(7) (8) where is the initial gas pressure inside the bubble before mass conversion and expansion. Surface Tension In order to use Equation (1), the surface tension of the intumescent coating melt is required. Since there has been no measurement of this property for intumescent coating melt, the values of for polyethylene are adopted. This is shown in Figure 4. Figure 4 Surface tension vs. temperature for polyethylene melt [] Fortunately, prediction of intumescent coating expansion is not sensitive to the value of surface tension. For example, Figure 5 indicates that when using the variable surface tension in Figure 4 and a constant value of 20 N/m2 for predicting one (C12L1) of the tests of , the results nearly coincide. Figure 5 Sensitivity of intumescent coating expansion ratios to surface tension Viscosity For the intumescent coating studied by and [], there was no measurement of viscosity. Therefore, for the purpose of this paper, the viscosity value has to be estimated. This estimate is based on the results of which provided viscosity data for a number of intumescent melts given by . These data are shown in Figure 6 and Figure 7. Comparing the mass conversion (loss) data shown in Figure 2 for the intumescent coatings studied by with the TGA data of
(7) (8) where is the initial gas pressure inside the bubble before mass conversion and expansion. Surface Tension In order to use Equation (1), the surface tension of the intumescent coating melt is required. Since there has been no measurement of this property for intumescent coating melt, the values of for polyethylene are adopted. This is shown in Figure 4. Figure 4 Surface tension vs. temperature for polyethylene melt [] Fortunately, prediction of intumescent coating expansion is not sensitive to the value of surface tension. For example, Figure 5 indicates that when using the variable surface tension in Figure 4 and a constant value of 20 N/m2 for predicting one (C12L1) of the tests of , the results nearly coincide. Figure 5 Sensitivity of intumescent coating expansion ratios to surface tension Viscosity For the intumescent coating studied by and [], there was no measurement of viscosity. Therefore, for the purpose of this paper, the viscosity value has to be estimated. This estimate is based on the results of which provided viscosity data for a number of intumescent melts given by . These data are shown in Figure 6 and Figure 7. Comparing the mass conversion (loss) data shown in Figure 2 for the intumescent coatings studied by with the TGA data of
with_Burak_theory.docx