Dynamic mechanical properties of polyurethane-urea microcapsules on coated paper

Polyurethane–urea microcapsules were prepared by an interfacial polymerization method. Dynamic mechanical measurements were carried out on the polyurethane–urea microcapsules coated on a paper substrate. The glass transition temperatures (Tg) of capsule wall were observed in the temperature scan data. Tg as the temperatures of tan δ peaks were decreased with increasing amounts of core materials. The apparent activation energies of the glass transition were estimated at about 100 kcal/mol. Master curves were obtained by shifting the tan δ spectra along the frequency axis, and the glass transition regions were unaffected by core materials studied. The shift factors were found to depend on the core/wall ratio and discussed in terms of a morphological change of microcapsules. © 1994 John Wiley & Sons, Inc.