The predicted enthalpy of reaction
of the 2K PU formulation in Table 1 was approximately 142 J/g assuming an average heat of reaction of 105 kj/mole for the isocyanate-hydroxyl reaction.
TMT is an analytical method used to determine the content of substances, which is measured on the basis of different values of enthalpy of reaction
where [n.sub.prod] and [n.sub.react] are the stoichiometric coefficients of reaction products and reactants, respectively, and [DELTA][H.sup.o.sub.prod] and [DELTA][H.sup.o.sub.react] are the variations of enthalpy of reaction
products and reactants, respectively.
Now for the calculation of the enthalpy of reaction
at a temperature other than the reference the following equations were used [21, 27].
Agreement is also shown between the calculated enthalpy of reaction
(2) with Ikeda et al.
Although the reaction heat for the copolymerization UP/styrene or for the homopolymerization of styrene are not rigorously equal, the structure of these double bonds (conjugated with an aromatic ring for styrene, or with carbonyl functions for UP) are close enough to consider, in a first approach, that the molar enthalpy of reaction
is the same for the homo- and copolymerization.
The reaction thermodynamic parameters indicate that P2 complex, [sup.1][O.sub.2] ([sup.11][[DELTA].sub.g]) + S[O.sub.2], formation is exothermic with enthalpy of reaction
, -170.708 kcal/mol, in comparison with the original reactants.
At concentrations below 5% there is no significant contribution to the enthalpy of reaction
for the epoxy + montmorillonite two part mixtures.
From the DSC plots, the enthalpy of reaction
([DELTA][H.sub.p]) and the temperature, which corresponds to the peak exotherm, were determined; see Fig.
A Mettler thermoanalyser TA 4000 DSC, operating in the -100 [degrees] C to 300 [degrees] C temperature range and equipped with a liquid nitrogen cooling system, was used to determine enthalpy of reaction
, [T.sub.g] (detected at the inflexion point of the deflection heat capacity change), and variation of the heat capacity [Delta][C.sub.p] through the [T.sub.g] of the resin samples.