The density averages of the evaluated samples (molded by injection) are shown on Fig. 2. The densities of the blends were significantly (p ≤ 0.05) higher than of the pure PP. For the blends, there was not significant difference with 95% of confidence between formulations. This effect can be attributed to the characteristic of thermoplastic starch, since it has higher density (Roy et al., 2011).As observed in Fig. 2b, the samples made with and without compatibilizer agent did not show significant void content differences.
Voids are expected once the weak interfacial adhesion between phases can produced gaps. In this case, natural compatibilizer agents had the same behavior of the PPgMA presenting 3% of void content, on average.