PBT/PET Blends with mPEO. Figure 2 shows the plot of tan [delta] vs.
Figure 3 shows the X-ray diffraction patterns of pure mPEO, of the 5/1 matrix, and that of its mixture with 30 wt% mPEO content, as an example.
Figures 4 and 5 show representative morphologies of the surfaces of cryofractured impact specimens of the (5/1)/mPEO and (2/1)/mPEO blends, respectively, with 10, 20, and 30 wt% mPEO contents (Figs.
mPEO (%) (5/l)/mPEO (2/l)/mPEO 5 0.56 0.55 10 0.69 0.71 15 0.97 0.76 20 1.02 0.77 25 1.18 1.10 30 1.55 1.05 The mean polydispersity of the size distributions was 1.29 and 1.38, respectively.
We now discuss the adhesion level of the mPEO particles to the PBT/PET matrices.
Figures 6 and 7 show the Young's modulus and the yield stress, respectively, of both (5/l)/mPEO and (2/1)/ mPEO blends.
With respect to the mPEO blends, we find that the Young's modulus decreases almost linearly with increasing contents of the impact modifier in both PBT/PETbased systems.
Figure 8 shows the ductility of both (5/l)/mPEO and (2/l)/mPEO blends with increasing mPEO contents.
Particle size, however, is not the only parameter that explains the enhanced ductility behavior of the (2/1)/mPEO blends, because the compositions with 5 and 10 wt% mPEO show larger ductility values with respect to those of their (5/1)/mPEO analogues, where the average particle size was very similar.
Figure 9 shows the notched impact strength as a function of mPEO content of both (5/1)/mPEO and (2/1)/ mPEO blends.
This is the case of the super-tough PBT/PET blends with mPEO of this work, according to the generalized stress whitening observed in the fracture surfaces.
Considering that the rest of intrinsic parameters were also constant, a possible saturation of the interacting groups of the mPEO was proposed to explain the similar [ID.sub.c] of PTT/mPEO and PET/mPEO blends despite the lower density of interacting ester groups of PTT with respect to PET.