Factors influencing adhesion

Adhesion depends on a number of factors. Good adhesion is defined by most customers as substrate failure. The major adhesive manufacturers possess equipment that allows them to make bonds with customer substrates under conditions that closely simulate actual packaging lines. These bonds are peeled either automatically or by hand to gauge adhesion. The most important factors influencing adhesion are the wet-out of the substrate, partieularly by the polymer component of the adhesive system, and the specific adhesion with the substrate. Choice of resin is critical for both. Rosin, rosin esters and terpene phenolics are eommonly added for these purposes in EVA and EnBA-based systems. Adhesion at low temperatures is also influenced by the overall toughness of the system at the test temperature. 

By far, the most detrimental factors influencing adhesives aged in a nonseacoast environment are heat and humidity. The reasons why warm, moist climates degrade many adhesive joints were presented in the last section. Near the seacoast, corrosion due to salt water and salt spray must also be considered when one is designing an adhesive joint. Thermal cycling due to weather, oxygen, ultraviolet radiation, and cold are relatively minor factors with most structural adhesives. 

Factors influencing adhesion efficiency include the following. 

How Adhesion is Influenced Two factors influence adhesion of any polymer to a substrate—the... 

The science of adhesion is truly multi-disciplinary, demanding a consideration of concepts from such topics as surface chemistry, polymer chemistry, rheology, stress analysis and fracture mechanics. It is, nevertheless, important for the technologist to possess a qualitatively correct overall picture of the various factors influencing adhesion and controlling joint performance in order to make rational judgements concerning the selection and use of adhesives. 

Many factors influence adhesive selection and the procedure below will identify the most appropriate family or families for a particular application, but individual formulations should only be chosen in discussions with a manufacturer. Only then can the true interplay between the considerations of Table 5.4 be objectively reviewed along with other significant factors - particularly those involving production. 

The most detrimental factors influencing adhesives aged outdoors are heat and humidity. Thermal cycling, ultraviolet radiation, and cold are relatively minor factors. The reasons why warm, moist chmates degrade adhesive joints were presented in the previous section. 

Sharpe and Schonhorn [125] have emphasized the importance of wetting and proposed that one of the most important factors influencing adhesive joint strength is the ability of the adhesive to spread spontaneously on the substrate when the joint is initially formed. They developed a criterion from Equation... 

It has been observed by Koleske et al. [76] that factors other than specific chemical interaction can influence adhesion measurements. They studied a film of mixed-chain-length fatty acid and found that the adhesion of the tip over the shorter chain was 20% larger than over the longer chain, despite the fact that both had the same CH3 terminating... 

A variety of substrate- and cell-attached factors influence neural development by regulating adhesion properties of cells (see Ch. 7). Interactions occur directly between cells or between a cell and the extracellular matrix (see Ch. 2). The molecules mediating these interactions have been implicated in regulating the specificity and timing of cell-cell adhesion and the consequences on cell morphology and physiology. Hence, they influence the ability of cells not only to migrate but to sort themselves out and to stabilize spatial relationships considered important for the process of differentiation. 

Since, in general, factors which influence the adhesion of metal/epoxy resin structural joints also influence adhesion in metal/epoxy resin protective coating systems, these two separate cases will often be combined and referred to simply as metal/epoxy adhesion systems. 

Mustard JF, Packham MA. Factors influencing platelrt function Adhesion, release and aggregation. Pharmacol Rev 1970 22 97-187. 

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