DIFFERENTIAL SCANNING CALORIMETRY ANALYSIS OF THERMOSET CURE KINETICS - PHENOLIC RESOL RESIN

The Differential Scanning Calorimetry (DSC) trace for a commerical phenolic resole resin shows two distinct peaks. Assuming that these represent two independent cure reactions results in a kinetic model of the form: dx/dt = pk1(1 - x1)n1 + (1 - p)k2(1 - x2)n2 with k(i) = k(io)exp(-B(i)/T). The Arrhenius parameters were estimated from a plot of ln(beta/T(p)2) versus 1/T(p). The parameters, p, n1, and n2 were obtained by writing the DSC response predicted by the equation above in terms of a function which contains temperature as the only variable. q = q(tot)[pk1(1 - theta-1/r1)r1-1 + (1 - p)k2(1 - theta-2/2)r2-1] with theta-i = (1/beta) integral-T(o)/T(k(i)dT less-than-or-equal-to r(i) and r(i) = 1/(1 - n(i)). Fitting this equation to the DSC response measured at a scan rate of 4-degrees-C/min obtains p almost-equal-to 0.66; n1 almost-equal-to 0.55; n2 almost-equal-to 2.2; B1 almost-equal-to 8285; B2 almost-equal-to 7480; k1 almost-equal-to 1.12 x 10(8) s-1; k2 almost-equal-to 0.99 x 10(6) s-1.