of polyurethane formation between several polyols and isocyanates with dibutyltin
dilaurate (DBTDL) as the curing catalyst, were studied in the bulk state by
differential scanning calorimetry (DSC) using an improved method of interpretation.
The molar enthalpy of urethane formation from secondary hydroxyl groups and
aliphatic isocyanates is 723 kJ mol-1
and for aromatic isocyanates it is 552 kJ mol-1
. In the case of a single second order reaction for aliphatic isocyanates
reaction, activation energy is 705 kJ mol-1
with oxypropylated polyols and 503 kJ mol-1
with Castor oil. For aromatic isocyanates and oxypropylated polyols the activation
energy is higher around 77 kJ mol-1 .
In the case of two
parallel reactions (situation for IPDI and TDI 2-4) best fits are observed
considering two different activation energies.