RHEOLOGICAL BEHAVIOR OF MOLTEN EPOXIDE PREPOLYMERS

Flow properties of four molten epoxide prepolymers of number average molecular weight 900(I), 1,500(II), 2,100(III) and 4,000(IV), were measured at temperatures ranging from 361 to 463K, and shear rates from 500 to 10,000 s−1. Apparent shear viscosities showed that all prepolymers used have Newtonian behavior up to shear rates of 2,000 s−1. Shear thinning occurs at higher shear rates. Flow activation energies at constant shear rates in the range of 500 to 7,000 s−1 vary for prepolymer III from 5 to 24 kcal/mol, and for prepolymer IV from 9 to 25 kcal/mol. Flow indices in the same shear rate range vary for prepolymer III from 1.0 to 0.7 and for prepolymer IV from 1.0 to 0.3. Copyright © 1978 Society of Plastics Engineers, Inc.