The effect of viscosity ratio on the morphology of polypropylene/polycarbonate blends during processing

Abstract

The size of the minor phase in an immiscible polymer blend can have a significant effect on properties such as the impact strength. Few studies, however, have quantitatively considered the parameters controlling the size of the dispersed phase. In this paper, light and scanning electron microscopy have been used to examine the size of the minor phase in polypropylene/polycarbonate blends after melt processing. The size was examined as a function of both the viscosity ratio (p) and the torque ratio (TR). The viscosity ratio is studied in the regions of p > 1 and p < 1. p has a marked effect on the morphology of the dispersed phase with the phase size increasing by a factor of 3 to 4 times from p = 4.5 to p = 17.3. Reduction in the size of the minor phase was achieved below p = 1 with the minimum particle size occurring at p ≃ 0.15. The results for these systems indicate the presence of upper and lower limits of p beyond which deformation becomes difficult. This is shown to be similar in some respects to the behavior of Newtonian fluids in shear flow, although the upper limit extends beyond that observed in the Newtonian fluid studies.

THERMAL properties and morphology of Polypropylene/Polycarbonate/Polypropylene-Graft-Maleic anhydride blends

“…From earlier researches, one of the prime objectives of blending PP with other polymer was to improve PP's disadvantage which is poor impact strength [7,8]. Blending with PC was attempted to get PP-based material that has considerably good impact strength with sufficient stiffness.…”

Composition effect on the core–shell morphology and mechanical properties of ternary polystyrene/styrene–butadiene rubber/polyethylene blends

“…The present work will focus on three-component blends in which two minor components are dispersed in the major one, such as to form mixed dispersed phases. In this respect, the tendency for one phase to encapsulate a second one can be predicted by the following equation, which is an alternative form of Harkin's equation [1]: λ 31 =γ 12 −γ 32 −γ 13 ,…”

Ternary polymer blend with core–shell dispersed phases: effect of the core-forming polymer on phase morphology and mechanical properties

“…In this respect, the interfacial tensions between the individual phases and their relative viscosities are two predominant factors. In binary blends, the size of the minor phase depends on the interfacial tension and the viscosity (or torque) ratio of the dispersed phase with respect to the matrix [7][8][9]. The interplay of these factors although more complex in ternary blends remains essential for the control of the blend morphology, in which each component, is either separately dispersed, or forms a core-shell structure (one minor component forming shell around small domains of the second one) or an intermediate phase organization [1][2][3][4].…”

“…Clearly, the size of the PO particles increases with the torque of this component measured at 200°C. Favis and Chalifoux have reported on the well-defined dependence of the phase size on the torque ratio for binary polymer blends [7]. Upon decreasing the torque ratio of the minor phase with respect to the major one down to ca.…”