Morphology evolution of polypropylene in immiscible polymer blends for fabrication of nanofibers

Abstract

Immiscible blends of cellulose acetate butyrate (CAB) and isotactic polypropylenes (iPPs) with different melting index were extruded through a two‐strand rod die. The extrudates were hot‐drawn at the die exit at different draw ratios by controlling the drawing speed. The morphologies of iPP fibers extracted from the as‐obtained extrudates after removal of CAB by acetone were investigated by scanning electron microscopy. The influences of draw ratio, viscosity ratio, and composition ratio of CAB/iPP on the morphology evolution of iPP phase into nanofibers in the immiscible blends were studied. It was found that the thermoplastic iPP nanofibers were formed from the elongation of iPP ellipsoids, end‐to‐end merging of elongated iPP microfibers, and the size decrease of iPP microfibers in the processes of extrusion and drawing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 921–931, 2010

Extraction of nanofibers from polymer blends: A brief review

“…With regard to the extraction of nanofibers from the blend of thermoplastic polymers with CAB, a few general points are noticeable . The immiscible blends of thermoplastic polymers with CAB lead to the formation of nanofiber mat and nanofiber yarn.…”

“…Preparation of polypropylene nanofibers by electrospinning has been examined by investigators, and Table shows the diameters of the produced fibrils . As seen in this table, the smallest diameter of PP fiber is 300 nm, while those produced by extraction were less than 100 nm …”

“…Cellulose acetate butyrate (CAB) is a biologically based thermoplastic polymer derived from cellulosic materials; it is a kind of polysaccharide prepared from esterification of cellulose derived from plant residues and wastes . CAB has excellent solubility, and it is used by several researchers as a matrix and the major component in the blends with other synthetic polymers for an environmentally safe method of nanofibers preparation . Most researchers have used acetone as a solvent to remove CAB; however, different reaction times and temperatures have been reported.…”

“…Xue et al prepared blends of CAB/iPPs, and the blends were extruded through a two‐strand rod die and then the extrudates were hot‐drawn at the die exit at different draw ratios . It was found that the sizes of iPP microfibers decreased in the processes of extrusion and drawing.…”

Morphology development and size control of poly(trimethylene terephthalate) nanofibers prepared from poly(trimethylene terephthalate)/cellulose acetate butyrate in situ fibrillar composites

“…It is well known that an elongation flow is beneficial to the fibrillation of the dispersed phase particles in an immiscible blend, so draw ratio is also an important factor in controlling the phase shapes and size of the polymer blends during the deformation processing [40,41]. Figure 8 shows the fracture surface of PTT/CAB composite fibers with different draw ratio.…”