Paper Number
SM50 

Session
Polymer Solutions and Melts

Title
Exploring the effects of compatibilizer on the morphology and interface of polymer blends by means of rheology and dielectric spectroscopy

Presentation Date and Time
October 15, 2015 (Thursday) 10:50

Track / Room
Track 2 / Constellation D

Authors (Click on name to view author profile)

1. Bharati, Avanish (KU Leuven, Department of Chemical Engineering)
2. Cardinaels, Ruth (TU Eindhoven, Department of Mechanical Engineering)
3. Wübbenhorst, Michael (KU Leuven, Department of Physics and Astronomy)
4. Moldenaers, Paula (KU Leuven, Department of Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Avanish Bharati¹, Ruth Cardinaels², Michael Wübbenhorst³, and Paula Moldenaers^1
1Department of Chemical Engineering, KU Leuven, Leuven 3001, Belgium; ²Department of Mechanical Engineering, TU Eindhoven, Eindhoven 513, The Netherlands; ³Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium

Speaker / Presenter 
Bharati, Avanish

Text of Abstract
A bi-phasic PαMSAN/PMMA blend undergoing spinodal decomposition was compatibilized with an interfacially segregated PS-r-PMMA random copolymer. Both the interfacial elasticity as probed by rheology and the interfacial contribution to the dielectric loss were used to study the effect of the copolymer on the interface. The matrix-droplet morphology as a function of coalescence time in a step down experiment in shear rate was characterized by means of small amplitude oscillatory shear. The fact that an interface generates an additional elasticity allows determining the ratio of droplet size (R_v) to interfacial tension (α) using the Palierne model. From the attenuation of the interfacial contribution to the storage modulus and the reduction in interfacial relaxation time it was inferred that compatibilization led to a reduced interfacial tension resulting in morphology refinement. From dielectric spectroscopy, conductivity free dielectric loss spectra revealed blocking of charge carriers at low frequencies owing to the conductivity contrast of the blend components, resulting in a dielectric interfacial peak. The latter is governed by the intrinsic length scale of the system, i.e. the ratio of domain size (D_v) to Debye length (L_D). Addition of compatibilizer caused a substantial increase of the peak intensity of the interfacial polarization. To estimate L_D, the dielectric response of stacked polymer films with interfacially localized copolymer was investigated. The interfacial polarization was significantly suppressed when the thickness of the conducting film approached L_D, on the basis of which L_D could be calculated. Upon compatibilization, an increase of the relaxation strength of the interfacial polarization occurred, which corroborated a pronounced decrease of L_D. In summary, combining the knowledge of rheology and dielectric spectroscopy allows characterization and tuning of bi-phasic morphologies at various length scales.