Factors influencing the formation of elongated morphologies in immiscible polymer blends during melt processing

Abstract

The morphology of the dispersed phase in immiscible polymer blends plays an important role in the determination of the final physical properties. This paper considers factors that influence the final state of deformation of the dispersed phase, and in particular, the formation of fibers and lamellae. Blends of polyethylene and nylon-6 were extruded by ribbon extrusion at different draw ratios. Prior to single-screw extrusion the materials were blended in a co-rotating twinscrew extruder, and the size of the dispersed phase was studied as a function of the viscosity ratio. As the blends are extruded into ribbons and drawn through the calender rolls, the morphology of the dispersed phase undergoes drastic transformations. The fiber formation is enhanced by increasing the draw ratio. At high draw ratios, long thin fibers are observed. Some biaxial deformation is obtained for the noncompatibilized systems when the extruded materials enter the calender with the maximum closing pressure applied to the rolls. The same effect is observed for the compatibilized systems with lower values of the viscosity ratio. As a general rule, it has been observed that the final dispersed phase deformation is diminished in interfacially compatibilized systems.

Oxygen barrier properties of biaxially oriented polypropylene/polyvinyl alcohol blend films

“…In other words, the viscosity ratio ðh dðPVAÞ =h mðPPÞ Þ of PP/PVA blend diminished, and the thinner and wider platelets were formed. It was known that the dispersed phase was easily deformed by the induced shear stress from the matrix phase with decreasing the viscosity ratio ðh dispersed phase =h matrix phase Þ [9,11,12,15,16]. In addition, the higher viscosity of matrix PP phase more uniformly transferred the shear stress to a dispersed PVA phase during stretching process.…”

Formation of in situ CB/PET Microfibers in CB/PET/PE Composites by Slit Die Extrusion and Hot Stretching

“…In the available literature, this case has not been reported, though deformation and fibrillation of the dispersed phase in a polymer blend have been widely investigated. [2,[21][22][23][24][25][26][27][28][29][30] In this study, our interest lies in the possibility that in situ microfibrillation of a CB/ PET compound may occur in a PE matrix through slit die extrusion and hot stretching.…”

In‐Situ Fiberized Poly(ethylene terephthalate) as a Reinforcement to Poly(propylene) Matrix

“…[12] Since the droplet size and its dispersity in the extruded melt increases with f w , the number of elongated fibers formed both directly from the virgin droplets and from the coalesced droplets will increase with f w , and the proportion of the latter in the total fiberization also increases with f w . [15,16] This is the main reason why the dispersed phase can fiberize even at low f w (e.g., 5%) and the number of fibers increases continuously with f w (Figure 3). …”