**4.3.1 Elongation at break (b)**

The relative elongation at break (b/b0) in the machine direction of PE1/TPS blends is shown in Figure 9a. The results are excellent and demonstrate that at high glycerol contents (36% and 40%), the blends have an b comparable to the virgin polyethylene (b0) even at 53 wt% TPS. The b values of PE1 blends drop with the addition of TPS29. If these data are compared with the morphology results from the previous section, it is clear that the high <sup>b</sup> for blends with TPS36 and TPS40 is closely related to the ability to deform the TPS phase.

In St-Pierre's work (St. Pierre et al., 1997), PE/TPS blends presented a maximum in the b at around 10 wt% TPS followed by a dramatic drop at 22 wt%. In this work, the improved extrusion process and the controlled deformation of the TPS phase yields an important improvement in the b of PE/TPS blends as a function of composition, as observed in Figure 9a. Such an improvement in b is also, in part, due to a highly effective removal of water by venting before blending with polyethylene. In St-Pierre's process, TPS was blended with LDPE and then passed through the venting section. At low concentration, TPS was probably encapsulated into a LDPE matrix, which impeded proper water removal. The presence of water at the blending temperature (150C) can lead to the formation of bubbles in the extrudate, which weakens the final product (Verhoogt et al., 1995). In the present system, water was completely devolatilized from TPS before mixing with polyethylene (Favis et al., 2003).
