  Thermosetting polyurethanes were obtained using an aromatic isocyanate and a
hydrophobic polyol formulation obtained from epoxidized soybean oil (ESO)
crosslinked with glycerin. A systematic DSC analysis of the effect of catalyst
type, crosslinker concentration, isocyanate index and ESO crystallization on
the cure kinetics was conducted. The combination of a stannic catalyst at 0.2
wt.\% and glycerin at 20 wt.\% produced a cure kinetics governed by
autocatalytic heat flow where vitrification played a key role in the formation
of chemical bonds. The evolution of Tg as a function of conversion, which
followed Di-Benedetto{\'}s predictions, supported the hypothesis that
vitrification was a preponderant phenomenon during cure. The ESO
crystallization had a melting endotherm centered at 35{\deg}C, affecting
substantially the availability of reactive hydroxide groups. Dynamic Mechanical
Analysis (DMA) of a post-cured sample revealed a Tg centered at 220{\deg}C,
whereas quasi-static flexural mechanical tests revealed a flexural modulus of
2.14 GPa and a flexural strength of 99.4 MPa. Rheological experiments using a
rheometer at isothermal conditions supported the hypothesis that vitrification
played a key role in the evolution of apparent viscosity. A master model using
Kim-Macosko equations was obtained for the proposed formulation.

Applied Physics