Morphologically Special Features of Poly(3-Hydroxybutyrate)/Low-Density Polyethylene Blends

In an effort to investigate the morphology of biodegradable films, the combination of differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared polarization spectroscopy methods are used. The methods enable one to examine the structural and morphological peculiarities of extruded blend compositions on the base of low-density polyethylene (LDPE) and poly(3-hydroxybutyrate) (PHB) at concentrations of the latter ranges from 0 to 32 wt%. The blend components are thermodynamically incompatible and form the proper morphological elements with good visible interfaces between the disperse phase (PHB) and the continuous matrix LDPE. For film extrusion, blend components affect each other, as is seen by the crystallinity drop for both PHB and LDPE. The dichroism measurements show that the axes of LDPE and PHB molecules are presumably located at right angles, therewith the largest axes of the PHB crystallites are oriented along the extrusion direction. The matrices at all blend ratios, besides 32 wt% composition, are reinforced by alternative bandlike and cylinderlike fibriles of PHB. The architecture of such morphological elements is carefully studied by the SEM method.