Differential scanning calorimetry has been used to study the influence
of hydroquinone as an inhibitor on the curing of an unsaturated polye
ster resin using benzoyl peroxide as an initiator. The isothermal kine
tic analysis was performed by isoconversional adjustment ln t = A + E/
RT. This adjustment makes it possible to predict the variations in the
activation energy with the degree of conversion without the need to k
now the rate equations. The results obtained through this adjustment w
ere compared with those obtained by applying an autocatalytic model. T
he kinetic parameters obtained by both methods permitted the simulatio
n of the curing process inside and outside the experimental range of t
emperatures. From the experimental results and the kinetic analysis, i
t was possible to elucidate the dual mechanism of inhibition and retar
dation exerted by hydroquinone. With the knowledge of the inhibition m
echanism, we proposed a method for using the induction times to determ
ine the kinetic parameters associated with the decomposition of the in
itiator and/or the instantaneous inhibitor content in unsaturated poly
ester resins.