Modulated differential scanning calorimetry: 12. Interphase boundaries andfractal scattering in interpenetrating polymer networks

The morphology of polyurethane (PU)-poly(methyl methacrylate) (PEMA) interp enetrating polymer networks (IPNs) were investigated by means of small-angl e X-ray scattering (SAXS) and modulated-temperature differential scanning c alorimetry (M-TDSC) techniques. Based on the analysis method employed by Ta n et al. [Polymer 1997;38:4571], the interfacial thickness in the IPNs was calculated from SAXS data. The conclusion is that the interfacial thickness is zero and there are sharp domain boundaries in the PU-PEMA IPNs. M-TDSC results show that the PU-PEMA IPNs have a multi-phase morphology with a dif fuse interphase region. The M-TDSC results are in agreement with DMTA and T EM findings. The M-TDSC, TEM and DMTA results, therefore, conflict with tho se obtained from the analysis of the SAXS data. We believe that the analysi s method employed by Tan et al. is questionable for IPNs. (C) 1999 Elsevier Science Ltd. All rights reserved.