VARYING PHASE CONTINUITY IN POLYMER BLENDS BY SEQUENCE OF MIXING

 

J. Martin1, A. Lele2, S. Velankar1 (email: velankar@pitt.edu)

  1.  Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA 15261
  2.  Polymer Science & Engineering Division, National Chemical Laboratory, Pune-411008, India

 

 

            Immiscible polymers are often blended together in the melt state to obtain a material with a desired set of properties.  The properties of such a blend depend on the properties of the constituents, as well as on the morphology of the multiphase structure; generally the desired properties are achieved only by specific morphologies.  There are several well-established concepts in the literature on small-molecule emulsions which have not percolated into the polymer blend community.  The principle of controlling the morphology of a multiphase system by modifying the sequence of blending is one such example.  In this work, we use systems of both commercially common and model polymers to create unusual morphologies.  By modifying the sequence of blending and exploiting coalescence suppression caused by compatibilizers (polymeric surfactants), we are able to realize droplet-in-droplet (double emulsion) morphologies in our polymer blends.  We show that the presence of the sub-drops increases the blend viscosity through an increase in the effective droplet volume fraction and that the stability of our double emulsion morphologies is dependant upon the stress and type of mixing.