= log Ttref -cref (T-Tref) cret +-Tref Problem 3. The shear viscosity (n) of a thermosetting resin at To=90 C is n=3x1010. Find the viscosity values at 100, 110, 120 and 130 C. b) Plot the shift factor (at) as a function of temperature (i.e., Ln(at) vs 1/T) where at=n(T)(Tref). c) Plot n vs T and n vs 1/T. What do you observe? (Hint use the following VFT equation and assume that Trer=96 C): T Logar = A= log(, 'miref WLF constants, obtained at any reference temperature (Tr), can be used to calculate the corresponding values at Tg, using the following relationships (Ferry (1980)]: Cich (5) Ca+Tg-T;' C2 = C+Tg-Tr, (6) where C1 and C2 are WLF constants at Ig, and C and Care WLF constants at Tr. For VFT equation (when considering Tref # Tg): C = Trer - To and 2.303 Cref chef =B CE = log Ttref -cref (T-Tref) cret +-Tref Problem 3. The shear viscosity (n) of a thermosetting resin at To=90 C is n=3x1010. Find the viscosity values at 100, 110, 120 and 130 C. b) Plot the shift factor (at) as a function of temperature (i.e., Ln(at) vs 1/T) where at=n(T)(Tref). c) Plot n vs T and n vs 1/T. What do you observe? (Hint use the following VFT equation and assume that Trer=96 C): T Logar = A= log(, 'miref WLF constants, obtained at any reference temperature (Tr), can be used to calculate the corresponding values at Tg, using the following relationships (Ferry (1980)]: Cich (5) Ca+Tg-T;' C2 = C+Tg-Tr, (6) where C1 and C2 are WLF constants at Ig, and C and Care WLF constants at Tr. For VFT equation (when considering Tref # Tg): C = Trer - To and 2.303 Cref chef =B CE