Influences of the Viscosity Ratio and Processing Conditionson the Formation of Highly Oriented Ribbons in Polymer Blends by TapeExtrusion.

Thedeformation of the dispersed phase in polymer blends by tapeextrusion was studied systematically under different processing conditionsand viscosity ratios of the dispersed phase to the matrix. Duringtape extrusion, the spherical dispersed phases were first elongatedinto rotational ellipsoidal or rodlike shapes and then merged to formlonger and even endless microfibrils by coalescence, which were eventuallysqueezed into highly oriented ribbons. The speed of two running rollershas a large effect on the morphology development of the dispersedphase. With an increase of the roller surface speed, the stretchingand squeezing forces increased dramatically. As a result, the dispersedphase gradually deformed from spherical to ellipsoidal, fibrous, andribbonlike shapes. More interestingly, the tensile strength of theobtained blend film with highly oriented ribbons increased significantlyas well. The viscosity ratio of the dispersed phase to the matrixis another important factor influencing the formation of a highlyoriented polymer blend. It is found that a low viscosity ratio facilitatesthe deformation and coalescence of the dispersed phase to form highlyoriented ribbons. Therefore, in order to prepare a well-controlledpolymer blend with highly oriented ribbons, the combination of a high-viscositymatrix and a low-viscosity dispersed phase is preferred. [ABSTRACT FROM AUTHOR]