Effect of a dual compatibilizer on the formation of co-continuous morphology of immiscible po`lymer blends

• A dual compatibilizer composed of a graft copolymer with a short trunk chain and long grafts and another one with a long trunk chain and long grafts favors the formation of co-continuous morphologies of immiscible polymer blends.
• The graft copolymer with a short trunk chain thermodynamically favors the formation of flat interfaces while the latter mechanically favors the shear stress transfer from matrix to dispersed phase.
• The former alone is not enough to form co-continuous morphologies because it cannot ensure effective shear stress transfer from matrix to dispersed phase due to weak interfacial entanglements.
• A certain amount of the graft copolymer with a long trunk chain must be added to ensure effective shear stress transfer from the matrix to dispersed phase.

This work aims at investigating the effect of a dual compatibilizer on the formation of co-continuous morphology of immiscible polymer blends. More specifically, the blend is composed of polystyrene (PS) and polyamide 6 (PA6), and the dual compatibilizer is composed of a low molecular weight styrene-co-maleic anhydride copolymer (Mw = 11.500 g/mol, maleic anhydride MAH content = 14 wt%) denoted as lSMA and a high molecular weight SMA denoted as hSMA. The latter has a Mw of 250,000 g/mol and a MAH content of 8 wt% (hSMA1) or a Mw of 110,000 g/mol and a MAH content of 23 wt% (hSMA2). When the PA6 is the minor phase, the morphology of the PS/PA6 blend is co-continuous using the lSMA-hSMA (hSMA can be hSMA1 or hSMA2) dual compatibilizer. However, when the PA6 is the major phase, its morphology is co-continuous only for the lSMA-hSMA2 dual compatibilizer and not for the lSMA-hSMA1 one. This could be due to fewer PA6 grafts in the in-situ formed hSMA1-g-PA6 graft copolymer and consequently less entanglements of the PA6 grafts with the PA6 major phase compared to the in-situ formed hSMA2-g-PA6 graft copolymer.

Figure optionsDownload as PowerPoint slide