Viscosity rework

Dolby, R.M. 1941b. The rheology of butter. II. The relation between rate of shear and shearing stress. The effect of temperature and of reworking on hardness and on structural viscosity. J. Dairy Res. 12, 337-343. 

Product quality is usually determined and certified off-line in a quality control laboratory to ensure that specified properties of a production batch fall within the established range. Specifications related to molecular weight, charge density, composition, particle size, viscosity, rate of dissolution, solution viscosity, and residual monomer are common. Production batches that do not meet the specifications either require further processing, rework, or disposal and reduce production efficiency. As online analytical methods are employed, first pass yields (the proportion of production that meets specifications the first time) usually increase. 

In general, hot-melt adhesives are in solid form at temperatures below 79°C, and as the temperature is increased beyond this point, the solid adhesive material rapidly melts to a relatively low-viscosity fluid that can be applied easily. Upon cooling, the adhesive solidifles rapidly. Since these adhesives are thermoplastics, the melting/resolidiflcation process is repeat-able with subsequent heating/cooling cycles. Consequently, these adhesives allow reworking of the bonded parts, when necessary. Typical application temperatures of hot-melt adhesives are 149-188°C. 

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