The plasticizing effect on the thermal transitions of the toluenediisocyanate-based polyurethanes monitored by thermally stimulated current technique

Abstract

A liquefied curative in methylene-bis-orthochloroaniline/dioctyl or di-2-ethylhexyl phthalate (MOCA/DOP) was used as the substitute curative for the hot-melt MOCA curative in a two-component preparative system for the toluene diisocyanate (TDI)-based polyurethane elastomers. The polyurethane elastomer specimens based on this liquefied curative were prepared with three different soft segments with the addition of various plasticizers. The DOP-added specimens were evaluated by the depolarization technique in the thermally stimulated current/relaxation mapping analysis (TSC/RMA). The results were also compared with differential scanning calorimeter and dynamic mechanical analyzer on the observation on the changes in thermal transitions. Results indicated that at a low DOP content of less than 26 wt %, little disruption on the urethanic matrix was found in the TDI-polycaprolactone (PCL)/MOCA-DOP system. However, at a high DOP content of 47 wt %, a disruption in TDI-poly(tetramethylene) oxide (PTMO) amorphous phase by DOP was observed. The optimum weight ratio of MOCA/DOP was found to be 1 : 2 and this liquefied solution was stable at the ambient temperature, and can be applicable for use as a curative for the preparation of the TDI-based polyurethane elastomers at ambient temperature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 743–761, 2000