Hershey drop

Epoxy-PVC plastisols are a type of PVC plastisol adhesive that is used in large quantities in the automobile industry. It is used to bond sheet steel to inner stiffener panels and to seal around the crimped panel edges. These adhesives are formulated as high-solids, thixotropic pastes and are applied as discrete dots or droplets to the stiffener surface or panel edge before joining or crimping. These adhesives are called Hershey drops in the trade because of the characteristic geometry of the droplets. 

Hershey drops of plastisol adhesive are used in the assembly of hood inner and outer panels. The outer panel is often hem flanged around the periphery of the inner panel to immobilize the parts until they cure in the paint oven. Modem plastisols are able to absorb thin films of oil from the metal as they cure. This ability to bond through oil is of immense value in an industry where thorough cleaning before assembly is traditionally a problem. 

Fig. 2.7.8 T1-T2 spectra for a cough drop candy magnetic field and at room temperature. The (A), Hershey chocolate (B) and Swiss Thins, lines are contours at 10, 30, 70 and 90% of the...

For this example we combine the approaches used in Examples 2-lb and 2-lc, neglecting turbulent dispersion (see Section 2-3). Since the eddies are all assumed to be at their minimum size, all we need to determine is the time needed for the diffusion across an eddy radius (lt/2 = 0.05 mm) for 99% diffusion. If the turbulence in the various test and commercial units does not change, the calculation will be the same for all cases, as it is based on a fixed eddy size, not on the system size. Of course, the total power will increase with the volume of the system. The only real difference from Example 2-lb is that we need to consider a sphere rather than a slab. The value of DabI/L drops from 2.0 to 0.56 (see Brodkey and Hershey, 1988, p. 680), giving a diffusion time of... 

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