| Abstract: | The modification of an amorphous random ethylene-propylene rubbery copolymer (EPM) has been accomplished by solution grafting of maleic anhydride molecules promoted by radical initiators, The resulting EPM-g-succinic anhydride (EPM-g-SA) and EPM have been used to obtain binary polyamide 6/EPM or polyamide 6/EPM-g-SA and ternary polyamide 6/EPM/EPM-g-SA blends by melt mixing. The formation of an EPM-g-PA6 graft copolymer during the blend preparation has been assumed. Different blend morphologies were observed by scanning electron microscopy (SEM) according to the nature and content of the rubber used. The tensile mechanical properties and the impact behavior of the prepared blends were investigated and correlated with the SEM analysis of the fracture surfaces. Binary and ternary blends containing 20 percent by weight of total rubber show a significant improvement of the impact properties at low temperature (?20°C) when the rubber is partly or entirely EPM-g-SA. In the case of PA6/EPM-g-SA (80/20) blend these results are related to the presence of rubbery domains of very small size strongly adherent to the PA6 matrix. In the case of 80/10/10 ternary blends, a much more complicated overall morphology is observed. Such morphology is characterized by the presence of large EPM domains, likely containing some EPM-g-PA6 graft molecules acting as an interfacial agent, and domains of EPM-g-PA6 of smaller size strongly adherent to the matrix as in the previous case. |
