ldpe and poly(1-butene) blends: morphology, crystallinity and rheological properties

In this work, the compatibility and crystallinity of low density polyethylene (ldpe) and polybutene1 (pb1) blends were studied. various blends of ldpe/pb1 containing 5, 10 and 20 wt.% pb1 were prepared in a corotating twinscrew extruder and characterized by scanning electron microscopy (sem), shear oscillation rheology and wideangle xray diffractometry (waxd). a matrixdroplet morphology was observed in sem images, indicating incompatibility of the two polymers in the solid state. compared to neat ldpe, the relaxation spectra of the blends were broadened, and a slight increase in their relaxation times was observed. the relaxation time of the blends was enhanced by increasing pb1 content, which was further proved by fitting rheological data in the carreauyasuda model. deviation of colecole diagrams from circular shape means that the blend samples were not miscible and the positivedeviation behavior of the complex viscosity and storage modulus from the mixing rule revealed the formation of strong interfacial interactions. the crystallinity of both lldpe and pb1 was decreased as a result of blending. the peaks attributed to the form ii of pb1 crystals were eliminated and the peaks related to ldpe were obviously weakened, suggesting to prevent crystallinity of polymers which is associated with a reduction in the total crystallinity percentage for the blend. the reduction of crystallinity was more pronounced in pb-1 phase.