Cold wall effects

With cold-wall effect, two cold-wall correction factors, FA and Fc, are used, and the correlation becomes, (Reddy and Fighetti, 1982)... 

Once the calibration constants and n have been determined for a given polymer-solvent system, Eq. (4) can be used for all thermal FFF channels, provided the temperature of the cold wall (T ) is held constant. The cold-wall temperature affects the calibration plot because the Soret coefficient DjID) and, therefore, varies with T. For a detailed discussion of temperature effects see the entry Cold-Wall Effects in Thermal FFF. In a thorough study of temperature effects, Myers and co-workers [3] demonstrated that the dependence of the Soret coefficient on can be accurately modeled by... 

The difference between 5m and b can be explained by the fact that components of different M experience different temperatures as they separate in the ThFFF channel (see ThFFF Cold Wall Effects, p. 2312). ... 

Temperature differential or cold wall effect It is not imcommon to see blistering in a vessel at the uninsulated areas or areas that are heat sinks. The blistering caused by this temperature differential (AT) between the exterior and interior areas of the metal may be partly overcome by force curing to drive off the residual solvents in the film. However, the real solution may be to insulate the exterior surface in order to reduce the temperature differential AT. 

General immersion tests General immersion tests can be as simple as the standard saltwater immersion test for coatings to be used in the atmosphere, or as complicated as cold wall effect immersion tests for heavy coatings to be used constantly in immersion service. It is essential to reproduce the anticipated conditions of the field exposure as dosely as possible when evaluating coatings for immersion service. 

ASTM D 4398 [254] is used for the evaluation of chemical resistance of fiberglass-reinforced thermosetting resins subjected to one-side panel exposure to specific environments. It takes into consideration both cold wall effects and radiation losses by heat transfer through the laminate wall [256]. 

---