Effect of Dual Reactive Compatibilizers on the Formation of Co-Continuous Morphology of Low Density Polyethylene/Polyamide 6 Blends with Low Polyamide 6 Content

Abstract

The coexistence of two kinds of reactive compatibilizers at the interface in immiscible LDPE/PA6 blends, namely, polyethylene graft maleic anhydride (PE-g-MAH) with a long backbone length and polybutadiene graft maleic anhydride (PB-g-MAH) with a short backbone length, promoted the formation of a flat interface and induced a co-continuous morphology in blends containing 30 wt % PA6. The relationships between the contents and content ratios of the dual reactive compatibilizers as well as the morphologies of the resulting LDPE/PA6 blends are examined quantitatively. The morphologies of the blends are characterized by SEM and TEM combined with a selective solvent extraction process. It is found that in these systems, when the total content of the dual compatibilizers is within 20-30 wt % and the content ratio of PE-g-MAH and PB-g-MAH is within 2:1-3:1, the minor PA6 phase can also form a co-continuous morphology in the LDPE matrix. The balance between the stability (determined by in situ formed PE-g-PA6 grafted copolymer with long backbone length) and flexibility of the flat interface (determined by in situ formed PB-g-PA6 grafted copolymer with short backbone length) in the compatibilized LDPE/PA6 blends is the key factor that controls the formation of the co-continuous morphology with low PA6 contents.