Interfacial aspects and adhesion of polysulfides have been studied extensively and reported by us [3,17]. The epoxy-modified poly sulfide has improved adhesion due to chemical reactions that increase electronic attraction forces. Water has been found to be the most potent debonding agent in cured polysulfides. Formation of thiourethane is responsible for excellent adhesion of polysulfide onto polyurethane coatings. 

Uses Disinfectant cleanser sterilizer antistat, deodorant, dandruff remover, emulsion stabilizer in cosmetics base, softener, antistat for hair conditioners and creme rinses emulsifier for creams and lotions in mildew control in fungicides to inc. affinity of dyes for film in photography in coating of pigment particles to improve dispersibility to inc. adhesion of road paints as biocide antistat, fabric softener for dryer sheets surfactant, debonding agent, antistat, emulsifier, softener for home and commercial laundry fabric and tissue softeners... 

Conte, J. S. and Bender, G. W., Softening/Debonding Agents, Tappi Papermaking Chemical Processing Aids, Vol. 47, Tappi Press, Atlanta, GA, 1986. 

The dowel bars are recommended to be plain round steel bars of grade 250 N and 450 mm long, placed at 300 mm centres. More than half of the length of the dowel bar should be coated with a debonding agent to ensure effective debonding from the concrete on that side of the joint. The dowel diameters vary from 24 to 36 mm, depending on the slab thickness. 

Uses Textile softener, antistat for home and commercial laundry fabric and tissue softeners debonding agent emulsifier hair conditioner and lotion component minimizes metal corrosion... 

Fig, 4.27. Comparisons between experiments and theory of (a) maximum debond stress, oj, and (b) initial frictional pull-out stress for steel fiber-epoxy matrix composites (O) uncoated fibers ( ) release agent... 

Fig. 4.38. Comparisons of partial debond stress, (rj, between fiber pull-out and fiber push-out as a function of debond length, f, for (a) release agent coated steel fiber-epoxy matrix composites and (b) untreated SiC fiber-glass matrix composites. After Kim ct al. (1994c).

Use Paper debonders, dye retarders, organophilic clays, antistatic agents, car-wash rinse aids, sugar clarification, fabric softeners, creme rinses. A high performance cationic quaternary fabric softener for retail, industrial, laundry, textile, and paper softener applications. 

In his test, a thin film of adhesive on a glass microscope slide or a metal coupon is cured and soaked in hot water until the film can be loosened with a razor blade. There is usually a sharp transition between samples that exhibited cohesive failure in the polymer and those which exhibited more of an interfacial failure. Since the diffusion of water into the interface is very rapid in this test, the time to failure is dependent only on interfacial properties and may differ dramatically between unmodified epoxy bonds and epoxy bonds primed with an appropriate silane coupling agent. The time to debond in the hot water for various silane primers differed by several thousandfold when used with a given epoxy. In parallel tests, a thick film of epoxy adhesive on nonsilaned aluminum coupon showed about the same degree of failure after 2h in 70°C water as a silaned joint exhibited after more than 150 days (3600 h) under the same conditions. 

The use of various coupling agents, which build chemical and hydrogen bonds between the matrix and fibers, has also been shown to reduce the moisture absorption of cellulose fibers in LPCs. The improved fiber-matrix adhesion generated by the coupling agent reduces the moisture absorption that results from fiber-matrix debonding. 

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