Cohesive Bond Strength

In contrast to adhesive bond strength, cohesive bond strength is the force within a material, reflecting the strength of the secondary forces between molecules. In a 

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The participation of the 2p band in the bonding of metallic beryllium explains the greater cohesiveness (bond strength) of the metal when compared to that of lithium, and also why the enthalpies of atomization and the melting temperatures of the two metals are different, as shown by the data in Table 7.2. 

To obtain maximum adhesion, the adhesive bond strength between the adhesive and adherend should be greater than the cohesive bond strength of the adhesive, as indicated in Fig. 6.2. (Of course, the overall strength is also limited by the cohesive strength of the substrates.)... 

Solid state has higher cohesive bond strength than liquid... 

High average molecular weight and cross-linking increase cohesive bond strength... 

Once it is solidified, the performance of the adhesive depends on its adhesive bond strength, as discussed, and on its cohesive bond strength. In many applications, the adhesive is selected so that the adhesive bond strength exceeds the cohesive bond strength. In that case, the overall strength of the adhesive joint will be the cohesive bond strength of the adhesive itself, or of the substrates, whichever is less. 

Cohesive bond strength depends on both the chemical nature and the physical state of a material. Temperature and the molecular weight of the adhesive are two important factors. Increasing the molecular weight of an adhesive increases its cohesive strength, but also increases its viscosity and decreases wettability. 

The cohesive bond strength of an adhesive can be estimated by the following equation ... 

Estimate the cohesive bond strength of a PE-based adhesive with a surface tension of 31 dynes/cm and d = 5 x 10" cm. 

Cohesive bond strength. Cohesive bond strength is the force within the adhesive itself when bonding two substrates. The cohesive bond strength depends mainly on the intermolecular forces of the adhesive, molecular mass, and temperature. 

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